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135 .IX Title "EVP_PKEY_verify 3"
136 .TH EVP_PKEY_verify 3 "2016-05-03" "1.0.2h" "OpenSSL"
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142 EVP_PKEY_verify_init, EVP_PKEY_verify \- signature verification using a public key algorithm
144 .IX Header "SYNOPSIS"
146 \& #include <openssl/evp.h>
148 \& int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx);
149 \& int EVP_PKEY_verify(EVP_PKEY_CTX *ctx,
150 \& const unsigned char *sig, size_t siglen,
151 \& const unsigned char *tbs, size_t tbslen);
154 .IX Header "DESCRIPTION"
155 The \fIEVP_PKEY_verify_init()\fR function initializes a public key algorithm
156 context using key \fBpkey\fR for a signature verification operation.
158 The \fIEVP_PKEY_verify()\fR function performs a public key verification operation
159 using \fBctx\fR. The signature is specified using the \fBsig\fR and
160 \&\fBsiglen\fR parameters. The verified data (i.e. the data believed originally
161 signed) is specified using the \fBtbs\fR and \fBtbslen\fR parameters.
164 After the call to \fIEVP_PKEY_verify_init()\fR algorithm specific control
165 operations can be performed to set any appropriate parameters for the
168 The function \fIEVP_PKEY_verify()\fR can be called more than once on the same
169 context if several operations are performed using the same parameters.
171 .IX Header "RETURN VALUES"
172 \&\fIEVP_PKEY_verify_init()\fR and \fIEVP_PKEY_verify()\fR return 1 if the verification was
173 successful and 0 if it failed. Unlike other functions the return value 0 from
174 \&\fIEVP_PKEY_verify()\fR only indicates that the signature did not not verify
175 successfully (that is tbs did not match the original data or the signature was
176 of invalid form) it is not an indication of a more serious error.
178 A negative value indicates an error other that signature verification failure.
179 In particular a return value of \-2 indicates the operation is not supported by
180 the public key algorithm.
183 Verify signature using PKCS#1 and \s-1SHA256\s0 digest:
186 \& #include <openssl/evp.h>
187 \& #include <openssl/rsa.h>
189 \& EVP_PKEY_CTX *ctx;
190 \& unsigned char *md, *sig;
191 \& size_t mdlen, siglen;
192 \& EVP_PKEY *verify_key;
193 \& /* NB: assumes verify_key, sig, siglen md and mdlen are already set up
194 \& * and that verify_key is an RSA public key
196 \& ctx = EVP_PKEY_CTX_new(verify_key);
198 \& /* Error occurred */
199 \& if (EVP_PKEY_verify_init(ctx) <= 0)
201 \& if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
203 \& if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
206 \& /* Perform operation */
207 \& ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
209 \& /* ret == 1 indicates success, 0 verify failure and < 0 for some
214 .IX Header "SEE ALSO"
215 \&\fIEVP_PKEY_CTX_new\fR\|(3),
216 \&\fIEVP_PKEY_encrypt\fR\|(3),
217 \&\fIEVP_PKEY_decrypt\fR\|(3),
218 \&\fIEVP_PKEY_sign\fR\|(3),
219 \&\fIEVP_PKEY_verify_recover\fR\|(3),
220 \&\fIEVP_PKEY_derive\fR\|(3)
223 These functions were first added to OpenSSL 1.0.0.