EVP_PKEY_SIGN(3) | Library Functions Manual | EVP_PKEY_SIGN(3) |
EVP_PKEY_sign_init
,
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
(EVP_PKEY_CTX *ctx,
unsigned char *sig, size_t
*siglen, const unsigned char *tbs,
size_t tbslen);
The EVP_PKEY_sign_init
() function
initializes a public key algorithm context using the key
ctx->pkey for a signing operation.
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 = 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_ctrl(3), EVP_PKEY_CTX_new(3), EVP_PKEY_decrypt(3), EVP_PKEY_derive(3), EVP_PKEY_encrypt(3), EVP_PKEY_meth_set_sign(3), EVP_PKEY_verify(3), EVP_PKEY_verify_recover(3)
EVP_PKEY_sign_init
() and
EVP_PKEY_sign
() first appeared in OpenSSL 1.0.0 and
have been available since OpenBSD 4.9.
March 23, 2018 | OpenBSD-current |