From 58cd3349db447a392c8b5c34352460fe217fad19 Mon Sep 17 00:00:00 2001
From: Rob Wu <rob@robwu.nl>
Date: Fri, 8 Aug 2014 12:36:29 +0200
Subject: [PATCH] AES cipher: make padding optional
Fixes #5152
---
src/core/crypto.js | 30 +++++++++++++++++++++++++-----
1 file changed, 25 insertions(+), 5 deletions(-)
diff --git a/src/core/crypto.js b/src/core/crypto.js
index 92cb1b908..1f13239fa 100644
--- a/src/core/crypto.js
+++ b/src/core/crypto.js
@@ -978,8 +978,18 @@ var AES128Cipher = (function AES128CipherClosure() {
if (finalize) {
// undo a padding that is described in RFC 2898
var lastBlock = result[result.length - 1];
- outputLength -= lastBlock[15];
- result[result.length - 1] = lastBlock.subarray(0, 16 - lastBlock[15]);
+ var psLen = lastBlock[15];
+ if (psLen <= 16) {
+ for (i = 15, ii = 16 - psLen; i >= ii; --i) {
+ if (lastBlock[i] !== psLen) {
+ // Invalid padding, assume that the block has no padding.
+ psLen = 0;
+ break;
+ }
+ }
+ outputLength -= psLen;
+ result[result.length - 1] = lastBlock.subarray(0, 16 - psLen);
+ }
}
var output = new Uint8Array(outputLength);
for (i = 0, j = 0, ii = result.length; i < ii; ++i, j += 16) {
@@ -1394,7 +1404,7 @@ var AES256Cipher = (function AES256CipherClosure() {
if (bufferLength < 16) {
continue;
}
- // buffer is full, encrypting
+ // buffer is full, decrypting
var plain = decrypt256(buffer, this.key);
// xor-ing the IV vector to get plain text
for (j = 0; j < 16; ++j) {
@@ -1417,8 +1427,18 @@ var AES256Cipher = (function AES256CipherClosure() {
if (finalize) {
// undo a padding that is described in RFC 2898
var lastBlock = result[result.length - 1];
- outputLength -= lastBlock[15];
- result[result.length - 1] = lastBlock.subarray(0, 16 - lastBlock[15]);
+ var psLen = lastBlock[15];
+ if (psLen <= 16) {
+ for (i = 15, ii = 16 - psLen; i >= ii; --i) {
+ if (lastBlock[i] !== psLen) {
+ // Invalid padding, assume that the block has no padding.
+ psLen = 0;
+ break;
+ }
+ }
+ outputLength -= psLen;
+ result[result.length - 1] = lastBlock.subarray(0, 16 - psLen);
+ }
}
var output = new Uint8Array(outputLength);
for (i = 0, j = 0, ii = result.length; i < ii; ++i, j += 16) {