/usr/man/cat.3/RSA_public_decrypt.3

RSA_private_encrypt(3)       OpenSSL       RSA_private_encrypt(3)

NAME

     RSA_private_encrypt, RSA_public_decrypt - low level
     signature operations

SYNOPSIS

      #include <openssl/rsa.h>

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

      int RSA_public_decrypt(int flen, const 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 (usually
     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)

1.0.2t               Last change: 2019-09-10                    1

RSA_private_encrypt(3)       OpenSSL       RSA_private_encrypt(3)

HISTORY

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

1.0.2t               Last change: 2019-09-10                    2

See also RSA_private_encrypt(3)