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
103 'aes with 128-bit key': 128,
104 'aes with 192-bit key': 128,
105 'aes with 256-bit key': 128,
109 _compression_algorithms = {
152 _string_to_key_types = {
156 3: 'iterated and salted',
170 _clean_type_regex = _re.compile('\W+')
172 def _clean_type(self):
173 return self._clean_type_regex.sub('_', self['type'])
175 def from_bytes(self, data):
176 offset = self._parse_header(data=data)
177 packet = data[offset:offset + self['length']]
178 if len(packet) < self['length']:
179 raise ValueError('packet too short ({} < {})'.format(
180 len(packet), self['length']))
181 offset += self['length']
182 method_name = '_parse_{}'.format(self._clean_type())
183 method = getattr(self, method_name, None)
185 raise NotImplementedError(
186 'cannot parse packet type {!r}'.format(self['type']))
190 def _parse_header(self, data):
193 always_one = packet_tag & 1 << 7
195 raise ValueError('most significant packet tag bit not set')
196 self['new-format'] = packet_tag & 1 << 6
197 if self['new-format']:
198 type_code = packet_tag & 0b111111
199 raise NotImplementedError('new-format packet length')
201 type_code = packet_tag >> 2 & 0b1111
202 self['length-type'] = packet_tag & 0b11
203 length_bytes, length_type = self._old_format_packet_length_type[
206 raise NotImplementedError(
207 'old-format packet of indeterminate length')
208 length_format = '>{}'.format(length_type)
209 length_data = data[offset: offset + length_bytes]
210 offset += length_bytes
211 self['length'] = _struct.unpack(length_format, length_data)[0]
212 self['type'] = self._packet_types[type_code]
216 def _parse_multiprecision_integer(data):
217 r"""Parse RFC 4880's multiprecision integers
219 >>> PGPPacket._parse_multiprecision_integer(b'\x00\x01\x01')
221 >>> PGPPacket._parse_multiprecision_integer(b'\x00\x09\x01\xff')
224 bits = _struct.unpack('>H', data[:2])[0]
226 length = (bits + 7) // 8
228 for i in range(length):
229 value += data[offset + i] * 1 << (8 * (length - i - 1))
231 return (offset, value)
233 def _parse_string_to_key_specifier(self, data):
234 self['string-to-key-type'] = self._string_to_key_types[data[0]]
236 if self['string-to-key-type'] == 'simple':
237 self['string-to-key-hash-algorithm'] = self._hash_algorithms[
240 elif self['string-to-key-type'] == 'salted':
241 self['string-to-key-hash-algorithm'] = self._hash_algorithms[
244 self['string-to-key-salt'] = data[offset: offset + 8]
246 elif self['string-to-key-type'] == 'iterated and salted':
247 self['string-to-key-hash-algorithm'] = self._hash_algorithms[
250 self['string-to-key-salt'] = data[offset: offset + 8]
252 self['string-to-key-coded-count'] = data[offset]
255 raise NotImplementedError(
256 'string-to-key type {}'.format(self['string-to-key-type']))
259 def _parse_public_key_packet(self, data):
260 self._parse_generic_public_key_packet(data=data)
262 def _parse_public_subkey_packet(self, data):
263 self._parse_generic_public_key_packet(data=data)
265 def _parse_generic_public_key_packet(self, data):
266 self['key-version'] = data[0]
268 if self['key-version'] != 4:
269 raise NotImplementedError(
270 'public (sub)key packet version {}'.format(
271 self['key-version']))
273 self['creation-time'], algorithm = _struct.unpack(
274 '>IB', data[offset: offset + length])
276 self['public-key-algorithm'] = self._public_key_algorithms[algorithm]
277 if self['public-key-algorithm'].startswith('rsa '):
278 o, self['public-modulus'] = self._parse_multiprecision_integer(
281 o, self['public-exponent'] = self._parse_multiprecision_integer(
284 elif self['public-key-algorithm'].startswith('dsa '):
285 o, self['prime'] = self._parse_multiprecision_integer(
288 o, self['group-order'] = self._parse_multiprecision_integer(
291 o, self['group-generator'] = self._parse_multiprecision_integer(
294 o, self['public-key'] = self._parse_multiprecision_integer(
297 elif self['public-key-algorithm'].startswith('elgamal '):
298 o, self['prime'] = self._parse_multiprecision_integer(
301 o, self['group-generator'] = self._parse_multiprecision_integer(
304 o, self['public-key'] = self._parse_multiprecision_integer(
308 raise NotImplementedError(
309 'algorithm-specific key fields for {}'.format(
310 self['public-key-algorithm']))
313 def _parse_secret_key_packet(self, data):
314 self._parse_generic_secret_key_packet(data=data)
316 def _parse_secret_subkey_packet(self, data):
317 self._parse_generic_secret_key_packet(data=data)
319 def _parse_generic_secret_key_packet(self, data):
320 offset = self._parse_generic_public_key_packet(data=data)
321 string_to_key_usage = data[offset]
323 if string_to_key_usage in [255, 254]:
324 self['symmetric-encryption-algorithm'] = (
325 self._symmetric_key_algorithms[data[offset]])
327 offset += self._parse_string_to_key_specifier(data=data[offset:])
329 self['symmetric-encryption-algorithm'] = (
330 self._symmetric_key_algorithms[string_to_key_usage])
331 if string_to_key_usage:
332 block_size_bits = self._cipher_block_size.get(
333 self['symmetric-encryption-algorithm'], None)
334 if block_size_bits % 8:
335 raise NotImplementedError(
336 ('{}-bit block size for {} is not an integer number of bytes'
338 block_size_bits, self['symmetric-encryption-algorithm']))
339 block_size = block_size_bits // 8
341 raise NotImplementedError(
342 'unknown block size for {}'.format(
343 self['symmetric-encryption-algorithm']))
344 self['initial-vector'] = data[offset: offset + block_size]
346 if string_to_key_usage in [0, 255]:
350 self['secret-key'] = data[offset:key_end]
352 self['secret-key-checksum'] = data[key_end:]
358 def packets_from_bytes(data):
360 while offset < len(data):
362 offset += packet.from_bytes(data=data[offset:])
366 def migrate(old_key, new_key):
367 """Add the old key and sub-keys to the new key
369 For example, to upgrade your master key, while preserving old
370 signatures you'd made. You will lose signature *on* your old key
371 though, since sub-keys can't be signed (I don't think).
373 old_key_export = _get_stdout(
374 ['gpg', '--export', old_key])
375 old_key_packets = list(
376 packets_from_bytes(data=old_key_export))
377 if old_key_packets[0]['type'] != 'public-key packet':
379 '{} does not start with a public-key packet'.format(
381 old_key_secret_export = _get_stdout(
382 ['gpg', '--export-secret-keys', old_key])
383 old_key_secret_packets = list(
384 packets_from_bytes(data=old_key_secret_export))
387 pprint.pprint(old_key_packets)
388 pprint.pprint(old_key_secret_packets)
391 if __name__ == '__main__':
394 old_key, new_key = _sys.argv[1:3]
395 migrate(old_key=old_key, new_key=new_key)