Breaking: Replace deprecated / archived crypto library

- Remove `gibberish-aes`
- Switch to Web Crypto API for encryption
- Replace old `md5` key-derivation with modern PBKDF2
- Follow OWASP recommendation for number of iterations in PBKDF2

This is marked as a breaking change as it fully removes the old
encryption code which breaks any secret stored with the previous
version. During the update the store must be cleared or the user will
receive a lot of garbage instead of their data.

Signed-off-by: Knut Ahlers <knut@ahlers.me>

src/app.vue

@@ -166,7 +166,7 @@
 
 <script>
 import axios from 'axios'
-import AES from 'gibberish-aes/src/gibberish-aes'
+import crypto from './crypto.js'
 
 const passwordCharset = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
 const passwordLength = 20
@@ -218,9 +218,8 @@ export default {
       this.securePassword = [...window.crypto.getRandomValues(new Uint8Array(passwordLength))]
         .map(n => passwordCharset[n % passwordCharset.length])
         .join('')
-      const secret = AES.enc(this.secret, this.securePassword)
-
-      axios.post('api/create', { secret })
+      crypto.enc(this.secret, this.securePassword)
+        .then(secret => axios.post('api/create', { secret })
           .then(resp => {
             this.secretId = resp.data.secret_id
             this.secret = ''
@@ -238,7 +237,7 @@ export default {
               this.error = this.$t('alert-something-went-wrong')
               this.showError = true
             }
-        })
+          }))
 
       return false
     },
@@ -267,11 +266,16 @@ export default {
     requestSecret() {
       axios.get(`api/get/${this.secretId}`)
         .then(resp => {
-          let secret = resp.data.secret
-          if (this.securePassword) {
-            secret = AES.dec(secret, this.securePassword)
-          }
+          const secret = resp.data.secret
+          if (!this.securePassword) {
             this.secret = secret
+            return
+          }
+
+          crypto.dec(secret, this.securePassword)
+            .then(secret => {
+              this.secret = secret
+            })
         })
         .catch(err => {
           switch (err.response.status) {

src/crypto.js

@@ -0,0 +1,35 @@
+const opensslBanner = new Uint8Array(new TextEncoder('utf8').encode('Salted__'))
+const pbkdf2Params = { hash: 'SHA-512', iterations: 300000, name: 'PBKDF2' }
+
+function decrypt(passphrase, encData) {
+  const data = new Uint8Array(atob(encData).split('')
+    .map(c => c.charCodeAt(0)))
+
+  return deriveKey(passphrase, data.slice(8, 16))
+    .then(({ iv, key }) => window.crypto.subtle.decrypt({ iv, name: 'AES-CBC' }, key, data.slice(16)))
+    .then(data => new TextDecoder('utf8').decode(data))
+}
+
+function deriveKey(passphrase, salt) {
+  return window.crypto.subtle.importKey('raw', new TextEncoder('utf8').encode(passphrase), 'PBKDF2', false, ['deriveBits'])
+    .then(passwordKey => window.crypto.subtle.deriveBits({ ...pbkdf2Params, salt }, passwordKey, 384))
+    .then(key => window.crypto.subtle.importKey('raw', key.slice(0, 32), { name: 'AES-CBC' }, false, ['encrypt', 'decrypt'])
+      .then(aesKey => ({ iv: key.slice(32, 48), key: aesKey })))
+}
+
+function encrypt(passphrase, salt, plainData) {
+  return deriveKey(passphrase, salt)
+    .then(({ iv, key }) => window.crypto.subtle.encrypt({ iv, name: 'AES-CBC' }, key, new TextEncoder('utf8').encode(plainData)))
+    .then(encData => new Uint8Array([...opensslBanner, ...salt, ...new Uint8Array(encData)]))
+    .then(data => btoa(String.fromCharCode.apply(null, data)))
+}
+
+function generateSalt() {
+  const salt = new Uint8Array(8) // Salt MUST consist of 8 byte
+  return window.crypto.getRandomValues(salt)
+}
+
+export default {
+  dec: (cipherText, passphrase) => decrypt(passphrase, cipherText),
+  enc: (plainText, passphrase) => encrypt(passphrase, generateSalt(), plainText),
+}

src/package-lock.json

@@ -10,7 +10,6 @@
         "bootstrap": "^4.6.0",
         "bootstrap-vue": "^2.21.2",
         "bootswatch": "^4.6.0",
-        "gibberish-aes": "^1.0.0",
         "popper.js": "^1.16.1",
         "vue": "^2.6.14",
         "vue-i18n": "^8.25.0"
@@ -3907,11 +3906,6 @@
         "assert-plus": "^1.0.0"
       }
     },
-    "node_modules/gibberish-aes": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/gibberish-aes/-/gibberish-aes-1.0.0.tgz",
-      "integrity": "sha1-9kHEWPuCLgrWHDwN6hWOC5Q+n8U="
-    },
     "node_modules/glob": {
       "version": "7.1.7",
       "resolved": "https://registry.npmjs.org/glob/-/glob-7.1.7.tgz",

src/package.json

@@ -27,7 +27,6 @@
     "bootstrap": "^4.6.0",
     "bootstrap-vue": "^2.21.2",
     "bootswatch": "^4.6.0",
-    "gibberish-aes": "^1.0.0",
     "popper.js": "^1.16.1",
     "vue": "^2.6.14",
     "vue-i18n": "^8.25.0"