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+=pod
+
+=head1 NAME
+
+EVP_VerifyInit, EVP_VerifyUpdate, EVP_VerifyFinal - EVP signature verification functions
+
+=head1 SYNOPSIS
+
+ #include <openssl/evp.h>
+
+ int EVP_VerifyInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
+ int EVP_VerifyUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
+ int EVP_VerifyFinal(EVP_MD_CTX *ctx,unsigned char *sigbuf, unsigned int siglen,EVP_PKEY *pkey);
+
+ int EVP_VerifyInit(EVP_MD_CTX *ctx, const EVP_MD *type);
+
+=head1 DESCRIPTION
+
+The EVP signature verification routines are a high level interface to digital
+signatures.
+
+EVP_VerifyInit_ex() sets up verification context B<ctx> to use digest
+B<type> from ENGINE B<impl>. B<ctx> must be initialized by calling
+EVP_MD_CTX_init() before calling this function.
+
+EVP_VerifyUpdate() hashes B<cnt> bytes of data at B<d> into the
+verification context B<ctx>. This function can be called several times on the
+same B<ctx> to include additional data.
+
+EVP_VerifyFinal() verifies the data in B<ctx> using the public key B<pkey>
+and against the B<siglen> bytes at B<sigbuf>.
+
+EVP_VerifyInit() initializes verification context B<ctx> to use the default
+implementation of digest B<type>.
+
+=head1 RETURN VALUES
+
+EVP_VerifyInit_ex() and EVP_VerifyUpdate() return 1 for success and 0 for
+failure.
+
+EVP_VerifyFinal() returns 1 for a correct signature, 0 for failure and -1 if some
+other error occurred.
+
+The error codes can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>.
+
+=head1 NOTES
+
+The B<EVP> interface to digital signatures should almost always be used in
+preference to the low level interfaces. This is because the code then becomes
+transparent to the algorithm used and much more flexible.
+
+Due to the link between message digests and public key algorithms the correct
+digest algorithm must be used with the correct public key type. A list of
+algorithms and associated public key algorithms appears in
+L<EVP_DigestInit(3)|EVP_DigestInit(3)>.
+
+The call to EVP_VerifyFinal() internally finalizes a copy of the digest context.
+This means that calls to EVP_VerifyUpdate() and EVP_VerifyFinal() can be called
+later to digest and verify additional data.
+
+Since only a copy of the digest context is ever finalized the context must
+be cleaned up after use by calling EVP_MD_CTX_cleanup() or a memory leak
+will occur.
+
+=head1 BUGS
+
+Older versions of this documentation wrongly stated that calls to
+EVP_VerifyUpdate() could not be made after calling EVP_VerifyFinal().
+
+=head1 SEE ALSO
+
+L<evp(3)|evp(3)>,
+L<EVP_SignInit(3)|EVP_SignInit(3)>,
+L<EVP_DigestInit(3)|EVP_DigestInit(3)>, L<err(3)|err(3)>,
+L<evp(3)|evp(3)>, L<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>,
+L<md5(3)|md5(3)>, L<mdc2(3)|mdc2(3)>, L<ripemd(3)|ripemd(3)>,
+L<sha(3)|sha(3)>, L<dgst(1)|dgst(1)>
+
+=head1 HISTORY
+
+EVP_VerifyInit(), EVP_VerifyUpdate() and EVP_VerifyFinal() are
+available in all versions of SSLeay and OpenSSL.
+
+EVP_VerifyInit_ex() was added in OpenSSL 0.9.7
+
+=cut