RSAprivateencrypt(3) OpenSSL RSAprivateencrypt(3)

NAME
       RSAprivateencrypt, RSApublicdecrypt - low level signature
       operations

SYNOPSIS
        #include 

        int RSAprivateencrypt(int flen, unsigned char *from,
           unsigned char *to, RSA *rsa, int padding);

        int RSApublicdecrypt(int flen, unsigned char *from,
           unsigned char *to, RSA *rsa, int padding);

DESCRIPTION
       These functions handle RSA signatures at a low level.

       RSAprivateencrypt() signs the fflleenn bytes at ffrroomm (usually a message
       digest with an algorithm identifier) using the private key rrssaa and
       stores the signature in ttoo. ttoo must point to RRSSAAssiizzee((rrssaa)) bytes of
       memory.

       ppaaddddiinngg denotes one of the following modes:

       RSAPKCS1PADDING
           PKCS #1 v1.5 padding. This function does not handle the
           aallggoorriitthhmmIIddeennttiiffiieerr specified in PKCS #1. When generating or
           verifying PKCS #1 signatures, RSAsign(3) and RSAverify(3) should
           be used.

       RSANOPADDING
           Raw RSA signature. This mode should only be used to implement
           cryptographically sound padding modes in the application code.
           Signing user data directly with RSA is insecure.

       RSApublicdecrypt() recovers the message digest from the fflleenn bytes
       long signature at ffrroomm using the signer's public key rrssaa. ttoo must point
       to a memory section large enough to hold the message digest (which is
       smaller than RRSSAAssiizzee((rrssaa)) - 1111). ppaaddddiinngg is the padding mode that was
       used to sign the data.

RETURN VALUES
       RSAprivateencrypt() returns the size of the signature (i.e.,
       RSAsize(rsa)). RSApublicdecrypt() returns the size of the recovered
       message digest.

       On error, -1 is returned; the error codes can be obtained by
       ERRgeterror(3).

SEE ALSO
       ERRgeterror(3), rsa(3), RSAsign(3), RSAverify(3)

HISTORY       The ppaaddddiinngg argument was added in SSLeay 0.8. RSANOPADDING is
       available since SSLeay 0.9.0.



0.9.7l                            2002-09-25            RSAprivateencrypt(3)