/xlv3/openssl/0.9.7e-sgipl1/work/0.9.7e-sgipl1/openssl-
0.9.7e/doc/crypto
Page 1 (printed 10/20/05)
EVP_VerifyInit(3) 10/Jul/2002 (0.9.7e) EVP_VerifyInit(3)
NAME
EVP_VerifyInit, EVP_VerifyUpdate, EVP_VerifyFinal - EVP
signature verification functions
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);
DESCRIPTION
The EVP signature verification routines are a high level
interface to digital signatures.
EVP_VerifyInit_ex() sets up verification context ctx to use
digest type from ENGINE impl. ctx must be initialized by
calling EVP_MD_CTX_init() before calling this function.
EVP_VerifyUpdate() hashes cnt bytes of data at d into the
verification context ctx. This function can be called
several times on the same ctx to include additional data.
EVP_VerifyFinal() verifies the data in ctx using the public
key pkey and against the siglen bytes at sigbuf.
EVP_VerifyInit() initializes verification context ctx to use
the default implementation of digest type.
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 ERR_get_error(3).
NOTES
The 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
EVP_DigestInit(3).
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EVP_VerifyInit(3) 10/Jul/2002 (0.9.7e) EVP_VerifyInit(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.
BUGS
Older versions of this documentation wrongly stated that
calls to EVP_VerifyUpdate() could not be made after calling
EVP_VerifyFinal().
SEE ALSO
evp(3), EVP_SignInit(3), EVP_DigestInit(3), err(3), evp(3),
hmac(3), md2(3), md5(3), mdc2(3), ripemd(3), sha(3), dgst(1)
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
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