1ECDSA_SIG_NEW(3) OpenSSL ECDSA_SIG_NEW(3)
2
6 ECDSA_SIG_get0, ECDSA_SIG_get0_r, ECDSA_SIG_get0_s, ECDSA_SIG_set0,
7 ECDSA_SIG_new, ECDSA_SIG_free, ECDSA_size, ECDSA_sign, ECDSA_do_sign,
8 ECDSA_verify, ECDSA_do_verify, ECDSA_sign_setup, ECDSA_sign_ex,
9 ECDSA_do_sign_ex - low level elliptic curve digital signature algorithm
10 (ECDSA) functions
11
13 #include <openssl/ecdsa.h>
14 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);
21 int ECDSA_size(const EC_KEY *eckey);
22 int ECDSA_sign(int type, const unsigned char *dgst, int dgstlen,
24 unsigned char *sig, unsigned int *siglen, EC_KEY *eckey);
25 ECDSA_SIG *ECDSA_do_sign(const unsigned char *dgst, int dgst_len,
26 EC_KEY *eckey);
27 int ECDSA_verify(int type, const unsigned char *dgst, int dgstlen,
29 const unsigned char *sig, int siglen, EC_KEY *eckey);
30 int ECDSA_do_verify(const unsigned char *dgst, int dgst_len,
31 const ECDSA_SIG *sig, EC_KEY* eckey);
32 ECDSA_SIG *ECDSA_do_sign_ex(const unsigned char *dgst, int dgstlen,
34 const BIGNUM *kinv, const BIGNUM *rp,
35 EC_KEY *eckey);
36 int ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv, BIGNUM **rp);
37 int ECDSA_sign_ex(int type, const unsigned char *dgst, int dgstlen,
38 unsigned char *sig, unsigned int *siglen,
39 const BIGNUM *kinv, const BIGNUM *rp, EC_KEY *eckey);
40
42 Note: these functions provide a low level interface to ECDSA. Most
43 applications should use the higher level EVP interface such as
44 EVP_DigestSignInit(3) or EVP_DigestVerifyInit(3) instead.
45 ECDSA_SIG is an opaque structure consisting of two BIGNUMs for the r
47 and s value of an ECDSA signature (see X9.62 or FIPS 186-2).
48 ECDSA_SIG_new() allocates an empty ECDSA_SIG structure. Note: before
50 OpenSSL 1.1.0 the: the r and s components were initialised.
51 ECDSA_SIG_free() frees the ECDSA_SIG structure sig.
53 ECDSA_SIG_get0() returns internal pointers the r and s values contained
55 in sig and stores them in *pr and *ps, respectively. The pointer pr or
56 ps can be NULL, in which case the corresponding value is not returned.
57 The values r, s can also be retrieved separately by the corresponding
59 function ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s(), respectively.
60 The r and s values can be set by calling ECDSA_SIG_set0() and passing
62 the new values for r and s as parameters to the function. Calling this
63 function transfers the memory management of the values to the ECDSA_SIG
64 object, and therefore the values that have been passed in should not be
65 freed directly after this function has been called.
66 See i2d_ECDSA_SIG(3) and d2i_ECDSA_SIG(3) for information about
68 encoding and decoding ECDSA signatures to/from DER.
69 ECDSA_size() returns the maximum length of a DER encoded ECDSA
71 signature created with the private EC key eckey.
72 ECDSA_sign() computes a digital signature of the dgstlen bytes hash
74 value dgst using the private EC key eckey. The DER encoded signatures
75 is stored in sig and its length is returned in sig_len. Note: sig must
76 point to ECDSA_size(eckey) bytes of memory. The parameter type is
77 currently ignored. ECDSA_sign() is wrapper function for ECDSA_sign_ex()
78 with kinv and rp set to NULL.
79 ECDSA_do_sign() is similar to ECDSA_sign() except the signature is
81 returned as a newly allocated ECDSA_SIG structure (or NULL on error).
82 ECDSA_do_sign() is a wrapper function for ECDSA_do_sign_ex() with kinv
83 and rp set to NULL.
84 ECDSA_verify() verifies that the signature in sig of size siglen is a
86 valid ECDSA signature of the hash value dgst of size dgstlen using the
87 public key eckey. The parameter type is ignored.
