||SQL Server Tips by Gama and Naughter
Public Key Management
To facilitate usage of the signature
verification functions, the public key part of the public key /
private key pair used to generate signatures must be available, as
the verification XPís require it as a parameter. To facilitate this,
three XPís are provided, namely XP_RSA_EXPORT_SIGNKEY,
XP_RSA_EXPORT_ENCRYPTKEY and XP_DSA_EXPORT. These export the public
keys into the single output parameter, which these XPís require.
Since XP_CRYPTOAPI uses RSA both for signing and encryption, two
different methods are provided to export these keys.
The above book excerpt is from:
Turbocharge Database Performance with C++ External Procedures
Joseph Gama, P. J. Naughter