Category Archives: Encryption

What Is Encryption? | Surveillance Self-Defense

Encryption is the mathematical science of codes, ciphers, and secret messages. Throughout history, people have used encryption to send messages to each other that (hopefully) couldn’t be read by anyone besides the intended recipient.

Today, we have computers that are capable of performing encryption for us. Digital encryption technology has expanded beyond simple secret messages; today, encryption can be used for more elaborate purposes, for example to verify the author of messages or to browse the Web anonymously with Tor.

Under some circumstances, encryption can be fairly automatic and simple. But there are ways encryption can go wrong, and the more you understand it, the safer you will be against such situations.

One of the most important concepts to understand in encryption is a key. Common types of encryption include a private key, which is kept secret on your computer and lets you read messages that are intended only for you. A private key also lets you place unforgeable digital signatures on messages you send to other people. A public key is a file that you can give to others or publish that allows people to communicate with you in secret, and check signatures from you. Private and public keys come in matched pairs, like the halves of a rock that has been split into two perfectly matching pieces, but they are not the same.

Another extremely valuable concept to understand is a security certificate. The Web browser on your computer can make encrypted connections to sites using HTTPS. When they do that, they examine certificates to check the public keys of domain names(like,, or Certificates are one way of trying to determine if you know the right public key for a person or website, so that you can communicate securely with them.

From time to time, you will see certificate-related error messages on the Web. Most commonly, this is because a hotel or cafe network is trying to break your secret communications with the website. It is also common to see an error because of a bureaucratic mistake in the system of certificates. But occasionally, it is because a hacker, thief, police agency, or spy agency is breaking the encrypted connection.

Unfortunately, it is extremely difficult to tell the difference between these cases. This means you should never click past a certificate warning if it relates to a site where you have an account, or are reading any sensitive information.

The word “fingerprint” means lots of different things in the field of computer security. One use of the term is a “key fingerprint,” a string of characters like “342e 2309 bd20 0912 ff10 6c63 2192 1928” that should allow you to uniquely and securely check that someone on the Internet is using the right private key. If you check that someone’s key fingerprint is correct, that gives you a higher degree of certainty that it’s really them. But it’s not perfect, because if the keys are copied or stolen someone else would be able to use the same fingerprint.

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What Is Encryption? | Surveillance Self-Defense

Comodo Disk Encryption Download –

Comodo Disk Encryption is a reliable application that protects your sensitive data by encrypting your drives using complex algorithms.

It provides you with two different methods of securing your information. Either you encrypt any drive partition that contains personal information using combinations of different hashing and encryption algorithms or simply mount the virtual partitions in your hard drive, then save your data.

Since the encryption process can be carried out with two different authentication types, namely Password and USB Stick, the application helps you to add an extra layer of security, thus protecting your critical data from unauthorized users.

When you launch Comodo Disk Encryption for the first time, you will notice that all your drives are automatically recognized (after a restart has been performed). When you click on a random partition, detailed information such as file system, free space, encryption method and total size are displayed in the bottom pane of the program.

The right-click menu enables you to easily encrypt or decrypt the selected partition, edit the available settings, as well as format it by modifying the file system to NTFS, FAT32 or FAT and the allocation unit size.

By accessing the Encrypt option, you are able to choose one of the available authentication types, then set the properties according to your whims such as hash algorithm and password.

The ‘Virtual Drives’ tab enables you to view all the mounted drives in your system and create, mount, remove or unmount them, as well as edit the encryption settings effortlessly.

In case you want to decrypt a drive, you will just have to choose the proper option from the context menu and bring back the partition to its original form so that the drive becomes accessible for any user.

Overall, Comodo Disk Encryption keeps all your sensitive data protected from hackers, thieves and online scammers by encrypting your hard disks with ease.

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Comodo Disk Encryption Download –

Encryption – Simple English Wikipedia, the free encyclopedia

Encryption allows information to be hidden so that it cannot be read without special knowledge (such as a password). This is done with a secret code or cypher. The hidden information is said to be encrypted.

Decryption is a way to change encrypted information back into plaintext. This is the decrypted form. The study of encryption is called cryptography. Cryptanalysis can be done by hand if the cypher is simple. Complex cyphers need a computer to search for possible keys. Decryption is a field of computer science and mathematics that looks at how difficult it is to break a cypher.

A simple kind of encryption for words is ROT13. In ROT13, letters of the alphabet are changed with each other using a simple pattern. For example, A changes to N, B changes to O, C changes to P, and so on. Each letter is “rotated” by 13 spaces. Using the ROT13 cipher, the words Simple English Wikipedia becomes Fvzcyr Ratyvfu Jvxvcrqvn. The ROT13 cipher is very easy to decrypt. Because there are 26 letters in the English alphabet, if a letter is rotated two times by 13 letters each time, the original letter will be obtained. So applying the ROT13 cipher a second time brings back the original text. When he communicated with his army, Julius Caesar sometimes used what is known as Caesar cipher today. This cipher works by shifting the position of letters: each letter is rotated by 3 positions.

Most kinds of encryption are made more complex so cryptanalysis will be difficult. Some are made only for text. Others are made for binary computer files like pictures and music. Today, many people use the asymmetric encryption system called RSA. Any computer file can be encrypted with RSA. AES is a common symmetric algorithm.

Most types of encryption can theoretically be cracked: an enemy might be able to decrypt a message without knowing the password, if he has clever mathematicians, powerful computers and lots of time. The one-time pad is special because, if it is used correctly, it is impossible to crack. There are three rules that must be followed:

If these three rules are obeyed, then it is impossible to read the secret message without knowing the secret key. For this reason, during the Cold War, embassies and large military units often used one-time pads to communicate secretly with their governments. They had little books (“pads”) filled with random letters or random numbers. Each page from the pad could only be used once: this is why it is called a “one-time pad”.

Encryption is often used on the Internet, as many web sites use it to protect private information. On the Internet, several encryption protocols are used, such as Secure Sockets Layer (SSL), IPsec, and SSH. They use the RSA encryption system and others. The protocol for protected web browsing is called HTTPS. URL encryption mostly uses the MD5 Algorithm. Various algorithms are used in the internet market depending upon the need.

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Encryption – Simple English Wikipedia, the free encyclopedia

BitLocker Drive Encryption Overview –

BitLocker Drive Encryption is a data protection feature available Windows Server2008R2 and in some editions of Windows7. Having BitLocker integrated with the operating system addresses the threats of data theft or exposure from lost, stolen, or inappropriately decommissioned computers.

Data on a lost or stolen computer is vulnerable to unauthorized access, either by running a software-attack tool against it or by transferring the computer’s hard disk to a different computer. BitLocker helps mitigate unauthorized data access by enhancing file and system protections. BitLocker also helps render data inaccessible when BitLocker-protected computers are decommissioned or recycled.

BitLocker provides the most protection when used with a Trusted Platform Module (TPM) version1.2. The TPM is a hardware component installed in many newer computers by the computer manufacturers. It works with BitLocker to help protect user data and to ensure that a computer has not been tampered with while the system was offline.

