4 import subprocess as _subprocess
5 import struct as _struct
8 def _get_stdout(args, stdin=None):
11 stdin_pipe = _subprocess.PIPE
12 p = _subprocess.Popen(args, stdin=stdin_pipe, stdout=_subprocess.PIPE)
13 stdout, stderr = p.communicate(stdin)
16 raise RuntimeError(status)
20 class PGPPacket (dict):
21 # http://tools.ietf.org/search/rfc4880
22 _old_format_packet_length_type = { # type: (bytes, struct type)
23 0: (1, 'B'), # 1-byte unsigned integer
24 1: (2, 'H'), # 2-byte unsigned integer
25 2: (4, 'I'), # 4-byte unsigned integer
31 1: 'public-key encrypted session key packet',
32 2: 'signature packet',
33 3: 'symmetric-key encrypted session key packet',
34 4: 'one-pass signature packet',
35 5: 'secret-key packet',
36 6: 'public-key packet',
37 7: 'secret-subkey packet',
38 8: 'compressed data packet',
39 9: 'symmetrically encrypted data packet',
41 11: 'literal data packet',
44 14: 'public-subkey packet',
45 17: 'user attribute packet',
46 18: 'sym. encrypted and integrity protected data packet',
47 19: 'modification detection code packet',
54 _public_key_algorithms = {
55 1: 'rsa (encrypt or sign)',
56 2: 'rsa encrypt-only',
58 16: 'elgamal (encrypt-only)',
59 17: 'dsa (digital signature algorithm)',
60 18: 'reserved for elliptic curve',
61 19: 'reserved for ecdsa',
62 20: 'reserved (formerly elgamal encrypt or sign)',
63 21: 'reserved for diffie-hellman',
77 _symmetric_key_algorithms = {
78 0: 'plaintext or unencrypted data',
85 7: 'aes with 128-bit key',
86 8: 'aes with 192-bit key',
87 9: 'aes with 256-bit key',
102 _cipher_block_size = { # in bits
105 _compression_algorithms = {
148 _string_to_key_types = {
152 3: 'iterated and salted',
166 _clean_type_regex = _re.compile('\W+')
168 def _clean_type(self):
169 return self._clean_type_regex.sub('_', self['type'])
171 def from_bytes(self, data):
172 offset = self._parse_header(data=data)
173 packet = data[offset:offset + self['length']]
174 if len(packet) < self['length']:
175 raise ValueError('packet too short ({} < {})'.format(
176 len(packet), self['length']))
177 offset += self['length']
178 method_name = '_parse_{}'.format(self._clean_type())
179 method = getattr(self, method_name, None)
181 raise NotImplementedError(
182 'cannot parse packet type {!r}'.format(self['type']))
186 def _parse_header(self, data):
189 always_one = packet_tag & 1 << 7
191 raise ValueError('most significant packet tag bit not set')
192 self['new-format'] = packet_tag & 1 << 6
193 if self['new-format']:
194 type_code = packet_tag & 0b111111
195 raise NotImplementedError('new-format packet length')
197 type_code = packet_tag >> 2 & 0b1111
198 self['length-type'] = packet_tag & 0b11
199 length_bytes, length_type = self._old_format_packet_length_type[
202 raise NotImplementedError(
203 'old-format packet of indeterminate length')
204 length_format = '>{}'.format(length_type)
205 length_data = data[offset: offset + length_bytes]
206 offset += length_bytes
207 self['length'] = _struct.unpack(length_format, length_data)[0]
208 self['type'] = self._packet_types[type_code]
212 def _parse_multiprecision_integer(data):
213 r"""Parse RFC 4880's multiprecision integers
215 >>> PGPPacket._parse_multiprecision_integer(b'\x00\x01\x01')
217 >>> PGPPacket._parse_multiprecision_integer(b'\x00\x09\x01\xff')
220 bits = _struct.unpack('>H', data[:2])[0]
222 length = (bits + 7) // 8
224 for i in range(length):
225 value += data[offset + i] * 1 << (8 * (length - i - 1))
227 return (offset, value)
229 def _parse_string_to_key_specifier(self, data):
230 self['string-to-key-type'] = self._string_to_key_types[data[0]]
232 if self['string-to-key-type'] == 'simple':
233 self['string-to-key-hash-algorithm'] = self._hash_algorithms[
236 elif self['string-to-key-type'] == 'salted':
237 self['string-to-key-hash-algorithm'] = self._hash_algorithms[
240 self['string-to-key-salt'] = data[offset: offset + 8]
242 elif self['string-to-key-type'] == 'iterated and salted':
243 self['string-to-key-hash-algorithm'] = self._hash_algorithms[
