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1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
11031468 MC |
5 | EVP_PKEY_verify_init_ex, EVP_PKEY_verify_init, EVP_PKEY_verify |
6 | - signature verification using a public key algorithm | |
6535bd42 DSH |
7 | |
8 | =head1 SYNOPSIS | |
9 | ||
10 | #include <openssl/evp.h> | |
11 | ||
11031468 | 12 | int EVP_PKEY_verify_init_ex(EVP_PKEY_CTX *ctx, EVP_SIGNATURE *signature); |
6535bd42 DSH |
13 | int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx); |
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); | |
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17 | |
18 | =head1 DESCRIPTION | |
19 | ||
11031468 MC |
20 | The EVP_PKEY_verify_init_ex() function initializes a public key algorithm |
21 | context for performing signature verification using the signature algorithm | |
22 | B<signature>. | |
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 | |
26 | algorithm. | |
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. | |
30 | ||
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. | |
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33 | |
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. | |
38 | ||
39 | =head1 NOTES | |
40 | ||
41 | After the call to EVP_PKEY_verify_init() algorithm specific control | |
42 | operations can be performed to set any appropriate parameters for the | |
43 | operation. | |
44 | ||
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. | |
47 | ||
48 | =head1 RETURN VALUES | |
49 | ||
29cf84c6 DSH |
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 | |
a970b14f | 52 | EVP_PKEY_verify() only indicates that the signature did not verify |
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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. | |
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55 | |
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. | |
59 | ||
cda77422 | 60 | =head1 EXAMPLES |
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61 | |
62 | Verify signature using PKCS#1 and SHA256 digest: | |
63 | ||
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64 | #include <openssl/evp.h> |
65 | #include <openssl/rsa.h> | |
66 | ||
67 | EVP_PKEY_CTX *ctx; | |
68 | unsigned char *md, *sig; | |
1bc74519 | 69 | size_t mdlen, siglen; |
43636910 | 70 | EVP_PKEY *verify_key; |
e9b77246 | 71 | |
2947af32 BB |
72 | /* |
73 | * NB: assumes verify_key, sig, siglen md and mdlen are already set up | |
43636910 DSH |
74 | * and that verify_key is an RSA public key |
75 | */ | |
9db6673e | 76 | ctx = EVP_PKEY_CTX_new(verify_key, NULL /* no engine */); |
43636910 | 77 | if (!ctx) |
2947af32 | 78 | /* Error occurred */ |
43636910 | 79 | if (EVP_PKEY_verify_init(ctx) <= 0) |
2947af32 | 80 | /* Error */ |
43636910 | 81 | if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0) |
2947af32 | 82 | /* Error */ |
43636910 | 83 | if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0) |
2947af32 | 84 | /* Error */ |
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85 | |
86 | /* Perform operation */ | |
6f413ef4 | 87 | ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen); |
43636910 | 88 | |
2947af32 BB |
89 | /* |
90 | * ret == 1 indicates success, 0 verify failure and < 0 for some | |
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91 | * other error. |
92 | */ | |
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93 | |
94 | =head1 SEE ALSO | |
95 | ||
9b86974e RS |
96 | L<EVP_PKEY_CTX_new(3)>, |
97 | L<EVP_PKEY_encrypt(3)>, | |
98 | L<EVP_PKEY_decrypt(3)>, | |
99 | L<EVP_PKEY_sign(3)>, | |
100 | L<EVP_PKEY_verify_recover(3)>, | |
1bc74519 | 101 | L<EVP_PKEY_derive(3)> |
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102 | |
103 | =head1 HISTORY | |
104 | ||
11031468 MC |
105 | EVP_PKEY_verify_init_ex() was added in OpenSSL 3.0. |
106 | All other functions were added in OpenSSL 1.0.0. | |
6535bd42 | 107 | |
e2f92610 RS |
108 | =head1 COPYRIGHT |
109 | ||
48e5119a | 110 | Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved. |
e2f92610 | 111 | |
4746f25a | 112 | Licensed under the Apache License 2.0 (the "License"). You may not use |
e2f92610 RS |
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>. | |
116 | ||
117 | =cut |