5 EVP_DigestVerifyInit_ex, EVP_DigestVerifyInit, EVP_DigestVerifyUpdate,
6 EVP_DigestVerifyFinal, EVP_DigestVerify - EVP signature verification functions
10 #include <openssl/evp.h>
12 int EVP_DigestVerifyInit_ex(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
13 const char *mdname, OSSL_LIB_CTX *libctx,
14 const char *props, EVP_PKEY *pkey,
15 const OSSL_PARAM params[]);
16 int EVP_DigestVerifyInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
17 const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey);
18 int EVP_DigestVerifyUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
19 int EVP_DigestVerifyFinal(EVP_MD_CTX *ctx, const unsigned char *sig,
21 int EVP_DigestVerify(EVP_MD_CTX *ctx, const unsigned char *sig,
22 size_t siglen, const unsigned char *tbs, size_t tbslen);
26 The EVP signature routines are a high-level interface to digital signatures.
27 Input data is digested first before the signature verification takes place.
29 EVP_DigestVerifyInit_ex() sets up verification context B<ctx> to use a
30 digest with the name B<mdname> and public key B<pkey>. The name of the digest to
31 be used is passed to the provider of the signature algorithm in use. How that
32 provider interprets the digest name is provider specific. The provider may
33 implement that digest directly itself or it may (optionally) choose to fetch it
34 (which could result in a digest from a different provider being selected). If
35 the provider supports fetching the digest then it may use the B<props> argument
36 for the properties to be used during the fetch. Finally, the passed parameters
37 I<params>, if not NULL, are set on the context before returning.
39 The I<pkey> algorithm is used to fetch a B<EVP_SIGNATURE> method implicitly, to
40 be used for the actual signing. See L<provider(7)/Implicit fetch> for
41 more information about implicit fetches.
43 The OpenSSL default and legacy providers support fetching digests and can fetch
44 those digests from any available provider. The OpenSSL FIPS provider also
45 supports fetching digests but will only fetch digests that are themselves
46 implemented inside the FIPS provider.
48 B<ctx> must be created with EVP_MD_CTX_new() before calling this function. If
49 B<pctx> is not NULL, the EVP_PKEY_CTX of the verification operation will be
50 written to B<*pctx>: this can be used to set alternative verification options.
51 Note that any existing value in B<*pctx> is overwritten. The EVP_PKEY_CTX value
52 returned must not be freed directly by the application if B<ctx> is not assigned
53 an EVP_PKEY_CTX value before being passed to EVP_DigestVerifyInit_ex()
54 (which means the EVP_PKEY_CTX is created inside
55 EVP_DigestVerifyInit_ex() and it will be freed automatically when the
56 EVP_MD_CTX is freed). If the EVP_PKEY_CTX to be used is created by
57 EVP_DigestVerifyInit_ex then it will use the B<OSSL_LIB_CTX> specified
58 in I<libctx> and the property query string specified in I<props>.
60 No B<EVP_PKEY_CTX> will be created by EVP_DigestVerifyInit_ex() if the
61 passed B<ctx> has already been assigned one via L<EVP_MD_CTX_set_pkey_ctx(3)>.
64 Not all digests can be used for all key types. The following combinations apply.
70 Supports SHA1, SHA224, SHA256, SHA384 and SHA512
74 Supports SHA1, SHA224, SHA256, SHA384, SHA512 and SM3
76 =item RSA with no padding
78 Supports no digests (the digest B<type> must be NULL)
80 =item RSA with X931 padding
82 Supports SHA1, SHA256, SHA384 and SHA512
84 =item All other RSA padding types
86 Support SHA1, SHA224, SHA256, SHA384, SHA512, MD5, MD5_SHA1, MD2, MD4, MDC2,
87 SHA3-224, SHA3-256, SHA3-384, SHA3-512
89 =item Ed25519 and Ed448
91 Support no digests (the digest B<type> must be NULL)
97 =item CMAC, Poly1305 and Siphash
99 Will ignore any digest provided.
103 If RSA-PSS is used and restrictions apply then the digest must match.
105 EVP_DigestVerifyInit() works in the same way as
106 EVP_DigestVerifyInit_ex() except that the B<mdname> parameter will be
107 inferred from the supplied digest B<type>, and B<props> will be NULL. Where
108 supplied the ENGINE B<e> will be used for the signature verification and digest
109 algorithm implementations. B<e> may be NULL.
