NAME¶
EVP_PKEY_verify_init, EVP_PKEY_verify - signature verification using a public
key algorithm
SYNOPSIS¶
#include <openssl/evp.h>
int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_verify(EVP_PKEY_CTX *ctx,
const unsigned char *sig, size_t siglen,
const unsigned char *tbs, size_t tbslen);
DESCRIPTION¶
The
EVP_PKEY_verify_init() function initializes a public key algorithm
context using key
pkey for a signature verification operation.
The
EVP_PKEY_verify() function performs a public key verification
operation using
ctx. The signature is specified using the
sig
and
siglen parameters. The verified data (i.e. the data believed
originally signed) is specified using the
tbs and
tbslen
parameters.
NOTES¶
After the call to
EVP_PKEY_verify_init() algorithm specific control
operations can be performed to set any appropriate parameters for the
operation.
The function
EVP_PKEY_verify() can be called more than once on the same
context if several operations are performed using the same parameters.
RETURN VALUES¶
EVP_PKEY_verify_init() and
EVP_PKEY_verify() return 1 if the
verification was successful and 0 if it failed. Unlike other functions the
return value 0 from
EVP_PKEY_verify() only indicates that the signature
did not not verify successfully (that is tbs did not match the original data
or the signature was of invalid form) it is not an indication of a more
serious error.
A negative value indicates an error other that signature verification failure.
In particular a return value of -2 indicates the operation is not supported by
the public key algorithm.
EXAMPLE¶
Verify signature using PKCS#1 and SHA256 digest:
#include <openssl/evp.h>
#include <openssl/rsa.h>
EVP_PKEY_CTX *ctx;
unsigned char *md, *sig;
size_t mdlen, siglen;
EVP_PKEY *verify_key;
/* NB: assumes verify_key, sig, siglen md and mdlen are already set up
* and that verify_key is an RSA public key
*/
ctx = EVP_PKEY_CTX_new(verify_key);
if (!ctx)
/* Error occurred */
if (EVP_PKEY_verify_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 */
/* Perform operation */
ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
/* ret == 1 indicates success, 0 verify failure and < 0 for some
* other error.
*/
SEE ALSO¶
EVP_PKEY_CTX_new(3),
EVP_PKEY_encrypt(3),
EVP_PKEY_decrypt(3),
EVP_PKEY_sign(3),
EVP_PKEY_verify_recover(3),
EVP_PKEY_derive(3)
HISTORY¶
These functions were first added to OpenSSL 1.0.0.