From dc67354e864179a90a9bec14aa1c9af1344e1394 Mon Sep 17 00:00:00 2001
From: Dmitry Chestnykh <dchest@gmail.com>
Date: Sat, 6 Oct 2012 10:03:43 -0400
Subject: [PATCH] go.crypto/blowfish: document that only 16 bytes of salt are
 used.

Also fix salt expansion code to fill the properly sized array,
since the following code never uses more than 4 uints.

Also remove unused expandedKey array.

R=golang-dev, agl
CC=golang-dev
https://golang.org/cl/6622050
---
 blowfish/block.go  | 12 +++++-------
 blowfish/cipher.go |  2 +-
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/blowfish/block.go b/blowfish/block.go
index 326292d..7b14dec 100644
--- a/blowfish/block.go
+++ b/blowfish/block.go
@@ -14,7 +14,7 @@ func ExpandKey(key []byte, c *Cipher) {
 	for i := 0; i < 18; i++ {
 		var d uint32
 		for k := 0; k < 4; k++ {
-			d = d<<8 | uint32(key[j])&0x000000FF
+			d = d<<8 | uint32(key[j])
 			j++
 			if j >= len(key) {
 				j = 0
@@ -53,26 +53,24 @@ func ExpandKey(key []byte, c *Cipher) {
 // and specializing it here is useful.
 func expandKeyWithSalt(key []byte, salt []byte, c *Cipher) {
 	j := 0
-	expandedKey := make([]uint32, 18)
 	for i := 0; i < 18; i++ {
 		var d uint32
 		for k := 0; k < 4; k++ {
-			d = d<<8 | uint32(key[j])&0x000000FF
+			d = d<<8 | uint32(key[j])
 			j++
 			if j >= len(key) {
 				j = 0
 			}
 		}
-		expandedKey[i] = d
 		c.p[i] ^= d
 	}
 
 	j = 0
-	expandedSalt := make([]uint32, 18)
-	for i := 0; i < 18; i++ {
+	var expandedSalt [4]uint32
+	for i := range expandedSalt {
 		var d uint32
 		for k := 0; k < 4; k++ {
-			d = d<<8 | uint32(salt[j])&0x000000FF
+			d = d<<8 | uint32(salt[j])
 			j++
 			if j >= len(salt) {
 				j = 0
diff --git a/blowfish/cipher.go b/blowfish/cipher.go
index 94e10f0..2f712ad 100644
--- a/blowfish/cipher.go
+++ b/blowfish/cipher.go
@@ -41,7 +41,7 @@ func NewCipher(key []byte) (*Cipher, error) {
 // NewSaltedCipher creates a returns a Cipher that folds a salt into its key
 // schedule. For most purposes, NewCipher, instead of NewSaltedCipher, is
 // sufficient and desirable. For bcrypt compatiblity, the key can be over 56
-// bytes.
+// bytes. Only the first 16 bytes of salt are used.
 func NewSaltedCipher(key, salt []byte) (*Cipher, error) {
 	var result Cipher
 	k := len(key)