xref: /plan9/sys/man/2/dsa (revision e12a987081f10894b49298514b3a97b41db862b0)
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:

.EX 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:

.EX 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 corresponding 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

.EX 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 signature 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)