From b15799e7cbf1d4e650571731223659d0425b125e Mon Sep 17 00:00:00 2001
From: sachaaaaa <sacha@loki.network>
Date: Wed, 7 Aug 2019 16:19:20 +1000
Subject: [PATCH 1/3] Generate 13 word seeds by default - still accept 25 word
 seeds.

---
 libtextsecure/account_manager.js | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/libtextsecure/account_manager.js b/libtextsecure/account_manager.js
index 219d8bb7a..2e7b96748 100644
--- a/libtextsecure/account_manager.js
+++ b/libtextsecure/account_manager.js
@@ -123,7 +123,12 @@
       let generateKeypair;
       if (mnemonic) {
         generateKeypair = () => {
-          const seedHex = window.mnemonic.mn_decode(mnemonic, mnemonicLanguage);
+          let seedHex = window.mnemonic.mn_decode(mnemonic, mnemonicLanguage);
+          // handle shorter than 32 bytes seeds
+          if (seedHex.length !== 32 * 2) {
+            seedHex = seedHex.concat(seedHex);
+            seedHex = seedHex.substring(0, 32 * 2);
+          }
           const privKeyHex = window.mnemonic.sc_reduce32(seedHex);
           const privKey = dcodeIO.ByteBuffer.wrap(
             privKeyHex,
@@ -517,8 +522,8 @@
       });
     },
     async generateMnemonic(language = 'english') {
-      const keys = await libsignal.KeyHelper.generateIdentityKeyPair();
-      const hex = StringView.arrayBufferToHex(keys.privKey);
+      const seed = window.Signal.Crypto.getRandomBytes(16);
+      const hex = StringView.arrayBufferToHex(seed);
       return mnemonic.mn_encode(hex, language);
     },
     getCurrentMnemonic() {

From 16e51a2c7a20aa35ca85228099c5b3e45c5236ca Mon Sep 17 00:00:00 2001
From: sachaaaaa <sacha@loki.network>
Date: Thu, 8 Aug 2019 10:20:17 +1000
Subject: [PATCH 2/3] use variable for magic number

---
 libtextsecure/account_manager.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/libtextsecure/account_manager.js b/libtextsecure/account_manager.js
index 2e7b96748..98621fba1 100644
--- a/libtextsecure/account_manager.js
+++ b/libtextsecure/account_manager.js
@@ -125,9 +125,10 @@
         generateKeypair = () => {
           let seedHex = window.mnemonic.mn_decode(mnemonic, mnemonicLanguage);
           // handle shorter than 32 bytes seeds
-          if (seedHex.length !== 32 * 2) {
+          const privKeyHexLength = 32 * 2;
+          if (seedHex.length !== privKeyHexLength) {
             seedHex = seedHex.concat(seedHex);
-            seedHex = seedHex.substring(0, 32 * 2);
+            seedHex = seedHex.substring(0, privKeyHexLength);
           }
           const privKeyHex = window.mnemonic.sc_reduce32(seedHex);
           const privKey = dcodeIO.ByteBuffer.wrap(

From 0e61ab8ccc553e1420efc31941d2fa4cb986eb3f Mon Sep 17 00:00:00 2001
From: sachaaaaa <sacha@loki.network>
Date: Thu, 8 Aug 2019 13:44:46 +1000
Subject: [PATCH 3/3] Better document magic numbers

---
 libtextsecure/account_manager.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libtextsecure/account_manager.js b/libtextsecure/account_manager.js
index 98621fba1..db0c9192a 100644
--- a/libtextsecure/account_manager.js
+++ b/libtextsecure/account_manager.js
@@ -523,7 +523,10 @@
       });
     },
     async generateMnemonic(language = 'english') {
-      const seed = window.Signal.Crypto.getRandomBytes(16);
+      // Note: 4 bytes are converted into 3 seed words, so length 12 seed words
+      // (13 - 1 checksum) are generated using 12 * 4 / 3 = 16 bytes.
+      const seedSize = 16;
+      const seed = window.Signal.Crypto.getRandomBytes(seedSize);
       const hex = StringView.arrayBufferToHex(seed);
       return mnemonic.mn_encode(hex, language);
     },