5 EVP_PKEY_verify_init_ex, EVP_PKEY_verify_init, EVP_PKEY_verify
6 - signature verification using a public key algorithm
10 #include <openssl/evp.h>
12 int EVP_PKEY_verify_init_ex(EVP_PKEY_CTX *ctx, EVP_SIGNATURE *signature);
13 int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx);
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 The EVP_PKEY_verify_init_ex() function initializes a public key algorithm
21 context for performing signature verification using the signature algorithm
23 The signature algorithm B<signature> should be fetched using a call to
24 L<EVP_SIGNATURE_fetch(3)>.
25 The EVP_PKEY object associated with B<ctx> must be compatible with that
27 B<signature> may be NULL in which case the EVP_SIGNATURE algorithm is fetched
28 implicitly based on the type of EVP_PKEY associated with B<ctx>.
29 See L<provider(7)/Implicit fetch> for more information about implict fetches.
31 The EVP_PKEY_verify_init() function is the same as EVP_PKEY_verify_init_ex()
32 except that the EVP_SIGNATURE algorithm is always implicitly fetched.
34 The EVP_PKEY_verify() function performs a public key verification operation
35 using B<ctx>. The signature is specified using the B<sig> and
36 B<siglen> parameters. The verified data (i.e. the data believed originally
37 signed) is specified using the B<tbs> and B<tbslen> parameters.
41 After the call to EVP_PKEY_verify_init() algorithm specific control
42 operations can be performed to set any appropriate parameters for the
45 The function EVP_PKEY_verify() can be called more than once on the same
46 context if several operations are performed using the same parameters.
50 EVP_PKEY_verify_init() and EVP_PKEY_verify() return 1 if the verification was
51 successful and 0 if it failed. Unlike other functions the return value 0 from
52 EVP_PKEY_verify() only indicates that the signature did not verify
53 successfully (that is tbs did not match the original data or the signature was
54 of invalid form) it is not an indication of a more serious error.
56 A negative value indicates an error other that signature verification failure.
57 In particular a return value of -2 indicates the operation is not supported by
58 the public key algorithm.
62 Verify signature using PKCS#1 and SHA256 digest:
64 #include <openssl/evp.h>
65 #include <openssl/rsa.h>
68 unsigned char *md, *sig;
73 * NB: assumes verify_key, sig, siglen md and mdlen are already set up
74 * and that verify_key is an RSA public key
76 ctx = EVP_PKEY_CTX_new(verify_key, NULL /* no engine */);
79 if (EVP_PKEY_verify_init(ctx) <= 0)
81 if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
83 if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
86 /* Perform operation */
87 ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
90 * ret == 1 indicates success, 0 verify failure and < 0 for some
96 L<EVP_PKEY_CTX_new(3)>,
97 L<EVP_PKEY_encrypt(3)>,
98 L<EVP_PKEY_decrypt(3)>,
100 L<EVP_PKEY_verify_recover(3)>,
101 L<EVP_PKEY_derive(3)>
105 EVP_PKEY_verify_init_ex() was added in OpenSSL 3.0.
106 All other functions were added in OpenSSL 1.0.0.
110 Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved.
112 Licensed under the Apache License 2.0 (the "License"). You may not use
113 this file except in compliance with the License. You can obtain a copy
114 in the file LICENSE in the source distribution or at
115 L<https://www.openssl.org/source/license.html>.