glenda.party
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DSA(2)                        System Calls Manual                       DSA(2)



NAME
       dsagen,  dsasign,  dsaverify,  dsapuballoc,  dsapubfree,  dsaprivalloc,
       dsaprivfree, dsasigalloc, dsasigfree, dsaprivtopub - digital  signature
       algorithm

SYNOPSIS
       #include <u.h>
       #include <libc.h>
       #include <mp.h>
       #include <libsec.h>

       DSApriv*  dsagen(DSApub *opub)

       DSAsig*   dsasign(DSApriv *k, mpint *m)

       int       dsaverify(DSApub *k, DSAsig *sig, mpint *m)

       DSApub*   dsapuballoc(void)

       void      dsapubfree(DSApub*)

       DSApriv*  dsaprivalloc(void)

       void      dsaprivfree(DSApriv*)

       DSAsig*   dsasigalloc(void)

       void      dsasigfree(DSAsig*)

       DSApub*   dsaprivtopub(DSApriv*)

DESCRIPTION
       DSA  is  the NIST approved digital signature algorithm.  The owner of a
       key publishes the public part of the key:

              struct DSApub
              {
                   mpint     *p;  // modulus
                   mpint     *q;  // group order, q divides p-1
                   mpint     *alpha;   // group generator
                   mpint     *key;     // alpha**secret mod p
              };

       This part can be used for verifying signatures (with dsaverify) created
       by the owner.  The owner signs (with dsasign) using his private key:

              struct DSApriv
              {
                   DSApub    pub;
                   mpint     *secret; // (decryption key)
              };

       Keys  are  generated using dsagen.  If dsagen's argument opub is nil, a
       key is created using  a  new  p  and  q  generated  by  DSAprimes  (see
       prime(2)).  Otherwise, p and q are copied from the old key.

       Dsaprivtopub  returns  a  newly allocated copy of the public key corre‐
       sponding to the private key.

       The routines dsapuballoc, dsapubfree, dsaprivalloc, and dsaprivfree are
       provided to manage key storage.

       Dsasign signs message m using a private key k yielding a

              struct DSAsig
              {
                   mpint     *r, *s;
              };

       Dsaverify returns 0 if the signature is valid and -1 if not.

       The  routines  dsasigalloc and dsasigfree are provided to manage signa‐
       ture storage.

SOURCE
       /sys/src/libsec

SEE ALSO
       mp(2),  aes(2),  blowfish(2),  des(2),  rc4(2),   rsa(2),   sechash(2),
       prime(2), rand(2), dsa(8)



                                                                        DSA(2)