Add pyadb keygen command to generate keypairs

Address (google#95 and google#131)

Author: joeleong

adb/adb_debug.py

@@ -25,6 +25,7 @@
 
 from adb import adb_commands
 from adb import common_cli
+from adb import android_pubkey
 
 try:
     from adb import sign_m2crypto
@@ -149,6 +150,14 @@ def main():
     subparser.add_argument(
         '--output_port_path', action='store_true',
         help='Outputs the port_path alongside the serial')
+    subparser = subparsers.add_parser(
+        name='keygen', help='generate adb public/private key '
+        'private key stored in {filepath} '
+        'public key stored in {filepath}.pub '
+        '(existing files overwritten)')
+    subparser.add_argument(
+        'filepath',
+        help='File path to write the private/public keypair (existing files overwritten)')
 
     common_cli.MakeSubparser(
         subparsers, parents, adb_commands.AdbCommands.Install)
@@ -195,6 +204,8 @@ def main():
     if args.command_name == 'help':
         parser.print_help()
         return 0
+    if args.command_name == 'keygen':
+        return android_pubkey.keygen(args.filepath)
     if args.command_name == 'logcat':
         args.positional = args.options
     elif args.command_name == 'shell':

adb/android_pubkey.py

@@ -139,3 +139,19 @@ def write_public_keyfile(private_key_path, public_key_path):
     with open(public_key_path, 'wb') as public_key_file:
         public_key_file.write(base64.b64encode(public_key))
         public_key_file.write(get_user_info().encode())
+
+
+def keygen(filepath):
+    """generate adb public/private key
+    private key stored in {filepath}
+    public key stored in {filepath}.pub
+    (existing files overwritten)
+
+    Args:
+      filepath: File path to write the private/public keypair
+    """
+    key = Crypto.PublicKey.RSA.generate(2048)
+    with open(filepath, 'wb') as private_key_file:
+        private_key_file.write(key.export_key(format='PEM', pkcs=8))
+
+    write_public_keyfile(filepath, filepath + '.pub')