5 ECDSA_SIG_get0, ECDSA_SIG_get0_r, ECDSA_SIG_get0_s, ECDSA_SIG_set0,
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,
8 ECDSA_do_sign_ex - low level elliptic curve digital signature algorithm (ECDSA)
13 #include <openssl/ecdsa.h>
15 ECDSA_SIG *ECDSA_SIG_new(void);
16 void ECDSA_SIG_free(ECDSA_SIG *sig);
17 void ECDSA_SIG_get0(const ECDSA_SIG *sig, const BIGNUM **pr, const BIGNUM **ps);
18 const BIGNUM *ECDSA_SIG_get0_r(const ECDSA_SIG *sig);
19 const BIGNUM *ECDSA_SIG_get0_s(const ECDSA_SIG *sig);
20 int ECDSA_SIG_set0(ECDSA_SIG *sig, BIGNUM *r, BIGNUM *s);
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)>:
26 int ECDSA_size(const EC_KEY *eckey);
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,
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);
38 ECDSA_SIG *ECDSA_do_sign_ex(const unsigned char *dgst, int dgstlen,
39 const BIGNUM *kinv, const BIGNUM *rp,
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);
48 B<ECDSA_SIG> is an opaque structure consisting of two BIGNUMs for the
49 B<r> and B<s> value of an ECDSA signature (see X9.62 or FIPS 186-2).
51 ECDSA_SIG_new() allocates an empty B<ECDSA_SIG> structure. Note: before
52 OpenSSL 1.1.0 the: the B<r> and B<s> components were initialised.
54 ECDSA_SIG_free() frees the B<ECDSA_SIG> structure B<sig>.
56 ECDSA_SIG_get0() returns internal pointers the B<r> and B<s> values contained
57 in B<sig> and stores them in B<*pr> and B<*ps>, respectively.
58 The pointer B<pr> or B<ps> can be NULL, in which case the corresponding value
61 The values B<r>, B<s> can also be retrieved separately by the corresponding
62 function ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s(), respectively.
64 The B<r> and B<s> values can be set by calling ECDSA_SIG_set0() and passing the
65 new values for B<r> and B<s> as parameters to the function. Calling this
66 function transfers the memory management of the values to the ECDSA_SIG object,
67 and therefore the values that have been passed in should not be freed directly
68 after this function has been called.
70 See L<i2d_ECDSA_SIG(3)> and L<d2i_ECDSA_SIG(3)> for information about encoding
71 and decoding ECDSA signatures to/from DER.
73 All of the functions described below are deprecated. Applications should
74 use the higher level B<EVP> interface such as L<EVP_DigestSignInit(3)>
75 or L<EVP_DigestVerifyInit(3)> instead.
77 ECDSA_size() returns the maximum length of a DER encoded ECDSA signature
78 created with the private EC key B<eckey>. To obtain the actual signature
79 size use L<EVP_PKEY_sign(3)> with a NULL B<sig> parameter.
81 ECDSA_sign() computes a digital signature of the B<dgstlen> bytes hash value
82 B<dgst> using the private EC key B<eckey>. The DER encoded signatures is
83 stored in B<sig> and its length is returned in B<sig_len>. Note: B<sig> must
84 point to ECDSA_size(eckey) bytes of memory. The parameter B<type> is currently
85 ignored. ECDSA_sign() is wrapper function for ECDSA_sign_ex() with B<kinv>
86 and B<rp> set to NULL.
88 ECDSA_do_sign() is similar to ECDSA_sign() except the signature is returned
89 as a newly allocated B<ECDSA_SIG> structure (or NULL on error). ECDSA_do_sign()
90 is a wrapper function for ECDSA_do_sign_ex() with B<kinv> and B<rp> set to
93 ECDSA_verify() verifies that the signature in B<sig> of size B<siglen> is a
94 valid ECDSA signature of the hash value B<dgst> of size B<dgstlen> using the
95 public key B<eckey>. The parameter B<type> is ignored.
