- Symmetric Algorithms
- Algorithms For Generating Symmetric Key And Functions
- Algorithms For Generating Symmetric Key System
The algorithm has to be specified when generating an asymmetric key. This is another big difference to certificates and maybe the biggest reason to use asymmetric keys at all. Certificates that are generated in SQL Server always use 1024 bit as key length. Asymmetric keys allow you to generate a longer and hence more secure key.
Generating Symmetric Private Key In C# and.NET. Major symmetric algorithms are AES, DES, RC2, Rijndael, and TripleDES. The GenerateKey and GenerateIV methods return the private secret key and initialization vector. 10.2.1: Some Variations on the KDC Approach to Key Distribution. ItisnotpracticaltohaveasingleKDCserviceverylargenetworks or network of networks. One can think of KDC’s organized hierarchically, with each lo- cal network serviced by its own KDC, and a group of networks serviced by a more global KDC, and so on. Symmetric algorithms use the same key for encryption and decryption (or the decryption key is easily derived from the encryption key), whereas asymmetric algorithms use a different key for encryption and decryption, and the decryption key cannot be derived from the encryption key. The same goes for computers, but, of course, the keys are usually much longer. The first major symmetric algorithm developed for computers in the United States was the Data Encryption Standard (DES), approved for use in the 1970s. The DES uses a 56-bit key. Apr 16, 2018 Symmetric-key encryption. Symmetric-key algorithms use the same keys for both encryption and decryption. The keys may be identical or there may be a simple transformation to switch between the two.
How to Generate a Symmetric Key by Usingthe pktool Command
Some applications require a symmetric key for encryption and decryptionof communications. In this procedure, you create a symmetric key and storeit.
- If your site has a random number generator, you can use thegenerator to create a random number for the key. This procedure does not useyour site's random number generator.
- You can instead use the dd command withthe Solaris /dev/urandom device as input. The dd commanddoes not store the key. For the procedure, see How to Generate a Symmetric Key by Using the dd Command.
- (Optional) If you plan touse a keystore, create it.
- To create and initialize a PKCS #11 keystore, see How to Generate a Passphrase by Using the pktool setpin Command.
- To create and initialize an NSS database, see Example 15–5.
- Generate a random number for use as a symmetric key.Useone of the following methods.
- Generate a key and store it in a file.The advantageof a file-stored key is that you can extract the key from this file for usein an application's key file, such as the /etc/inet/secret/ipseckeys fileor IPsec.
- keystore
- The value file specifies the file typeof storage location for the key.
- outkey=key-fn
- Is the filename when keystore=file.
- keytype=specific-symmetric-algorithm
- For a particular algorithm, specify aes, arcfour, des, or 3des.
- keylen=size-in-bits
- Is the length of the key in bits. The number must be divisibleby 8. Do not specify for des or 3des.
- dir=directory
- Is the directory path to key-fn.By default, directory is the current directory.
- print=n
- Prints the key to the terminal window. By default, the valueof print is n.
- Generate a key and store it in a PKCS #11 keystore.Theadvantage of the PKCS #11 keystore is that you can retrieve the key by itslabel. This method is useful for keys that encrypt and decrypt files. Youmust complete Step 1 beforeusing this method.
- label=key-label
- Is a user-specified label for the key. The key can be retrievedfrom the keystore by its label.
- keytype=specific-symmetric-algorithm
- For a particular algorithm, specify aes, arcfour, des, or 3des.
- keylen=size-in-bits
- Is the length of the key in bits. The number must be divisibleby 8. Do not specify for des or 3des.
- token=token
- Is the token name. By default, the token is Sun SoftwarePKCS#11 softtoken.
- sensitive=n
- Specifies the sensitivity of the key. When the value is y, the key cannot be printed by using the print=y argument.By default, the value of sensitive is n.
- extractable=y
- Specifies that the key can be extracted from the keystore.Specify n to prevent the key from being extracted.
- print=n
- Prints the key to the terminal window. By default, the valueof print is n.
- Generate a key and store it in an NSS keystore.Youmust complete Step 1 beforeusing this method.
- keystore
- The value nss specifies the NSS type ofstorage location for the key.
- label=key-label
- Is a user-specified label for the key. The key can be retrievedfrom the keystore by its label.All the best are includedLatest versions of the best audio codecs are included with the software. Freely convert between all supported audio formats. Edit metadata of audio files. Easy cd-da extractor free key generator for microsoft office 2007. Keep the folder structure on mass conversions or customize output folder and file names with metadata tags. Transfer all metadata tags from source files to destination files on audio file conversions.
- keytype=specific-symmetric-algorithm
- For a particular algorithm, specify aes, arcfour, des, or 3des.
- keylen=size-in-bits
- Is the length of the key in bits. The number must be divisibleby 8. Do not specify for des or 3des.
- token=token
- Is the token name. By default, the token is the NSS internaltoken.
- dir=directory
- Is the directory path to the NSS database. By default, directory is the current directory.
