/usr/man/cat.3/RSA_sign.3

RSA_sign(3)                  OpenSSL                  RSA_sign(3)

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

1.0.2t               Last change: 2019-09-10                    1

RSA_sign(3)                  OpenSSL                  RSA_sign(3)

     SSLeay and OpenSSL.

1.0.2t               Last change: 2019-09-10                    2

See also RSA_verify(3)