- NAME
- SYNOPSIS
- DESCRIPTION
- RETURN VALUES
- BUGS
- CONFORMING TO
- SEE ALSO
- HISTORY

# 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 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 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.

# 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, objects, rsa, RSA_private_encrypt, RSA_public_decrypt

# HISTORY

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