On computers that do not have a TPM version1.2, you can still use BitLocker to encrypt the Windows operating system drive. However, this implementation will require the user to insert a USB startup key to start the computer or resume from hibernation, and it does not provide the pre-startup system integrity verification offered by BitLocker with a TPM.

In addition to the TPM, BitLocker offers the option to lock the normal startup process until the user supplies a personal identification number (PIN) or inserts a removable device, such as a USB flash drive, that contains a startup key. These additional security measures provide multifactor authentication and assurance that the computer will not start or resume from hibernation until the correct PIN or startup key is presented.

BitLocker can use a TPM to verify the integrity of early boot components and boot configuration data. This helps ensure that BitLocker makes the encrypted drive accessible only if those components have not been tampered with and the encrypted drive is located in the original computer.

BitLocker helps ensure the integrity of the startup process by taking the following actions:

To use BitLocker, a computer must satisfy certain requirements:

BitLocker is installed automatically as part of the operating system installation. However, BitLocker is not enabled until it is turned on by using the BitLocker setup wizard, which can be accessed from either the Control Panel or by right-clicking the drive in Windows Explorer.

At any time after installation and initial operating system setup, the system administrator can use the BitLocker setup wizard to initialize BitLocker. There are two steps in the initialization process:

When a local administrator initializes BitLocker, the administrator should also create a recovery password or a recovery key. Without a recovery key or recovery password, all data on the encrypted drive may be inaccessible and unrecoverable if there is a problem with the BitLocker-protected drive.

For detailed information about configuring and deploying BitLocker, see the Windows BitLocker Drive Encryption Step-by-Step Guide (

BitLocker can use an enterprise’s existing Active Directory Domain Services (ADDS) infrastructure to remotely store recovery keys. BitLocker provides a wizard for setup and management, as well as extensibility and manageability through a Windows Management Instrumentation (WMI) interface with scripting support. BitLocker also has a recovery console integrated into the early boot process to enable the user or helpdesk personnel to regain access to a locked computer.

For more information about writing scripts for BitLocker, see Win32_EncryptableVolume (

Many personal computers today are reused by people other than the computer’s initial owner or user. In enterprise scenarios, computers may be redeployed to other departments, or they might be recycled as part of a standard computer hardware refresh cycle.

On unencrypted drives, data may remain readable even after the drive has been formatted. Enterprises often make use of multiple overwrites or physical destruction to reduce the risk of exposing data on decommissioned drives.

BitLocker can help create a simple, cost-effective decommissioning process. By leaving data encrypted by BitLocker and then removing the keys, an enterprise can permanently reduce the risk of exposing this data. It becomes nearly impossible to access BitLocker-encrypted data after removing all BitLocker keys because this would require cracking 128-bit or 256-bit AES encryption.

BitLocker cannot protect a computer against all possible attacks. For example, if malicious users, or programs such as viruses or rootkits, have access to the computer before it is lost or stolen, they might be able to introduce weaknesses through which they can later access encrypted data. And BitLocker protection can be compromised if the USB startup key is left in the computer, or if the PIN or Windows logon password are not kept secret.

The TPM-only authentication mode is easiest to deploy, manage, and use. It might also be more appropriate for computers that are unattended or must restart while unattended. However, the TPM-only mode offers the least amount of data protection. If parts of your organization have data that is considered highly sensitive on mobile computers, consider deploying BitLocker with multifactor authentication on those computers.

For more information about BitLocker security considerations, see Data Encryption Toolkit for Mobile PCs (

For servers in a shared or potentially non-secure environment, such as a branch office location, BitLocker can be used to encrypt the operating system drive and additional data drives on the same server.

By default, BitLocker is not installed with Windows Server2008R2. Add BitLocker from the Windows Server2008R2 Server Manager page. You must restart after installing BitLocker on a server. Using WMI, you can enable BitLocker remotely.

BitLocker is supported on Extensible Firmware Interface (EFI) servers that use a 64-bit processor architecture.

After the drive has been encrypted and protected with BitLocker, local and domain administrators can use the Manage BitLocker page in the BitLocker Drive Encryption item in Control Panel to change the password to unlock the drive, remove the password from the drive, add a smart card to unlock the drive, save or print the recovery key again, automatically unlock the drive, duplicate keys, and reset the PIN.

An administrator may want to temporarily disable BitLocker in certain scenarios, such as:

These scenarios are collectively referred to as the computer upgrade scenario. BitLocker can be enabled or disabled through the BitLocker Drive Encryption item in Control Panel.

The following steps are necessary to upgrade a BitLocker-protected computer:

Forcing BitLocker into disabled mode will keep the drive encrypted, but the drive master key will be encrypted with a symmetric key stored unencrypted on the hard disk. The availability of this unencrypted key disables the data protection offered by BitLocker but ensures that subsequent computer startups succeed without further user input. When BitLocker is enabled again, the unencrypted key is removed from the disk and BitLocker protection is turned back on. Additionally, the drive master key is keyed and encrypted again.

Moving the encrypted drive (that is, the physical disk) to another BitLocker-protected computer does not require any additional steps because the key protecting the drive master key is stored unencrypted on the disk.

For detailed information about disabling BitLocker, see Windows BitLocker Drive Encryption Step-by-Step Guide (

A number of scenarios can trigger a recovery process, for example:

An administrator can also trigger recovery as an access control mechanism (for example, during computer redeployment). An administrator may decide to lock an encrypted drive and require that users obtain BitLocker recovery information to unlock the drive.

Using Group Policy, an IT administrator can choose which recovery methods to require, deny, or make optional for users who enable BitLocker. The recovery password can be stored in ADDS, and the administrator can make this option mandatory, prohibited, or optional for each user of the computer. Additionally, the recovery data can be stored on a USB flash drive.

The recovery password is a 48-digit, randomly generated number that can be created during BitLocker setup. If the computer enters recovery mode, the user will be prompted to type this password by using the function keys (F0 through F9). The recovery password can be managed and copied after BitLocker is enabled. Using the Manage BitLocker page in the BitLocker Drive Encryption item in Control Panel, the recovery password can be printed or saved to a file for future use.

A domain administrator can configure Group Policy to generate recovery passwords automatically and back them up to ADDS as soon as BitLocker is enabled. The domain administrator can also choose to prevent BitLocker from encrypting a drive unless the computer is connected to the network and ADDS backup of the recovery password is successful.

The recovery key can be created and saved to a USB flash drive during BitLocker setup; it can also be managed and copied after BitLocker is enabled. If the computer enters recovery mode, the user will be prompted to insert the recovery key into the computer.

