restore single account behavior, refactor a bit :)

README.md

@@ -16,7 +16,10 @@ Requires:
 git clone https://github.com/CooperRS/decrypt-otpauth-files.git
 cd decrypt-otpauth-files
 pipenv install
-pipenv run python decrypt_otpauth.py --encrypted-otpauth-backup <path to your OTP Auth backup>
+# Decrypt a full backup file
+pipenv run python decrypt_otpauth.py decrypt_backup --encrypted-otpauth-backup <path to your OTP Auth backup>
+# Decrypt a single account export
+pipenv run python decrypt_otpauth.py decrypt_account --encrypted-otpauth-account <path to your OTP Auth account>
 ```
 
 ## Demo

decrypt_otpauth.py

@@ -4,7 +4,6 @@ import getpass
 import hashlib
 
 from enum import Enum
-from itertools import chain
 from urllib.parse import quote
 
 import pyqrcode
@@ -95,6 +94,32 @@ class OTPAccount:
         refDate = archive.decode("refDate")
         return OTPAccount(label, issuer, secret, type, algorithm, digits, counter, period, refDate)
 
+    def from_dict(in_dict):
+        label = in_dict.get("label")
+        issuer = in_dict.get("issuer")
+        secret = bytes(in_dict.get("secret"))
+        type = Type(in_dict.get("type"))
+        algorithm = Algorithm(in_dict.get("algorithm"))
+        digits = in_dict.get("digits")
+        counter = in_dict.get("counter")
+        period = in_dict.get("period")
+        refDate = in_dict.get("refDate")
+        return OTPAccount(label, issuer, secret, type, algorithm, digits, counter, period, refDate)
+
+    def otp_uri(self):
+        otp_type = self.type
+        otp_label = quote(f'{self.issuer}:{self.label}')
+        otp_parameters = {
+            'secret': base64.b32encode(self.secret).decode("utf-8"),
+            'algorithm': self.algorithm,
+            'period': self.period,
+            'digits': self.digits,
+            'issuer': self.issuer,
+            'counter': self.counter,
+        }
+        otp_parameters = '&'.join([f'{str(k)}={quote(str(v))}' for (k, v) in otp_parameters.items() if v])
+        return f'otpauth://{otp_type}/{otp_label}?{otp_parameters}'
+
 
 archiver.update_class_map({'NSMutableData': MutableData})
 archiver.update_class_map({'NSMutableString': MutableString})
@@ -130,12 +155,62 @@ class DangerousUnarchive(archiver.Unarchive):
         return obj
 
 
-@click.command()
+def render_qr_to_terminal(otp_uri, type, issuer, label):
+    qr = pyqrcode.create(otp_uri, error="L")
+    click.echo("")
+    click.echo(f'{type}: {issuer} - {label}')
+    click.echo(qr.terminal(quiet_zone=4))
+    click.echo("")
+
+
+@click.group()
+def cli():
+    pass
+
+
+@cli.command()
+@click.option('--encrypted-otpauth-account',
+              help="path to your encrypted OTP Auth account (.otpauth)",
+              required=True,
+              type=click.File('rb'))
+def decrypt_account(encrypted_otpauth_account):
+    # Get password from user
+    password = getpass.getpass(f'Password for export file {encrypted_otpauth_account.name}: ')
+
+    # Get IV and key for wrapping archive
+    iv = bytes(16)
+    key = hashlib.sha256('OTPAuth'.encode('utf-8')).digest()
+
+    # Decrypt wrapping archive
+    data = AES.new(key, AES.MODE_CBC, iv).decrypt(encrypted_otpauth_account.read())
+    data = data[:-data[-1]]
+
+    # Decode wrapping archive
+    archive = archiver.Unarchive(data).top_object()
+
+    # Get IV and key for actual archive
+    iv = hashlib.sha1(archive['IV']).digest()[:16]
+    salt = archive['Salt']
+    key = hashlib.sha256((salt + '-' + password).encode('utf-8')).digest()
+
+    # Decrypt actual archive
+    data = AES.new(key, AES.MODE_CBC, iv).decrypt(archive['Data'])
+    data = data[:-data[-1]]
+
+    # Decode actual archive
+    archive = DangerousUnarchive(data).top_object()
+
+    # Construct OTPAccount object from returned dictionary
+    account = OTPAccount.from_dict(archive)
+    render_qr_to_terminal(account.otp_uri(), account.type, account.issuer, account.label)
+
+
+@cli.command()
 @click.option('--encrypted-otpauth-backup',
               help="path to your encrypted OTP Auth backup (.otpauthdb)",
               required=True,
               type=click.File('rb'))
-def main(encrypted_otpauth_backup):
+def decrypt_backup(encrypted_otpauth_backup):
     # Get password from user
     password = getpass.getpass(f'Password for export file {encrypted_otpauth_backup.name}: ')
 
@@ -164,25 +239,9 @@ def main(encrypted_otpauth_backup):
 
     accounts = [account for folder in archive['Folders'] for account in folder.accounts]
     for account in accounts:
-        otp_type = account.type
-        otp_label = quote(f'{account.issuer}:{account.label}')
-        otp_parameters = {
-            'secret': base64.b32encode(account.secret).decode("utf-8"),
-            'algorithm': account.algorithm,
-            'period': account.period,
-            'digits': account.digits,
-            'issuer': account.issuer,
-            'counter': account.counter,
-        }
-        otp_parameters = '&'.join([f'{str(k)}={quote(str(v))}' for (k, v) in otp_parameters.items() if v])
-        otp_uri = f'otpauth://{otp_type}/{otp_label}?{otp_parameters}'
-        qr = pyqrcode.create(otp_uri, error="L")
-        click.echo("")
-        click.echo(f'{account.type}: {account.issuer} - {account.label}')
-        click.echo(qr.terminal(quiet_zone=4))
-        click.echo("")
+        render_qr_to_terminal(account.otp_uri(), account.type, account.issuer, account.label)
         input("Press Enter to continue...")
 
 
 if __name__ == '__main__':
-    main()
+    cli()