move to new identity key mechanism

now we do as followed:
• Generate 16 bytes of random data
• Add 16 bytes of zeros
• Use the 16 bytes of random + 16 bytes of zeros to generate an ED25519 key pair
• Convert the ED25519 key pair to an X25519 key pair

All of this is happening with libsodiumm called over IPC

libtextsecure/account_manager.js

@@ -60,11 +60,11 @@
           // handle shorter than 32 bytes seeds
           const privKeyHexLength = 32 * 2;
           if (seedHex.length !== privKeyHexLength) {
-            seedHex = seedHex.concat(seedHex);
+            seedHex = seedHex.concat('0'.repeat(32));
             seedHex = seedHex.substring(0, privKeyHexLength);
           }
           const seed = dcodeIO.ByteBuffer.wrap(seedHex, 'hex').toArrayBuffer();
-          return libsignal.Curve.async.createKeyPair(seed);
+          return window.sessionGenerateKeyPair(seed);
         };
       } else {
         generateKeypair = libsignal.KeyHelper.generateIdentityKeyPair;

main.js

@@ -1178,6 +1178,42 @@ ipc.on('decrypt-lns-entry', (event, lnsName, ciphertext) => {
   decryptLns(event, lnsName, ciphertext);
 });
 
+async function sessionGenerateKeyPair(event, seed) {
+  const sodium = await getSodium();
+
+  try {
+    const ed25519KeyPair = sodium.crypto_sign_seed_keypair(
+      new Uint8Array(seed)
+    );
+    const x25519PublicKey = sodium.crypto_sign_ed25519_pk_to_curve25519(
+      ed25519KeyPair.publicKey
+    );
+    // prepend version byte (coming from `processKeys(raw_keys)`)
+    const origPub = new Uint8Array(x25519PublicKey);
+    const prependedX25519PublicKey = new Uint8Array(33);
+    prependedX25519PublicKey.set(origPub, 1);
+    prependedX25519PublicKey[0] = 5;
+    const x25519SecretKey = sodium.crypto_sign_ed25519_sk_to_curve25519(
+      ed25519KeyPair.privateKey
+    );
+
+    // prepend with 05 the public key
+    const x25519KeyPair = {
+      pubKey: prependedX25519PublicKey.buffer,
+      privKey: x25519SecretKey.buffer,
+    };
+
+    // null as first parameter to indivate no error
+    event.reply('generate-keypair-seed-response', null, x25519KeyPair);
+  } catch (err) {
+    event.reply('generate-keypair-seed-response', err);
+  }
+}
+
+ipc.on('generate-keypair-seed', (event, seed) => {
+  sessionGenerateKeyPair(event, seed);
+});
+
 ipc.on('set-auto-update-setting', (event, enabled) => {
   userConfig.set('autoUpdate', !!enabled);
 

preload.js

@@ -118,7 +118,7 @@ const localeMessages = ipc.sendSync('locale-data');
 
 window.blake2b = input =>
   new Promise((resolve, reject) => {
-    ipc.once('blake2b-digest-response', (event, error, res) => {
+    ipc.once('blake2b-digest-response', (_, error, res) => {
       // eslint-disable-next-line no-unused-expressions
       error ? reject(error) : resolve(res);
     });
@@ -128,7 +128,7 @@ window.blake2b = input =>
 
 window.decryptLnsEntry = (key, value) =>
   new Promise((resolve, reject) => {
-    ipc.once('decrypt-lns-response', (event, error, res) => {
+    ipc.once('decrypt-lns-response', (_, error, res) => {
       // eslint-disable-next-line no-unused-expressions
       error ? reject(error) : resolve(res);
     });
@@ -136,6 +136,16 @@ window.decryptLnsEntry = (key, value) =>
     ipc.send('decrypt-lns-entry', key, value);
   });
 
+window.sessionGenerateKeyPair = seed =>
+  new Promise((resolve, reject) => {
+    ipc.once('generate-keypair-seed-response', (_, error, res) => {
+      // eslint-disable-next-line no-unused-expressions
+      error ? reject(error) : resolve(res);
+    });
+
+    ipc.send('generate-keypair-seed', seed);
+  });
+
 window.updateZoomFactor = () => {
   const zoomFactor = window.getSettingValue('zoom-factor-setting') || 100;
   window.setZoomFactor(zoomFactor / 100);

ts/components/session/RegistrationTabs.tsx

@@ -174,14 +174,14 @@ export class RegistrationTabs extends React.Component<{}, State> {
       // handle shorter than 32 bytes seeds
       const privKeyHexLength = 32 * 2;
       if (seedHex.length !== privKeyHexLength) {
-        seedHex = seedHex.concat(seedHex);
+        seedHex = seedHex.concat('0'.repeat(32));
         seedHex = seedHex.substring(0, privKeyHexLength);
       }
       const seed = window.dcodeIO.ByteBuffer.wrap(
         seedHex,
         'hex'
       ).toArrayBuffer();
-      const keyPair = await window.libsignal.Curve.async.createKeyPair(seed);
+      const keyPair = await window.sessionGenerateKeyPair(seed);
       const hexGeneratedPubKey = StringUtils.decode(keyPair.pubKey, 'hex');
 
       this.setState({
@@ -297,9 +297,7 @@ export class RegistrationTabs extends React.Component<{}, State> {
 
             {this.renderRegistrationContent()}
             <SessionButton
-              onClick={() => {
-                this.onCompleteSignUpClick();
-              }}
+              onClick={this.onCompleteSignUpClick}
               buttonType={SessionButtonType.Brand}
               buttonColor={SessionButtonColor.Green}
               text={window.i18n('getStarted')}

ts/window.d.ts

@@ -99,5 +99,6 @@ declare global {
     GroupBuffer: any;
     SwarmPolling: SwarmPolling;
     owsDesktopApp: any;
+    sessionGenerateKeyPair: (seed: ArrayBuffer) => Promise<{ pubKey: ArrayBufferLike;  privKey: ArrayBufferLike; }>;
   }
 }