RSA_private_encrypt(3)      OpenSSL      RSA_private_encrypt(3)





NAME
       RSA_private_encrypt, RSA_public_decrypt - low level sig-
       nature operations

SYNOPSIS
        #include <openssl/rsa.h>

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

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

DESCRIPTION
       These functions handle RSA signatures at a low level.

       RSA_private_encrypt() signs the flen bytes at from (usu-
       ally a message digest with an algorithm identifier)
       using the private key rsa and stores the signature in
       to. to must point to RSA_size(rsa) bytes of memory.

       padding denotes one of the following modes:

       RSA_PKCS1_PADDING
           PKCS #1 v1.5 padding. This function does not handle
           the algorithmIdentifier specified in PKCS #1. When
           generating or verifying PKCS #1 signatures,
           RSA_sign(3) and RSA_verify(3) should be used.

       RSA_NO_PADDING
           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.

       RSA_public_decrypt() recovers the message digest from
       the flen bytes long signature at from using the signer's
       public key rsa. to must point to a memory section large
       enough to hold the message digest (which is smaller than
       RSA_size(rsa) - 11). padding is the padding mode that
       was used to sign the data.

RETURN VALUES
       RSA_private_encrypt() returns the size of the signature
       (i.e., RSA_size(rsa)). RSA_public_decrypt() returns the
       size of the recovered message digest.

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

SEE ALSO
       ERR_get_error(3), rsa(3), RSA_sign(3), RSA_verify(3)

HISTORY
       The padding argument was added in SSLeay 0.8.
       RSA_NO_PADDING is available since SSLeay 0.9.0.



0.9.7c                     2002-09-25    RSA_private_encrypt(3)
