EVP_DigestVerifyInit_ex, EVP_DigestVerifyInit, EVP_DigestVerifyUpdate,
EVP_DigestVerifyFinal, EVP_DigestVerify - EVP signature verification functions
#include <openssl/evp.h>
int EVP_DigestVerifyInit_ex(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
const char *mdname, OSSL_LIB_CTX *libctx,
const char *props, EVP_PKEY *pkey,
const OSSL_PARAM params[]);
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.
Input data is digested first before the signature verification takes place.
EVP_DigestVerifyInit_ex() sets up verification context
ctx to use
a digest with the name
mdname and public key
pkey. The name of
the digest to be used is passed to the provider of the signature algorithm in
use. How that provider interprets the digest name is provider specific. The
provider may implement that digest directly itself or it may (optionally)
choose to fetch it (which could result in a digest from a different provider
being selected). If the provider supports fetching the digest then it may use
the
props argument for the properties to be used during the fetch.
Finally, the passed parameters
params, if not NULL, are set on the
context before returning.
The
pkey algorithm is used to fetch a
EVP_SIGNATURE method
implicitly, to be used for the actual signing. See "Implicit fetch"
in
provider(7) for more information about implicit fetches.
The OpenSSL default and legacy providers support fetching digests and can fetch
those digests from any available provider. The OpenSSL FIPS provider also
supports fetching digests but will only fetch digests that are themselves
implemented inside the FIPS provider.
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_DigestVerifyInit_ex() (which means the EVP_PKEY_CTX is
created inside
EVP_DigestVerifyInit_ex() and it will be freed
automatically when the EVP_MD_CTX is freed). If the EVP_PKEY_CTX to be used is
created by EVP_DigestVerifyInit_ex then it will use the
OSSL_LIB_CTX
specified in
libctx and the property query string specified in
props.
No
EVP_PKEY_CTX will be created by
EVP_DigestVerifyInit_ex() if
the passed
ctx has already been assigned one via
EVP_MD_CTX_set_pkey_ctx(3). See also
SM2(7).
Not all digests can be used for all key types. The following combinations apply.
- DSA
- Supports SHA1, SHA224, SHA256, SHA384 and SHA512
- ECDSA
- Supports SHA1, SHA224, SHA256, SHA384, SHA512 and SM3
- RSA with no padding
- Supports no digests (the digest type must be
NULL)
- RSA with X931 padding
- Supports SHA1, SHA256, SHA384 and SHA512
- All other RSA padding types
- Support SHA1, SHA224, SHA256, SHA384, SHA512, MD5,
MD5_SHA1, MD2, MD4, MDC2, SHA3-224, SHA3-256, SHA3-384, SHA3-512
- Ed25519 and Ed448
- Support no digests (the digest type must be
NULL)
- HMAC
- Supports any digest
- CMAC, Poly1305 and Siphash
- Will ignore any digest provided.
If RSA-PSS is used and restrictions apply then the digest must match.
EVP_DigestVerifyInit() works in the same way as
EVP_DigestVerifyInit_ex() except that the
mdname parameter will
be inferred from the supplied digest
type, and
props will be
NULL. Where supplied the ENGINE
e will be used for the signature
verification and digest algorithm implementations.
e may be NULL.
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.
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. If
the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to external
circumstances (see
RAND(7)), 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.
EVP_DigestVerifyInit() and
EVP_DigestVerifyInit_ex() functions can
be called multiple times on a context and the parameters set by previous calls
should be preserved if the
pkey parameter is NULL. The call then just
resets the state of the
ctx.
Ignoring failure returns of
EVP_DigestVerifyInit() and
EVP_DigestVerifyInit_ex() functions can lead to subsequent undefined
behavior when calling
EVP_DigestVerifyUpdate(),
EVP_DigestVerifyFinal(), or
EVP_DigestVerify().
EVP_DigestSignInit(3),
EVP_DigestInit(3),
evp(7),
HMAC(3),
MD2(3),
MD5(3),
MDC2(3),
RIPEMD160(3),
SHA1(3),
openssl-dgst(1),
RAND(7)
EVP_DigestVerifyInit(),
EVP_DigestVerifyUpdate() and
EVP_DigestVerifyFinal() were added in OpenSSL 1.0.0.
EVP_DigestVerifyInit_ex() was added in OpenSSL 3.0.
EVP_DigestVerifyUpdate() was converted from a macro to a function in
OpenSSL 3.0.
Copyright 2006-2023 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (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>.