RSA_sign(3ssl)

RSA_sign3ssl

Rsa signatures

Usage

 #include <openssl/rsa.h>

The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

 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);

Overview

All of the functions described on this page are deprecated. Applications should instead use EVP_PKEY_sign_init(3), EVP_PKEY_sign(3), EVP_PKEY_verify_init(3) and EVP_PKEY_verify(3).

RSA_sign() signs the message digest m of size m_len using the private key rsa using RSASSA-PKCS1-v1_5 as specified in RFC 3447. 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. 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 and 0 for failure. RSA_verify() returns 1 on successful verification and 0 for failure.

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

Releases

13 releases since Debian 3.0 (Woody); the text changed 12 times.

  1. 3.0
  2. 3.1
  3. 4.0
  4. 5.0
  5. 6.0
  6. 7
  7. 8
  8. 9
  9. 10
  10. 11
  11. 12
  12. 13
  13. Arch

Conforming to

SSL, PKCS #1 v2.0

History

All of these functions were deprecated in OpenSSL 3.0.

From openssl 3.6.5-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.