EVP_DigestVerifyInit, EVP_DigestVerifyUpdate, EVP_DigestVerifyFinal,
EVP_DigestVerify - EVP signature verification functions
#include <openssl/evp.h>
int EVP_DigestVerifyInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey);
int EVP_DigestVerifyUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
int EVP_DigestVerifyFinal(EVP_MD_CTX *ctx, const unsigned char *sig,
size_t siglen);
int EVP_DigestVerify(EVP_MD_CTX *ctx, const unsigned char *sigret,
size_t siglen, const unsigned char *tbs, size_t tbslen);
The EVP signature routines are a high level interface to digital signatures.
EVP_DigestVerifyInit() sets up verification context
ctx to use
digest
type from ENGINE
e and public key
pkey.
ctx
must be created with
EVP_MD_CTX_new() before calling this function. If
pctx is not NULL, the EVP_PKEY_CTX of the verification operation will
be written to
*pctx: this can be used to set alternative verification
options. Note that any existing value in
*pctx is overwritten. The
EVP_PKEY_CTX value returned must not be freed directly by the application if
ctx is not assigned an EVP_PKEY_CTX value before being passed to
EVP_DigestSignInit() (which means the EVP_PKEY_CTX is created inside
EVP_DigestSignInit() and it will be freed automatically when the
EVP_MD_CTX is freed).
No
EVP_PKEY_CTX will be created by
EVP_DigsetSignInit() if the
passed
ctx has already been assigned one via
EVP_MD_CTX_set_ctx(3). See also
SM2(7).
EVP_DigestVerifyUpdate() 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. This function is currently
implemented using a macro.
EVP_DigestVerifyFinal() verifies the data in
ctx against the
signature in
sig of length
siglen.
EVP_DigestVerify() verifies
tbslen bytes at
tbs against the
signature in
sig of length
siglen.
EVP_DigestVerifyInit() and
EVP_DigestVerifyUpdate() return 1 for
success and 0 for failure.
EVP_DigestVerifyFinal() and
EVP_DigestVerify() return 1 for
success; any other value indicates failure. A return value of zero indicates
that the signature did not verify successfully (that is,
tbs did not
match the original data or the signature had an invalid form), while other
values indicate a more serious error (and sometimes also indicate an invalid
signature form).
The error codes can be obtained from
ERR_get_error(3).
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.
EVP_DigestVerify() is a one shot operation which verifies a single block
of data in one function. For algorithms that support streaming it is
equivalent to calling
EVP_DigestVerifyUpdate() and
EVP_DigestVerifyFinal(). For algorithms which do not support streaming
(e.g. PureEdDSA) it is the only way to verify data.
In previous versions of OpenSSL there was a link between message digest types
and public key algorithms. This meant that "clone" digests such as
EVP_dss1() needed to be used to sign using SHA1 and DSA. This is no
longer necessary and the use of clone digest is now discouraged.
For some key types and parameters the random number generator must be seeded or
the operation will fail.
The call to
EVP_DigestVerifyFinal() internally finalizes a copy of the
digest context. This means that
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_free() or a memory leak will
occur.
EVP_DigestSignInit(3),
EVP_DigestInit(3),
evp(7),
HMAC(3),
MD2(3),
MD5(3),
MDC2(3),
RIPEMD160(3),
SHA1(3),
dgst(1)
EVP_DigestVerifyInit(),
EVP_DigestVerifyUpdate() and
EVP_DigestVerifyFinal() were first added to OpenSSL 1.0.0.
Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy in the
file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.