| 1 | .\" Automatically generated by Pod::Man 2.23 (Pod::Simple 3.14) |
| 2 | .\" |
| 3 | .\" Standard preamble: |
| 4 | .\" ======================================================================== |
| 5 | .de Sp \" Vertical space (when we can't use .PP) |
| 6 | .if t .sp .5v |
| 7 | .if n .sp |
| 8 | .. |
| 9 | .de Vb \" Begin verbatim text |
| 10 | .ft CW |
| 11 | .nf |
| 12 | .ne \\$1 |
| 13 | .. |
| 14 | .de Ve \" End verbatim text |
| 15 | .ft R |
| 16 | .fi |
| 17 | .. |
| 18 | .\" Set up some character translations and predefined strings. \*(-- will |
| 19 | .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left |
| 20 | .\" double quote, and \*(R" will give a right double quote. \*(C+ will |
| 21 | .\" give a nicer C++. Capital omega is used to do unbreakable dashes and |
| 22 | .\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff, |
| 23 | .\" nothing in troff, for use with C<>. |
| 24 | .tr \(*W- |
| 25 | .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' |
| 26 | .ie n \{\ |
| 27 | . ds -- \(*W- |
| 28 | . ds PI pi |
| 29 | . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch |
| 30 | . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch |
| 31 | . ds L" "" |
| 32 | . ds R" "" |
| 33 | . ds C` "" |
| 34 | . ds C' "" |
| 35 | 'br\} |
| 36 | .el\{\ |
| 37 | . ds -- \|\(em\| |
| 38 | . ds PI \(*p |
| 39 | . ds L" `` |
| 40 | . ds R" '' |
| 41 | 'br\} |
| 42 | .\" |
| 43 | .\" Escape single quotes in literal strings from groff's Unicode transform. |
| 44 | .ie \n(.g .ds Aq \(aq |
| 45 | .el .ds Aq ' |
| 46 | .\" |
| 47 | .\" If the F register is turned on, we'll generate index entries on stderr for |
| 48 | .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index |
| 49 | .\" entries marked with X<> in POD. Of course, you'll have to process the |
| 50 | .\" output yourself in some meaningful fashion. |
| 51 | .ie \nF \{\ |
| 52 | . de IX |
| 53 | . tm Index:\\$1\t\\n%\t"\\$2" |
| 54 | .. |
| 55 | . nr % 0 |
| 56 | . rr F |
| 57 | .\} |
| 58 | .el \{\ |
| 59 | . de IX |
| 60 | .. |
| 61 | .\} |
| 62 | .\" |
| 63 | .\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). |
| 64 | .\" Fear. Run. Save yourself. No user-serviceable parts. |
| 65 | . \" fudge factors for nroff and troff |
| 66 | .if n \{\ |
| 67 | . ds #H 0 |
| 68 | . ds #V .8m |
| 69 | . ds #F .3m |
| 70 | . ds #[ \f1 |
| 71 | . ds #] \fP |
| 72 | .\} |
| 73 | .if t \{\ |
| 74 | . ds #H ((1u-(\\\\n(.fu%2u))*.13m) |
| 75 | . ds #V .6m |
| 76 | . ds #F 0 |
| 77 | . ds #[ \& |
| 78 | . ds #] \& |
| 79 | .\} |
| 80 | . \" simple accents for nroff and troff |
| 81 | .if n \{\ |
| 82 | . ds ' \& |
| 83 | . ds ` \& |
| 84 | . ds ^ \& |
| 85 | . ds , \& |
| 86 | . ds ~ ~ |
| 87 | . ds / |
| 88 | .\} |
| 89 | .if t \{\ |
| 90 | . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" |
| 91 | . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' |
| 92 | . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' |
| 93 | . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' |
| 94 | . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' |
| 95 | . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' |
| 96 | .\} |
| 97 | . \" troff and (daisy-wheel) nroff accents |
| 98 | .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' |
| 99 | .ds 8 \h'\*(#H'\(*b\h'-\*(#H' |
| 100 | .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] |
| 101 | .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' |
