def _decodeLen(self, s):
"""Decode DER length octets from a file."""
length = bord(s.read_byte())
if length<=127:
return length
payloadLength = bytes_to_long(s.read(length & 0x7F))
# According to DER (but not BER) the long form is used
# only when the length doesn't fit into 7 bits.
if payloadLength<=127:
raise ValueError("Not a DER length tag (but still valid BER).")
return payloadLength
def importKey(self, extern_key, passphrase=None):
"""Import an RSA key (public or private half), encoded in standard
form.
:Parameter extern_key:
The RSA key to import, encoded as a string.
An RSA public key can be in any of the following formats:
- X.509 ``subjectPublicKeyInfo`` DER SEQUENCE (binary or PEM
encoding)
- `PKCS#1`_ ``RSAPublicKey`` DER SEQUENCE (binary or PEM encoding)
- OpenSSH (textual public key only)
An RSA private key can be in any of the following formats:
- PKCS#1 ``RSAPrivateKey`` DER SEQUENCE (binary or PEM encoding)
- `PKCS#8`_ ``PrivateKeyInfo`` or ``EncryptedPrivateKeyInfo``
DER SEQUENCE (binary or PEM encoding)
- OpenSSH (textual public key only)
For details about the PEM encoding, see `RFC1421`_/`RFC1423`_.
The private key may be encrypted by means of a certain pass phrase
either at the PEM level or at the PKCS#8 level.
:Type extern_key: string
:Parameter passphrase:
In case of an encrypted private key, this is the pass phrase from
which the decryption key is derived.
:Type passphrase: string
:Return: An RSA key object (`_RSAobj`).
:Raise ValueError/IndexError/TypeError:
When the given key cannot be parsed (possibly because the pass
phrase is wrong).
.. _RFC1421: http://www.ietf.org/rfc/rfc1421.txt
.. _RFC1423: http://www.ietf.org/rfc/rfc1423.txt
.. _`PKCS#1`: http://www.ietf.org/rfc/rfc3447.txt
.. _`PKCS#8`: http://www.ietf.org/rfc/rfc5208.txt
"""
extern_key = tobytes(extern_key)
if passphrase is not None:
passphrase = tobytes(passphrase)
if extern_key.startswith(b('-----')):
# This is probably a PEM encoded key.
(der, marker, enc_flag) = PEM.decode(tostr(extern_key), passphrase)
if enc_flag:
passphrase = None
return self._importKeyDER(der, passphrase)
if extern_key.startswith(b('ssh-rsa ')):
# This is probably an OpenSSH key
keystring = binascii.a2b_base64(extern_key.split(b(' '))[1])
keyparts = []
while len(keystring) > 4:
l = struct.unpack(">I", keystring[:4])[0]
keyparts.append(keystring[4:4 + l])
keystring = keystring[4 + l:]
e = bytes_to_long(keyparts[1])
n = bytes_to_long(keyparts[2])
return self.construct([n, e])
if bord(extern_key[0]) == 0x30:
# This is probably a DER encoded key
return self._importKeyDER(extern_key, passphrase)
raise ValueError("RSA key format is not supported")