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BitLocker Drive Encryption Overview –

The Encrypting File System –

By Roberta Bragg

An Overview of the Encrypting File SystemWhat EFS IsBasic How-tosPlanning for and Recovering Encrypted Files: Recovery PolicyHow EFS WorksKey Differences Between EFS on Windows 2000, Windows XP, and Windows Server 2003Misuse and Abuse of EFS and How to Avoid Data Loss or ExposureRemote Storage of Encrypted Files Using SMB File Shares and WebDAVBest Practices for SOHO and Small BusinessesEnterprise How-tosTroubleshootingRadical EFS: Using EFS to Encrypt Databases and Using EFS with Other Microsoft ProductsDisaster RecoveryOverviews and Larger ArticlesSummary

The Encrypting File System (EFS) is a component of the NTFS file system on Windows 2000, Windows XP Professional, and Windows Server 2003. (Windows XP Home doesn’t include EFS.) EFS enables transparent encryption and decryption of files by using advanced, standard cryptographic algorithms. Any individual or program that doesn’t possess the appropriate cryptographic key cannot read the encrypted data. Encrypted files can be protected even from those who gain physical possession of the computer that the files reside on. Even persons who are authorized to access the computer and its file system cannot view the data. While other defensive strategies should be used, and encryption isn’t the correct countermeasure for every threat, encryption is a powerful addition to any defensive strategy. EFS is the built-in file encryption tool for Windows file systems.

However, every defensive weapon, if used incorrectly, carries the potential for harm. EFS must be understood, implemented appropriately, and managed effectively to ensure that your experience, the experience of those to whom you provide support, and the data you wish to protect aren’t harmed. This document will

Provide an overview and pointers to resources on EFS.

Point to implementation strategies and best practices.

Name the dangers and counsel mitigation and prevention from harm.

Many online and published resources on EFS exist. The major sources of information are the Microsoft resource kits, product documentation, white papers, and Knowledge Base articles. This paper provides a brief overview of major EFS issues. Wherever possible, it doesn’t rework existing documentation; rather, it provides links to the best resources. In short, it maps the list of desired knowledge and instruction to the actual documents where they can be found. In addition, the paper catalogs the key elements of large documents so that you’ll be able to find the information you need without having to work your way through hundreds of pages of information each time you have a new question.

The paper discusses the following key EFS knowledge areas:

What EFS is

Basic how-tos, such as how to encrypt and decrypt files, recover encrypted files, archive keys, manage certificates, and back up files, and how to disable EFS

How EFS works and EFS architecture and algorithms

Key differences between EFS on Windows 2000, Windows XP, and Windows Server 2003

Misuse and abuse of EFS and how to avoid data loss or exposure

Remote storage of encrypted files using SMB file shares and WebDAV

Best practices for SOHO and small businesses

Enterprise how-tos: how to implement data recovery strategies with PKI and how to implement key recovery with PKI


Radical EFS: using EFS to encrypt databases and using EFS with other Microsoft products

Disaster recovery

Where to download EFS-specific tools

Using EFS requires only a few simple bits of knowledge. However, using EFS without knowledge of best practices and without understanding recovery processes can give you a mistaken sense of security, as your files might not be encrypted when you think they are, or you might enable unauthorized access by having a weak password or having made the password available to others. It might also result in a loss of data, if proper recovery steps aren’t taken. Therefore, before using EFS you should read the information links in the section “Misuse and Abuse of EFS and How to Avoid Data Loss or Exposure.” The knowledge in this section warns you where lack of proper recovery operations or misunderstanding can cause your data to be unnecessarily exposed. To implement a secure and recoverable EFS policy, you should have a more comprehensive understanding of EFS.

You can use EFS to encrypt files stored in the file system of Windows 2000, Windows XP Professional, and Windows Server 2003 computers. EFS isn’t designed to protect data while it’s transferred from one system to another. EFS uses symmetric (one key is used to encrypt the files) and asymmetric (two keys are used to protect the encryption key) cryptography. An excellent primer on cryptography is available in the Windows 2000 Resource Kit as is an introduction to Certificate Services. Understanding both of these topics will assist you in understanding EFS.

A solid overview of EFS and a comprehensive collection of information on EFS in Windows 2000 are published in the Distributed Systems Guide of the Windows 2000 Server Resource Kit. This information, most of which resides in Chapter 15 of that guide, is published online at (On this site’s page, use the TOC to go to the Distributed Systems Guide, Distributed Security, Encrypting File System.)

There are differences between EFS in Windows 2000, Windows XP Professional, and Windows Server 2003. The Windows XP Professional Resource Kit explains the differences between Windows 2000 and Windows XP Professionals implementation of EFS, and the document “Encrypting File System in Windows XP and Windows Server 2003” ( details Windows XP and Windows Server 2003 modifications. The section below, “Key Differences between EFS on Windows 2000, Windows XP, and Windows Server 2003,” summarizes these differences.

The following are important basic facts about EFS:

EFS encryption doesn’t occur at the application level but rather at the file-system level; therefore, the encryption and decryption process is transparent to the user and to the application. If a folder is marked for encryption, every file created in or moved to the folder will be encrypted. Applications don’t have to understand EFS or manage EFS-encrypted files any differently than unencrypted files. If a user attempts to open a file and possesses the key to do so, the file opens without additional effort on the user’s part. If the user doesn’t possess the key, they receive an “Access denied” error message.

File encryption uses a symmetric key, which is then itself encrypted with the public key of a public key encryption pair. The related private key must be available in order for the file to be decrypted. This key pair is bound to a user identity and made available to the user who has possession of the user ID and password. If the private key is damaged or missing, even the user that encrypted the file cannot decrypt it. If a recovery agent exists, then the file may be recoverable. If key archival has been implemented, then the key may be recovered, and the file decrypted. If not, the file may be lost. EFS is an excellent file encryption systemthere is no “back door.”

File encryption keys can be archived (e.g. exported to a floppy disk) and kept in a safe place to ensure recovery should keys become damaged.

EFS keys are protected by the user’s password. Any user who can obtain the user ID and password can log on as that user and decrypt that user’s files. Therefore, a strong password policy as well as strong user education must be a component of each organization’s security practices to ensure the protection of EFS-encrypted files.

EFS-encrypted files don’t remain encrypted during transport if saved to or opened from a folder on a remote server. The file is decrypted, traverses the network in plaintext, and, if saved to a folder on the local drive that’s marked for encryption, is encrypted locally. EFS-encrypted files can remain encrypted while traversing the network if they’re being saved to a Web folder using WebDAV. This method of remote storage isn’t available for Windows 2000.

EFS uses FIPS 140-evaluated Microsoft Cryptographic Service Providers (CSPcomponents which contain encryption algorithms for Microsoft products).

EFS functionality is straightforward, and you can find step-by-step instructions in many documents online. Links to specific articles for each possible EFS function, as well as some documents which summarize multiple functionality, follow. If the document is a Knowledge Base article, the Knowledge Base number appears in parentheses after the article title.

Encrypting and Decrypting

The process of encrypting and decrypting files is very straightforward, but its important to decide what to encrypt and to note differences in EFS based on the operating system.

Sharing Encrypted Files

The GUI for sharing encrypted files is available only in Windows XP and Windows Server 2003.