| 102 | .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' |
| 103 | .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] |
| 104 | .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] |
| 105 | .ds ae a\h'-(\w'a'u*4/10)'e |
| 106 | .ds Ae A\h'-(\w'A'u*4/10)'E |
| 107 | . \" corrections for vroff |
| 108 | .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' |
| 109 | .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' |
| 110 | . \" for low resolution devices (crt and lpr) |
| 111 | .if \n(.H>23 .if \n(.V>19 \ |
| 112 | \{\ |
| 113 | . ds : e |
| 114 | . ds 8 ss |
| 115 | . ds o a |
| 116 | . ds d- d\h'-1'\(ga |
| 117 | . ds D- D\h'-1'\(hy |
| 118 | . ds th \o'bp' |
| 119 | . ds Th \o'LP' |
| 120 | . ds ae ae |
| 121 | . ds Ae AE |
| 122 | .\} |
| 123 | .rm #[ #] #H #V #F C |
| 124 | .\" ======================================================================== |
| 125 | .\" |
| 126 | .IX Title "ecdsa 3" |
| 127 | .TH ecdsa 3 "2010-06-01" "1.0.0a" "OpenSSL" |
| 128 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
| 129 | .\" way too many mistakes in technical documents. |
| 130 | .if n .ad l |
| 131 | .nh |
| 132 | .SH "NAME" |
| 133 | ecdsa \- Elliptic Curve Digital Signature Algorithm |
| 134 | .SH "SYNOPSIS" |
| 135 | .IX Header "SYNOPSIS" |
| 136 | .Vb 1 |
| 137 | \& #include <openssl/ecdsa.h> |
| 138 | \& |
| 139 | \& ECDSA_SIG* ECDSA_SIG_new(void); |
| 140 | \& void ECDSA_SIG_free(ECDSA_SIG *sig); |
| 141 | \& int i2d_ECDSA_SIG(const ECDSA_SIG *sig, unsigned char **pp); |
| 142 | \& ECDSA_SIG* d2i_ECDSA_SIG(ECDSA_SIG **sig, const unsigned char **pp, |
| 143 | \& long len); |
| 144 | \& |
| 145 | \& ECDSA_SIG* ECDSA_do_sign(const unsigned char *dgst, int dgst_len, |
| 146 | \& EC_KEY *eckey); |
| 147 | \& ECDSA_SIG* ECDSA_do_sign_ex(const unsigned char *dgst, int dgstlen, |
| 148 | \& const BIGNUM *kinv, const BIGNUM *rp, |
| 149 | \& EC_KEY *eckey); |
| 150 | \& int ECDSA_do_verify(const unsigned char *dgst, int dgst_len, |
| 151 | \& const ECDSA_SIG *sig, EC_KEY* eckey); |
| 152 | \& int ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx, |
| 153 | \& BIGNUM **kinv, BIGNUM **rp); |
| 154 | \& int ECDSA_sign(int type, const unsigned char *dgst, |
| 155 | \& int dgstlen, unsigned char *sig, |
| 156 | \& unsigned int *siglen, EC_KEY *eckey); |
| 157 | \& int ECDSA_sign_ex(int type, const unsigned char *dgst, |
| 158 | \& int dgstlen, unsigned char *sig, |
| 159 | \& unsigned int *siglen, const BIGNUM *kinv, |
| 160 | \& const BIGNUM *rp, EC_KEY *eckey); |
| 161 | \& int ECDSA_verify(int type, const unsigned char *dgst, |
| 162 | \& int dgstlen, const unsigned char *sig, |
| 163 | \& int siglen, EC_KEY *eckey); |
| 164 | \& int ECDSA_size(const EC_KEY *eckey); |
| 165 | \& |
| 166 | \& const ECDSA_METHOD* ECDSA_OpenSSL(void); |
| 167 | \& void ECDSA_set_default_method(const ECDSA_METHOD *meth); |
| 168 | \& const ECDSA_METHOD* ECDSA_get_default_method(void); |
| 169 | \& int ECDSA_set_method(EC_KEY *eckey,const ECDSA_METHOD *meth); |
| 170 | \& |
| 171 | \& int ECDSA_get_ex_new_index(long argl, void *argp, |
| 172 | \& CRYPTO_EX_new *new_func, |
| 173 | \& CRYPTO_EX_dup *dup_func, |
| 174 | \& CRYPTO_EX_free *free_func); |
| 175 | \& int ECDSA_set_ex_data(EC_KEY *d, int idx, void *arg); |
| 176 | \& void* ECDSA_get_ex_data(EC_KEY *d, int idx); |
| 177 | .Ve |
| 178 | .SH "DESCRIPTION" |
| 179 | .IX Header "DESCRIPTION" |
| 180 | The \fB\s-1ECDSA_SIG\s0\fR structure consists of two BIGNUMs for the |
