EVP_VerifyInit(3)EVP_VerifyInit(3)NAME
EVP_VerifyInit, EVP_VerifyUpdate, EVP_VerifyFinal - EVP signature veri‐
fication 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.
The EVP_VerifyInit() function initializes a verification context ctx to
using digest type. This will typically be supplied by a function such
as EVP_sha1().
The EVP_VerifyUpdate() function 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.
The EVP_VerifyFinal() function verifies the data in ctx using the pub‐
lic key pkey and against the siglen bytes at sigbuf. After calling the
EVP_VerifyFinal() function no additional calls to the EVP_VerifyUp‐
date() function can be made, but the EVP_VerifyInit() function can be
called to initialize a new verification operation.
NOTES
The EVP interface to digital signatures should be used in preference to
the low level interfaces. This is because the code then becomes trans‐
parent 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).
RESTRICTIONS
Several of the functions do not return values. Although the internal
digest operations will never fail some future hardware based operations
might.
RETURN VALUES
The EVP_VerifyInit() and EVP_VerifyUpdate() functions do not return
values.
The EVP_VerifyFinal() function returns 1 for a correct signature, 0 for
failure and -1 if some other error occurred.
The error codes can be obtained by using ERR_get_error().
HISTORY
The EVP_VerifyInit(), EVP_VerifyUpdate(), and EVP_VerifyFinal() func‐
tions are available in all versions of SSLeay and OpenSSL.
SEE ALSO
Commands: dgst(1)
Functions: evp(3), EVP_SignInit(3), EVP_DigestInit(3), err(3), evp(3),
hmac(3), md2(3), md5(3), mdc2(3), ripemd(3), sha(3)EVP_VerifyInit(3)