- prefix=directory
- Is the prefix to the NSS database. The default is no prefix.
- print=n
- Prints the key to the terminal window. By default, the valueof print is n.
- (Optional) Verify that the key exists.Useone of the following commands, depending on where you stored the key.
- Verify the key in the key-fn file.
- Verify the key in the PKCS #11 or the NSS keystore.
Example 14–5 Creating a DES Key by Using the pktool Command
In the following example, a secret key for the DES algorithm is created.The key is stored in a local file for later decryption. The command protectsthe file with 400 permissions. When the key is created,the print=y option displays the generated key in the terminalwindow.
DES mechanisms use a 64-bit key. The user who owns the keyfile retrievesthe key by using the od command.
Generates a symmetric key and specifies its properties in SQL Server.
This feature is incompatible with database export using Data Tier Application Framework (DACFx). You must drop all symmetric keys before exporting.
Syntax
Arguments
Key_name
Specifies the unique name by which the symmetric key is known in the database. Temporary keys are designated when the key_name begins with one number (#) sign. For example, #temporaryKey900007. You cannot create a symmetric key that has a name that starts with more than one #. You cannot create a temporary symmetric key using an EKM provider.
Specifies the unique name by which the symmetric key is known in the database. Temporary keys are designated when the key_name begins with one number (#) sign. For example, #temporaryKey900007. You cannot create a symmetric key that has a name that starts with more than one #. You cannot create a temporary symmetric key using an EKM provider.
AUTHORIZATION owner_name
Specifies the name of the database user or application role that will own this key.
Specifies the name of the database user or application role that will own this key.
FROM PROVIDER provider_name
Specifies an Extensible Key Management (EKM) provider and name. The key is not exported from the EKM device. The provider must be defined first using the CREATE PROVIDER statement. For more information about creating external key providers, see Extensible Key Management (EKM).
Specifies an Extensible Key Management (EKM) provider and name. The key is not exported from the EKM device. The provider must be defined first using the CREATE PROVIDER statement. For more information about creating external key providers, see Extensible Key Management (EKM).
Note
This option is not available in a contained database.
KEY_SOURCE ='pass_phrase'
Specifies a pass phrase from which to derive the key.
Specifies a pass phrase from which to derive the key.
IDENTITY_VALUE ='identity_phrase'
Specifies an identity phrase from which to generate a GUID for tagging data that is encrypted with a temporary key.
Specifies an identity phrase from which to generate a GUID for tagging data that is encrypted with a temporary key.
PROVIDER_KEY_NAME**='key_name_in_provider'**
Specifies the name referenced in the Extensible Key Management provider.
Specifies the name referenced in the Extensible Key Management provider.
Note
This option is not available in a contained database.
CREATION_DISPOSITION = CREATE_NEW
Creates a new key on the Extensible Key Management device. If a key already exists on the device, the statement fails with error.
Creates a new key on the Extensible Key Management device. If a key already exists on the device, the statement fails with error.
![Key Key](/uploads/1/2/5/8/125872482/331065081.png)
CREATION_DISPOSITION = OPEN_EXISTING
Maps a SQL Server symmetric key to an existing Extensible Key Management key. If CREATION_DISPOSITION = OPEN_EXISTING is not provided, this defaults to CREATE_NEW.
Maps a SQL Server symmetric key to an existing Extensible Key Management key. If CREATION_DISPOSITION = OPEN_EXISTING is not provided, this defaults to CREATE_NEW.
certificate_name
Specifies the name of the certificate that will be used to encrypt the symmetric key. The certificate must already exist in the database.
Specifies the name of the certificate that will be used to encrypt the symmetric key. The certificate must already exist in the database.
'password'
Specifies a password from which to derive a TRIPLE_DES key with which to secure the symmetric key. password must meet the Windows password policy requirements of the computer that is running the instance of SQL Server. Always use strong passwords.
Specifies a password from which to derive a TRIPLE_DES key with which to secure the symmetric key. password must meet the Windows password policy requirements of the computer that is running the instance of SQL Server. Always use strong passwords.
symmetric_key_name
Specifies a symmetric key, used to encrypt the key that is being created. The specified key must already exist in the database, and the key must be open.
Specifies a symmetric key, used to encrypt the key that is being created. The specified key must already exist in the database, and the key must be open.
asym_key_name
Specifies an asymmetric key, used to encrypt the key that is being created. This asymmetric key must already exist in the database.
Specifies an asymmetric key, used to encrypt the key that is being created. This asymmetric key must already exist in the database.
<algorithm>
Specify the encrypting algorithm.
Specify the encrypting algorithm.
Warning
Beginning with SQL Server 2016 (13.x), all algorithms other than AES_128, AES_192, and AES_256 are deprecated. To use older algorithms (not recommended), you must set the database to database compatibility level 120 or lower.
