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+# -*- coding: utf-8 -*-
+#
+# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+'''RSA key generation code.
+
+Create new keys with the newkeys() function. It will give you a PublicKey and a
+PrivateKey object.
+
+Loading and saving keys requires the pyasn1 module. This module is imported as
+late as possible, such that other functionality will remain working in absence
+of pyasn1.
+
+'''
+
+import logging
+from rsa._compat import b, bytes_type
+
+import rsa.prime
+import rsa.pem
+import rsa.common
+
+log = logging.getLogger(__name__)
+
+
+
+class AbstractKey(object):
+ '''Abstract superclass for private and public keys.'''
+
+ @classmethod
+ def load_pkcs1(cls, keyfile, format='PEM'):
+ r'''Loads a key in PKCS#1 DER or PEM format.
+
+ :param keyfile: contents of a DER- or PEM-encoded file that contains
+ the public key.
+ :param format: the format of the file to load; 'PEM' or 'DER'
+
+ :return: a PublicKey object
+
+ '''
+
+ methods = {
+ 'PEM': cls._load_pkcs1_pem,
+ 'DER': cls._load_pkcs1_der,
+ }
+
+ if format not in methods:
+ formats = ', '.join(sorted(methods.keys()))
+ raise ValueError('Unsupported format: %r, try one of %s' % (format,
+ formats))
+
+ method = methods[format]
+ return method(keyfile)
+
+ def save_pkcs1(self, format='PEM'):
+ '''Saves the public key in PKCS#1 DER or PEM format.
+
+ :param format: the format to save; 'PEM' or 'DER'
+ :returns: the DER- or PEM-encoded public key.
+
+ '''
+
+ methods = {
+ 'PEM': self._save_pkcs1_pem,
+ 'DER': self._save_pkcs1_der,
+ }
+
+ if format not in methods:
+ formats = ', '.join(sorted(methods.keys()))
+ raise ValueError('Unsupported format: %r, try one of %s' % (format,
+ formats))
+
+ method = methods[format]
+ return method()
+
+class PublicKey(AbstractKey):
+ '''Represents a public RSA key.
+
+ This key is also known as the 'encryption key'. It contains the 'n' and 'e'
+ values.
+
+ Supports attributes as well as dictionary-like access. Attribute accesss is
+ faster, though.
+
+ >>> PublicKey(5, 3)
+ PublicKey(5, 3)
+
+ >>> key = PublicKey(5, 3)
+ >>> key.n
+ 5
+ >>> key['n']
+ 5
+ >>> key.e
+ 3
+ >>> key['e']
+ 3
+
+ '''
+
+ __slots__ = ('n', 'e')
+
+ def __init__(self, n, e):
+ self.n = n
+ self.e = e
+
+ def __getitem__(self, key):
+ return getattr(self, key)
+
+ def __repr__(self):
+ return 'PublicKey(%i, %i)' % (self.n, self.e)
+
+ def __eq__(self, other):
+ if other is None:
+ return False
+
+ if not isinstance(other, PublicKey):
+ return False
+
+ return self.n == other.n and self.e == other.e
+
+ def __ne__(self, other):
+ return not (self == other)
+
+ @classmethod
+ def _load_pkcs1_der(cls, keyfile):
+ r'''Loads a key in PKCS#1 DER format.
+
+ @param keyfile: contents of a DER-encoded file that contains the public
+ key.
+ @return: a PublicKey object
+
+ First let's construct a DER encoded key:
+
+ >>> import base64
+ >>> b64der = 'MAwCBQCNGmYtAgMBAAE='
+ >>> der = base64.decodestring(b64der)
+
+ This loads the file:
+
+ >>> PublicKey._load_pkcs1_der(der)
+ PublicKey(2367317549, 65537)
+
+ '''
+
+ from pyasn1.codec.der import decoder
+ from rsa.asn1 import AsnPubKey
+
+ (priv, _) = decoder.decode(keyfile, asn1Spec=AsnPubKey())
+ return cls(n=int(priv['modulus']), e=int(priv['publicExponent']))
+
+ def _save_pkcs1_der(self):
+ '''Saves the public key in PKCS#1 DER format.
