NAME

	asn1toDSApriv, 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*) DSApriv*     asn1toDSApriv(uchar *priv, int npriv)

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(3)). 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 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. Asn1toDSApriv converts an ASN1 formatted DSA private key into the corresponding DSApriv structure; see rsa(3) for other ASN1 routines.

SOURCE

	/usr/local/plan9/src/libsec

SEE ALSO

	mp(3), aes(3), blowfish(3), des(3), rc4(3), rsa(3), sechash(3), prime(3), rand(3)