246 self['string-to-key-salt'] = data[offset: offset + 8]
248 self['string-to-key-coded-count'] = data[offset]
251 raise NotImplementedError(
252 'string-to-key type {}'.format(self['string-to-key-type']))
255 def _parse_public_key_packet(self, data):
256 self._parse_generic_public_key_packet(data=data)
258 def _parse_public_subkey_packet(self, data):
259 self._parse_generic_public_key_packet(data=data)
261 def _parse_generic_public_key_packet(self, data):
262 self['key-version'] = data[0]
264 if self['key-version'] != 4:
265 raise NotImplementedError(
266 'public (sub)key packet version {}'.format(
267 self['key-version']))
269 self['creation-time'], algorithm = _struct.unpack(
270 '>IB', data[offset: offset + length])
272 self['public-key-algorithm'] = self._public_key_algorithms[algorithm]
273 if self['public-key-algorithm'].startswith('rsa '):
274 o, self['public-modulus'] = self._parse_multiprecision_integer(
277 o, self['public-exponent'] = self._parse_multiprecision_integer(
280 elif self['public-key-algorithm'].startswith('dsa '):
281 o, self['prime'] = self._parse_multiprecision_integer(
284 o, self['group-order'] = self._parse_multiprecision_integer(
287 o, self['group-generator'] = self._parse_multiprecision_integer(
290 o, self['public-key'] = self._parse_multiprecision_integer(
293 elif self['public-key-algorithm'].startswith('elgamal '):
294 o, self['prime'] = self._parse_multiprecision_integer(
297 o, self['group-generator'] = self._parse_multiprecision_integer(
300 o, self['public-key'] = self._parse_multiprecision_integer(
304 raise NotImplementedError(
305 'algorithm-specific key fields for {}'.format(
306 self['public-key-algorithm']))
309 def _parse_secret_key_packet(self, data):
310 self._parse_generic_secret_key_packet(data=data)
312 def _parse_secret_subkey_packet(self, data):
313 self._parse_generic_secret_key_packet(data=data)
315 def _parse_generic_secret_key_packet(self, data):
316 offset = self._parse_generic_public_key_packet(data=data)
317 string_to_key_usage = data[offset]
319 if string_to_key_usage in [255, 254]:
320 self['symmetric-encryption-algorithm'] = (
321 self._symmetric_key_algorithms[data[offset]])
323 offset += self._parse_string_to_key_specifier(data=data[offset:])
325 self['symmetric-encryption-algorithm'] = (
326 self._symmetric_key_algorithms[string_to_key_usage])
327 if string_to_key_usage:
328 block_size_bits = self._cipher_block_size.get(
329 self['symmetric-encryption-algorithm'], None)
330 if block_size_bits % 8:
331 raise NotImplementedError(
332 ('{}-bit block size for {} is not an integer number of bytes'
334 block_size_bits, self['symmetric-encryption-algorithm']))
335 block_size = block_size_bits // 8
337 raise NotImplementedError(
338 'unknown block size for {}'.format(
339 self['symmetric-encryption-algorithm']))
340 self['initial-vector'] = data[offset: offset + block_size]
342 if string_to_key_usage in [0, 255]:
346 self['secret-key'] = data[offset:key_end]
348 self['secret-key-checksum'] = data[key_end:]
354 def packets_from_bytes(data):
356 while offset < len(data):
358 offset += packet.from_bytes(data=data[offset:])
362 def migrate(old_key, new_key):
363 """Add the old key and sub-keys to the new key
365 For example, to upgrade your master key, while preserving old
366 signatures you'd made. You will lose signature *on* your old key
367 though, since sub-keys can't be signed (I don't think).
369 old_key_export = _get_stdout(
370 ['gpg', '--export', old_key])
371 old_key_packets = list(
372 packets_from_bytes(data=old_key_export))
373 if old_key_packets[0]['type'] != 'public-key packet':
375 '{} does not start with a public-key packet'.format(
377 old_key_secret_export = _get_stdout(
378 ['gpg', '--export-secret-keys', old_key])
379 old_key_secret_packets = list(
380 packets_from_bytes(data=old_key_secret_export))
383 pprint.pprint(old_key_packets)
384 pprint.pprint(old_key_secret_packets)
387 if __name__ == '__main__':
390 old_key, new_key = _sys.argv[1:3]
391 migrate(old_key=old_key, new_key=new_key)