+
+ @returns: the DER-encoded public key.
+ '''
+
+ from pyasn1.codec.der import encoder
+ from rsa.asn1 import AsnPubKey
+
+ # Create the ASN object
+ asn_key = AsnPubKey()
+ asn_key.setComponentByName('modulus', self.n)
+ asn_key.setComponentByName('publicExponent', self.e)
+
+ return encoder.encode(asn_key)
+
+ @classmethod
+ def _load_pkcs1_pem(cls, keyfile):
+ '''Loads a PKCS#1 PEM-encoded public key file.
+
+ The contents of the file before the "-----BEGIN RSA PUBLIC KEY-----" and
+ after the "-----END RSA PUBLIC KEY-----" lines is ignored.
+
+ @param keyfile: contents of a PEM-encoded file that contains the public
+ key.
+ @return: a PublicKey object
+ '''
+
+ der = rsa.pem.load_pem(keyfile, 'RSA PUBLIC KEY')
+ return cls._load_pkcs1_der(der)
+
+ def _save_pkcs1_pem(self):
+ '''Saves a PKCS#1 PEM-encoded public key file.
+
+ @return: contents of a PEM-encoded file that contains the public key.
+ '''
+
+ der = self._save_pkcs1_der()
+ return rsa.pem.save_pem(der, 'RSA PUBLIC KEY')
+
+ @classmethod
+ def load_pkcs1_openssl_pem(cls, keyfile):
+ '''Loads a PKCS#1.5 PEM-encoded public key file from OpenSSL.
+
+ These files can be recognised in that they start with BEGIN PUBLIC KEY
+ rather than BEGIN RSA PUBLIC KEY.
+
+ The contents of the file before the "-----BEGIN PUBLIC KEY-----" and
+ after the "-----END PUBLIC KEY-----" lines is ignored.
+
+ @param keyfile: contents of a PEM-encoded file that contains the public
+ key, from OpenSSL.
+ @return: a PublicKey object
+ '''
+
+ der = rsa.pem.load_pem(keyfile, 'PUBLIC KEY')
+ return cls.load_pkcs1_openssl_der(der)
+
+ @classmethod
+ def load_pkcs1_openssl_der(cls, keyfile):
+ '''Loads a PKCS#1 DER-encoded public key file from OpenSSL.
+
+ @param keyfile: contents of a DER-encoded file that contains the public
+ key, from OpenSSL.
+ @return: a PublicKey object
+ '''
+
+ from rsa.asn1 import OpenSSLPubKey
+ from pyasn1.codec.der import decoder
+ from pyasn1.type import univ
+
+ (keyinfo, _) = decoder.decode(keyfile, asn1Spec=OpenSSLPubKey())
+
+ if keyinfo['header']['oid'] != univ.ObjectIdentifier('1.2.840.113549.1.1.1'):
+ raise TypeError("This is not a DER-encoded OpenSSL-compatible public key")
+
+ return cls._load_pkcs1_der(keyinfo['key'][1:])
+
+
+
+
+class PrivateKey(AbstractKey):
+ '''Represents a private RSA key.
+
+ This key is also known as the 'decryption key'. It contains the 'n', 'e',
+ 'd', 'p', 'q' and other values.
+
+ Supports attributes as well as dictionary-like access. Attribute accesss is
+ faster, though.
