.rn '' }`
'''
'''
.de Sh
.br
.if t .Sp
.ne 5
.PP
\fB\\$1\fR
.PP
..
.de Sp
.if t .sp .5v
.if n .sp
..
.de Ip
.br
.ie \\n(.$>=3 .ne \\$3
.el .ne 3
.IP "\\$1" \\$2
..
.de Vb
.ft CW
.nf
.ne \\$1
..
.de Ve
.ft R

.fi
..
'''
'''
'''     Set up \*(-- to give an unbreakable dash;
'''     string Tr holds user defined translation string.
'''     Bell System Logo is used as a dummy character.
'''
.tr \(*W-|\(bv\*(Tr
.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" ""
'''   \*(M", \*(S", \*(N" and \*(T" are the equivalent of
'''   \*(L" and \*(R", except that they are used on ".xx" lines,
'''   such as .IP and .SH, which do another additional levels of
'''   double-quote interpretation
.ds M" """
.ds S" """
.ds N" """""
.ds T" """""
.ds L' '
.ds R' '
.ds M' '
.ds S' '
.ds N' '
.ds T' '
'br\}
.el\{\
.ds -- \(em\|
.tr \*(Tr
.ds L" ``
.ds R" ''
.ds M" ``
.ds S" ''
.ds N" ``
.ds T" ''
.ds L' `
.ds R' '
.ds M' `
.ds S' '
.ds N' `
.ds T' '
.ds PI \(*p
'br\}
.\"	If the F register is turned on, we'll generate
.\"	index entries out stderr for the following things:
.\"		TH	Title 
.\"		SH	Header
.\"		Sh	Subsection 
.\"		Ip	Item
.\"		X<>	Xref  (embedded
.\"	Of course, you have to process the output yourself
.\"	in some meaninful fashion.
.if \nF \{
.de IX
.tm Index:\\$1\t\\n%\t"\\$2"
..
.nr % 0
.rr F
.\}
.TH dsa 3 "0.9.5a" "22/Jul/100" "OpenSSL"
.UC
.if n .hy 0
.if n .na
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.de CQ          \" put $1 in typewriter font
.ft CW
'if n "\c
'if t \\&\\$1\c
'if n \\&\\$1\c
'if n \&"
\\&\\$2 \\$3 \\$4 \\$5 \\$6 \\$7
'.ft R
..
.\" @(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2
.	\" AM - accent mark definitions
.bd B 3
.	\" 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 ? ?
.	ds ! !
.	ds /
.	ds q
.\}
.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 ? \s-2c\h'-\w'c'u*7/10'\u\h'\*(#H'\zi\d\s+2\h'\w'c'u*8/10'
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.	ds q o\h'-\w'o'u*8/10'\s-4\v'.4m'\z\(*i\v'-.4m'\s+4\h'\w'o'u*8/10'
.\}
.	\" 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 v \\k:\h'-(\\n(.wu*9/10-\*(#H)'\v'-\*(#V'\*(#[\s-4v\s0\v'\*(#V'\h'|\\n:u'\*(#]
.ds _ \\k:\h'-(\\n(.wu*9/10-\*(#H+(\*(#F*2/3))'\v'-.4m'\z\(hy\v'.4m'\h'|\\n:u'
.ds . \\k:\h'-(\\n(.wu*8/10)'\v'\*(#V*4/10'\z.\v'-\*(#V*4/10'\h'|\\n:u'
.ds 3 \*(#[\v'.2m'\s-2\&3\s0\v'-.2m'\*(#]
.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
.ds oe o\h'-(\w'o'u*4/10)'e
.ds Oe O\h'-(\w'O'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 v \h'-1'\o'\(aa\(ga'
.	ds _ \h'-1'^
.	ds . \h'-1'.
.	ds 3 3
.	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
.	ds oe oe
.	ds Oe OE
.\}
.rm #[ #] #H #V #F C
.SH "NAME"
dsa \- Digital Signature Algorithm
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.PP
.Vb 1
\& #include <openssl/dsa.h>
.Ve
.Vb 2
\& DSA *  DSA_new(void);
\& void   DSA_free(DSA *dsa);
.Ve
.Vb 1
\& int    DSA_size(DSA *dsa);
.Ve
.Vb 3
\& DSA *  DSA_generate_parameters(int bits, unsigned char *seed,
\&                int seed_len, int *counter_ret, unsigned long *h_ret,
\&                void (*callback)(int, int, void *), void *cb_arg);
.Ve
.Vb 1
\& DH *   DSA_dup_DH(DSA *r);
.Ve
.Vb 1
\& int    DSA_generate_key(DSA *dsa);
.Ve
.Vb 6
\& int    DSA_sign(int dummy, const unsigned char *dgst, int len,
\&                unsigned char *sigret, unsigned int *siglen, DSA *dsa);
\& int    DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp,
\&                BIGNUM **rp);
