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6535bd42 DSH |
1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
ee22fca5 | 5 | EVP_PKEY_verify_init, EVP_PKEY_verify_init_ex, EVP_PKEY_verify |
11031468 | 6 | - signature verification using a public key algorithm |
6535bd42 DSH |
7 | |
8 | =head1 SYNOPSIS | |
9 | ||
10 | #include <openssl/evp.h> | |
11 | ||
12 | int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx); | |
ee22fca5 | 13 | int EVP_PKEY_verify_init_ex(EVP_PKEY_CTX *ctx, const OSSL_PARAM params[]); |
6535bd42 | 14 | int EVP_PKEY_verify(EVP_PKEY_CTX *ctx, |
e9b77246 BB |
15 | const unsigned char *sig, size_t siglen, |
16 | const unsigned char *tbs, size_t tbslen); | |
6535bd42 DSH |
17 | |
18 | =head1 DESCRIPTION | |
19 | ||
0e521004 RL |
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> | |
8c1cbc72 | 24 | for more information about implicit fetches. |
6535bd42 | 25 | |
ee22fca5 P |
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. | |
28 | ||
6535bd42 | 29 | The EVP_PKEY_verify() function performs a public key verification operation |
0e521004 RL |
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. | |
6535bd42 DSH |
33 | |
34 | =head1 NOTES | |
35 | ||
36 | After the call to EVP_PKEY_verify_init() algorithm specific control | |
37 | operations can be performed to set any appropriate parameters for the | |
38 | operation. | |
39 | ||
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. | |
42 | ||
43 | =head1 RETURN VALUES | |
44 | ||
29cf84c6 DSH |
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 | |
a970b14f | 47 | EVP_PKEY_verify() only indicates that the signature did not verify |
29cf84c6 DSH |
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. | |
6535bd42 DSH |
50 | |
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. | |
54 | ||
cda77422 | 55 | =head1 EXAMPLES |
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56 | |
57 | Verify signature using PKCS#1 and SHA256 digest: | |
58 | ||
43636910 DSH |
59 | #include <openssl/evp.h> |
60 | #include <openssl/rsa.h> | |
61 | ||
62 | EVP_PKEY_CTX *ctx; | |
63 | unsigned char *md, *sig; | |
1bc74519 | 64 | size_t mdlen, siglen; |
43636910 | 65 | EVP_PKEY *verify_key; |
e9b77246 | 66 | |
2947af32 BB |
67 | /* |
68 | * NB: assumes verify_key, sig, siglen md and mdlen are already set up | |
43636910 DSH |
69 | * and that verify_key is an RSA public key |
70 | */ | |
9db6673e | 71 | ctx = EVP_PKEY_CTX_new(verify_key, NULL /* no engine */); |
43636910 | 72 | if (!ctx) |
2947af32 | 73 | /* Error occurred */ |
43636910 | 74 | if (EVP_PKEY_verify_init(ctx) <= 0) |
2947af32 | 75 | /* Error */ |
43636910 | 76 | if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0) |
2947af32 | 77 | /* Error */ |
43636910 | 78 | if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0) |
2947af32 | 79 | /* Error */ |
43636910 DSH |
80 | |
81 | /* Perform operation */ | |
6f413ef4 | 82 | ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen); |
43636910 | 83 | |
2947af32 BB |
84 | /* |
85 | * ret == 1 indicates success, 0 verify failure and < 0 for some | |
43636910 DSH |
86 | * other error. |
87 | */ | |
6535bd42 DSH |
88 | |
89 | =head1 SEE ALSO | |
90 | ||
9b86974e RS |
91 | L<EVP_PKEY_CTX_new(3)>, |
92 | L<EVP_PKEY_encrypt(3)>, | |
93 | L<EVP_PKEY_decrypt(3)>, | |
94 | L<EVP_PKEY_sign(3)>, | |
95 | L<EVP_PKEY_verify_recover(3)>, | |
1bc74519 | 96 | L<EVP_PKEY_derive(3)> |
6535bd42 DSH |
97 | |
98 | =head1 HISTORY | |
99 | ||
ee22fca5 P |
100 | The EVP_PKEY_verify_init() and EVP_PKEY_verify() functions were added in |
101 | OpenSSL 1.0.0. | |
102 | ||
103 | The EVP_PKEY_verify_init_ex() function was added in OpenSSL 3.0. | |
6535bd42 | 104 | |
e2f92610 RS |
105 | =head1 COPYRIGHT |
106 | ||
3c2bdd7d | 107 | Copyright 2006-2021 The OpenSSL Project Authors. All Rights Reserved. |
e2f92610 | 108 | |
4746f25a | 109 | Licensed under the Apache License 2.0 (the "License"). You may not use |
e2f92610 RS |
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>. | |
113 | ||
114 | =cut |