from __future__ import absolute_import, print_function """ M2Crypto wrapper for OpenSSL DSA API. Copyright (c) 1999-2003 Ng Pheng Siong. All rights reserved. Portions created by Open Source Applications Foundation (OSAF) are Copyright (C) 2004 OSAF. All Rights Reserved. """ from M2Crypto import BIO, m2, util from typing import Any, AnyStr, Callable, Tuple # noqa class DSAError(Exception): pass m2.dsa_init(DSAError) class DSA(object): """ This class is a context supporting DSA key and parameter values, signing and verifying. Simple example:: from M2Crypto import EVP, DSA, util message = 'Kilroy was here!' md = EVP.MessageDigest('sha1') md.update(message) digest = md.final() dsa = DSA.gen_params(1024) dsa.gen_key() r, s = dsa.sign(digest) good = dsa.verify(digest, r, s) if good: print(' ** success **') else: print(' ** verification failed **') """ m2_dsa_free = m2.dsa_free def __init__(self, dsa, _pyfree=0): # type: (bytes, int) -> None """ Use one of the factory functions to create an instance. :param dsa: binary representation of OpenSSL DSA type """ assert m2.dsa_type_check(dsa), "'dsa' type error" self.dsa = dsa self._pyfree = _pyfree def __del__(self): # type: () -> None if getattr(self, '_pyfree', 0): self.m2_dsa_free(self.dsa) def __len__(self): # type: () -> int """ Return the key length. :return: the DSA key length in bits """ assert m2.dsa_type_check(self.dsa), "'dsa' type error" return m2.dsa_keylen(self.dsa) def __getattr__(self, name): # type: (str) -> bytes """ Return specified DSA parameters and key values. :param name: name of variable to be returned. Must be one of 'p', 'q', 'g', 'pub', 'priv'. :return: value of specified variable (a "byte string") """ if name in ['p', 'q', 'g', 'pub', 'priv']: method = getattr(m2, 'dsa_get_%s' % (name,)) assert m2.dsa_type_check(self.dsa), "'dsa' type error" return method(self.dsa) else: raise AttributeError def __setattr__(self, name, value): # type: (str, bytes) -> None if name in ['p', 'q', 'g']: raise DSAError('set (p, q, g) via set_params()') elif name in ['pub', 'priv']: raise DSAError('generate (pub, priv) via gen_key()') else: self.__dict__[name] = value def set_params(self, p, q, g): # type: (bytes, bytes, bytes) -> None """ Set new parameters. :param p: MPI binary representation ... format that consists of the number's length in bytes represented as a 4-byte big-endian number, and the number itself in big-endian format, where the most significant bit signals a negative number (the representation of numbers with the MSB set is prefixed with null byte). :param q: ditto :param g: ditto @warning: This does not change the private key, so it may be unsafe to use this method. It is better to use gen_params function to create a new DSA object. """ m2.dsa_set_pqg(self.dsa, p, q, g) def gen_key(self): # type: () -> None """ Generate a key pair. """ assert m2.dsa_type_check(self.dsa), "'dsa' type error" m2.dsa_gen_key(self.dsa) def save_params(self, filename): # type: (AnyStr) -> int """ Save the DSA parameters to a file. :param filename: Save the DSA parameters to this file. :return: 1 (true) if successful """ with BIO.openfile(filename, 'wb') as bio: ret = m2.dsa_write_params_bio(self.dsa, bio._ptr()) return ret def save_params_bio(self, bio): # type: (BIO.BIO) -> int """ Save DSA parameters to a BIO object. :param bio: Save DSA parameters to this object. :return: 1 (true) if successful """ return m2.dsa_write_params_bio(self.dsa, bio._ptr()) def save_key(self, filename, cipher='aes_128_cbc', callback=util.passphrase_callback): # type: (AnyStr, str, Callable) -> int """ Save the DSA key pair to a file. :param filename: Save the DSA key pair to this file. :param cipher: name of symmetric key algorithm and mode to encrypt the private key. :return: 1 (true) if successful """ with BIO.openfile(filename, 'wb') as bio: ret = self.save_key_bio(bio, cipher, callback) return ret def save_key_bio(self, bio, cipher='aes_128_cbc', callback=util.passphrase_callback): # type: (BIO.BIO, str, Callable) -> int """ Save DSA key pair to a BIO object. :param bio: Save DSA parameters to this object. :param cipher: name of symmetric key algorithm and mode to encrypt the private key. :return: 1 (true) if successful """ if cipher is None: return m2.dsa_write_key_bio_no_cipher(self.dsa, bio._ptr(), callback) else: ciph = getattr(m2, cipher, None) if ciph is None: raise DSAError('no such cipher: %s' % cipher) else: ciph = ciph() return m2.dsa_write_key_bio(self.dsa, bio._ptr(), ciph, callback) def save_pub_key(self, filename): # type: (AnyStr) -> int """ Save the DSA public key (with parameters) to a file. :param filename: Save DSA public key (with parameters) to this file. :return: 1 (true) if successful """ with BIO.openfile(filename, 'wb') as bio: ret = self.save_pub_key_bio(bio) return ret def save_pub_key_bio(self, bio): # type: (BIO.BIO) -> int """ Save DSA public key (with parameters) to a BIO object. :param bio: Save DSA public key (with parameters) to this object. :return: 1 (true) if successful """ return m2.dsa_write_pub_key_bio(self.dsa, bio._ptr()) def sign(self, digest): # type: (bytes) -> Tuple[bytes, bytes] """ Sign the digest. :param digest: SHA-1 hash of message (same as output from MessageDigest, a "byte string") :return: DSA signature, a tuple of two values, r and s, both "byte strings". """ assert self.check_key(), 'key is not initialised' return m2.dsa_sign(self.dsa, digest) def verify(self, digest, r, s): # type: (bytes, bytes, bytes) -> int """ Verify a newly calculated digest against the