A recovery policy can be an organization’s security policy instituted to plan for proper recovery of encrypted files. It’s also the policy enforced by Local Security Policy Public Key Policy or Group Policy Public Key Policy. In the latter, the recovery policy specifies how encrypted files may be recovered should the user private key be damaged or lost and the encrypted file unharmed. Recovery certificate(s) are specified in the policy. Recovery can be either data recovery (Windows 2000, Windows XP Professional, and Windows Server 2003) or key recovery (Windows Server 2003 with Certificate Services). Windows 2000 EFS requires the presence of a recovery agent (no recovery agent, no file encryption), but Windows XP and Windows Server 2003 don’t. By default, Windows 2000 and Windows Server 2003 have default recovery agents assigned. Windows XP Professional doesn’t.

The data recovery process is simple. The user account bound to the recovery agent certificate is used to decrypt the file. The file should then be delivered in a secure manner to the file owner, who may then encrypt the file. Recovery via automatically archived keys is available only with Windows Server 2003 Certificate Services. Additional configuration beyond the installation of Certificate Services is required. In either case, it’s most important that a written policy and procedures for recovery are in place. These procedures, if well written and if followed, can ensure that recovery keys and agents are available for use and that recovery is securely carried out. Keep in mind that there are two definitions for “recovery policy.” The first definition refers to a written recovery policy and procedures that describe the who, what, where, and when of recovery, as well as what steps should be taken to ensure recovery components are available. The second definition, which is often referred to in the documents below, is the Public Key Policy that’s part of the Local Security Policy on stand-alone systems, or Group Policy in a domain. It can specify which certificates are used for recovery, as well as other aspects of Public Key Policies in the domain. You can find more information in the following documents:

Disabling or Preventing Encryption

You may decide that you don’t wish users to have the ability to encrypt files. By default, they do. You may decide that specific folders shouldn’t contain encrypted files. You may also decide to disable EFS until you can implement a sound EFS policy and train users in proper procedures. There are different ways of disabling EFS depending on the operating system and the desired effect:

System folders cannot be marked for encryption. EFS keys aren’t available during the boot process; thus, if system files were encrypted, the system file couldn’t boot. To prevent other folders being marked for encryption, you can mark them as system folders. If this isn’t possible, then a method to prevent encryption within a folder is defined in “Encrypting File System.”

NT 4.0 doesn’t have the ability to use EFS. If you need to disable EFS for Windows 2000 computers joined to a Windows NT 4.0 domain, see “Need to Turn Off EFS on a Windows 2000-Based Computer in Windows NT 4.0-Based Domain” (288579). The registry key mentioned can also be used to disable EFS in Window XP Professional and Windows Server 2003.

Disabling EFS for Windows XP Professional can also be done by clearing the checkbox for the property page of the Local Security Policy Public Key Policy. EFS can be disabled in XP and Windows Server 2003 computers joined in a Windows Server 2003 domain by clearing the checkbox for the property pages of the domain or organizational unit (OU) Group Policy Public Key Policy.

“HOW TO: Disable/Enable EFS on a Stand-Alone Windows 2000-Based Computer” (243035) details how to save the recovery agent’s certificate and keys when disabling EFS so that you can enable EFS at a future date.

“HOW TO: Disable EFS for All Computers in a Windows 2000-Based Domain” (222022) provides the best instruction set and clearly defines the difference between deleted domain policy (an OU-based policy or Local Security Policy can exist) versus Initialize Empty Policy (no Windows 2000 EFS encryption is possible throughout the domain).

Special Operations

Let enough people look at anything, and you’ll find there are questions that are just not answered by existing documentation or options. A number of these issues, third-party considerations, and post introduction issues can be resolved by reviewing the following articles.

Specifications for the use of a third-party Certification Authority (CA) can be found at “Third-Party Certification Authority Support for Encrypting File System” (273856). If you wish to use third-party CA certificates for EFS, you should also investigate certificate revocation processing. Windows 2000 EFS certificates aren’t checked for revocation. Windows XP and Windows Server 2003 EFS certificates are checked for revocation in some cases, and third-party certificates may be rejected. Information about certificate revocation handling in EFS can be found in the white paper “Encrypting File System in Windows XP and Windows Server 2003”.

When an existing plaintext file is marked for encryption, it’s first copied to a temporary file. When the process is complete, the temporary file is marked for deletion, which means portions of the original file may remain on the disk and could potentially be accessible via a disk editor. These bits of data, referred to as data shreds or remanence, may be permanently removed by using a revised version of the cipher.exe tool. The tool is part of Service Pack 3 (SP3) for Windows 2000 and is included in Windows Server 2003. Instructions for using the tool, along with the location of a downloadable version, can be found in “HOW TO: Use Cipher.exe to Overwrite Deleted Data in Windows” (315672) and in “Cipher.exe Security Tool for the Encrypting File System” (298009).

How to make encrypted files display in green in Windows Explorer is explained in “HOW TO: Identify Encrypted Files in Windows XP” (320166).

“How to Enable the Encryption Command on the Shortcut Menu” (241121) provides a registry key to modify for this purpose.

You may wish to protect printer spool files or hard copies of encrypted files while they’re printing. Encryption is transparent to the printing process. If you have the right (possess the key) to decrypt the file and a method exists for printing files, the file will print. However, two issues should concern you. First, if the file is sensitive enough to encrypt, how will you protect the printed copy? Second, the spool file resides in the system32SpoolPrinters folder. How can you protect it while its there? You could encrypt that folder, but that would slow printing enormously. The Windows 2000 Resource Kit proposes a separate printer for the printing of these files and how to best secure that printer in the Distributed Systems, Distributed Security, Encrypting Files System, Printing EFS Files section.

To understand EFS, and therefore anticipate problems, envision potential attacks, and troubleshoot and protect EFS-encrypted files, you should understand the architecture of EFS and the basic encryption, decryption, and recovery algorithms. Much of this information is in the Windows 2000 Resource Kit Distributed Systems Guide, the Windows XP Professional Resource Kit, and the white paper, “Encrypting File System in Windows XP and Windows Server 2003.” Many of the algorithms are also described in product documentation. The examples that follow are from the Windows XP Professional Resource Kit:

A straightforward discussion of the components of EFS, including the EFS service, EFS driver, and the File System Run Time Library, is found in “Components of EFS,” a subsection of Chapter 17, “Encrypting File System” in the Windows XP Professional Resource Kit.

A description of the encryption, decryption, and recovery algorithms EFS uses is in the Resource Kit section “How Files Are Encrypted.” This section includes a discussion of the file encryption keys (FEKs) and file Data Recovery Fields and Data Decryption Fields used to hold FEKs encrypted by user and recovery agent public keys.

“Working with Encryption” includes how-to steps that define the effect of decisions made about changing the encryption properties of folders. The table defines what happens for each file (present, added later, or copied to the folder) for the choice “This folder only” or the option “This folder, subfolders and files.”

“Remote EFS Operations on File Shares and Web Folders” defines what happens to encrypted files and how to enable remote storage.

