Other versions are also available for the following:
SQL Server 2008 Books Online (October 2009)
Cryptographic Functions (Transact-SQL)
The following functions support encryption, decryption, digital signing, and the validation of digital signatures.

Symmetric Encryption and Decryption

Asymmetric Encryption and Decryption

Signing and Signature Verification

Symmetric Decryption with Automatic Key Handling

See Also