111 EVP_DigestVerifyUpdate() hashes B<cnt> bytes of data at B<d> into the
112 verification context B<ctx>. This function can be called several times on the
113 same B<ctx> to include additional data.
115 EVP_DigestVerifyFinal() verifies the data in B<ctx> against the signature in
116 B<sig> of length B<siglen>.
118 EVP_DigestVerify() verifies B<tbslen> bytes at B<tbs> against the signature
119 in B<sig> of length B<siglen>.
123 EVP_DigestVerifyInit() and EVP_DigestVerifyUpdate() return 1 for success and 0
126 EVP_DigestVerifyFinal() and EVP_DigestVerify() return 1 for success; any other
127 value indicates failure. A return value of zero indicates that the signature
128 did not verify successfully (that is, B<tbs> did not match the original data or
129 the signature had an invalid form), while other values indicate a more serious
130 error (and sometimes also indicate an invalid signature form).
132 The error codes can be obtained from L<ERR_get_error(3)>.
136 The B<EVP> interface to digital signatures should almost always be used in
137 preference to the low-level interfaces. This is because the code then becomes
138 transparent to the algorithm used and much more flexible.
140 EVP_DigestVerify() is a one shot operation which verifies a single block of
141 data in one function. For algorithms that support streaming it is equivalent
142 to calling EVP_DigestVerifyUpdate() and EVP_DigestVerifyFinal(). For
143 algorithms which do not support streaming (e.g. PureEdDSA) it is the only way
146 In previous versions of OpenSSL there was a link between message digest types
147 and public key algorithms. This meant that "clone" digests such as EVP_dss1()
148 needed to be used to sign using SHA1 and DSA. This is no longer necessary and
149 the use of clone digest is now discouraged.
151 For some key types and parameters the random number generator must be seeded.
152 If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to
153 external circumstances (see L<RAND(7)>), the operation will fail.
155 The call to EVP_DigestVerifyFinal() internally finalizes a copy of the digest
156 context. This means that EVP_VerifyUpdate() and EVP_VerifyFinal() can
157 be called later to digest and verify additional data. Applications may disable
158 this behavior by setting the EVP_MD_CTX_FLAG_FINALISE context flag via
159 L<EVP_MD_CTX_set_flags(3)>.
161 Note that not all providers support continuation, in case the selected
162 provider does not allow to duplicate contexts EVP_DigestVerifyFinal() will
163 finalize the digest context and attempting to process additional data via
164 EVP_DigestVerifyUpdate() will result in an error.
166 EVP_DigestVerifyInit() and EVP_DigestVerifyInit_ex() functions can be called
167 multiple times on a context and the parameters set by previous calls should be
168 preserved if the I<pkey> parameter is NULL. The call then just resets the state
171 Ignoring failure returns of EVP_DigestVerifyInit() and EVP_DigestVerifyInit_ex()
172 functions can lead to subsequent undefined behavior when calling
173 EVP_DigestVerifyUpdate(), EVP_DigestVerifyFinal(), or EVP_DigestVerify().
177 L<EVP_DigestSignInit(3)>,
178 L<EVP_DigestInit(3)>,
179 L<evp(7)>, L<HMAC(3)>, L<MD2(3)>,
180 L<MD5(3)>, L<MDC2(3)>, L<RIPEMD160(3)>,
181 L<SHA1(3)>, L<openssl-dgst(1)>,
186 EVP_DigestVerifyInit(), EVP_DigestVerifyUpdate() and EVP_DigestVerifyFinal()
187 were added in OpenSSL 1.0.0.
189 EVP_DigestVerifyInit_ex() was added in OpenSSL 3.0.
191 EVP_DigestVerifyUpdate() was converted from a macro to a function in OpenSSL
196 Copyright 2006-2021 The OpenSSL Project Authors. All Rights Reserved.
198 Licensed under the Apache License 2.0 (the "License"). You may not use
199 this file except in compliance with the License. You can obtain a copy
200 in the file LICENSE in the source distribution or at
201 L<https://www.openssl.org/source/license.html>.