EFS was introduced in Windows 2000. However, there are differences when compared with Windows XP Professional EFS and Windows Server 2003 EFS, including the following:

You can authorize additional users to access encrypted files (see the section “Sharing Encrypted Files”, above). In Windows 2000, you can implement a programmatic solution for the sharing of encrypted files; however, no interface is available. Windows XP and Windows Server 2003 have this interface.

Offline files can be encrypted. See “HOW TO: Encrypt Offline Files to Secure Data in Windows XP.”

Data recovery agents are recommended but optional. XP doesn’t automatically include a default recovery agent. XP will take advantage of an existing Windows 2000 domain-level recovery agent if one is present, but the lack of a domain recovery agent wont prevent encryption of files on an XP system. A self-signed recovery agent certificate can be requested by using the cipher /R:filename command, where filename is the name that will be used to create a *.cer file to hold the certificate and a *.pfx file to hold the certificate and private key.

The Triple DES (3DES) encryption algorithm can be used to replace Data Encryption Standard X (DESX), and after XP SP1, Advanced Encryption Standard (AES) becomes the default encryption algorithm for EFS.

For Windows XP and Windows Server 2003 local accounts, a password reset disk can be used to safely reset a user’s password. (Domain passwords cannot be reset using the disk.) If an administrator uses the “reset password” option from the user’s account in the Computer Management console users container, EFS files won’t be accessible. If users change the password back to the previous password, they can regain access to encrypted files. To create a password reset disk and for instructions about how to use a password reset disk, see product documentation and/or the article “HOW TO: Create and Use a Password Reset Disk for a Computer That Is Not a Domain Member in Windows XP” (305478).

Encrypted files can be stored in Web folders. The Windows XP Professional Resource Kit section “Remote EFS Operations in a Web Folder Environment” explains how.

Windows Server 2003 incorporates the changes introduced in Windows XP Professional and adds the following:

A default domain Public Key recovery policy is created, and a recovery agent certificate is issued to the Administrator account.

Certificate Services include the ability for customization of certificate templates and key archival. With appropriate configuration, archival of user EFS keys can be instituted and recovery of EFS-encrypted files can be accomplished by recovering the user’s encryption keys instead of decrypting via a file recovery agent. A walk-through providing a step-by-step configuration of Certificate Services for key archival is available in “Certificate Services Example Implementation: Key Archival and Recovery.”

Windows Server 2003 enables users to back up their EFS key(s) directly from the command line and from the details property page by clicking a “Backup Keys” button.

Unauthorized persons may attempt to obtain the information encrypted by EFS. Sensitive data may also be inadvertently exposed. Two possible causes of data loss or exposure are misuse (improper use of EFS) or abuse (attacks mounted against EFS-encrypted files or systems where EFS-encrypted files exist).

Inadvertent Problems Due to Misuse

Several issues can cause problems when using EFS. First, when improperly used, sensitive files may be inadvertently exposed. In many cases this is due to improper or weak security policies and a failure to understand EFS. The problem is made all the worse because users think their data is secure and thus may not follow usual precautionary methods. This can occur in several scenarios:

If, for example, users copy encrypted files to FAT volumes, the files will be decrypted and thus no longer protected. Because the user has the right to decrypt files that they encrypted, the file is decrypted and stored in plaintext on the FAT volume. Windows 2000 gives no warning when this happens, but Windows XP and Windows Server 2003 do provide a warning.

If users provide others with their passwords, these people can log on using these credentials and decrypt the user’s encrypted files. (Once a user has successfully logged on, they can decrypt any files the user account has the right to decrypt.)

If the recovery agent’s private key isn’t archived and removed from the recovery agent profile, any user who knows the recovery agent credentials can log on and transparently decrypt any encrypted files.

By far, the most frequent problem with EFS occurs when EFS encryption keys and/or recovery keys aren’t archived. If keys aren’t backed up, they cannot be replaced when lost. If keys cannot be used or replaced, data can be lost. If Windows is reinstalled (perhaps as the result of a disk crash) the keys are destroyed. If a user’s profile is damaged, then keys are destroyed. In these, or in any other cases in which keys are damaged or lost and backup keys are unavailable, then encrypted files cannot be decrypted. The encryption keys are bound to the user account, and a new iteration of the operating system means new user accounts. A new user profile means new user keys. If keys are archived, or exported, they can be imported to a new account. If a revocation agent for the files exists, then that account can be used to recover the files. However, in many cases in which keys are destroyed, both user and revocation keys are absent and there is no backup, resulting in lost data.

Additionally, many other smaller things may render encrypted files unusable or expose some sensitive data, such as the following:

Finally, keeping data secure takes more than simply encrypting files. A systems-wide approach to security is necessary. You can find several articles that address best practices for systems security on the TechNet Best Practices page at The articles include

Attacks and Countermeasures: Additional Protection Mechanisms for Encrypted Files

Any user of encrypted files should recognize potential weaknesses and avenues of attack. Just as its not enough to lock the front door of a house without considering back doors and windows as avenues for a burglar, encrypting files alone isn’t enough to ensure confidentiality.

Use defense in depth and use file permissions. The use of EFS doesn’t obviate the need to use file permissions to limit access to files. File permissions should be used in addition to EFS. If users have obtained encryption keys, they can import them to their account and decrypt files. However, if the user accounts are denied access to the file, the users will be foiled in their attempts to gain this sensitive information.

Use file permissions to deny delete. Encrypted files can be deleted. If attackers cannot decrypt the file, they may choose to simply delete it. While they don’t have the sensitive information, you don’t have your file.

Protect user credentials. If an attacker can discover the identity and password of a user who can decrypt a file, the attacker can log on as that user and view the files. Protecting these credentials is paramount. A strong password policy, user training on devising strong passwords, and best practices on protecting these credentials will assist in preventing this type of attack. An excellent best practices approach to password policy can be found in the Windows Server 2003 product documentation. If account passwords are compromised, anyone can log on using the user ID and password. Once user have successfully logged on, they can decrypt any files the user account has the right to decrypt. The best defense is a strong password policy, user education, and the use of sound security practices.

Protect recovery agent credentials. Similarly, if an attacker can log on as a recovery agent, and the recovery agent private key hasn’t been removed, the attacker can read the files. Best practices dictate the removal of the recovery agent keys, the restriction of this account’s usage to recovery work only, and the careful protection of credentials, among other recovery policies. The sections about recovery and best practices detail these steps.

Seek out and manage areas where plaintext copies of the encrypted files or parts of the encrypted files may exist. If attackers have possession of, or access to, the computer on which encrypted files reside, they may be able to recover sensitive data from these areas, including the following:

Data shreds (remanence) that exist after encrypting a previously unencrypted file (see the “Special Operations” section of this paper for information about using cipher.exe to remove them)

The paging file (see “Increasing Security for Open Encrypted Files,” an article in the Windows XP Professional Resource Kit, for instructions and additional information about how to clear the paging file on shutdown)

Hibernation files (see “Increasing Security for Open Encrypted Files” at

Temporary files (to determine where applications store temporary files and encrypt these folders as well to resolve this issue

Printer spool files (see the “Special Operations” section)

Provide additional protection by using the System Key. Using Syskey provides additional protection for password values and values protected in the Local Security Authority (LSA) Secrets (such as the master key used to protect user’s cryptographic keys). Read the article “Using the System Key” in the Windows 2000 Resource Kit’s Encrypting File System chapter. A discussion of the use of Syskey, and possible attacks against a Syskey-protected Windows 2000 computer and countermeasures, can be found in the article “Analysis of Alleged Vulnerability in Windows 2000 Syskey and the Encrypting File System.”

