5 EVP_PKEY_verify_init, EVP_PKEY_verify_init_ex, EVP_PKEY_verify
6 - signature verification using a public key algorithm
10 #include <openssl/evp.h>
12 int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx);
13 int EVP_PKEY_verify_init_ex(EVP_PKEY_CTX *ctx, const OSSL_PARAM params[]);
14 int EVP_PKEY_verify(EVP_PKEY_CTX *ctx,
15 const unsigned char *sig, size_t siglen,
16 const unsigned char *tbs, size_t tbslen);
20 EVP_PKEY_verify_init() initializes a public key algorithm context I<ctx> for
21 signing using the algorithm given when the context was created
22 using L<EVP_PKEY_CTX_new(3)> or variants thereof. The algorithm is used to
23 fetch a B<EVP_SIGNATURE> method implicitly, see L<provider(7)/Implicit fetch>
24 for more information about implicit fetches.
26 EVP_PKEY_verify_init_ex() is the same as EVP_PKEY_verify_init() but additionally
27 sets the passed parameters I<params> on the context before returning.
29 The EVP_PKEY_verify() function performs a public key verification operation
30 using I<ctx>. The signature is specified using the I<sig> and
31 I<siglen> parameters. The verified data (i.e. the data believed originally
32 signed) is specified using the I<tbs> and I<tbslen> parameters.
36 After the call to EVP_PKEY_verify_init() algorithm specific control
37 operations can be performed to set any appropriate parameters for the
40 The function EVP_PKEY_verify() can be called more than once on the same
41 context if several operations are performed using the same parameters.
45 EVP_PKEY_verify_init() and EVP_PKEY_verify() return 1 if the verification was
46 successful and 0 if it failed. Unlike other functions the return value 0 from
47 EVP_PKEY_verify() only indicates that the signature did not verify
48 successfully (that is tbs did not match the original data or the signature was
49 of invalid form) it is not an indication of a more serious error.
51 A negative value indicates an error other that signature verification failure.
52 In particular a return value of -2 indicates the operation is not supported by
53 the public key algorithm.
57 Verify signature using PKCS#1 and SHA256 digest:
59 #include <openssl/evp.h>
60 #include <openssl/rsa.h>
63 unsigned char *md, *sig;
68 * NB: assumes verify_key, sig, siglen md and mdlen are already set up
69 * and that verify_key is an RSA public key
71 ctx = EVP_PKEY_CTX_new(verify_key, NULL /* no engine */);
74 if (EVP_PKEY_verify_init(ctx) <= 0)
76 if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
78 if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
81 /* Perform operation */
82 ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
85 * ret == 1 indicates success, 0 verify failure and < 0 for some
91 L<EVP_PKEY_CTX_new(3)>,
92 L<EVP_PKEY_encrypt(3)>,
93 L<EVP_PKEY_decrypt(3)>,
95 L<EVP_PKEY_verify_recover(3)>,
100 The EVP_PKEY_verify_init() and EVP_PKEY_verify() functions were added in
103 The EVP_PKEY_verify_init_ex() function was added in OpenSSL 3.0.
107 Copyright 2006-2021 The OpenSSL Project Authors. All Rights Reserved.
109 Licensed under the Apache License 2.0 (the "License"). You may not use
110 this file except in compliance with the License. You can obtain a copy
111 in the file LICENSE in the source distribution or at
112 L<https://www.openssl.org/source/license.html>.