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5075521e GT |
1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
0396401d | 5 | ECDSA_SIG_get0, ECDSA_SIG_get0_r, ECDSA_SIG_get0_s, ECDSA_SIG_set0, |
bbda7997 MC |
6 | ECDSA_SIG_new, ECDSA_SIG_free, ECDSA_size, ECDSA_sign, ECDSA_do_sign, |
7 | ECDSA_verify, ECDSA_do_verify, ECDSA_sign_setup, ECDSA_sign_ex, | |
8c1cbc72 | 8 | ECDSA_do_sign_ex - low-level elliptic curve digital signature algorithm (ECDSA) |
bbda7997 | 9 | functions |
5075521e GT |
10 | |
11 | =head1 SYNOPSIS | |
12 | ||
13 | #include <openssl/ecdsa.h> | |
14 | ||
580b557b DSH |
15 | ECDSA_SIG *ECDSA_SIG_new(void); |
16 | void ECDSA_SIG_free(ECDSA_SIG *sig); | |
9267c11b | 17 | void ECDSA_SIG_get0(const ECDSA_SIG *sig, const BIGNUM **pr, const BIGNUM **ps); |
0396401d DMSP |
18 | const BIGNUM *ECDSA_SIG_get0_r(const ECDSA_SIG *sig); |
19 | const BIGNUM *ECDSA_SIG_get0_s(const ECDSA_SIG *sig); | |
7ca3ea22 | 20 | int ECDSA_SIG_set0(ECDSA_SIG *sig, BIGNUM *r, BIGNUM *s); |
579422c8 P |
21 | |
22 | Deprecated since OpenSSL 3.0, can be hidden entirely by defining | |
23 | B<OPENSSL_API_COMPAT> with a suitable version value, see | |
24 | L<openssl_user_macros(7)>: | |
25 | ||
580b557b DSH |
26 | int ECDSA_size(const EC_KEY *eckey); |
27 | ||
28 | int ECDSA_sign(int type, const unsigned char *dgst, int dgstlen, | |
29 | unsigned char *sig, unsigned int *siglen, EC_KEY *eckey); | |
30 | ECDSA_SIG *ECDSA_do_sign(const unsigned char *dgst, int dgst_len, | |
31 | EC_KEY *eckey); | |
32 | ||
33 | int ECDSA_verify(int type, const unsigned char *dgst, int dgstlen, | |
34 | const unsigned char *sig, int siglen, EC_KEY *eckey); | |
35 | int ECDSA_do_verify(const unsigned char *dgst, int dgst_len, | |
36 | const ECDSA_SIG *sig, EC_KEY* eckey); | |
37 | ||
38 | ECDSA_SIG *ECDSA_do_sign_ex(const unsigned char *dgst, int dgstlen, | |
39 | const BIGNUM *kinv, const BIGNUM *rp, | |
40 | EC_KEY *eckey); | |
41 | int ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv, BIGNUM **rp); | |
42 | int ECDSA_sign_ex(int type, const unsigned char *dgst, int dgstlen, | |
43 | unsigned char *sig, unsigned int *siglen, | |
44 | const BIGNUM *kinv, const BIGNUM *rp, EC_KEY *eckey); | |
5075521e | 45 | |
5075521e GT |
46 | =head1 DESCRIPTION |
47 | ||
580b557b | 48 | B<ECDSA_SIG> is an opaque structure consisting of two BIGNUMs for the |
a7e62fbd | 49 | I<r> and I<s> value of an ECDSA signature (see X9.62 or FIPS 186-2). |
5075521e | 50 | |
721f3980 | 51 | ECDSA_SIG_new() allocates an empty B<ECDSA_SIG> structure. Note: before |
a7e62fbd | 52 | OpenSSL 1.1.0 the: the I<r> and I<s> components were initialised. |
5075521e | 53 | |
a7e62fbd | 54 | ECDSA_SIG_free() frees the B<ECDSA_SIG> structure I<sig>. |
5075521e | 55 | |
a7e62fbd TM |
56 | ECDSA_SIG_get0() returns internal pointers the I<r> and I<s> values contained |
57 | in I<sig> and stores them in I<*pr> and I<*ps>, respectively. | |
58 | The pointer I<pr> or I<ps> can be NULL, in which case the corresponding value | |
0396401d DMSP |
59 | is not returned. |
60 | ||
a7e62fbd | 61 | The values I<r>, I<s> can also be retrieved separately by the corresponding |
0396401d | 62 | function ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s(), respectively. |
5075521e | 63 | |
a7e62fbd TM |
64 | Non-NULL I<r> and I<s> values can be set on the I<sig> by calling |
65 | ECDSA_SIG_set0(). Calling this function transfers the memory management of the | |
66 | values to the B<ECDSA_SIG> object, and therefore the values that have been | |
67 | passed in should not be freed by the caller. | |
6a571a18 | 68 | |
bbda7997 MC |
69 | See L<i2d_ECDSA_SIG(3)> and L<d2i_ECDSA_SIG(3)> for information about encoding |
