EVP_VerifyInit, EVP_VerifyUpdate, EVP_VerifyFinal - EVP
signature verification functions
SYNOPSIS
#include <openssl/evp.h>
void EVP_VerifyInit(EVP_MD_CTX *ctx, const EVP_MD *type);
void 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);
DESCRIPTION
The EVP signature verification routines are a high level
interface to digital signatures.
EVP_VerifyInit() initializes a verification context ctx to
using digest type: this will typically be supplied by a
function such as EVP_sha1().
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.
After calling EVP_VerifyFinal() no additional calls to
EVP_VerifyUpdate() can be made, but EVP_VerifyInit() can
be called to initialize a new verification operation.
RETURN VALUES
EVP_VerifyInit() and EVP_VerifyUpdate() do not return
values.
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).
BUGS
Several of the functions do not return values: maybe they
should. Although the internal digest operations will never
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), digest(1)
HISTORY
EVP_VerifyInit(), EVP_VerifyUpdate() and EVP_VerifyFinal()
are available in all versions of SSLeay and OpenSSL.
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