NAME

       RSA_sign, RSA_verify - RSA signatures

SYNOPSIS

        #include <openssl/rsa.h>

        int RSA_sign(int type, const unsigned char *m, unsigned int m_len,
           unsigned char *sigret, unsigned int *siglen, RSA *rsa);

        int RSA_verify(int type, const unsigned char *m, unsigned int m_len,
           unsigned char *sigbuf, unsigned int siglen, RSA *rsa);

DESCRIPTION

       RSA_sign() signs the message digest m of size m_len using the private key rsa as specified
       in PKCS #1 v2.0. It stores the signature in sigret and the signature size in siglen.
       sigret must point to RSA_size(rsa) bytes of memory.  Note that PKCS #1 adds meta-data,
       placing limits on the size of the key that can be used.  See RSA_private_encrypt(3) for
       lower-level operations.

       type denotes the message digest algorithm that was used to generate m. It usually is one
       of NID_sha1, NID_ripemd160 and NID_md5; see objects(3) for details. If type is
       NID_md5_sha1, an SSL signature (MD5 and SHA1 message digests with PKCS #1 padding and no
       algorithm identifier) is created.

       RSA_verify() verifies that the signature sigbuf of size siglen matches a given message
       digest m of size m_len. type denotes the message digest algorithm that was used to
       generate the signature.  rsa is the signer's public key.

RETURN VALUES

       RSA_sign() returns 1 on success, 0 otherwise.  RSA_verify() returns 1 on successful
       verification, 0 otherwise.

       The error codes can be obtained by ERR_get_error(3).

BUGS

       Certain signatures with an improper algorithm identifier are accepted for compatibility
       with SSLeay 0.4.5 :-)

CONFORMING TO

       SSL, PKCS #1 v2.0

SEE ALSO

       ERR_get_error(3), objects(3), rsa(3), RSA_private_encrypt(3), RSA_public_decrypt(3)

HISTORY

       RSA_sign() and RSA_verify() are available in all versions of SSLeay and OpenSSL.