Remarks
When a symmetric key is created, the symmetric key must be encrypted by using at least one of the following: certificate, password, symmetric key, asymmetric key, or PROVIDER. The key can have more than one encryption of each type. In other words, a single symmetric key can be encrypted by using multiple certificates, passwords, symmetric keys, and asymmetric keys at the same time.
Symmetric Algorithms
Caution
When a symmetric key is encrypted with a password instead of a certificate (or another key), the TRIPLE DES encryption algorithm is used to encrypt the password. Because of this, keys that are created with a strong encryption algorithm, such as AES, are themselves secured by a weaker algorithm.
The optional password can be used to encrypt the symmetric key before distributing the key to multiple users.
Temporary keys are owned by the user that creates them. Temporary keys are only valid for the current session.
IDENTITY_VALUE generates a GUID with which to tag data that is encrypted with the new symmetric key. This tagging can be used to match keys to encrypted data. The GUID generated by a specific phrase is always the same. After a phrase has been used to generate a GUID, the phrase cannot be reused as long as there is at least one session that is actively using the phrase. IDENTITY_VALUE is an optional clause; however, we recommend using it when you are storing data encrypted with a temporary key.
There is no default encryption algorithm.
Important
We do not recommend using the RC4 and RC4_128 stream ciphers to protect sensitive data. SQL Server does not further encode the encryption performed with such keys.
Information about symmetric keys is visible in the sys.symmetric_keys catalog view.
Symmetric keys cannot be encrypted by symmetric keys created from the encryption provider.
Autocad mechanical tutorial. Clarification regarding DES algorithms:
Algorithms For Generating Symmetric Key And Functions
- DESX was incorrectly named. Symmetric keys created with ALGORITHM = DESX actually use the TRIPLE DES cipher with a 192-bit key. The DESX algorithm is not provided. This feature is in maintenance mode and may be removed in a future version of Microsoft SQL Server. Avoid using this feature in new development work, and plan to modify applications that currently use this feature.
- Symmetric keys created with ALGORITHM = TRIPLE_DES_3KEY use TRIPLE DES with a 192-bit key.
- Symmetric keys created with ALGORITHM = TRIPLE_DES use TRIPLE DES with a 128-bit key.
Deprecation of the RC4 algorithm:
Repeated use of the same RC4 or RC4_128 KEY_GUID on different blocks of data, results in the same RC4 key because SQL Server does not provide a salt automatically. Using the same RC4 key repeatedly is a well known error that will result in very weak encryption. Therefore we have deprecated the RC4 and RC4_128 keywords. This feature will be removed in a future version of Microsoft SQL Server. Do not use this feature in new development work, and modify applications that currently use this feature as soon as possible.
Warning
The RC4 algorithm is only supported for backward compatibility. New material can only be encrypted using RC4 or RC4_128 when the database is in compatibility level 90 or 100. (Not recommended.) Use a newer algorithm such as one of the AES algorithms instead. In SQL Server 2019 (15.x) material encrypted using RC4 or RC4_128 can be decrypted in any compatibility level.
Permissions
Requires ALTER ANY SYMMETRIC KEY permission on the database. If AUTHORIZATION is specified, requires IMPERSONATE permission on the database user or ALTER permission on the application role. If encryption is by certificate or asymmetric key, requires VIEW DEFINITION permission on the certificate or asymmetric key. Only Windows logins, SQL Server logins, and application roles can own symmetric keys. Groups and roles cannot own symmetric keys.
Examples
A. Creating a symmetric key
The following example creates a symmetric key called
JanainaKey09
by using the AES 256
algorithm, and then encrypts the new key with certificate Shipping04
.![For For](/uploads/1/2/5/8/125872482/449924300.png)
Algorithms For Generating Symmetric Key System
B. Creating a temporary symmetric key
The following example creates a temporary symmetric key called
#MarketingXXV
from the pass phrase: The square of the hypotenuse is equal to the sum of the squares of the sides
. The key is provisioned with a GUID that is generated from the string Pythagoras
and encrypted with certificate Marketing25
.C. Creating a symmetric key using an Extensible Key Management (EKM) device
The following example creates a symmetric key called
MySymKey
by using a provider called MyEKMProvider
and a key name of KeyForSensitiveData
. It assigns authorization to User1
and assumes that the system administrator has already registered the provider called MyEKMProvider
in SQL Server.See Also
Choose an Encryption Algorithm
ALTER SYMMETRIC KEY (Transact-SQL)
DROP SYMMETRIC KEY (Transact-SQL)
Encryption Hierarchy
sys.symmetric_keys (Transact-SQL)
Extensible Key Management (EKM)
Extensible Key Management Using Azure Key Vault (SQL Server)
ALTER SYMMETRIC KEY (Transact-SQL)
DROP SYMMETRIC KEY (Transact-SQL)
Encryption Hierarchy
sys.symmetric_keys (Transact-SQL)
Extensible Key Management (EKM)
Extensible Key Management Using Azure Key Vault (SQL Server)