1=pod 2 3=head1 NAME 4 5EVP_PKEY_verify_init, EVP_PKEY_verify - signature verification using a public key algorithm 6 7=head1 SYNOPSIS 8 9 #include <openssl/evp.h> 10 11 int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx); 12 int EVP_PKEY_verify(EVP_PKEY_CTX *ctx, 13 const unsigned char *sig, size_t siglen, 14 const unsigned char *tbs, size_t tbslen); 15 16=head1 DESCRIPTION 17 18The EVP_PKEY_verify_init() function initializes a public key algorithm 19context using key B<pkey> for a signature verification operation. 20 21The EVP_PKEY_verify() function performs a public key verification operation 22using B<ctx>. The signature is specified using the B<sig> and 23B<siglen> parameters. The verified data (i.e. the data believed originally 24signed) is specified using the B<tbs> and B<tbslen> parameters. 25 26=head1 NOTES 27 28After the call to EVP_PKEY_verify_init() algorithm specific control 29operations can be performed to set any appropriate parameters for the 30operation. 31 32The function EVP_PKEY_verify() can be called more than once on the same 33context if several operations are performed using the same parameters. 34 35=head1 RETURN VALUES 36 37EVP_PKEY_verify_init() and EVP_PKEY_verify() return 1 if the verification was 38successful and 0 if it failed. Unlike other functions the return value 0 from 39EVP_PKEY_verify() only indicates that the signature did not verify 40successfully (that is tbs did not match the original data or the signature was 41of invalid form) it is not an indication of a more serious error. 42 43A negative value indicates an error other that signature verification failure. 44In particular a return value of -2 indicates the operation is not supported by 45the public key algorithm. 46 47=head1 EXAMPLES 48 49Verify signature using PKCS#1 and SHA256 digest: 50 51 #include <openssl/evp.h> 52 #include <openssl/rsa.h> 53 54 EVP_PKEY_CTX *ctx; 55 unsigned char *md, *sig; 56 size_t mdlen, siglen; 57 EVP_PKEY *verify_key; 58 59 /* 60 * NB: assumes verify_key, sig, siglen md and mdlen are already set up 61 * and that verify_key is an RSA public key 62 */ 63 ctx = EVP_PKEY_CTX_new(verify_key, NULL /* no engine */); 64 if (!ctx) 65 /* Error occurred */ 66 if (EVP_PKEY_verify_init(ctx) <= 0) 67 /* Error */ 68 if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0) 69 /* Error */ 70 if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0) 71 /* Error */ 72 73 /* Perform operation */ 74 ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen); 75 76 /* 77 * ret == 1 indicates success, 0 verify failure and < 0 for some 78 * other error. 79 */ 80 81=head1 SEE ALSO 82 83L<EVP_PKEY_CTX_new(3)>, 84L<EVP_PKEY_encrypt(3)>, 85L<EVP_PKEY_decrypt(3)>, 86L<EVP_PKEY_sign(3)>, 87L<EVP_PKEY_verify_recover(3)>, 88L<EVP_PKEY_derive(3)> 89 90=head1 HISTORY 91 92These functions were added in OpenSSL 1.0.0. 93 94=head1 COPYRIGHT 95 96Copyright 2006-2019 The OpenSSL Project Authors. All Rights Reserved. 97 98Licensed under the OpenSSL license (the "License"). You may not use 99this file except in compliance with the License. You can obtain a copy 100in the file LICENSE in the source distribution or at 101L<https://www.openssl.org/source/license.html>. 102 103=cut 104