fix: don't store CID length with encrypted, use CID.decodeFirst()

multiformats · Jan 29, 2021 · b6b58ce · b6b58ce
1 parent cc617bc
commit b6b58ce
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Showing 2 changed files with 10 additions and 37 deletions.
diff --git a/src/crypto/aes.js b/src/crypto/aes.js
@@ -2,30 +2,6 @@ import CID from '../cid.js'
 import random from 'js-crypto-random'
 import aes from 'js-crypto-aes'
 
-/**
- * @param {number} value
- */
-const enc32 = value => {
-  value = +value
-  const buff = new Uint8Array(4)
-  buff[3] = (value >>> 24)
-  buff[2] = (value >>> 16)
-  buff[1] = (value >>> 8)
-  buff[0] = (value & 0xff)
-  return buff
-}
-
-/**
- * @param {Uint8Array} buffer
- */
-const readUInt32LE = (buffer) => {
-  const offset = buffer.byteLength - 4
-  return ((buffer[offset]) |
-          (buffer[offset + 1] << 8) |
-          (buffer[offset + 2] << 16)) +
-          (buffer[offset + 3] * 0x1000000)
-}
-
 /**
  * @param {Uint8Array[]} buffers
  */
@@ -52,10 +28,8 @@ const mkcrypto = ({ name, code, ivsize }) => {
    */
   const decrypt = async ({ key, value: { iv, bytes } }) => {
     bytes = await aes.decrypt(bytes, key, { name: cyperType, iv, tagLength: 16 })
-    const len = readUInt32LE(bytes.subarray(0, 4))
-    const cid = CID.decode(bytes.subarray(4, 4 + len))
-    bytes = bytes.subarray(4 + len)
-    return { cid, bytes }
+    const [cid, remainder] = CID.decodeFirst(bytes)
+    return { cid, bytes: remainder }
   }
   /**
    * @param {Object} options
@@ -64,9 +38,8 @@ const mkcrypto = ({ name, code, ivsize }) => {
    * @param {CID} options.cid
    */
   const encrypt = async ({ key, cid, bytes }) => {
-    const len = enc32(cid.bytes.byteLength)
     const iv = random.getRandomBytes(ivsize)
-    const msg = concat([len, cid.bytes, bytes])
+    const msg = concat([cid.bytes, bytes])
     bytes = await aes.encrypt(msg, key, { name: cyperType, iv, tagLength: 16 })
     return { bytes, iv, code }
   }

diff --git a/test/test-block.js b/test/test-block.js
@@ -67,22 +67,22 @@ describe('block', () => {
   describe('ciphers', () => {
     const createTest = name => {
       const json = codec
-      test(`aes-${name}`, async () => {
+      test.only(`aes-${name}`, async () => {
         const block = await main.encode({ value: fixture, codec: json, hasher })
         const crypto = ciphers[name]
         const key = random.getRandomBytes(32)
         const value = await crypto.encrypt({ ...block, key })
         const eblock = await main.encode({ codec: encrypted, value, hasher })
         const eeblock = await main.decode({ codec: encrypted, bytes: eblock.bytes, hasher })
-        same(eblock.cid.toString(), eeblock.cid.toString())
-        same([...eblock.bytes], [...eeblock.bytes])
-        same([...eblock.value.bytes], [...eeblock.value.bytes])
-        same([...eblock.value.iv], [...eeblock.value.iv])
+        same(eeblock.cid.toString(), eblock.cid.toString())
+        same([...eeblock.bytes], [...eblock.bytes])
+        same([...eeblock.value.bytes], [...eblock.value.bytes])
+        same([...eeblock.value.iv], [...eblock.value.iv])
         const { cid, bytes } = await crypto.decrypt({ ...eblock, key })
-        same(block.cid.toString(), cid.toString())
+        same(cid.toString(), block.cid.toString())
         same([...bytes], [...block.bytes])
         const dblock = await main.create({ cid, bytes, codec: json, hasher })
-        same(block.value, dblock.value)
+        same(dblock.value, block.value)
       })
     }
     createTest('gcm')