5 EVP_PKEY_verify_init, EVP_PKEY_verify - signature verification using a public key algorithm
9 #include <openssl/evp.h>
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);
18 The EVP_PKEY_verify_init() function initializes a public key algorithm
19 context using key B<pkey> for a signature verification operation.
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.
28 After the call to EVP_PKEY_verify_init() algorithm specific control
29 operations can be performed to set any appropriate parameters for the
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.
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.
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.
49 Verify signature using PKCS#1 and SHA256 digest:
51 #include <openssl/evp.h>
52 #include <openssl/rsa.h>
55 unsigned char *md, *sig;
58 /* NB: assumes verify_key, sig, siglen md and mdlen are already set up
59 * and that verify_key is an RSA public key
61 ctx = EVP_PKEY_CTX_new(verify_key);
64 if (EVP_PKEY_verify_init(ctx) <= 0)
66 if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
68 if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
71 /* Perform operation */
72 ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
74 /* ret == 1 indicates success, 0 verify failure and < 0 for some
80 L<EVP_PKEY_CTX_new(3)|EVP_PKEY_CTX_new(3)>,
81 L<EVP_PKEY_encrypt(3)|EVP_PKEY_encrypt(3)>,
82 L<EVP_PKEY_decrypt(3)|EVP_PKEY_decrypt(3)>,
83 L<EVP_PKEY_sign(3)|EVP_PKEY_sign(3)>,
84 L<EVP_PKEY_verifyrecover(3)|EVP_PKEY_verifyrecover(3)>,
85 L<EVP_PKEY_derive(3)|EVP_PKEY_derive(3)>
89 These functions were first added to OpenSSL 1.0.0.