Edit File: ECDSA_size.3
.\" Automatically generated by Pod::Man 4.11 (Pod::Simple 3.35) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. Capital omega is used to do unbreakable dashes and .\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff, .\" nothing in troff, for use with C<>. .tr \(*W- .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' .ie n \{\ . ds -- \(*W- . ds PI pi . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch . ds L" "" . ds R" "" . ds C` "" . ds C' "" 'br\} .el\{\ . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' . ds C` . ds C' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is >0, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. Of course, you'll have to process the .\" output yourself in some meaningful fashion. .\" .\" Avoid warning from groff about undefined register 'F'. .de IX .. .nr rF 0 .if \n(.g .if rF .nr rF 1 .if (\n(rF:(\n(.g==0)) \{\ . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF .\" .\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). .\" Fear. Run. Save yourself. No user-serviceable parts. . \" fudge factors for nroff and troff .if n \{\ . ds #H 0 . ds #V .8m . ds #F .3m . ds #[ \f1 . ds #] \fP .\} .if t \{\ . ds #H ((1u-(\\\\n(.fu%2u))*.13m) . ds #V .6m . ds #F 0 . ds #[ \& . ds #] \& .\} . \" simple accents for nroff and troff .if n \{\ . ds ' \& . ds ` \& . ds ^ \& . ds , \& . ds ~ ~ . ds / .\} .if t \{\ . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' .\} . \" troff and (daisy-wheel) nroff accents .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' .ds 8 \h'\*(#H'\(*b\h'-\*(#H' .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] .ds ae a\h'-(\w'a'u*4/10)'e .ds Ae A\h'-(\w'A'u*4/10)'E . \" corrections for vroff .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' . \" for low resolution devices (crt and lpr) .if \n(.H>23 .if \n(.V>19 \ \{\ . ds : e . ds 8 ss . ds o a . ds d- d\h'-1'\(ga . ds D- D\h'-1'\(hy . ds th \o'bp' . ds Th \o'LP' . ds ae ae . ds Ae AE .\} .rm #[ #] #H #V #F C .\" ======================================================================== .\" .IX Title "ecdsa 3" .TH ecdsa 3 "2019-12-20" "1.0.2u" "OpenSSL" .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" ECDSA_SIG_new, ECDSA_SIG_free, i2d_ECDSA_SIG, d2i_ECDSA_SIG, ECDSA_size, ECDSA_sign_setup, ECDSA_sign, ECDSA_sign_ex, ECDSA_verify, ECDSA_do_sign, ECDSA_do_sign_ex, ECDSA_do_verify \- Elliptic Curve Digital Signature Algorithm .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/ecdsa.h> \& \& ECDSA_SIG* ECDSA_SIG_new(void); \& void ECDSA_SIG_free(ECDSA_SIG *sig); \& int i2d_ECDSA_SIG(const ECDSA_SIG *sig, unsigned char **pp); \& ECDSA_SIG* d2i_ECDSA_SIG(ECDSA_SIG **sig, const unsigned char **pp, \& long len); \& \& ECDSA_SIG* ECDSA_do_sign(const unsigned char *dgst, int dgst_len, \& EC_KEY *eckey); \& ECDSA_SIG* ECDSA_do_sign_ex(const unsigned char *dgst, int dgstlen, \& const BIGNUM *kinv, const BIGNUM *rp, \& EC_KEY *eckey); \& int ECDSA_do_verify(const unsigned char *dgst, int dgst_len, \& const ECDSA_SIG *sig, EC_KEY* eckey); \& int ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx, \& BIGNUM **kinv, BIGNUM **rp); \& int