+
+ >>> PrivateKey(3247, 65537, 833, 191, 17)
+ PrivateKey(3247, 65537, 833, 191, 17)
+
+ exp1, exp2 and coef don't have to be given, they will be calculated:
+
+ >>> pk = PrivateKey(3727264081, 65537, 3349121513, 65063, 57287)
+ >>> pk.exp1
+ 55063
+ >>> pk.exp2
+ 10095
+ >>> pk.coef
+ 50797
+
+ If you give exp1, exp2 or coef, they will be used as-is:
+
+ >>> pk = PrivateKey(1, 2, 3, 4, 5, 6, 7, 8)
+ >>> pk.exp1
+ 6
+ >>> pk.exp2
+ 7
+ >>> pk.coef
+ 8
+
+ '''
+
+ __slots__ = ('n', 'e', 'd', 'p', 'q', 'exp1', 'exp2', 'coef')
+
+ def __init__(self, n, e, d, p, q, exp1=None, exp2=None, coef=None):
+ self.n = n
+ self.e = e
+ self.d = d
+ self.p = p
+ self.q = q
+
+ # Calculate the other values if they aren't supplied
+ if exp1 is None:
+ self.exp1 = int(d % (p - 1))
+ else:
+ self.exp1 = exp1
+
+ if exp1 is None:
+ self.exp2 = int(d % (q - 1))
+ else:
+ self.exp2 = exp2
+
+ if coef is None:
+ self.coef = rsa.common.inverse(q, p)
+ else:
+ self.coef = coef
+
+ def __getitem__(self, key):
+ return getattr(self, key)
+
+ def __repr__(self):
+ return 'PrivateKey(%(n)i, %(e)i, %(d)i, %(p)i, %(q)i)' % self
+
+ def __eq__(self, other):
+ if other is None:
+ return False
+
+ if not isinstance(other, PrivateKey):
+ return False
+
+ return (self.n == other.n and
+ self.e == other.e and
+ self.d == other.d and
+ self.p == other.p and
+ self.q == other.q and
+ self.exp1 == other.exp1 and
+ self.exp2 == other.exp2 and
+ self.coef == other.coef)
+
+ def __ne__(self, other):
+ return not (self == other)
+
+ @classmethod
+ def _load_pkcs1_der(cls, keyfile):
+ r'''Loads a key in PKCS#1 DER format.
+
+ @param keyfile: contents of a DER-encoded file that contains the private
+ key.
+ @return: a PrivateKey object
+
+ First let's construct a DER encoded key:
+
+ >>> import base64
+ >>> b64der = 'MC4CAQACBQDeKYlRAgMBAAECBQDHn4npAgMA/icCAwDfxwIDANcXAgInbwIDAMZt'
+ >>> der = base64.decodestring(b64der)
+
+ This loads the file:
+
+ >>> PrivateKey._load_pkcs1_der(der)
+ PrivateKey(3727264081, 65537, 3349121513, 65063, 57287)
+
+ '''
+
+ from pyasn1.codec.der import decoder
+ (priv, _) = decoder.decode(keyfile)
+
+ # ASN.1 contents of DER encoded private key:
+ #
+ # RSAPrivateKey ::= SEQUENCE {
+ # version Version,
+ # modulus INTEGER, -- n
+ # publicExponent INTEGER, -- e
+ # privateExponent INTEGER, -- d
+ # prime1 INTEGER, -- p
+ # prime2 INTEGER, -- q
+ # exponent1 INTEGER, -- d mod (p-1)
+ # exponent2 INTEGER, -- d mod (q-1)
+ # coefficient INTEGER, -- (inverse of q) mod p
+ # otherPrimeInfos OtherPrimeInfos OPTIONAL
+ # }
+
+ if priv[0] != 0:
+ raise ValueError('Unable to read this file, version %s != 0' % priv[0])
+
+ as_ints = tuple(int(x) for x in priv[1:9])
+ return cls(*as_ints)
+
+ def _save_pkcs1_der(self):
+ '''Saves the private key in PKCS#1 DER format.
+
+ @returns: the DER-encoded private key.
