=head1 NAME
-EVP_DigestVerifyInit, EVP_DigestVerifyUpdate, EVP_DigestVerifyFinal,
-EVP_DigestVerify - EVP signature verification functions
+EVP_DigestVerifyInit_ex, EVP_DigestVerifyInit, EVP_DigestVerifyUpdate,
+EVP_DigestVerifyFinal, EVP_DigestVerify - EVP signature verification functions
=head1 SYNOPSIS
#include <openssl/evp.h>
+ int EVP_DigestVerifyInit_ex(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
+ const char *mdname, const char *props,
+ EVP_PKEY *pkey, OPENSSL_CTX *libctx);
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);
=head1 DESCRIPTION
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() sets up verification context B<ctx> to use digest
-B<type> from ENGINE B<e> and public key B<pkey>. B<ctx> must be created
-with EVP_MD_CTX_new() before calling this function. If B<pctx> is not NULL the
-EVP_PKEY_CTX of the verification operation will be written to B<*pctx>: this
-can be used to set alternative verification options.
+EVP_DigestVerifyInit_ex() sets up verification context B<ctx> to use a digest
+with the name B<mdname> and public key B<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 B<props> argument
+for the properties to be used during the fetch.
+
+The I<pkey> algorithm is used to fetch a B<EVP_SIGNATURE> method implicitly, to
+be used for the actual signing. See L<provider(7)/Implicit fetch> for
+more information about implict 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.
+
+B<ctx> must be created with EVP_MD_CTX_new() before calling this function. If
+B<pctx> is not NULL, the EVP_PKEY_CTX of the verification operation will be
+written to B<*pctx>: this can be used to set alternative verification options.
+Note that any existing value in B<*pctx> is overwritten. The EVP_PKEY_CTX value
+returned must not be freed directly by the application if B<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 B<OPENSSL_CTX>
+specified in I<libctx> and the property query string specified in I<props>.
+
+No B<EVP_PKEY_CTX> will be created by EVP_DigestSignInit_ex() if the passed
+B<ctx> has already been assigned one via L<EVP_MD_CTX_set_pkey_ctx(3)>. See also
+L<SM2(7)>.
+
+Not all digests can be used for all key types. The following combinations apply.
+
+=over 4
+
+=item DSA
+
+Supports SHA1, SHA224, SHA256, SHA384 and SHA512
+
+=item ECDSA
+
+Supports SHA1, SHA224, SHA256, SHA384, SHA512 and SM3
+
+=item RSA with no padding
+
+Supports no digests (the digest B<type> must be NULL)
+
+=item RSA with X931 padding
+
+Supports SHA1, SHA256, SHA384 and SHA512
+
+=item 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
+
+=item Ed25519 and Ed448
+
+Support no digests (the digest B<type> must be NULL)
+
+=item HMAC
+
+Supports any digest
+
+=item CMAC, Poly1305 and SipHash
+
+Will ignore any digest provided.
+
+=back
+
+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 B<mdname> parameter will be inferred from the supplied digest B<type>,
+and B<props> will be NULL. Where supplied the ENGINE B<e> will be used for the
+signature verification and digest algorithm implementations. B<e> may be NULL.
EVP_DigestVerifyUpdate() hashes B<cnt> bytes of data at B<d> into the
verification context B<ctx>. This function can be called several times on the
-same B<ctx> to include additional data. This function is currently implemented
-using a macro.
+same B<ctx> to include additional data.
EVP_DigestVerifyFinal() verifies the data in B<ctx> against the signature in
B<sig> of length B<siglen>.
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.
+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 L<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.
-Since only a copy of the digest context is ever finalized the context must
+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.
L<EVP_DigestInit(3)>,
L<evp(7)>, L<HMAC(3)>, L<MD2(3)>,
L<MD5(3)>, L<MDC2(3)>, L<RIPEMD160(3)>,
-L<SHA1(3)>, L<dgst(1)>
+L<SHA1(3)>, L<openssl-dgst(1)>,
+L<RAND(7)>
=head1 HISTORY
EVP_DigestVerifyInit(), EVP_DigestVerifyUpdate() and EVP_DigestVerifyFinal()
-were first added to OpenSSL 1.0.0.
+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.
=head1 COPYRIGHT
Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved.
-Licensed under the OpenSSL license (the "License"). You may not use
+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
L<https://www.openssl.org/source/license.html>.
projects / openssl.git / blobdiff