ECDSA_sign(int type, const unsigned char *dgst, \& int dgstlen, unsigned char *sig, \& unsigned int *siglen, EC_KEY *eckey); \& int ECDSA_sign_ex(int type, const unsigned char *dgst, \& int dgstlen, unsigned char *sig, \& unsigned int *siglen, const BIGNUM *kinv, \& const BIGNUM *rp, EC_KEY *eckey); \& int ECDSA_verify(int type, const unsigned char *dgst, \& int dgstlen, const unsigned char *sig, \& int siglen, EC_KEY *eckey); \& int ECDSA_size(const EC_KEY *eckey); \& \& const ECDSA_METHOD* ECDSA_OpenSSL(void); \& void ECDSA_set_default_method(const ECDSA_METHOD *meth); \& const ECDSA_METHOD* ECDSA_get_default_method(void); \& int ECDSA_set_method(EC_KEY *eckey,const ECDSA_METHOD *meth); \& \& int ECDSA_get_ex_new_index(long argl, void *argp, \& CRYPTO_EX_new *new_func, \& CRYPTO_EX_dup *dup_func, \& CRYPTO_EX_free *free_func); \& int ECDSA_set_ex_data(EC_KEY *d, int idx, void *arg); \& void* ECDSA_get_ex_data(EC_KEY *d, int idx); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" The \fB\s-1ECDSA_SIG\s0\fR structure consists of two BIGNUMs for the r and s value of a \s-1ECDSA\s0 signature (see X9.62 or \s-1FIPS 186\-2\s0). .PP .Vb 5 \& struct \& { \& BIGNUM *r; \& BIGNUM *s; \& } ECDSA_SIG; .Ve .PP \&\fBECDSA_SIG_new()\fR allocates a new \fB\s-1ECDSA_SIG\s0\fR structure (note: this function also allocates the BIGNUMs) and initialize it. .PP \&\fBECDSA_SIG_free()\fR frees the \fB\s-1ECDSA_SIG\s0\fR structure \fBsig\fR. .PP \&\fBi2d_ECDSA_SIG()\fR creates the \s-1DER\s0 encoding of the \s-1ECDSA\s0 signature \&\fBsig\fR and writes the encoded signature to \fB*pp\fR (note: if \fBpp\fR is \s-1NULL\s0 \fBi2d_ECDSA_SIG\fR returns the expected length in bytes of the \s-1DER\s0 encoded signature). \fBi2d_ECDSA_SIG\fR returns the length of the \s-1DER\s0 encoded signature (or 0 on error). .PP \&\fBd2i_ECDSA_SIG()\fR decodes a \s-1DER\s0 encoded \s-1ECDSA\s0 signature and returns the decoded signature in a newly allocated \fB\s-1ECDSA_SIG\s0\fR structure. \&\fB*sig\fR points to the buffer containing the \s-1DER\s0 encoded signature of size \fBlen\fR. .PP \&\fBECDSA_size()\fR returns the maximum length of a \s-1DER\s0 encoded \&\s-1ECDSA\s0 signature created with the private \s-1EC\s0 key \fBeckey\fR. .PP \&\fBECDSA_sign_setup()\fR may be used to precompute parts of the signing operation. \fBeckey\fR is the private \s-1EC\s0 key and \fBctx\fR is a pointer to \fB\s-1BN_CTX\s0\fR structure (or \s-1NULL\s0). The precomputed values or returned in \fBkinv\fR and \fBrp\fR and can be used in a later call to \fBECDSA_sign_ex\fR or \fBECDSA_do_sign_ex\fR. .PP \&\fBECDSA_sign()\fR is wrapper function for ECDSA_sign_ex with \fBkinv\fR and \fBrp\fR set to \s-1NULL.\s0 .PP \&\fBECDSA_sign_ex()\fR computes a digital signature of the \fBdgstlen\fR bytes hash value \fBdgst\fR using the private \s-1EC\s0 key \fBeckey\fR and the optional pre-computed values \fBkinv\fR and \fBrp\fR. The \s-1DER\s0 encoded signatures is stored in \fBsig\fR and it's length is returned in \fBsig_len\fR. Note: \fBsig\fR must point to \fBECDSA_size\fR bytes of memory. The parameter \fBtype\fR is ignored. .PP \&\fBECDSA_verify()\fR verifies that the signature in \fBsig\fR of size \&\fBsiglen\fR is a valid \s-1ECDSA\s0 signature of the hash value \&\fBdgst\fR of size \fBdgstlen\fR using the public key \fBeckey\fR. The parameter \fBtype\fR is ignored. .PP \&\fBECDSA_do_sign()\fR is wrapper function for ECDSA_do_sign_ex with \fBkinv\fR and \fBrp\fR set to \s-1NULL.