# Inferno Encrypt Key Exchange Protocol## Copyright © 1995-1999 Lucent Techologies Inc.  All rights reserved.## This code uses methods that are subject to one or more patents# held by Lucent Technologies Inc.  Its use outside Inferno# requires a separate licence from Lucent.#implement Login; include "sys.m";	sys: Sys; include "keyring.m";	kr: Keyring;	IPint: import kr; include "security.m"; include "string.m"; # see login(6)login(id, password, dest: string): (string, ref Keyring->Authinfo){	sys = load Sys Sys->PATH;	kr = load Keyring Keyring->PATH;	if(kr == nil)		return nomod(Keyring->PATH); 	ssl := load SSL SSL->PATH;	if(ssl == nil)		return nomod(SSL->PATH); 	rand := load Random Random->PATH;	if(rand == nil)		return nomod(Random->PATH); 	if(dest == nil)		dest = "$SIGNER";	for(j:=0; j<len dest && dest[j] != '!'; j++)		break;	if(j >= len dest)		dest = "net!"+dest+"!inflogin";	# BUG: must do better 	(ok, lc) := sys->dial(dest, nil);	if(ok < 0)		return (sys->sprint("can't contact login service: %r"), nil); 	# push ssl, leave in clear mode for now	(err, c) := ssl->connect(lc.dfd);	if(c == nil)		return ("can't push ssl: " + err, nil);	lc.dfd = nil;	lc.cfd = nil; 	# user->CA	name	if(kr->putstring(c.dfd, id) < 0)		return (sys->sprint("can't send user name: %r"), nil); 	# CA->user	ACK	(s, why) := kr->getstring(c.dfd);	if(why != nil)		return ("remote: " + why, nil);	if(s != id)		return ("unexpected reply from signer: " + s, nil); 	# user->CA	ivec	ivec := rand->randombuf(rand->ReallyRandom, 8);	if(kr->putbytearray(c.dfd, ivec, len ivec) < 0)		return (sys->sprint("can't send initialization vector: %r"), nil); 	# start encrypting	pwbuf := array of byte password;	digest := array[Keyring->SHA1dlen] of byte;	kr->sha1(pwbuf, len pwbuf, digest, nil);	pwbuf = array[8] of byte;	for(i := 0; i < 8; i++)		pwbuf[i] = digest[i] ^ digest[8+i];	for(i = 0; i < 4; i++)		pwbuf[i] ^= digest[16+i];	for(i = 0; i < 8; i++)		pwbuf[i] ^= ivec[i];	err = ssl->secret(c, pwbuf, pwbuf);	if(err != nil)		return ("can't set secret: " + err, nil);	if(sys->fprint(c.cfd, "alg rc4") < 0)		return (sys->sprint("can't push alg rc4: %r"), nil);	#if(sys->fprint(c.cfd, "alg desebc") < 0)	#	return (sys->sprint("can't push alg desecb: %r"), nil); 	# CA -> user	key(alpha**r0 mod p)	(s, err) = kr->getstring(c.dfd);	if(err != nil){		if(err == "failure") # calculated secret is wrong			return ("name or secret incorrect (alpha**r0 mod p)", nil);		return ("remote:" + err, nil);	} 	# stop encrypting	if(sys->fprint(c.cfd, "alg clear") < 0)		return (sys->sprint("can't push alg clear: %r"), nil);	alphar0 := IPint.b64toip(s); 	# CA->user	alpha	(s, err) = kr->getstring(c.dfd);	if(err != nil){		if(err == "failure")			return ("name or secret incorrect (alpha)", nil);		return ("remote: " + err, nil);	}	info := ref Keyring->Authinfo;	info.alpha = IPint.b64toip(s); 	# CA->user	p	(s, err) = kr->getstring(c.dfd);	if(err != nil){		if(err == "failure")			return ("name or secret incorrect (p)", nil);		return ("remote: " + err, nil);	}	info.p = IPint.b64toip(s); 	# sanity check	bits := info.p.bits();	abits := info.alpha.bits();	if(abits > bits || abits < 2)		return ("bogus diffie hellman constants", nil); 	# generate our random diffie hellman part	r1 := kr->IPint.random(bits/4, bits);	alphar1 := info.alpha.expmod(r1, info.p); 	# user->CA	alpha**r1 mod p	if(kr->putstring(c.dfd, alphar1.iptob64()) < 0)		return (sys->sprint("can't send (alpha**r1 mod p): %r"), nil); 	# compute alpha**(r0*r1) mod p	alphar0r1 := alphar0.expmod(r1, info.p); 	# turn on digesting	secret := alphar0r1.iptobytes();	err = ssl->secret(c, secret, secret);	if(err != nil)		return ("can't set digesting: " + err, nil);	if(sys->fprint(c.cfd, "alg sha1") < 0)		return (sys->sprint("can't push alg sha1: %r"), nil); 	# CA->user	CA's public key, SHA(CA's public key + secret)	(s, err) = kr->getstring(c.dfd);	if(err != nil)		return ("can't get signer's public key: " + err, nil); 	info.spk = kr->strtopk(s); 	# generate a key pair	info.mysk = kr->genSKfromPK(info.spk, id);	info.mypk = kr->sktopk(info.mysk); 	# user->CA	user's public key, SHA(user's public key + secret)	if(kr->putstring(c.dfd, kr->pktostr(info.mypk)) < 0)		return (sys->sprint("can't send your public: %r"), nil); 	# CA->user	user's public key certificate	(s, err) = kr->getstring(c.dfd);	if(err != nil)		return ("can't get certificate: " + err, nil); 	info.cert = kr->strtocert(s);	return(nil, info);} nomod(mod: string): (string, ref Keyring->Authinfo){	return (sys->sprint("can't load module %s: %r", mod), nil);}