1EVP_DIGESTSIGNINIT(3ossl) OpenSSL EVP_DIGESTSIGNINIT(3ossl)
2
6 EVP_DigestSignInit_ex, EVP_DigestSignInit, EVP_DigestSignUpdate,
7 EVP_DigestSignFinal, EVP_DigestSign - EVP signing functions
8
10 #include <openssl/evp.h>
11 int EVP_DigestSignInit_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_DigestSignInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
17 const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey);
18 int EVP_DigestSignUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
19 int EVP_DigestSignFinal(EVP_MD_CTX *ctx, unsigned char *sig, size_t *siglen);
20 int EVP_DigestSign(EVP_MD_CTX *ctx, unsigned char *sigret,
22 size_t *siglen, const unsigned char *tbs,
23 size_t tbslen);
24
26 The EVP signature routines are a high-level interface to digital
27 signatures. Input data is digested first before the signing takes
28 place.
29 EVP_DigestSignInit_ex() sets up signing context ctx to use a digest
31 with the name mdname and private key pkey. The name of the digest to be
32 used is passed to the provider of the signature algorithm in use. How
33 that provider interprets the digest name is provider specific. The
34 provider may implement that digest directly itself or it may
35 (optionally) choose to fetch it (which could result in a digest from a
36 different provider being selected). If the provider supports fetching
37 the digest then it may use the props argument for the properties to be
38 used during the fetch. Finally, the passed parameters params, if not
39 NULL, are set on the context before returning.
40 The pkey algorithm is used to fetch a EVP_SIGNATURE method implicitly,
42 to be used for the actual signing. See "Implicit fetch" in provider(7)
43 for more information about implicit fetches.
44 The OpenSSL default and legacy providers support fetching digests and
46 can fetch those digests from any available provider. The OpenSSL FIPS
47 provider also supports fetching digests but will only fetch digests
48 that are themselves implemented inside the FIPS provider.
49 ctx must be created with EVP_MD_CTX_new() before calling this function.
51 If pctx is not NULL, the EVP_PKEY_CTX of the signing operation will be
52 written to *pctx: this can be used to set alternative signing options.
53 Note that any existing value in *pctx is overwritten. The EVP_PKEY_CTX
54 value returned must not be freed directly by the application if ctx is
55 not assigned an EVP_PKEY_CTX value before being passed to
56 EVP_DigestSignInit_ex() (which means the EVP_PKEY_CTX is created inside
57 EVP_DigestSignInit_ex() and it will be freed automatically when the
58 EVP_MD_CTX is freed). If the EVP_PKEY_CTX to be used is created by
59 EVP_DigestSignInit_ex then it will use the OSSL_LIB_CTX specified in
60 libctx and the property query string specified in props.
61 The digest mdname may be NULL if the signing algorithm supports it. The
63 props argument can always be NULL.
64 No EVP_PKEY_CTX will be created by EVP_DigestSignInit_ex() if the
66 passed ctx has already been assigned one via
67 EVP_MD_CTX_set_pkey_ctx(3). See also SM2(7).
68 Only EVP_PKEY types that support signing can be used with these
70 functions. This includes MAC algorithms where the MAC generation is
71 considered as a form of "signing". Built-in EVP_PKEY types supported by
72 these functions are CMAC, Poly1305, DSA, ECDSA, HMAC, RSA, SipHash,
73 Ed25519 and Ed448.
74 Not all digests can be used for all key types. The following
76 combinations apply.
77 DSA Supports SHA1, SHA224, SHA256, SHA384 and SHA512
79 ECDSA
81 Supports SHA1, SHA224, SHA256, SHA384, SHA512 and SM3
82 RSA with no padding
84 Supports no digests (the digest type must be NULL)
85 RSA with X931 padding
87 Supports SHA1, SHA256, SHA384 and SHA512
88 All other RSA padding types
90 Support SHA1, SHA224, SHA256, SHA384, SHA512, MD5, MD5_SHA1, MD2,
91 MD4, MDC2, SHA3-224, SHA3-256, SHA3-384, SHA3-512
92 Ed25519 and Ed448
94 Support no digests (the digest type must be NULL)
95 HMAC
97 Supports any digest
98 CMAC, Poly1305 and SipHash
100 Will ignore any digest provided.
101 If RSA-PSS is used and restrictions apply then the digest must match.
103 EVP_DigestSignInit() works in the same way as EVP_DigestSignInit_ex()
105 except that the mdname parameter will be inferred from the supplied
106 digest type, and props will be NULL. Where supplied the ENGINE e will
107 be used for the signing and digest algorithm implementations. e may be
108 NULL.
109 EVP_DigestSignUpdate() hashes cnt bytes of data at d into the signature
111 context ctx. This function can be called several times on the same ctx
112 to include additional data.