+ '''
+
+ from pyasn1.type import univ, namedtype
+ from pyasn1.codec.der import encoder
+
+ class AsnPrivKey(univ.Sequence):
+ componentType = namedtype.NamedTypes(
+ namedtype.NamedType('version', univ.Integer()),
+ namedtype.NamedType('modulus', univ.Integer()),
+ namedtype.NamedType('publicExponent', univ.Integer()),
+ namedtype.NamedType('privateExponent', univ.Integer()),
+ namedtype.NamedType('prime1', univ.Integer()),
+ namedtype.NamedType('prime2', univ.Integer()),
+ namedtype.NamedType('exponent1', univ.Integer()),
+ namedtype.NamedType('exponent2', univ.Integer()),
+ namedtype.NamedType('coefficient', univ.Integer()),
+ )
+
+ # Create the ASN object
+ asn_key = AsnPrivKey()
+ asn_key.setComponentByName('version', 0)
+ asn_key.setComponentByName('modulus', self.n)
+ asn_key.setComponentByName('publicExponent', self.e)
+ asn_key.setComponentByName('privateExponent', self.d)
+ asn_key.setComponentByName('prime1', self.p)
+ asn_key.setComponentByName('prime2', self.q)
+ asn_key.setComponentByName('exponent1', self.exp1)
+ asn_key.setComponentByName('exponent2', self.exp2)
+ asn_key.setComponentByName('coefficient', self.coef)
+
+ return encoder.encode(asn_key)
+
+ @classmethod
+ def _load_pkcs1_pem(cls, keyfile):
+ '''Loads a PKCS#1 PEM-encoded private key file.
+
+ The contents of the file before the "-----BEGIN RSA PRIVATE KEY-----" and
+ after the "-----END RSA PRIVATE KEY-----" lines is ignored.
+
+ @param keyfile: contents of a PEM-encoded file that contains the private
+ key.
+ @return: a PrivateKey object
+ '''
+
+ der = rsa.pem.load_pem(keyfile, b('RSA PRIVATE KEY'))
+ return cls._load_pkcs1_der(der)
+
+ def _save_pkcs1_pem(self):
+ '''Saves a PKCS#1 PEM-encoded private key file.
+
+ @return: contents of a PEM-encoded file that contains the private key.
+ '''
+
+ der = self._save_pkcs1_der()
+ return rsa.pem.save_pem(der, b('RSA PRIVATE KEY'))
+
+def find_p_q(nbits, getprime_func=rsa.prime.getprime, accurate=True):
+ ''''Returns a tuple of two different primes of nbits bits each.
+
+ The resulting p * q has exacty 2 * nbits bits, and the returned p and q
+ will not be equal.
+
+ :param nbits: the number of bits in each of p and q.
+ :param getprime_func: the getprime function, defaults to
+ :py:func:`rsa.prime.getprime`.
+
+ *Introduced in Python-RSA 3.1*
+
+ :param accurate: whether to enable accurate mode or not.
+ :returns: (p, q), where p > q
+
+ >>> (p, q) = find_p_q(128)
+ >>> from rsa import common
+ >>> common.bit_size(p * q)
+ 256
+
+ When not in accurate mode, the number of bits can be slightly less
+
+ >>> (p, q) = find_p_q(128, accurate=False)
+ >>> from rsa import common
+ >>> common.bit_size(p * q) <= 256
+ True
+ >>> common.bit_size(p * q) > 240
+ True
+
+ '''
+
+ total_bits = nbits * 2
+
+ # Make sure that p and q aren't too close or the factoring programs can
+ # factor n.
+ shift = nbits // 16
+ pbits = nbits + shift
+ qbits = nbits - shift
+
+ # Choose the two initial primes
+ log.debug('find_p_q(%i): Finding p', nbits)
+ p = getprime_func(pbits)
+ log.debug('find_p_q(%i): Finding q', nbits)
+ q = getprime_func(qbits)
+
+ def is_acceptable(p, q):
+ '''Returns True iff p and q are acceptable:
+
+ - p and q differ
+ - (p * q) has the right nr of bits (when accurate=True)
+ '''
+
+ if p == q:
+ return False
+
+ if not accurate:
+ return True
+
+ # Make sure we have just the right amount of bits
+ found_size = rsa.common.bit_size(p * q)
+ return total_bits == found_size
+
+ # Keep choosing other primes until they match our requirements.