If your policy is to require that data is stored on file servers, not on desktop systems, you will need to choose a strategy for doing so. Two possibilities existeither storage in normal shared folders on file servers or the use of web folders. Both methods require configuration, and you should understand their benefits and risks.

If encrypted files are going to be stored on a remote server, the server must be configured to do so, and an alternative method, such as IP Security (IPSec) or Secure Sockets Layer (SSL), should be used to protect the files during transport. Instructions for configuring the server are discussed in “Recovery of Encrypted Files on a Server” (283223) and “HOW TO: Encrypt Files and Folders on a Remote Windows 2000 Server” (320044). However, the latter doesn’t mention a critical step, which is that the remote server must be trusted for delegation in Active Directory. Quite a number of articles can be found, in fact, that leave out this step. If the server isn’t trusted for delegation in Active Directory, and a user attempts to save the file to the remote server, an “Access Denied” error message will be the result.

If you need to store encrypted files on a remote server in plaintext (local copies are kept encrypted), you can. The server must, however, be configured to make this happen. You should also realize that once the server is so configured, no encrypted files can be stored on it. See the article “HOW TO: Prevent Files from Being Encrypted When Copied to a Server” (302093).

You can store encrypted files in Web folders when using Windows XP or Windows Server 2003. The Windows XP Professional Resource Kit section “Remote EFS Operations in a Web Folder Environment” explains how.

If your Web applications need to require authentication to access EFS files stored in a Web folder, the code for using a Web folder to store EFS files and require authentication to access them is detailed in “HOW TO: Use Encrypting File System (EFS) with Internet Information Services” (243756).

Once you know the facts about EFS and have decided how you are going to use it, you should use these documents as a checklist to determine that you have designed the best solution.

By default, EFS certificates are self-signed; that is, they don’t need to obtain certificates from a CA. When a user first encrypts a file, EFS looks for the existence of an EFS certificate. If one isn’t found, it looks for the existence of a Microsoft Enterprise CA in the domain. If a CA is found, a certificate is requested from the CA; if it isn’t, a self-signed certificate is created and used. However, more granular control of EFS, including EFS certificates and EFS recovery, can be established if a CA is present. You can use Windows 2000 or Windows Server 2003 Certificate Services. The following articles explain how.

Troubleshooting EFS is easier if you understand how EFS works. There are also well known causes for many of the common problems that arise. Here are a few common problems and their solutions:

You changed your user ID and password and can no longer decrypt your files. There are two possible approaches to this problem, depending on what you did. First, if the user account was simply renamed and the password reset, the problem may be that you’re using XP and this response is expected. When an administrator resets an XP user’s account password, the account’s association with the EFS certificate and keys is removed. Changing the password to the previous password can reestablish your ability to decrypt your files. For more information, see “User Cannot Gain Access to EFS Encrypted Files After Password Change or When Using a Roaming Profile” (331333), which explains how XP Professional encrypted files cannot be decrypted, even by the original account, if an administrator has changed the password. Second, if you truly have a completely different account (your account was damaged or accidentally deleted), then you must either import your keys (if you’ve exported them) or ask an administrator to use recovery agent keys (if implemented) to recover the files. Restoring keys is detailed in “HOW TO: Restore an Encrypting File System Private Key for Encrypted Data Recovery in Windows 2000” (242296). How to use a recovery agent to recover files is covered in “Five-Minute Security AdvisorRecovering Encrypted Data Using EFS.”

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The Encrypting File System –

FBI cant break the encryption on Texas shooters smartphone

Getty Images | Peter Dazeley

The Federal Bureau of Investigation has not been able to break the encryption on the phone owned by a gunman who killed 26 people in a Texas church on Sunday.

“We are unable to get into that phone,” FBI Special Agent Christopher Combs said in a press conference yesterday (see video).

Combs declined to say what kind of phone was used by gunman Devin Kelley, who killed himself after the mass shooting.”I’m not going to describe what phone it is because I don’t want to tell every bad guy out there what phone to buy, to harass our efforts on trying to find justice here,” Combs said.

The phone is an iPhone,The Washington Post reported today:

After the FBI said it was dealing with a phone it couldnt open, Apple reached out to the bureau to learn if the phone was an iPhone and if the FBI was seeking assistance. Late Tuesday an FBI official responded, saying it was an iPhone but the agency was not asking anything of the company at this point. Thats because experts at the FBIs lab in Quantico, Va., are trying to determine if there are other methods to access the phones data, such as through cloud storage backups or linked laptops, these people said.

The US government has been calling on phone makers to weaken their devices’ security, but companies have refused to do so.Last year, Apple refused to help the government unlock and decrypt the San Bernardino gunman’s iPhone, but the FBI ended up paying hackers for a vulnerability that it used to access data on the device.

Deliberately weakening the security of consumer devices would help criminals target innocent people who rely on encryption to ensure their digital safety, Apple and others have said.

“With the advance of the technology in the phones and the encryptions, law enforcement, whether it’s at the state, local, or the federal level, is increasingly not able to get into these phones,” Combs said yesterday.

Combs said he has no idea how long it will take before the FBI can break the encryption.”I can assure you we are working very hard to get into the phone, and that will continue until we find an answer,” he said. The FBI is also examining “other digital media” related to the gunman, he said.

There are currently “thousands of seized devices sit[ting] in storage, impervious to search warrants,” Deputy Attorney General Rod Rosenstein said last month.

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FBI cant break the encryption on Texas shooters smartphone

DOJ: Strong encryption that we dont have access to is …

Enlarge / US Deputy Attorney General Rod Rosenstein delivers remarks at the 65th Annual Attorney General’s Awards Ceremony at the Daughters of the American Revolution Constitution Hall October 25, 2017 in Washington, DC.

Just two days after the FBI said it could not get into the Sutherland Springs shooter’s seized iPhone, Politico Pro published a lengthy interview with a top Department of Justice official who has become the “governments unexpected encryption warrior.”

According to the interview, which was summarized and published in transcript form on Thursday for subscribers of the website, Deputy Attorney General Rod Rosenstein indicated that the showdown between the DOJ and Silicon Valley is quietly intensifying.

“We have an ongoing dialogue with a lot of tech companies in a variety of different areas,” he told Politico Pro. “There’s some areas where they are cooperative with us. But on this particular issue of encryption, the tech companies are moving in the opposite direction. They’re moving in favor of more and more warrant-proof encryption.”

