// public constructors
public digestrandomgenerator(digest digest) {
this.digest = digest;
this.seed = new byte[digest.getdigestsize()];
this.seedcounter = 1;
this.state = new byte[digest.getdigestsize()];
this.statecounter = 1;
}
protected byte[] enginesign() throws signatureexception {
byte[] hash = new byte[digest.getdigestsize()];
digest.dofinal(hash, 0);
try {
byte[] sigbytes = new byte[64];
biginteger[] sig = signer.generatesignature(hash);
byte[] r = sig[0].tobytearray();
byte[] s = sig[1].tobytearray();
if (s[0] != 0) {
system.arraycopy(s, 0, sigbytes, 32 - s.length, s.length);
} else {
system.arraycopy(s, 1, sigbytes, 32 - (s.length - 1), s.length - 1);
}
if (r[0] != 0) {
system.arraycopy(r, 0, sigbytes, 64 - r.length, r.length);
} else {
system.arraycopy(r, 1, sigbytes, 64 - (r.length - 1), r.length - 1);
}
return sigbytes;
} catch (exception e) {
throw new signatureexception(e.tostring());
}
}
protected boolean engineverify(byte[] sigbytes) throws signatureexception {
byte[] hash = new byte[digest.getdigestsize()];
digest.dofinal(hash, 0);
biginteger[] sig;
try {
byte[] r = new byte[32];
byte[] s = new byte[32];
system.arraycopy(sigbytes, 0, s, 0, 32);
system.arraycopy(sigbytes, 32, r, 0, 32);
sig = new biginteger[2];
sig[0] = new biginteger(1, r);
sig[1] = new biginteger(1, s);
} catch (exception e) {
throw new signatureexception("error decoding signature bytes.");
}
return signer.verifysignature(hash, sig[0], sig[1]);
}
private static byte[] dofinal(digest d) {
byte[] bs = new byte[d.getdigestsize()];
d.dofinal(bs, 0);
return bs;
}