NAME    [Toc]    [Back]

       RSA_private_encrypt, RSA_public_decrypt - Low level signature
 operations

SYNOPSIS    [Toc]    [Back]

       #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    [Toc]    [Back]

       These functions handle RSA signatures at a low level.

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

       The padding denotes one of the following  modes:  PKCS  #1
       v1.5  padding. This function does not handle the algorithmIdentifier
 specified in PKCS #1. When generating or verifying
  PKCS #1 signatures, the RSA_sign() and RSA_verify()
       functions should be used.  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.

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

RETURN VALUES    [Toc]    [Back]

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

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

HISTORY    [Toc]    [Back]

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

SEE ALSO    [Toc]    [Back]

       Functions: err(3), rsa(3), RSA_sign(3), RSA_verify(3)



                                           RSA_private_encrypt(3)