EVP_PKEY_sign_init, EVP_PKEY_sign_init_ex, EVP_PKEY_sign - sign using a public
key algorithm
#include <openssl/evp.h>
int EVP_PKEY_sign_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_sign_init_ex(EVP_PKEY_CTX *ctx, const OSSL_PARAM params[]);
int EVP_PKEY_sign(EVP_PKEY_CTX *ctx,
unsigned char *sig, size_t *siglen,
const unsigned char *tbs, size_t tbslen);
EVP_PKEY_sign_init() initializes a public key algorithm context
ctx for signing using the algorithm given when the context was created
using
EVP_PKEY_CTX_new(3) or variants thereof. The algorithm is used to
fetch a
EVP_SIGNATURE method implicitly, see "Implicit fetch"
in
provider(7) for more information about implicit fetches.
EVP_PKEY_sign_init_ex() is the same as
EVP_PKEY_sign_init() but
additionally sets the passed parameters
params on the context before
returning.
The
EVP_PKEY_sign() function performs a public key signing operation
using
ctx. The data to be signed is specified using the
tbs and
tbslen parameters. If
sig is NULL then the maximum size of the
output buffer is written to the
siglen parameter. If
sig is not
NULL then before the call the
siglen parameter should contain the
length of the
sig buffer, if the call is successful the signature is
written to
sig and the amount of data written to
siglen.
EVP_PKEY_sign() does not hash the data to be signed, and therefore is
normally used to sign digests. For signing arbitrary messages, see the
EVP_DigestSignInit(3) and
EVP_SignInit(3) signing interfaces
instead.
After the call to
EVP_PKEY_sign_init() algorithm specific control
operations can be performed to set any appropriate parameters for the
operation (see
EVP_PKEY_CTX_ctrl(3)).
The function
EVP_PKEY_sign() can be called more than once on the same
context if several operations are performed using the same parameters.
EVP_PKEY_sign_init() and
EVP_PKEY_sign() return 1 for success and
0 or a negative value for failure. In particular a return value of -2
indicates the operation is not supported by the public key algorithm.
Sign data using RSA with PKCS#1 padding and SHA256 digest:
#include <openssl/evp.h>
#include <openssl/rsa.h>
EVP_PKEY_CTX *ctx;
/* md is a SHA-256 digest in this example. */
unsigned char *md, *sig;
size_t mdlen = 32, siglen;
EVP_PKEY *signing_key;
/*
* NB: assumes signing_key and md are set up before the next
* step. signing_key must be an RSA private key and md must
* point to the SHA-256 digest to be signed.
*/
ctx = EVP_PKEY_CTX_new(signing_key, NULL /* no engine */);
if (!ctx)
/* Error occurred */
if (EVP_PKEY_sign_init(ctx) <= 0)
/* Error */
if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
/* Error */
if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
/* Error */
/* Determine buffer length */
if (EVP_PKEY_sign(ctx, NULL, &siglen, md, mdlen) <= 0)
/* Error */
sig = OPENSSL_malloc(siglen);
if (!sig)
/* malloc failure */
if (EVP_PKEY_sign(ctx, sig, &siglen, md, mdlen) <= 0)
/* Error */
/* Signature is siglen bytes written to buffer sig */
EVP_PKEY_CTX_new(3),
EVP_PKEY_CTX_ctrl(3),
EVP_PKEY_encrypt(3),
EVP_PKEY_decrypt(3),
EVP_PKEY_verify(3),
EVP_PKEY_verify_recover(3),
EVP_PKEY_derive(3)
The
EVP_PKEY_sign_init() and
EVP_PKEY_sign() functions were added
in OpenSSL 1.0.0.
The
EVP_PKEY_sign_init_ex() function was added in OpenSSL 3.0.
Copyright 2006-2021 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy in the
file LICENSE in the source distribution or at
<
https://www.openssl.org/source/license.html>.