Implement private key exporting.

app/scripts/keyring-controller.js

@@ -353,7 +353,6 @@ module.exports = class KeyringController extends EventEmitter {
       gasMultiplier: configManager.getGasMultiplier() || 1,
     }
 
-    console.log('addUnconfirmedTransaction:', txData)
 
     // keep the onTxDoneCb around for after approval/denial (requires user interaction)
     // This onTxDoneCb fires completion to the Dapp's write operation.
@@ -525,7 +524,13 @@ module.exports = class KeyringController extends EventEmitter {
   }
 
   exportAccount(address, cb) {
-    cb(null, '0xPrivateKey')
+    try {
+      const keyring = this.getKeyringForAccount(address)
+      const privateKey = keyring.exportAccount(normalize(address))
+      cb(null, privateKey)
+    } catch (e) {
+      cb(e)
+    }
   }
 
   getNetwork(err) {

app/scripts/keyrings/hd.js

@@ -48,6 +48,11 @@ module.exports = class HdKeyring extends EventEmitter {
     }
   }
 
+  exportAccount(address) {
+    const wallet = this.getWalletForAccount(address)
+    return wallet.getPrivateKey().toString('hex')
+  }
+
   addAccounts(n = 1) {
     if (!this.root) {
       this.initFromMnemonic(bip39.generateMnemonic())
@@ -87,7 +92,16 @@ module.exports = class HdKeyring extends EventEmitter {
   }
 
   getWalletForAccount(account) {
-    return this.wallets.find(w => w.getAddress().toString('hex') === account)
+    return this.wallets.find((w) => {
+      const address = w.getAddress().toString('hex')
+      return ((address === account) || (normalize(address) === account))
+    })
+  }
+
+
+
 }
 
+function normalize(address) {
+  return ethUtil.addHexPrefix(address.toLowerCase())
 }