While the battle against encryption has been going on within federal law enforcement circles since at least the early 1990s, Rosenstein has been the most outspoken DOJ official on this issue in recent months.

The DOJ’s number two has given multiple public speeches in which he has called for “responsible encryption.” The interview with Politico Pro represents the clearest articulation of the DOJs position on this issue, and it suggests that a redux of the 2016 FBI v. Apple showdown is inevitable in the near future.

“I want our prosecutors to know that, if there’s a case where they believe they have an appropriate need for information and there is a legal avenue to get it, they should not be reluctant to pursue it,” Rosenstein said. “I wouldn’t say we’re searching for a case. I’d say were receptive, if a case arises, that we would litigate.”

What Rosenstein didn’t note, however, is that the DOJ and its related agencies, including the FBI, are not taking encryption lying down.

The FBI maintains an office, known as the National Domestic Communications Assistance Center(NDCAC), which actively provides technical assistance to local law enforcement in high profile cases.

In its most recently published minutes from May 2017, the NDCAC said that one of its goals is to make such commercial tools, like Cellebrite’s services, “more widely available” to state and local law enforcement. Earlier this year, the NDCAC provided money to Miami authorities to pay Cellebrite to successfully get into a seized iPhone in a local sextortion case.

In the interview, Rosenstein also said he “favors strong encryption.”

“I favor strong encryption, because the stronger the encryption, the more secure data is against criminals who are trying to commit fraud,” he explained. “And I’m in favor of that, because that means less business for us prosecuting cases of people who have stolen data and hacked into computer networks and done all sorts of damage. So I’m in favor of strong encryption.”

“This is, obviously, a related issue, but it’s distinct, which is, what about cases where people are using electronic media to commit crimes? Having access to those devices is going to be critical to have evidence that we can present in court to prove the crime. I understand why some people merge the issues. I understand that they’re related. But I think logically, we have to look at these differently. People want to secure their houses, but they still need to get in and out. Same issue here.”

He later added that the claim that the “absolutist position” that strong encryption should be by definition, unbreakable, is “unreasonable.”

“And I think it’s necessary to weigh law enforcement equities in appropriate cases against the interest in security,” he said.

The DOJ’s position runs counter to the consensus of information security experts, who say that it is impossible to build the strongest encryption system possible that would also allow the government access under certain conditions.

“Of course, criminals and terrorists have used, are using, and will use encryption to hide their planning from the authorities, just as they will use many aspects of society’s capabilities and infrastructure: cars, restaurants, telecommunications,” Bruce Schneier, a well-known cryptographer, wrote last year.

“In general, we recognize that such things can be used by both honest and dishonest people. Society thrives nonetheless because the honest so outnumber the dishonest. Compare this with the tactic of secretly poisoning all the food at a restaurant. Yes, we might get lucky and poison a terrorist before he strikes, but we’ll harm all the innocent customers in the process. Weakening encryption for everyone is harmful in exactly the same way.”

Rosenstein closed his interview by noting that he understands re-engineering encryption to accommodate government may make it weaker.

“And I think that’s a legitimate issue that we can debatehow much risk are we willing to take in return for the reward?” he said.

“My point is simply that I think somebody needs to consider what’s on the other side of the balance. There is a cost to having impregnable security, and we’ve talked about some of the aspects of that. The cost is that criminals are going to be able to get away with stuff, and that’s going to prevent us in law enforcement from holding them accountable.”

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DOJ: Strong encryption that we dont have access to is …

DOJ Fires Up New War With Apple Over Encryption

The DOJ and FBI have been in a bit of a cold war with Apple and the tech community ever since the controversy in 2015 over unlocking the San Bernardino shooters iPhone. This week, the war heated up again with the FBI and Apple exchanging words about encryption, and on Thursday, the Deputy Attorney General of the United States stepped into the fray.

The Federal Bureau of Investigation apparently missed a key window in which they could have sought

The FBI is currently investigating the circumstances surrounding the shooting of 26 people at a church in Sutherland Springs, Texas. The shooter, Devin Kelley, is dead, so law enforcement has had to work with what evidence hes left behind. On Tuesday, FBI special agent Christopher Combs gave a press conference in which he lamented the fact that the FBI has, so far, been unable to unlock Kelleys phone. On Wednesday, Apple let the world know that it may have been able to help, but the FBI waited more than 48 hours to inform Apple or the public that it was trying to unlock an iPhone. At a minimum, Apple said that it couldve suggested trying the Touch ID feature in that 48 hours, but its too late now.

That could have been the end of the story. Until today, neither the FBI nor Apple has seemed to want to jump back into the heated debate on encryption that occurred in 2015. People from the FBI and DOJ have continued to make comments that they need a backdoor into encryption, but without a major case like San Bernardino to win over public sentiment, they havent made a huge public deal out of it. And Apple has been happy to walk away from that incident without being forced to create future backdoors for the US government. It would appear that Apples statement on Wednesday was an effort to nip a new uproar in the bud. But on Thursday, Deputy AG Rod Rosenstein brought the subject up once again. Rosenstein (conveniently) did not mention that Apple publicly shamed the FBI for not even attempting to approach the company for help.

At a breakfast for business leaders in Maryland, Rosenstein gave a wide-ranging speech that touched on the importance of law before politics, the increasing problem of cybercrime, and once again, how much hed love to be able to get into anyones phone whenever he has an investigation. Rosenstein is clearly being either willfully ignorant or hes gassing the public when he makes statements like, nobody has a legitimate expectation of privacy in that phone, referring to the shooters phone. The suspect is deceased, and even if he were alive, it would be legal for police and prosecutors to find out what is [on] the phone, he explained.

The FBI, and other government agencies around the world, tend to make their case for a backdoor into encryption based on either the need to protect the public or some sort of fine legal argument about warrants. Rosenstein went with both. When you shoot dozens of American citizens, we want law enforcement to investigate you, he told the attendees. There are things we need to know.

As always in this argument, the issue is that no ones talking about the privacy of a dead man, or the constitutionality of a search warrant for the phone, or even anyones physical safety. Opponents of governmental backdoors are talking about the privacy and safety of everyone who uses technology and the internet. Good encryption means no one can have a backdoor. If theres a backdoor, someone will end up being able to open it. Rosenstein, in a matter of a few sentences, was able to jump from rattling off dire warnings and statistics about cybercrime to suggesting a great way to make cybercrime a lot worse.

Even when Apple said most recently that it offered assistance and said we would expedite our response to any legal process they send us, it was only referring to offering training and technical assistance. It wasnt saying that it could crack the phones encryption. Apples official position is that it builds products so that the user is the only one with the key. The fact that the FBI was able to pay some hackers $900,000 to unlock the San Bernardino shooters phone means that Apple has not done a bulletproof job at building that encryption. But still, as far as we know, the goal is realto build a phone without backdoors because thats the safest way to do it.