| 181 | r and s value of a \s-1ECDSA\s0 signature (see X9.62 or \s-1FIPS\s0 186\-2). |
| 182 | .PP |
| 183 | .Vb 5 |
| 184 | \& struct |
| 185 | \& { |
| 186 | \& BIGNUM *r; |
| 187 | \& BIGNUM *s; |
| 188 | \& } ECDSA_SIG; |
| 189 | .Ve |
| 190 | .PP |
| 191 | \&\fIECDSA_SIG_new()\fR allocates a new \fB\s-1ECDSA_SIG\s0\fR structure (note: this |
| 192 | function also allocates the BIGNUMs) and initialize it. |
| 193 | .PP |
| 194 | \&\fIECDSA_SIG_free()\fR frees the \fB\s-1ECDSA_SIG\s0\fR structure \fBsig\fR. |
| 195 | .PP |
| 196 | \&\fIi2d_ECDSA_SIG()\fR creates the \s-1DER\s0 encoding of the \s-1ECDSA\s0 signature |
| 197 | \&\fBsig\fR and writes the encoded signature to \fB*pp\fR (note: if \fBpp\fR |
| 198 | is \s-1NULL\s0 \fBi2d_ECDSA_SIG\fR returns the expected length in bytes of |
| 199 | the \s-1DER\s0 encoded signature). \fBi2d_ECDSA_SIG\fR returns the length |
| 200 | of the \s-1DER\s0 encoded signature (or 0 on error). |
| 201 | .PP |
| 202 | \&\fId2i_ECDSA_SIG()\fR decodes a \s-1DER\s0 encoded \s-1ECDSA\s0 signature and returns |
| 203 | the decoded signature in a newly allocated \fB\s-1ECDSA_SIG\s0\fR structure. |
| 204 | \&\fB*sig\fR points to the buffer containing the \s-1DER\s0 encoded signature |
| 205 | of size \fBlen\fR. |
| 206 | .PP |
| 207 | \&\fIECDSA_size()\fR returns the maximum length of a \s-1DER\s0 encoded |
| 208 | \&\s-1ECDSA\s0 signature created with the private \s-1EC\s0 key \fBeckey\fR. |
| 209 | .PP |
| 210 | \&\fIECDSA_sign_setup()\fR may be used to precompute parts of the |
| 211 | signing operation. \fBeckey\fR is the private \s-1EC\s0 key and \fBctx\fR |
| 212 | is a pointer to \fB\s-1BN_CTX\s0\fR structure (or \s-1NULL\s0). The precomputed |
| 213 | values or returned in \fBkinv\fR and \fBrp\fR and can be used in a |
| 214 | later call to \fBECDSA_sign_ex\fR or \fBECDSA_do_sign_ex\fR. |
| 215 | .PP |
| 216 | \&\fIECDSA_sign()\fR is wrapper function for ECDSA_sign_ex with \fBkinv\fR |
| 217 | and \fBrp\fR set to \s-1NULL\s0. |
| 218 | .PP |
| 219 | \&\fIECDSA_sign_ex()\fR computes a digital signature of the \fBdgstlen\fR bytes |
| 220 | hash value \fBdgst\fR using the private \s-1EC\s0 key \fBeckey\fR and the optional |
| 221 | pre-computed values \fBkinv\fR and \fBrp\fR. The \s-1DER\s0 encoded signatures is |
| 222 | stored in \fBsig\fR and it's length is returned in \fBsig_len\fR. Note: \fBsig\fR |
| 223 | must point to \fBECDSA_size\fR bytes of memory. The parameter \fBtype\fR |
| 224 | is ignored. |
| 225 | .PP |
| 226 | \&\fIECDSA_verify()\fR verifies that the signature in \fBsig\fR of size |
| 227 | \&\fBsiglen\fR is a valid \s-1ECDSA\s0 signature of the hash value |
| 228 | value \fBdgst\fR of size \fBdgstlen\fR using the public key \fBeckey\fR. |
| 229 | The parameter \fBtype\fR is ignored. |
| 230 | .PP |
| 231 | \&\fIECDSA_do_sign()\fR is wrapper function for ECDSA_do_sign_ex with \fBkinv\fR |
| 232 | and \fBrp\fR set to \s-1NULL\s0. |
| 233 | .PP |
| 234 | \&\fIECDSA_do_sign_ex()\fR computes a digital signature of the \fBdgst_len\fR |
| 235 | bytes hash value \fBdgst\fR using the private key \fBeckey\fR and the |
| 236 | optional pre-computed values \fBkinv\fR and \fBrp\fR. The signature is |
| 237 | returned in a newly allocated \fB\s-1ECDSA_SIG\s0\fR structure (or \s-1NULL\s0 on error). |
| 238 | .PP |
| 239 | \&\fIECDSA_do_verify()\fR verifies that the signature \fBsig\fR is a valid |