\& int    DSA_verify(int dummy, const unsigned char *dgst, int len,
\&                unsigned char *sigbuf, int siglen, DSA *dsa);
.Ve
.Vb 5
\& void DSA_set_default_method(DSA_METHOD *meth);
\& DSA_METHOD *DSA_get_default_method(void);
\& DSA_METHOD *DSA_set_method(DSA *dsa, DSA_METHOD *meth);
\& DSA *DSA_new_method(DSA_METHOD *meth);
\& DSA_METHOD *DSA_OpenSSL(void);
.Ve
.Vb 4
\& int DSA_get_ex_new_index(long argl, char *argp, int (*new_func)(),
\&             int (*dup_func)(), void (*free_func)());
\& int DSA_set_ex_data(DSA *d, int idx, char *arg);
\& char *DSA_get_ex_data(DSA *d, int idx);
.Ve
.Vb 4
\& DSA_SIG *DSA_SIG_new(void);
\& void   DSA_SIG_free(DSA_SIG *a);
\& int    i2d_DSA_SIG(DSA_SIG *a, unsigned char **pp);
\& DSA_SIG *d2i_DSA_SIG(DSA_SIG **v, unsigned char **pp, long length);
.Ve
.Vb 3
\& DSA_SIG *DSA_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
\& int    DSA_do_verify(const unsigned char *dgst, int dgst_len,
\&             DSA_SIG *sig, DSA *dsa);
.Ve
.Vb 6
\& DSA *  d2i_DSAPublicKey(DSA **a, unsigned char **pp, long length);
\& DSA *  d2i_DSAPrivateKey(DSA **a, unsigned char **pp, long length);
\& DSA *  d2i_DSAparams(DSA **a, unsigned char **pp, long length);
\& int    i2d_DSAPublicKey(DSA *a, unsigned char **pp);
\& int    i2d_DSAPrivateKey(DSA *a, unsigned char **pp);
\& int    i2d_DSAparams(DSA *a,unsigned char **pp);
.Ve
.Vb 4
\& int    DSAparams_print(BIO *bp, DSA *x);
\& int    DSAparams_print_fp(FILE *fp, DSA *x);
\& int    DSA_print(BIO *bp, DSA *x, int off);
\& int    DSA_print_fp(FILE *bp, DSA *x, int off);
.Ve
.SH "DESCRIPTION"
These functions implement the Digital Signature Algorithm (DSA).  The
generation of shared DSA parameters is described in
the \fIDSA_generate_parameters(3)|DSA_generate_parameters(3)\fR manpage;
the \fIDSA_generate_key(3)|DSA_generate_key(3)\fR manpage describes how to
generate a signature key. Signature generation and verification are
described in the \fIDSA_sign(3)|DSA_sign(3)\fR manpage.
.PP
The \fBDSA\fR structure consists of several BIGNUM components.
.PP
.Vb 10
\& struct
\&        {
\&        BIGNUM *p;              // prime number (public)
\&        BIGNUM *q;              // 160-bit subprime, q | p-1 (public)
\&        BIGNUM *g;              // generator of subgroup (public)
\&        BIGNUM *priv_key;       // private key x
\&        BIGNUM *pub_key;        // public key y = g^x
\&        // ...
\&        }
\& DSA;
.Ve
In public keys, \fBpriv_key\fR is NULL.
.SH "CONFORMING TO"
US Federal Information Processing Standard FIPS 186 (Digital Signature
Standard, DSS), ANSI X9.30
.SH "SEE ALSO"
the \fIbn(3)|bn(3)\fR manpage, the \fIdh(3)|dh(3)\fR manpage, the \fIerr(3)|err(3)\fR manpage, the \fIrand(3)|rand(3)\fR manpage,
the \fIrsa(3)|rsa(3)\fR manpage, the \fIsha(3)|sha(3)\fR manpage, the \fIDSA_new(3)|DSA_new(3)\fR manpage,
the \fIDSA_size(3)|DSA_size(3)\fR manpage,
the \fIDSA_generate_parameters(3)|DSA_generate_parameters(3)\fR manpage,
the \fIDSA_dup_DH(3)|DSA_dup_DH(3)\fR manpage,
the \fIDSA_generate_key(3)|DSA_generate_key(3)\fR manpage,
the \fIDSA_sign(3)|DSA_sign(3)\fR manpage, the \fIDSA_set_method(3)|DSA_set_method(3)\fR manpage,
the \fIDSA_get_ex_new_index(3)|DSA_get_ex_new_index(3)\fR manpage,
the \fIRSA_print(3)|RSA_print(3)\fR manpage

.rn }` ''
.IX Title "dsa 3"
.IX Name "dsa - Digital Signature Algorithm"

.IX Header "NAME"

.IX Header "SYNOPSIS"

.IX Header "DESCRIPTION"

.IX Header "CONFORMING TO"

.IX Header "SEE ALSO"