EVP_PKEY_sign

NAME

SYNOPSIS

 #include <openssl/evp.h>

 int EVP_PKEY_sign_init(EVP_PKEY_CTX *ctx);
 int EVP_PKEY_sign(EVP_PKEY_CTX *ctx,
                        unsigned char *sig, size_t *siglen,
                        const unsigned char *tbs, size_t tbslen);

DESCRIPTION

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.  

NOTES

The function EVP_PKEY_sign() can be called more than once on the same context if several operations are performed using the same parameters.  

RETURN VALUES

EXAMPLE

 #include <openssl/evp.h>
 #include <openssl/rsa.h>

 EVP_PKEY_CTX *ctx;
 unsigned char *md, *sig;
 size_t mdlen, siglen; 
 EVP_PKEY *signing_key;
 /* NB: assumes signing_key, md and mdlen are already set up
  * and that signing_key is an RSA private key
  */
 ctx = EVP_PKEY_CTX_new(signing_key);
 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 */

SEE ALSO

HISTORY