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126 .IX Title "EVP_PKEY_verify 3"
127 .TH EVP_PKEY_verify 3 "2014-08-06" "1.0.1i" "OpenSSL"
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133 EVP_PKEY_verify_init, EVP_PKEY_verify \- signature verification using a public key algorithm
135 .IX Header "SYNOPSIS"
137 \& #include <openssl/evp.h>
139 \& int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx);
140 \& int EVP_PKEY_verify(EVP_PKEY_CTX *ctx,
141 \& const unsigned char *sig, size_t siglen,
142 \& const unsigned char *tbs, size_t tbslen);
145 .IX Header "DESCRIPTION"
146 The \fIEVP_PKEY_verify_init()\fR function initializes a public key algorithm
147 context using key \fBpkey\fR for a signature verification operation.
149 The \fIEVP_PKEY_verify()\fR function performs a public key verification operation
150 using \fBctx\fR. The signature is specified using the \fBsig\fR and
151 \&\fBsiglen\fR parameters. The verified data (i.e. the data believed originally
152 signed) is specified using the \fBtbs\fR and \fBtbslen\fR parameters.
155 After the call to \fIEVP_PKEY_verify_init()\fR algorithm specific control
156 operations can be performed to set any appropriate parameters for the
159 The function \fIEVP_PKEY_verify()\fR can be called more than once on the same
160 context if several operations are performed using the same parameters.
162 .IX Header "RETURN VALUES"
163 \&\fIEVP_PKEY_verify_init()\fR and \fIEVP_PKEY_verify()\fR return 1 if the verification was
164 successful and 0 if it failed. Unlike other functions the return value 0 from
165 \&\fIEVP_PKEY_verify()\fR only indicates that the signature did not not verify
166 successfully (that is tbs did not match the original data or the signature was
167 of invalid form) it is not an indication of a more serious error.
169 A negative value indicates an error other that signature verification failure.
170 In particular a return value of \-2 indicates the operation is not supported by
171 the public key algorithm.
174 Verify signature using PKCS#1 and \s-1SHA256\s0 digest:
177 \& #include <openssl/evp.h>
178 \& #include <openssl/rsa.h>
180 \& EVP_PKEY_CTX *ctx;
181 \& unsigned char *md, *sig;
182 \& size_t mdlen, siglen;
183 \& EVP_PKEY *verify_key;
184 \& /* NB: assumes verify_key, sig, siglen md and mdlen are already set up
185 \& * and that verify_key is an RSA public key
187 \& ctx = EVP_PKEY_CTX_new(verify_key);
189 \& /* Error occurred */
190 \& if (EVP_PKEY_verify_init(ctx) <= 0)
192 \& if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
194 \& if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
197 \& /* Perform operation */
198 \& ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
200 \& /* ret == 1 indicates success, 0 verify failure and < 0 for some
205 .IX Header "SEE ALSO"
206 \&\fIEVP_PKEY_CTX_new\fR\|(3),
207 \&\fIEVP_PKEY_encrypt\fR\|(3),
208 \&\fIEVP_PKEY_decrypt\fR\|(3),
209 \&\fIEVP_PKEY_sign\fR\|(3),
210 \&\fIEVP_PKEY_verify_recover\fR\|(3),
211 \&\fIEVP_PKEY_derive\fR\|(3)
214 These functions were first added to OpenSSL 1.0.0.