70 | and decoding ECDSA signatures to/from DER. | |
5075521e | 71 | |
579422c8 P |
72 | All of the functions described below are deprecated. Applications should |
73 | use the higher level B<EVP> interface such as L<EVP_DigestSignInit(3)> | |
74 | or L<EVP_DigestVerifyInit(3)> instead. | |
75 | ||
580b557b | 76 | ECDSA_size() returns the maximum length of a DER encoded ECDSA signature |
a7e62fbd TM |
77 | created with the private EC key I<eckey>. To obtain the actual signature |
78 | size use L<EVP_PKEY_sign(3)> with a NULL I<sig> parameter. | |
5075521e | 79 | |
a7e62fbd TM |
80 | ECDSA_sign() computes a digital signature of the I<dgstlen> bytes hash value |
81 | I<dgst> using the private EC key I<eckey>. The DER encoded signatures is | |
82 | stored in I<sig> and its length is returned in I<sig_len>. Note: I<sig> must | |
83 | point to ECDSA_size(eckey) bytes of memory. The parameter I<type> is currently | |
84 | ignored. ECDSA_sign() is wrapper function for ECDSA_sign_ex() with I<kinv> | |
85 | and I<rp> set to NULL. | |
b67d9889 | 86 | |
580b557b DSH |
87 | ECDSA_do_sign() is similar to ECDSA_sign() except the signature is returned |
88 | as a newly allocated B<ECDSA_SIG> structure (or NULL on error). ECDSA_do_sign() | |
a7e62fbd | 89 | is a wrapper function for ECDSA_do_sign_ex() with I<kinv> and I<rp> set to |
580b557b | 90 | NULL. |
5075521e | 91 | |
a7e62fbd TM |
92 | ECDSA_verify() verifies that the signature in I<sig> of size I<siglen> is a |
93 | valid ECDSA signature of the hash value I<dgst> of size I<dgstlen> using the | |
94 | public key I<eckey>. The parameter I<type> is ignored. | |
5075521e | 95 | |
580b557b DSH |
96 | ECDSA_do_verify() is similar to ECDSA_verify() except the signature is |
97 | presented in the form of a pointer to an B<ECDSA_SIG> structure. | |
98 | ||
a7e62fbd | 99 | The remaining functions utilise the internal I<kinv> and I<r> values used |
580b557b DSH |
100 | during signature computation. Most applications will never need to call these |
101 | and some external ECDSA ENGINE implementations may not support them at all if | |
a7e62fbd | 102 | either I<kinv> or I<r> is not NULL. |
b67d9889 | 103 | |
580b557b | 104 | ECDSA_sign_setup() may be used to precompute parts of the signing operation. |
a7e62fbd TM |
105 | I<eckey> is the private EC key and I<ctx> is a pointer to B<BN_CTX> structure |
106 | (or NULL). The precomputed values or returned in I<kinv> and I<rp> and can be | |
580b557b | 107 | used in a later call to ECDSA_sign_ex() or ECDSA_do_sign_ex(). |
5075521e | 108 | |
a7e62fbd TM |
109 | ECDSA_sign_ex() computes a digital signature of the I<dgstlen> bytes hash value |
110 | I<dgst> using the private EC key I<eckey> and the optional pre-computed values | |
111 | I<kinv> and I<rp>. The DER encoded signature is stored in I<sig> and its | |
112 | length is returned in I<sig_len>. Note: I<sig> must point to ECDSA_size(eckey) | |
113 | bytes of memory. The parameter I<type> is ignored. | |
580b557b DSH |
114 | |
115 | ECDSA_do_sign_ex() is similar to ECDSA_sign_ex() except the signature is | |
116 | returned as a newly allocated B<ECDSA_SIG> structure (or NULL on error). | |
5075521e GT |
117 | |
118 | =head1 RETURN VALUES | |
119 | ||
6da34cfb KG |
120 | ECDSA_SIG_new() returns NULL if the allocation fails. |
121 | ||
6a571a18 TS |
122 | ECDSA_SIG_set0() returns 1 on success or 0 on failure. |
123 | ||
0396401d DMSP |
124 | ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s() return the corresponding value, |
125 | or NULL if it is unset. | |
126 | ||
5075521e GT |
127 | ECDSA_size() returns the maximum length signature or 0 on error. |
