Import OpenSSL 1.0.2k (as of svn r86089)

doc/crypto/EVP_PKEY_verify.pod

@@ -0,0 +1,91 @@
+=pod
+
+=head1 NAME
+
+EVP_PKEY_verify_init, EVP_PKEY_verify - signature verification using a public key algorithm
+
+=head1 SYNOPSIS
+
+ #include <openssl/evp.h>
+
+ int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx);
+ int EVP_PKEY_verify(EVP_PKEY_CTX *ctx,
+			const unsigned char *sig, size_t siglen,
+			const unsigned char *tbs, size_t tbslen);
+
+=head1 DESCRIPTION
+
+The EVP_PKEY_verify_init() function initializes a public key algorithm
+context using key B<pkey> for a signature verification operation.
+
+The EVP_PKEY_verify() function performs a public key verification operation
+using B<ctx>. The signature is specified using the B<sig> and
+B<siglen> parameters. The verified data (i.e. the data believed originally
+signed) is specified using the B<tbs> and B<tbslen> parameters.
+
+=head1 NOTES
+
+After the call to EVP_PKEY_verify_init() algorithm specific control
+operations can be performed to set any appropriate parameters for the
+operation.
+
+The function EVP_PKEY_verify() can be called more than once on the same
+context if several operations are performed using the same parameters.
+
+=head1 RETURN VALUES
+
+EVP_PKEY_verify_init() and EVP_PKEY_verify() return 1 if the verification was
+successful and 0 if it failed. Unlike other functions the return value 0 from
+EVP_PKEY_verify() only indicates that the signature did not not verify
+successfully (that is tbs did not match the original data or the signature was
+of invalid form) it is not an indication of a more serious error.
+
+A negative value indicates an error other that signature verification failure.
+In particular a return value of -2 indicates the operation is not supported by
+the public key algorithm.
+
+=head1 EXAMPLE
+
+Verify signature using PKCS#1 and SHA256 digest:
+
+ #include <openssl/evp.h>
+ #include <openssl/rsa.h>
+
+ EVP_PKEY_CTX *ctx;
+ unsigned char *md, *sig;
+ size_t mdlen, siglen; 
+ EVP_PKEY *verify_key;
+ /* NB: assumes verify_key, sig, siglen md and mdlen are already set up
+  * and that verify_key is an RSA public key
+  */
+ ctx = EVP_PKEY_CTX_new(verify_key);
+ if (!ctx)
+	/* Error occurred */
+ if (EVP_PKEY_verify_init(ctx) <= 0)
+	/* Error */
+ if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
+	/* Error */
+ if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
+	/* Error */
+
+ /* Perform operation */
+ ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
+
+ /* ret == 1 indicates success, 0 verify failure and < 0 for some
+  * other error.
+  */
+
+=head1 SEE ALSO
+
+L<EVP_PKEY_CTX_new(3)|EVP_PKEY_CTX_new(3)>,
+L<EVP_PKEY_encrypt(3)|EVP_PKEY_encrypt(3)>,
+L<EVP_PKEY_decrypt(3)|EVP_PKEY_decrypt(3)>,
+L<EVP_PKEY_sign(3)|EVP_PKEY_sign(3)>,
+L<EVP_PKEY_verify_recover(3)|EVP_PKEY_verify_recover(3)>,
+L<EVP_PKEY_derive(3)|EVP_PKEY_derive(3)> 
+
+=head1 HISTORY
+
+These functions were first added to OpenSSL 1.0.0.
+
+=cut