# HG changeset patch
# User Laman
# Date 2019-07-05 15:42:03
# Node ID 12f10d9d594833d183bf52915a5d8d899acce777
# Parent  64020ac8e211d17165f0ee2f9df6f9d29f958a2c

refactored Chacha20.encrypt, .decrypt

diff --git a/spec/test/chachaSpec.js b/spec/test/chachaSpec.js
--- a/spec/test/chachaSpec.js
+++ b/spec/test/chachaSpec.js
@@ -34,7 +34,7 @@ describe("Chacha",function(){
 	describe("encrypt",function(){
 		it("should correctly encrypt an example text",function(){
 			let ciphertext=[110,46,53,154,37,104,249,128,65,186,7,40,221,13,105,129,233,126,122,236,29, 67,96,194,10,39,175,204,253,159,174,11,249,27,101,197,82,71,51,171,143,89,61,171,205,98,179,87,22, 57,214,36,230,81,82,171,143,83,12,53,159,8,97,216,7,202,13,191,80,13,106,97,86,163,142,8,138,34, 182,94,82,188,81,77,22,204,248,6,129,140,233,26,183,121,55,54,90,249,11,191,116,163,91,230,180,11, 142,237,242,120,94,66,135,77];
-			expect(encrypt(str2utf8(plaintext),key,nonce2)).toEqual(nonce2.concat(ciphertext));
+			expect(encrypt(str2utf8(plaintext),key,nonce2)).toEqual([nonce2,ciphertext]);
 		});
 	});
 	
@@ -45,7 +45,8 @@ describe("Chacha",function(){
 			for(let i=0;i<16;i++){key.push(Math.floor(Math.random()*256));}
 			let nonce=[];
 			for(let i=0;i<8;i++){nonce.push(Math.floor(Math.random()*256));}
-			expect(decrypt(encrypt(text,key,nonce),key)).toEqual(text);
+			let [_,ciphertext]=encrypt(text,key,nonce);
+			expect(decrypt(ciphertext,key,nonce)).toEqual(text);
 		});
 	});
 	
diff --git a/src/chacha.js b/src/chacha.js
--- a/src/chacha.js
+++ b/src/chacha.js
@@ -1,26 +1,21 @@
 // https://tools.ietf.org/html/rfc7539
-import {MASK,int32s2bytes,bytes2int32s,zeroPad} from "./util.js";
+import {MASK,int32s2bytes,bytes2int32s,zeroPad,createRandomNonce} from "./util.js";
 
 function lrot(x,shift){
 	return (x<<shift|x>>>(32-shift))&MASK;
 }
 
-export function createNonce(){
-	let nonce=new Uint8Array(12);
-	window.crypto.getRandomValues(nonce);
-	return Array.from(nonce);
-}
-
 /**
  * A Chacha20 cipher class.
  * @param {Array} key Array of bytes (integers: 0<=x<256). Short keys are padded to 32B, long keys are silently truncated.
  * @param {Array} nonce optional. If present, it must be an Array of bytes (integers: 0<=x<256). Short nonces are padded to 12B, long nonces are silently truncated.
  */
 export function Chacha20(key,nonce){
+	const NONCE_LEN=12;
 	if(nonce===undefined){
-		nonce=createNonce();
+		nonce=createRandomNonce(NONCE_LEN);
 	}
-	this._nonce=zeroPad(nonce,12);
+	this._nonce=zeroPad(nonce,NONCE_LEN);
 	nonce=bytes2int32s(this._nonce);
 	key=bytes2int32s(zeroPad(key,32));
 	
@@ -85,12 +80,10 @@ Chacha20.prototype._incrementPos=functio
 export function encrypt(data,key,nonce){
 	let cipher=new Chacha20(key,nonce);
 	nonce=cipher.getNonce();
-	return nonce.concat(data.map(b=>b^cipher.getByte()));
+	return [nonce,data.map(b=>b^cipher.getByte())];
 }
 
-export function decrypt(data,key){
-	let nonce=data.slice(0,12);
-	let ciphertext=data.slice(12);
+export function decrypt(ciphertext,key,nonce){
 	let cipher=new Chacha20(key,nonce);
 	return ciphertext.map(b=>b^cipher.getByte());
 }
diff --git a/src/main.js b/src/main.js
--- a/src/main.js
+++ b/src/main.js
@@ -1,17 +1,17 @@
 import * as util from "./util.js";
 import {blake2s} from "./blake.js";
 import {pbkdf2} from "./pbkdf2.js";
-import {createNonce,Chacha20,encrypt as _encrypt,decrypt as _decrypt} from "./chacha.js";
+import {Chacha20,encrypt as _encrypt,decrypt as _decrypt} from "./chacha.js";
 
 const VERSION=1;
 
 function encrypt(s,password){
 	let bs=util.str2utf8(s);
 	let pass=util.str2utf8(password);
-	let salt=createNonce();
+	let salt=util.createRandomNonce(12);
 	let [iters,key]=stretchKey(pass,salt);
-	let noncedCiphertext=_encrypt(bs,key,salt);
-	let payload=[iters].concat(noncedCiphertext);
+	let [_,ciphertext]=_encrypt(bs,key,salt);
+	let payload=[iters].concat(salt,ciphertext);
 	let signature=blake2s([VERSION].concat(payload),16,pass);
 	let arr=[VERSION].concat(signature,payload);
 	return util.bytes2base64(arr);
@@ -24,12 +24,12 @@ function decrypt(s,password){
 	let signature=arr.slice(1,17);
 	let iters=arr[17];
 	let salt=arr.slice(18,30);
-	let noncedCiphertext=arr.slice(18);
-	let check=blake2s([version].concat([iters],noncedCiphertext),16,pass);
+	let ciphertext=arr.slice(30);
+	let check=blake2s([version,iters].concat(salt,ciphertext),16,pass);
 	if(!signature.every((b,i)=>b===check[i])){return false;}
 	if(version>VERSION){return false;}
 	let key=pbkdf2(pass,salt,1<<iters,32);
-	let plainbytes=_decrypt(noncedCiphertext,key);
+	let plainbytes=_decrypt(ciphertext,key,salt);
 	return util.utf82str(plainbytes);
 }
 
diff --git a/src/util.js b/src/util.js
--- a/src/util.js
+++ b/src/util.js
@@ -138,3 +138,9 @@ export function base642bytes(str){
 
 	return out;
 }
+
+export function createRandomNonce(n){
+	let nonce=new Uint8Array(n);
+	window.crypto.getRandomValues(nonce);
+	return Array.from(nonce);
+}