128 | ||
580b557b DSH |
129 | ECDSA_sign(), ECDSA_sign_ex() and ECDSA_sign_setup() return 1 if successful |
130 | or 0 on error. | |
131 | ||
132 | ECDSA_do_sign() and ECDSA_do_sign_ex() return a pointer to an allocated | |
133 | B<ECDSA_SIG> structure or NULL on error. | |
5075521e GT |
134 | |
135 | ECDSA_verify() and ECDSA_do_verify() return 1 for a valid | |
136 | signature, 0 for an invalid signature and -1 on error. | |
9b86974e | 137 | The error codes can be obtained by L<ERR_get_error(3)>. |
5075521e GT |
138 | |
139 | =head1 EXAMPLES | |
140 | ||
580b557b DSH |
141 | Creating an ECDSA signature of a given SHA-256 hash value using the |
142 | named curve prime256v1 (aka P-256). | |
5075521e | 143 | |
b9b6a7e5 | 144 | First step: create an EC_KEY object (note: this part is B<not> ECDSA |
5075521e GT |
145 | specific) |
146 | ||
2947af32 | 147 | int ret; |
5075521e | 148 | ECDSA_SIG *sig; |
2947af32 | 149 | EC_KEY *eckey; |
e9b77246 | 150 | |
580b557b | 151 | eckey = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1); |
2947af32 BB |
152 | if (eckey == NULL) |
153 | /* error */ | |
154 | if (EC_KEY_generate_key(eckey) == 0) | |
155 | /* error */ | |
580b557b DSH |
156 | |
157 | Second step: compute the ECDSA signature of a SHA-256 hash value | |
158 | using ECDSA_do_sign(): | |
159 | ||
160 | sig = ECDSA_do_sign(digest, 32, eckey); | |
2947af32 BB |
161 | if (sig == NULL) |
162 | /* error */ | |
580b557b DSH |
163 | |
164 | or using ECDSA_sign(): | |
5075521e GT |
165 | |
166 | unsigned char *buffer, *pp; | |
2947af32 | 167 | int buf_len; |
e9b77246 | 168 | |
5075521e | 169 | buf_len = ECDSA_size(eckey); |
2947af32 | 170 | buffer = OPENSSL_malloc(buf_len); |
5075521e | 171 | pp = buffer; |
2947af32 BB |
172 | if (ECDSA_sign(0, dgst, dgstlen, pp, &buf_len, eckey) == 0) |
173 | /* error */ | |
5075521e | 174 | |
580b557b | 175 | Third step: verify the created ECDSA signature using ECDSA_do_verify(): |
5075521e | 176 | |
580b557b | 177 | ret = ECDSA_do_verify(digest, 32, sig, eckey); |
5075521e | 178 | |
580b557b | 179 | or using ECDSA_verify(): |
5075521e | 180 | |
580b557b | 181 | ret = ECDSA_verify(0, digest, 32, buffer, buf_len, eckey); |
5075521e GT |
182 | |
183 | and finally evaluate the return value: | |
184 | ||
2947af32 BB |
185 | if (ret == 1) |
186 | /* signature ok */ | |
187 | else if (ret == 0) | |
188 | /* incorrect signature */ | |
189 | else | |
190 | /* error */ | |
5075521e GT |
191 | |
192 | =head1 CONFORMING TO | |
193 | ||
194 | ANSI X9.62, US Federal Information Processing Standard FIPS 186-2 | |
195 | (Digital Signature Standard, DSS) | |
196 | ||
197 | =head1 SEE ALSO | |
198 | ||
87930507 | 199 | L<EC_KEY_new(3)>, |
580b557b | 200 | L<EVP_DigestSignInit(3)>, |
bbda7997 | 201 | L<EVP_DigestVerifyInit(3)>, |
579422c8 | 202 | L<EVP_PKEY_sign(3)> |
bbda7997 MC |
203 | L<i2d_ECDSA_SIG(3)>, |
204 | L<d2i_ECDSA_SIG(3)> | |
5075521e | 205 | |
579422c8 P |
206 | =head1 HISTORY |
207 | ||
208 | The ECDSA_size(), ECDSA_sign(), ECDSA_do_sign(), ECDSA_verify(), | |
209 | ECDSA_do_verify(), ECDSA_sign_setup(), ECDSA_sign_ex() and ECDSA_do_sign_ex() | |
210 | functions were deprecated in OpenSSL 3.0. | |
211 | ||
e2f92610 RS |
212 | =head1 COPYRIGHT |
213 | ||
33388b44 | 214 | Copyright 2004-2020 The OpenSSL Project Authors. All Rights Reserved. |
e2f92610 | 215 | |
4746f25a | 216 | Licensed under the Apache License 2.0 (the "License"). You may not use |
e2f92610 RS |
217 | this file except in compliance with the License. You can obtain a copy |
218 | in the file LICENSE in the source distribution or at | |
219 | L<https://www.openssl.org/source/license.html>. | |
220 | ||
221 | =cut |