97 ECDSA_do_verify() is similar to ECDSA_verify() except the signature is
98 presented in the form of a pointer to an B<ECDSA_SIG> structure.
100 The remaining functions utilise the internal B<kinv> and B<r> values used
101 during signature computation. Most applications will never need to call these
102 and some external ECDSA ENGINE implementations may not support them at all if
103 either B<kinv> or B<r> is not B<NULL>.
105 ECDSA_sign_setup() may be used to precompute parts of the signing operation.
106 B<eckey> is the private EC key and B<ctx> is a pointer to B<BN_CTX> structure
107 (or NULL). The precomputed values or returned in B<kinv> and B<rp> and can be
108 used in a later call to ECDSA_sign_ex() or ECDSA_do_sign_ex().
110 ECDSA_sign_ex() computes a digital signature of the B<dgstlen> bytes hash value
111 B<dgst> using the private EC key B<eckey> and the optional pre-computed values
112 B<kinv> and B<rp>. The DER encoded signature is stored in B<sig> and its
113 length is returned in B<sig_len>. Note: B<sig> must point to ECDSA_size(eckey)
114 bytes of memory. The parameter B<type> is ignored.
116 ECDSA_do_sign_ex() is similar to ECDSA_sign_ex() except the signature is
117 returned as a newly allocated B<ECDSA_SIG> structure (or NULL on error).
121 ECDSA_SIG_new() returns NULL if the allocation fails.
123 ECDSA_SIG_set0() returns 1 on success or 0 on failure.
125 ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s() return the corresponding value,
126 or NULL if it is unset.
128 ECDSA_size() returns the maximum length signature or 0 on error.
130 ECDSA_sign(), ECDSA_sign_ex() and ECDSA_sign_setup() return 1 if successful
133 ECDSA_do_sign() and ECDSA_do_sign_ex() return a pointer to an allocated
134 B<ECDSA_SIG> structure or NULL on error.
136 ECDSA_verify() and ECDSA_do_verify() return 1 for a valid
137 signature, 0 for an invalid signature and -1 on error.
138 The error codes can be obtained by L<ERR_get_error(3)>.
142 Creating an ECDSA signature of a given SHA-256 hash value using the
143 named curve prime256v1 (aka P-256).
145 First step: create an EC_KEY object (note: this part is B<not> ECDSA
152 eckey = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
155 if (EC_KEY_generate_key(eckey) == 0)
158 Second step: compute the ECDSA signature of a SHA-256 hash value
159 using ECDSA_do_sign():
161 sig = ECDSA_do_sign(digest, 32, eckey);
165 or using ECDSA_sign():
167 unsigned char *buffer, *pp;
170 buf_len = ECDSA_size(eckey);
171 buffer = OPENSSL_malloc(buf_len);
173 if (ECDSA_sign(0, dgst, dgstlen, pp, &buf_len, eckey) == 0)
176 Third step: verify the created ECDSA signature using ECDSA_do_verify():
178 ret = ECDSA_do_verify(digest, 32, sig, eckey);
180 or using ECDSA_verify():
182 ret = ECDSA_verify(0, digest, 32, buffer, buf_len, eckey);
184 and finally evaluate the return value:
189 /* incorrect signature */
195 ANSI X9.62, US Federal Information Processing Standard FIPS 186-2
196 (Digital Signature Standard, DSS)
201 L<EVP_DigestSignInit(3)>,
202 L<EVP_DigestVerifyInit(3)>,
209 The ECDSA_size(), ECDSA_sign(), ECDSA_do_sign(), ECDSA_verify(),
210 ECDSA_do_verify(), ECDSA_sign_setup(), ECDSA_sign_ex() and ECDSA_do_sign_ex()
211 functions were deprecated in OpenSSL 3.0.
215 Copyright 2004-2018 The OpenSSL Project Authors. All Rights Reserved.
217 Licensed under the Apache License 2.0 (the "License"). You may not use
218 this file except in compliance with the License. You can obtain a copy
219 in the file LICENSE in the source distribution or at
220 L<https://www.openssl.org/source/license.html>.