||SQL Server Tips by Gama and Naughter
RSA Signing / Verification
XP_CRYPTOAPI provides the following RSA XPís
for signing using the RSA public key algorithm: XP_RSA_MD2_SIGN,
XP_RSA_MD4_SIGN, XP_RSA_MD5_SIGN, XP_RSA_SHA1_SIGN and XP_DSA_SIGN.
The various XPís allow you to specify which hash algorithm is used.
The corresponding verification XPís are XP_RSA_MD2_VERIFY,
XP_RSA_MD4_VERIFY, XP_RSA_MD5_VERIFY and XP_RSA_SHA1_VERIFY.
DSA Signing / Verification
Unlike RSA, using the DSA signature, the DSS dictates that a SHA1
hash is used to sign the message. This means that there is only one
XP for DSA in XP_CRYPTOAPI. It is called XP_DSA_SIGN. The
corresponding verification XP is XP_DSA_VERIFY.
The above book excerpt is from:
Turbocharge Database Performance with C++ External Procedures
Joseph Gama, P. J. Naughter