88 ECDSA_do_verify() is similar to ECDSA_verify() except the signature is
90 presented in the form of a pointer to an ECDSA_SIG structure.
91 The remaining functions utilise the internal kinv and r values used
93 during signature computation. Most applications will never need to call
94 these and some external ECDSA ENGINE implementations may not support
95 them at all if either kinv or r is not NULL.
96 ECDSA_sign_setup() may be used to precompute parts of the signing
98 operation. eckey is the private EC key and ctx is a pointer to BN_CTX
99 structure (or NULL). The precomputed values or returned in kinv and rp
100 and can be used in a later call to ECDSA_sign_ex() or
101 ECDSA_do_sign_ex().
102 ECDSA_sign_ex() computes a digital signature of the dgstlen bytes hash
104 value dgst using the private EC key eckey and the optional pre-computed
105 values kinv and rp. The DER encoded signature is stored in sig and its
106 length is returned in sig_len. Note: sig must point to
107 ECDSA_size(eckey) bytes of memory. The parameter type is ignored.
108 ECDSA_do_sign_ex() is similar to ECDSA_sign_ex() except the signature
110 is returned as a newly allocated ECDSA_SIG structure (or NULL on
111 error).
112
114 ECDSA_SIG_new() returns NULL if the allocation fails.
115 ECDSA_SIG_set0() returns 1 on success or 0 on failure.
117 ECDSA_SIG_get0_r() and ECDSA_SIG_get0_s() return the corresponding
119 value, or NULL if it is unset.
120 ECDSA_size() returns the maximum length signature or 0 on error.
122 ECDSA_sign(), ECDSA_sign_ex() and ECDSA_sign_setup() return 1 if
124 successful or 0 on error.
125 ECDSA_do_sign() and ECDSA_do_sign_ex() return a pointer to an allocated
127 ECDSA_SIG structure or NULL on error.
128 ECDSA_verify() and ECDSA_do_verify() return 1 for a valid signature, 0
130 for an invalid signature and -1 on error. The error codes can be
131 obtained by ERR_get_error(3).
132
134 Creating an ECDSA signature of a given SHA-256 hash value using the
135 named curve prime256v1 (aka P-256).
136 First step: create an EC_KEY object (note: this part is not ECDSA
138 specific)
139 int ret;
141 ECDSA_SIG *sig;
142 EC_KEY *eckey;
143 eckey = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
145 if (eckey == NULL)
146 /* error */
147 if (EC_KEY_generate_key(eckey) == 0)
148 /* error */
149 Second step: compute the ECDSA signature of a SHA-256 hash value using
151 ECDSA_do_sign():
152 sig = ECDSA_do_sign(digest, 32, eckey);
154 if (sig == NULL)
155 /* error */
156 or using ECDSA_sign():
158 unsigned char *buffer, *pp;
160 int buf_len;
161 buf_len = ECDSA_size(eckey);
163 buffer = OPENSSL_malloc(buf_len);
164 pp = buffer;
165 if (ECDSA_sign(0, dgst, dgstlen, pp, &buf_len, eckey) == 0)
166 /* error */
167 Third step: verify the created ECDSA signature using ECDSA_do_verify():
169 ret = ECDSA_do_verify(digest, 32, sig, eckey);
171 or using ECDSA_verify():
173 ret = ECDSA_verify(0, digest, 32, buffer, buf_len, eckey);
175 and finally evaluate the return value:
177 if (ret == 1)
179 /* signature ok */
180 else if (ret == 0)
181 /* incorrect signature */
182 else
183 /* error */
184
186 ANSI X9.62, US Federal Information Processing Standard FIPS 186-2
187 (Digital Signature Standard, DSS)
188
190 EC_KEY_new(3), EVP_DigestSignInit(3), EVP_DigestVerifyInit(3),
191 i2d_ECDSA_SIG(3), d2i_ECDSA_SIG(3)
192
194 Copyright 2004-2019 The OpenSSL Project Authors. All Rights Reserved.
195 Licensed under the OpenSSL license (the "License"). You may not use
197 this file except in compliance with the License. You can obtain a copy
198 in the file LICENSE in the source distribution or at
199 <https://www.openssl.org/source/license.html>.
2001.1.1d 2019-10-03 ECDSA_SIG_NEW(3)