Rosenstein and his colleagues act as if companies like Apple are protecting criminals, and dodging legal warrants. In fact, companies like Apple are protecting Rosenstein and his colleagues, because they most certainly use technology every day. Warrants dont apply here because the tech is designed so that no one can be ordered to open it up. Before smartphones and laptops existed, FBI agents werent demanding that a neurologist autopsy a dead suspects brain to try and find some phone numbers of people they were in contact with. If there was a phone book in the suspects house, a warrant allowed them to find it. That hasnt changed today. Law enforcement needs to start thinking of a locked and encrypted phone as a dead brain. If they can hire some Frankenstein hacker to bring it back to life, fine. But otherwise, just do the police work the old-fashioned way.

If the past few days are any indication, this could turn into another prolonged war of words. Rosenstein and the FBI probably see a political opportunity with public and political sentiment turning against the tech world. Tech needs to do a lot of things better, but one of those things is making encryption more impervious to the FBI.

[The Hill, The Washington Examiner, Baltimore Sun]

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DOJ Fires Up New War With Apple Over Encryption

Security Awareness – Encryption | Office of Information …


Encryption is the transformation of information into a form that is only readable by those with particular knowledge or technology to prevent others who might have access to the information from reading it. It has long been used for messages in transit, whether carried by hand, transmitted via radio or sent over a computer network if the message is intercepted, the interceptor would be unable to interpret the information. It also serves an important role for stored information to protect it in case of loss or theft.

While the concepts and processes of encryption greatly pre-date modern computing, the topic has become increasingly popular in computing over the past few years. This has largely been fueled by the vast increase of information transfer over computer networks and the increased security concerns that accompany a massively interconnected “always online” computing environment.

OIToffers and supports PGP software and licenses to faculty and staff for whole disk encryption. Whole disk encryption will keep educational records and confidential data secure in case your laptop is lost or stolen. This information should only be stored on a mobile device, like a laptop, when there is a specific business purpose. Find out if PGP whole disk encryption is right for you.

If we had a number we wished to keep secret (say the combination to a safe), one option to protect it is to encrypt the number, after all we can’t store the combination to the safe inside the safe. Let’s say the combination is 12-28-11 which we shorten to just 122811. Let’s use some simple math to make it into a scrambled number.

Here’s an equation that adds a secret number (n) to the combination and then multiplies the result by the same secret number:

If we pick 5 as our secret number, then we get:

Our scrambled number, 614080, is an encrypted version of our safe combination. To get our combination number back, we need to know our secret number and the formula used to create the scrambled number. Here’s the formula:

We insert our secret number and our scrambled number:

And solve the equation to find our combination:

We have successfully developed our own encryption process for our safe combination.

The process of transforming readable information into an unreadable form. Making the safe combination into the scrambled number.


The process of transforming encrypted information back into its readable form. Making the scrambled number back into the safe combination.


The item used, along with the algorithm, to encrypt and decrypt information. . In the example above, the secret number, n, was our key. The key could be a password, a special file or a hardware device often called a token Strong encryption processes may use multiple keys like both a password and a token.

Key length


The mathematical technique used, along with the key(s), to encrypt and decrypt information. In the example above, the equation, n*(combination + n)=scrambled number, was our algorithm. Popular encryption algorithms include: AES, DES, triple-DES, RSA, blowfish, IDEA

Information is considered “at rest” when it is saved to a computer or storage device (like a CD, tape or thumbdrive) which is usually in contrast to “in transit”. Note that data can be considered “at rest” while physically moving like someone carrying a CD with information.

Information is “in transit” when it is being transferred over a network. This could be copying a file from a file server, submitting a webpage order form or sending an email.

The behavior of an encryption technology/product which keeps a file encrypted when it is moved between disks or computers. Many forms of encryption only keep information encrypted when stored in a particular location.

Symmetrical vs Asymmetrical

Encryption/decryption processes are often referred to as being either symmetrical or asymmetrical, which relates to what keys are used to encrypt and decrypt information.

In symmetrical encryption, the same key is used to encrypt and decrypt the information. The most common use of this technique is password encryption where the same password is used to encrypt and decrypt the information. This method is simple and useful when sharing the key isn’t problematic (either the key isn’t shared or all parties are trusted with the information). It requires that all parties who need to encrypt or decrypt the information safely obtain the key.

In asymmetrical encryption, there are two different keys one used to encrypt the information and one used to decrypt the information. In this approach, the key used to encrypt the information cannot be used to decrypt it. This technique is useful when sharing a key might be problematic. These two keys are often referred to as public and private keys. As the names imply, the public key is openly distributed as it can only be used to encrypt information and the private key that can decrypt the information is protected.

Key managementPerhaps the most important aspect of encryption deployment is management of keys. This includes what types of keys are used (passwords, files, tokens, certificates, etc), how they are given to users, how they are protected and how to deal with a lost key scenario. Each technology and product handles this differently, but the lost key scenario is usually the most concerning since it could lead to either an unauthorized person decrypting information or the inability for authorized people to decrypt information. Many encryption horror stories come in the form of not being able to decrypt the only copy of very important information. Pay careful attention to key generation, distribution, use, recovery and security when looking into encryption options.

Impacts to system/data managementWhen files or disks are encrypted, an IT administrator might have to adapt some of their management processes or tools. For example, what impact do encrypted hard drives have on system imaging? What about the use of wake-on-LAN for management? The answers to these questions vary with your management processes and the encryption product, so it’s important to understand how encryption products will impact your IT environment.

When does encryption stay with the file?Many forms of encryption only protect information while it is transferred over the network (like a website using SSL) or while it is stored in a particular place (like on an encrypted hard drive). This means that once the file is moved out of the situation, it is no longer encrypted. This often confuses users who think encryption “sticks” to files and they can email a file stored on an encrypted disk and it will stay encrypted as an email attachment, or copy a file from an encrypted disk to a thumb drive and the file will remain encrypted. It’s important to understand the conditions under which a file will be encrypted and explain those conditions to those in your department. Since encryption conditions vary by technology, product and implementation, there isn’t a general rule.

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Security Awareness – Encryption | Office of Information …

Data Encryption and Decryption (Windows)

This documentation is archived and is not being maintained.

Encryption is the process of translating plain text data (plaintext) into something that appears to be random and meaningless (ciphertext). Decryption is the process of converting ciphertext back to plaintext.

To encrypt more than a small amount of data, symmetric encryption is used. A symmetric key is used during both the encryption and decryption processes. To decrypt a particular piece of ciphertext, the key that was used to encrypt the data must be used.

The goal of every encryption algorithm is to make it as difficult as possible to decrypt the generated ciphertext without using the key. If a really good encryption algorithm is used, there is no technique significantly better than methodically trying every possible key. For such an algorithm, the longer the key, the more difficult it is to decrypt a piece of ciphertext without possessing the key.

It is difficult to determine the quality of an encryption algorithm. Algorithms that look promising sometimes turn out to be very easy to break, given the proper attack. When selecting an encryption algorithm, it is a good idea to choose one that has been in use for several years and has successfully resisted all attacks.

For more information, see Data Encryption and Decryption Functions.

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Data Encryption and Decryption (Windows)