Symmetric Encryption Algorithms

Every PROV_RSA_FULL or PROV_RSA_SIG CSP must provide an implementation of the RC2 block cipher and the RC4 stream cipher encryption. These algorithms are used to create session keys for bulk data encryption and decryption.

The Microsoft Base Cryptographic Provider uses 40-bit session keys with 88-bit salt values (128 bits total). New CSPs are free to use larger keys, although using longer keys can make exporting the CSP outside the USA and Canada more difficult. For more information on export control, see Microsoft's CSP Signing Policy. In addition, using a session key larger than 40-bits makes key exchange with a Microsoft Base Cryptographic Provider more difficult.