+ change_p = False
+ while not is_acceptable(p, q):
+ # Change p on one iteration and q on the other
+ if change_p:
+ p = getprime_func(pbits)
+ else:
+ q = getprime_func(qbits)
+
+ change_p = not change_p
+
+ # We want p > q as described on
+ # http://www.di-mgt.com.au/rsa_alg.html#crt
+ return (max(p, q), min(p, q))
+
+def calculate_keys(p, q, nbits):
+ '''Calculates an encryption and a decryption key given p and q, and
+ returns them as a tuple (e, d)
+
+ '''
+
+ phi_n = (p - 1) * (q - 1)
+
+ # A very common choice for e is 65537
+ e = 65537
+
+ try:
+ d = rsa.common.inverse(e, phi_n)
+ except ValueError:
+ raise ValueError("e (%d) and phi_n (%d) are not relatively prime" %
+ (e, phi_n))
+
+ if (e * d) % phi_n != 1:
+ raise ValueError("e (%d) and d (%d) are not mult. inv. modulo "
+ "phi_n (%d)" % (e, d, phi_n))
+
+ return (e, d)
+
+def gen_keys(nbits, getprime_func, accurate=True):
+ '''Generate RSA keys of nbits bits. Returns (p, q, e, d).
+
+ Note: this can take a long time, depending on the key size.
+
+ :param nbits: the total number of bits in ``p`` and ``q``. Both ``p`` and
+ ``q`` will use ``nbits/2`` bits.
+ :param getprime_func: either :py:func:`rsa.prime.getprime` or a function
+ with similar signature.
+ '''
+
+ (p, q) = find_p_q(nbits // 2, getprime_func, accurate)
+ (e, d) = calculate_keys(p, q, nbits // 2)
+
+ return (p, q, e, d)
+
+def newkeys(nbits, accurate=True, poolsize=1):
+ '''Generates public and private keys, and returns them as (pub, priv).
+
+ The public key is also known as the 'encryption key', and is a
+ :py:class:`rsa.PublicKey` object. The private key is also known as the
+ 'decryption key' and is a :py:class:`rsa.PrivateKey` object.
+
+ :param nbits: the number of bits required to store ``n = p*q``.
+ :param accurate: when True, ``n`` will have exactly the number of bits you
+ asked for. However, this makes key generation much slower. When False,
+ `n`` may have slightly less bits.
+ :param poolsize: the number of processes to use to generate the prime
+ numbers. If set to a number > 1, a parallel algorithm will be used.
+ This requires Python 2.6 or newer.
+
+ :returns: a tuple (:py:class:`rsa.PublicKey`, :py:class:`rsa.PrivateKey`)
+
+ The ``poolsize`` parameter was added in *Python-RSA 3.1* and requires
+ Python 2.6 or newer.
+
+ '''
+
+ if nbits < 16:
+ raise ValueError('Key too small')
+
+ if poolsize < 1:
+ raise ValueError('Pool size (%i) should be >= 1' % poolsize)
+
+ # Determine which getprime function to use
+ if poolsize > 1:
+ from rsa import parallel
+ import functools
+
+ getprime_func = functools.partial(parallel.getprime, poolsize=poolsize)
+ else: getprime_func = rsa.prime.getprime
+
+ # Generate the key components
+ (p, q, e, d) = gen_keys(nbits, getprime_func)
+
+ # Create the key objects
+ n = p * q
+
+ return (
+ PublicKey(n, e),
+ PrivateKey(n, e, d, p, q)
+ )
+
+__all__ = ['PublicKey', 'PrivateKey', 'newkeys']
+
+if __name__ == '__main__':
+ import doctest
+
+ try:
+ for count in range(100):
+ (failures, tests) = doctest.testmod()
+ if failures:
+ break
+
+ if (count and count % 10 == 0) or count == 1:
+ print('%i times' % count)
+ except KeyboardInterrupt:
+ print('Aborted')
+ else:
+ print('Doctests done')
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