1EVP_PKEY_verify(3)                  OpenSSL                 EVP_PKEY_verify(3)
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NAME

6       EVP_PKEY_verify_init, EVP_PKEY_verify - signature verification using a
7       public key algorithm
8

SYNOPSIS

10        #include <openssl/evp.h>
11
12        int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx);
13        int EVP_PKEY_verify(EVP_PKEY_CTX *ctx,
14                               const unsigned char *sig, size_t siglen,
15                               const unsigned char *tbs, size_t tbslen);
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DESCRIPTION

18       The EVP_PKEY_verify_init() function initializes a public key algorithm
19       context using key pkey for a signature verification operation.
20
21       The EVP_PKEY_verify() function performs a public key verification
22       operation using ctx. The signature is specified using the sig and
23       siglen parameters. The verified data (i.e. the data believed originally
24       signed) is specified using the tbs and tbslen parameters.
25

NOTES

27       After the call to EVP_PKEY_verify_init() algorithm specific control
28       operations can be performed to set any appropriate parameters for the
29       operation.
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31       The function EVP_PKEY_verify() can be called more than once on the same
32       context if several operations are performed using the same parameters.
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RETURN VALUES

35       EVP_PKEY_verify_init() and EVP_PKEY_verify() return 1 if the
36       verification was successful and 0 if it failed. Unlike other functions
37       the return value 0 from EVP_PKEY_verify() only indicates that the
38       signature did not not verify successfully (that is tbs did not match
39       the original data or the signature was of invalid form) it is not an
40       indication of a more serious error.
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42       A negative value indicates an error other that signature verification
43       failure.  In particular a return value of -2 indicates the operation is
44       not supported by the public key algorithm.
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EXAMPLE

47       Verify signature using PKCS#1 and SHA256 digest:
48
49        #include <openssl/evp.h>
50        #include <openssl/rsa.h>
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52        EVP_PKEY_CTX *ctx;
53        unsigned char *md, *sig;
54        size_t mdlen, siglen;
55        EVP_PKEY *verify_key;
56        /* NB: assumes verify_key, sig, siglen md and mdlen are already set up
57         * and that verify_key is an RSA public key
58         */
59        ctx = EVP_PKEY_CTX_new(verify_key);
60        if (!ctx)
61               /* Error occurred */
62        if (EVP_PKEY_verify_init(ctx) <= 0)
63               /* Error */
64        if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
65               /* Error */
66        if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
67               /* Error */
68
69        /* Perform operation */
70        ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
71
72        /* ret == 1 indicates success, 0 verify failure and < 0 for some
73         * other error.
74         */
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SEE ALSO

77       EVP_PKEY_CTX_new(3), EVP_PKEY_encrypt(3), EVP_PKEY_decrypt(3),
78       EVP_PKEY_sign(3), EVP_PKEY_verify_recover(3), EVP_PKEY_derive(3)
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HISTORY

81       These functions were first added to OpenSSL 1.0.0.
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851.0.2o                            2020-08-01                EVP_PKEY_verify(3)
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