113 Unless sig is NULL EVP_DigestSignFinal() signs the data in ctx and
115 places the signature in sig. Otherwise the maximum necessary size of
116 the output buffer is written to the siglen parameter. If sig is not
117 NULL then before the call the siglen parameter should contain the
118 length of the sig buffer. If the call is successful the signature is
119 written to sig and the amount of data written to siglen.
120 EVP_DigestSign() signs tbslen bytes of data at tbs and places the
122 signature in sig and its length in siglen in a similar way to
123 EVP_DigestSignFinal(). In the event of a failure EVP_DigestSign()
124 cannot be called again without reinitialising the EVP_MD_CTX. If sig is
125 NULL before the call then siglen will be populated with the required
126 size for the sig buffer. If sig is non-NULL before the call then siglen
127 should contain the length of the sig buffer.
128
130 EVP_DigestSignInit(), EVP_DigestSignUpdate(), EVP_DigestSignFinal() and
131 EVP_DigestSign() return 1 for success and 0 for failure.
132 The error codes can be obtained from ERR_get_error(3).
134
136 The EVP interface to digital signatures should almost always be used in
137 preference to the low-level interfaces. This is because the code then
138 becomes transparent to the algorithm used and much more flexible.
139 EVP_DigestSign() is a one shot operation which signs a single block of
141 data in one function. For algorithms that support streaming it is
142 equivalent to calling EVP_DigestSignUpdate() and EVP_DigestSignFinal().
143 For algorithms which do not support streaming (e.g. PureEdDSA) it is
144 the only way to sign data.
145 In previous versions of OpenSSL there was a link between message digest
147 types and public key algorithms. This meant that "clone" digests such
148 as EVP_dss1() needed to be used to sign using SHA1 and DSA. This is no
149 longer necessary and the use of clone digest is now discouraged.
150 For some key types and parameters the random number generator must be
152 seeded. If the automatic seeding or reseeding of the OpenSSL CSPRNG
153 fails due to external circumstances (see RAND(7)), the operation will
154 fail.
155 The call to EVP_DigestSignFinal() internally finalizes a copy of the
157 digest context. This means that calls to EVP_DigestSignUpdate() and
158 EVP_DigestSignFinal() can be called later to digest and sign additional
159 data.
160 EVP_DigestSignInit() and EVP_DigestSignInit_ex() functions can be
162 called multiple times on a context and the parameters set by previous
163 calls should be preserved if the pkey parameter is NULL. The call then
164 just resets the state of the ctx.
165 The use of EVP_PKEY_get_size() with these functions is discouraged
167 because some signature operations may have a signature length which
168 depends on the parameters set. As a result EVP_PKEY_get_size() would
169 have to return a value which indicates the maximum possible signature
170 for any set of parameters.
171
173 EVP_DigestVerifyInit(3), EVP_DigestInit(3), evp(7), HMAC(3), MD2(3),
174 MD5(3), MDC2(3), RIPEMD160(3), SHA1(3), openssl-dgst(1), RAND(7)
175
177 EVP_DigestSignInit(), EVP_DigestSignUpdate() and EVP_DigestSignFinal()
178 were added in OpenSSL 1.0.0.
179 EVP_DigestSignInit_ex() was added in OpenSSL 3.0.
181 EVP_DigestSignUpdate() was converted from a macro to a function in
183 OpenSSL 3.0.
184
186 Copyright 2006-2022 The OpenSSL Project Authors. All Rights Reserved.
187 Licensed under the Apache License 2.0 (the "License"). You may not use
189 this file except in compliance with the License. You can obtain a copy
190 in the file LICENSE in the source distribution or at
191 <https://www.openssl.org/source/license.html>.
1923.0.5 2022-07-05 EVP_DIGESTSIGNINIT(3ossl)