EVP_VerifyInit(3) OpenSSL EVP_VerifyInit(3)NAME
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 VALUESEVP_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 fail some future
hardware based operations might.
SEE ALSOevp(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)HISTORYEVP_VerifyInit(), EVP_VerifyUpdate() and EVP_VerifyFinal() are
available in all versions of SSLeay and OpenSSL.
3rd Berkeley Distribution 0.9.6m EVP_VerifyInit(3)