\s0 .PP \&\fBECDSA_do_sign_ex()\fR computes a digital signature of the \fBdgst_len\fR bytes hash value \fBdgst\fR using the private key \fBeckey\fR and the optional pre-computed values \fBkinv\fR and \fBrp\fR. The signature is returned in a newly allocated \fB\s-1ECDSA_SIG\s0\fR structure (or \s-1NULL\s0 on error). .PP \&\fBECDSA_do_verify()\fR verifies that the signature \fBsig\fR is a valid \&\s-1ECDSA\s0 signature of the hash value \fBdgst\fR of size \fBdgst_len\fR using the public key \fBeckey\fR. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBECDSA_SIG_new()\fR returns \s-1NULL\s0 if the allocation fails. .PP \&\fBECDSA_size()\fR returns the maximum length signature or 0 on error. .PP \&\fBECDSA_sign_setup()\fR and \fBECDSA_sign()\fR return 1 if successful or 0 on error. .PP \&\fBECDSA_verify()\fR and \fBECDSA_do_verify()\fR return 1 for a valid signature, 0 for an invalid signature and \-1 on error. The error codes can be obtained by \fBERR_get_error\fR\|(3). .SH "EXAMPLES" .IX Header "EXAMPLES" Creating a \s-1ECDSA\s0 signature of given \s-1SHA\-1\s0 hash value using the named curve secp192k1. .PP First step: create a \s-1EC_KEY\s0 object (note: this part is \fBnot\fR \s-1ECDSA\s0 specific) .PP .Vb 12 \& int ret; \& ECDSA_SIG *sig; \& EC_KEY *eckey; \& eckey = EC_KEY_new_by_curve_name(NID_secp192k1); \& if (eckey == NULL) \& { \& /* error */ \& } \& if (!EC_KEY_generate_key(eckey)) \& { \& /* error */ \& } .Ve .PP Second step: compute the \s-1ECDSA\s0 signature of a \s-1SHA\-1\s0 hash value using \fBECDSA_do_sign\fR .PP .Vb 5 \& sig = ECDSA_do_sign(digest, 20, eckey); \& if (sig == NULL) \& { \& /* error */ \& } .Ve .PP or using \fBECDSA_sign\fR .PP .Vb 9 \& unsigned char *buffer, *pp; \& int buf_len; \& buf_len = ECDSA_size(eckey); \& buffer = OPENSSL_malloc(buf_len); \& pp = buffer; \& if (!ECDSA_sign(0, dgst, dgstlen, pp, &buf_len, eckey); \& { \& /* error */ \& } .Ve .PP Third step: verify the created \s-1ECDSA\s0 signature using \fBECDSA_do_verify\fR .PP .Vb 1 \& ret = ECDSA_do_verify(digest, 20, sig, eckey); .Ve .PP or using \fBECDSA_verify\fR .PP .Vb 1 \& ret = ECDSA_verify(0, digest, 20, buffer, buf_len, eckey); .Ve .PP and finally evaluate the return value: .PP .Vb 12 \& if (ret == \-1) \& { \& /* error */ \& } \& else if (ret == 0) \& { \& /* incorrect signature */ \& } \& else /* ret == 1 */ \& { \& /* signature ok */ \& } .Ve .SH "CONFORMING TO" .IX Header "CONFORMING TO" \&\s-1ANSI X9.62, US\s0 Federal Information Processing Standard \s-1FIPS 186\-2\s0 (Digital Signature Standard, \s-1DSS\s0) .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBdsa\fR\|(3), \fBrsa\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" The ecdsa implementation was first introduced in OpenSSL 0.9.8 .SH "AUTHOR" .IX Header "AUTHOR" Nils Larsch for the OpenSSL project (http://www.openssl.org).