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1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
5 | EVP_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 | ||
18 | The EVP_PKEY_verify_init() function initializes a public key algorithm | |
19 | context using key B<pkey> for a signature verification operation. | |
20 | ||
21 | The EVP_PKEY_verify() function performs a public key verification operation | |
22 | using B<ctx>. The signature is specified using the B<sig> and | |
23 | B<siglen> parameters. The verified data (i.e. the data believed originally | |
24 | signed) is specified using the B<tbs> and B<tbslen> parameters. | |
25 | ||
26 | =head1 NOTES | |
27 | ||
28 | After the call to EVP_PKEY_verify_init() algorithm specific control | |
29 | operations can be performed to set any appropriate parameters for the | |
30 | operation. | |
31 | ||
32 | The function EVP_PKEY_verify() can be called more than once on the same | |
33 | context if several operations are performed using the same parameters. | |
34 | ||
35 | =head1 RETURN VALUES | |
36 | ||
29cf84c6 DSH |
37 | EVP_PKEY_verify_init() and EVP_PKEY_verify() return 1 if the verification was |
38 | successful and 0 if it failed. Unlike other functions the return value 0 from | |
39 | EVP_PKEY_verify() only indicates that the signature did not not verify | |
40 | successfully (that is tbs did not match the original data or the signature was | |
41 | of invalid form) it is not an indication of a more serious error. | |
6535bd42 DSH |
42 | |
43 | A negative value indicates an error other that signature verification failure. | |
44 | In particular a return value of -2 indicates the operation is not supported by | |
45 | the public key algorithm. | |
46 | ||
47 | =head1 EXAMPLE | |
48 | ||
49 | Verify signature using PKCS#1 and SHA256 digest: | |
50 | ||
43636910 DSH |
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 | /* NB: assumes verify_key, sig, siglen md and mdlen are already set up | |
59 | * and that verify_key is an RSA public key | |
60 | */ | |
61 | ctx = EVP_PKEY_CTX_new(verify_key); | |
62 | if (!ctx) | |
63 | /* Error occurred */ | |
64 | if (EVP_PKEY_verify_init(ctx) <= 0) | |
65 | /* Error */ | |
66 | if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0) | |
67 | /* Error */ | |
68 | if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0) | |
69 | /* Error */ | |
70 | ||
71 | /* Perform operation */ | |
6f413ef4 | 72 | ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen); |
43636910 DSH |
73 | |
74 | /* ret == 1 indicates success, 0 verify failure and < 0 for some | |
75 | * other error. | |
76 | */ | |
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77 | |
78 | =head1 SEE ALSO | |
79 | ||
9b86974e RS |
80 | L<EVP_PKEY_CTX_new(3)>, |
81 | L<EVP_PKEY_encrypt(3)>, | |
82 | L<EVP_PKEY_decrypt(3)>, | |
83 | L<EVP_PKEY_sign(3)>, | |
84 | L<EVP_PKEY_verify_recover(3)>, | |
85 | L<EVP_PKEY_derive(3)> | |
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86 | |
87 | =head1 HISTORY | |
88 | ||
fb552ac6 | 89 | These functions were first added to OpenSSL 1.0.0. |
6535bd42 DSH |
90 | |
91 | =cut | |
e2f92610 RS |
92 | |
93 | =head1 COPYRIGHT | |
94 | ||
95 | Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved. | |
96 | ||
97 | Licensed under the OpenSSL license (the "License"). You may not use | |
98 | this file except in compliance with the License. You can obtain a copy | |
99 | in the file LICENSE in the source distribution or at | |
100 | L<https://www.openssl.org/source/license.html>. | |
101 | ||
102 | =cut |