| 240 | \&\s-1ECDSA\s0 signature of the hash value \fBdgst\fR of size \fBdgst_len\fR |
| 241 | using the public key \fBeckey\fR. |
| 242 | .SH "RETURN VALUES" |
| 243 | .IX Header "RETURN VALUES" |
| 244 | \&\fIECDSA_size()\fR returns the maximum length signature or 0 on error. |
| 245 | .PP |
| 246 | \&\fIECDSA_sign_setup()\fR and \fIECDSA_sign()\fR return 1 if successful or \-1 |
| 247 | on error. |
| 248 | .PP |
| 249 | \&\fIECDSA_verify()\fR and \fIECDSA_do_verify()\fR return 1 for a valid |
| 250 | signature, 0 for an invalid signature and \-1 on error. |
| 251 | The error codes can be obtained by \fIERR_get_error\fR\|(3). |
| 252 | .SH "EXAMPLES" |
| 253 | .IX Header "EXAMPLES" |
| 254 | Creating a \s-1ECDSA\s0 signature of given \s-1SHA\-1\s0 hash value using the |
| 255 | named curve secp192k1. |
| 256 | .PP |
| 257 | First step: create a \s-1EC_KEY\s0 object (note: this part is \fBnot\fR \s-1ECDSA\s0 |
| 258 | specific) |
| 259 | .PP |
| 260 | .Vb 10 |
| 261 | \& int ret; |
| 262 | \& ECDSA_SIG *sig; |
| 263 | \& EC_KEY *eckey = EC_KEY_new(); |
| 264 | \& if (eckey == NULL) |
| 265 | \& { |
| 266 | \& /* error */ |
| 267 | \& } |
| 268 | \& key\->group = EC_GROUP_new_by_nid(NID_secp192k1); |
| 269 | \& if (key\->group == NULL) |
| 270 | \& { |
| 271 | \& /* error */ |
| 272 | \& } |
| 273 | \& if (!EC_KEY_generate_key(eckey)) |
| 274 | \& { |
| 275 | \& /* error */ |
| 276 | \& } |
| 277 | .Ve |
| 278 | .PP |
| 279 | Second step: compute the \s-1ECDSA\s0 signature of a \s-1SHA\-1\s0 hash value |
| 280 | using \fBECDSA_do_sign\fR |
| 281 | .PP |
| 282 | .Vb 5 |
| 283 | \& sig = ECDSA_do_sign(digest, 20, eckey); |
| 284 | \& if (sig == NULL) |
| 285 | \& { |
| 286 | \& /* error */ |
| 287 | \& } |
| 288 | .Ve |
| 289 | .PP |
| 290 | or using \fBECDSA_sign\fR |
| 291 | .PP |
| 292 | .Vb 9 |
| 293 | \& unsigned char *buffer, *pp; |
| 294 | \& int buf_len; |
| 295 | \& buf_len = ECDSA_size(eckey); |
| 296 | \& buffer = OPENSSL_malloc(buf_len); |
| 297 | \& pp = buffer; |
| 298 | \& if (!ECDSA_sign(0, dgst, dgstlen, pp, &buf_len, eckey); |
| 299 | \& { |
| 300 | \& /* error */ |
| 301 | \& } |
| 302 | .Ve |
| 303 | .PP |
| 304 | Third step: verify the created \s-1ECDSA\s0 signature using \fBECDSA_do_verify\fR |
| 305 | .PP |
| 306 | .Vb 1 |
| 307 | \& ret = ECDSA_do_verify(digest, 20, sig, eckey); |
| 308 | .Ve |
| 309 | .PP |
| 310 | or using \fBECDSA_verify\fR |
| 311 | .PP |
| 312 | .Vb 1 |
| 313 | \& ret = ECDSA_verify(0, digest, 20, buffer, buf_len, eckey); |
| 314 | .Ve |
| 315 | .PP |
| 316 | and finally evaluate the return value: |
| 317 | .PP |
| 318 | .Vb 12 |
| 319 | \& if (ret == \-1) |
| 320 | \& { |
| 321 | \& /* error */ |
| 322 | \& } |
| 323 | \& else if (ret == 0) |
| 324 | \& { |
| 325 | \& /* incorrect signature */ |
| 326 | \& } |
| 327 | \& else /* ret == 1 */ |
| 328 | \& { |
| 329 | \& /* signature ok */ |
| 330 | \& } |
| 331 | .Ve |
| 332 | .SH "CONFORMING TO" |
| 333 | .IX Header "CONFORMING TO" |
| 334 | \&\s-1ANSI\s0 X9.62, \s-1US\s0 Federal Information Processing Standard \s-1FIPS\s0 186\-2 |
| 335 | (Digital Signature Standard, \s-1DSS\s0) |
| 336 | .SH "SEE ALSO" |
| 337 | .IX Header "SEE ALSO" |
| 338 | \&\fIdsa\fR\|(3), \fIrsa\fR\|(3) |
| 339 | .SH "HISTORY" |
| 340 | .IX Header "HISTORY" |
| 341 | The ecdsa implementation was first introduced in OpenSSL 0.9.8 |
| 342 | .SH "AUTHOR" |
| 343 | .IX Header "AUTHOR" |
| 344 | Nils Larsch for the OpenSSL project (http://www.openssl.org). |