signature values r and s. :param digest: SHA-1 hash of message (same as output from MessageDigest, a "byte string") :param r: r value of the signature, a "byte string" :param s: s value of the signature, a "byte string" :return: 1 (true) if verify succeeded, 0 if failed """ assert self.check_key(), 'key is not initialised' return m2.dsa_verify(self.dsa, digest, r, s) def sign_asn1(self, digest): assert self.check_key(), 'key is not initialised' return m2.dsa_sign_asn1(self.dsa, digest) def verify_asn1(self, digest, blob): assert self.check_key(), 'key is not initialised' return m2.dsa_verify_asn1(self.dsa, digest, blob) def check_key(self): """ Check to be sure the DSA object has a valid private key. :return: 1 (true) if a valid private key """ assert m2.dsa_type_check(self.dsa), "'dsa' type error" return m2.dsa_check_key(self.dsa) class DSA_pub(DSA): """ This class is a DSA context that only supports a public key and verification. It does NOT support a private key or signing. """ def sign(self, *argv): # type: (*Any) -> None raise DSAError('DSA_pub object has no private key') sign_asn1 = sign def check_key(self): # type: () -> int """ :return: does DSA_pub contain a pub key? """ return m2.dsa_check_pub_key(self.dsa) save_key = DSA.save_pub_key save_key_bio = DSA.save_pub_key_bio # -------------------------------------------------------------- # factories and other functions def gen_params(bits, callback=util.genparam_callback): # type: (int, Callable) -> DSA """ Factory function that generates DSA parameters and instantiates a DSA object from the output. :param bits: The length of the prime to be generated. If 'bits' < 512, it is set to 512. :param callback: A Python callback object that will be invoked during parameter generation; it usual purpose is to provide visual feedback. :return: instance of DSA. """ dsa = m2.dsa_generate_parameters(bits, callback) return DSA(dsa, 1) def set_params(p, q, g): # type: (bytes, bytes, bytes) -> DSA """ Factory function that instantiates a DSA object with DSA parameters. :param p: value of p, a "byte string" :param q: value of q, a "byte string" :param g: value of g, a "byte string" :return: instance of DSA. """ dsa = m2.dsa_new() m2.dsa_set_pqg(dsa, p, q, g) return DSA(dsa, 1) def load_params(file, callback=util.passphrase_callback): # type: (AnyStr, Callable) -> DSA """ Factory function that instantiates a DSA object with DSA parameters from a file. :param file: Names the file (a path) that contains the PEM representation of the DSA parameters. :param callback: A Python callback object that will be invoked if the DSA parameters file is passphrase-protected. :return: instance of DSA. """ with BIO.openfile(file) as bio: ret = load_params_bio(bio, callback) return ret def load_params_bio(bio, callback=util.passphrase_callback): # type: (BIO.BIO, Callable) -> DSA """ Factory function that instantiates a DSA object with DSA parameters from a M2Crypto.BIO object. :param bio: Contains the PEM representation of the DSA parameters. :param callback: A Python callback object that will be invoked if the DSA parameters file is passphrase-protected. :return: instance of DSA. """ dsa = m2.dsa_read_params(bio._ptr(), callback) return DSA(dsa, 1) def load_key(file, callback=util.passphrase_callback): # type: (AnyStr, Callable) -> DSA """ Factory function that instantiates a DSA object from a PEM encoded DSA key pair. :param file: Names the file (a path) that contains the PEM representation of the DSA key pair. :param callback: A Python callback object that will be invoked if the DSA key pair is passphrase-protected. :return: instance of DSA. """ with BIO.openfile(file) as bio: ret = load_key_bio(bio, callback) return ret def load_key_bio(bio, callback=util.passphrase_callback): # type: (BIO.BIO, Callable) -> DSA """ Factory function that instantiates a DSA object from a PEM encoded DSA key pair. :param bio: Contains the PEM representation of the DSA key pair. :param callback: A Python callback object that will be invoked if the DSA key pair is passphrase-protected. :return: instance of DSA. """ dsa = m2.dsa_read_key(bio._ptr(), callback) return DSA(dsa, 1) def pub_key_from_params(p, q, g, pub): # type: (bytes, bytes, bytes, bytes) -> DSA_pub """ Factory function that instantiates a DSA_pub object using the parameters and public key specified. :param p: value of p :param q: value of q :param g: value of g :param pub: value of the public key :return: instance of DSA_pub. """ dsa = m2.dsa_new() m2.dsa_set_pqg(dsa, p, q, g) m2.dsa_set_pub(dsa, pub) return DSA_pub(dsa, 1) def load_pub_key(file, callback=util.passphrase_callback): # type: (AnyStr, Callable) -> DSA_pub """ Factory function that instantiates a DSA_pub object using a DSA public key contained in PEM file. The PEM file must contain the parameters in addition to the public key. :param file: Names the file (a path) that contains the PEM representation of the DSA public key. :param callback: A Python callback object that will be invoked should the DSA public key be passphrase-protected. :return: instance of DSA_pub. """ with BIO.openfile(file) as bio: ret = load_pub_key_bio(bio, callback) return ret def load_pub_key_bio(bio, callback=util.passphrase_callback): # type: (BIO.BIO, Callable) -> DSA_pub """ Factory function that instantiates a DSA_pub object using a DSA public key contained in PEM format. The PEM must contain the parameters in addition to the public key. :param bio: Contains the PEM representation of the DSA public key (with params). :param callback: A Python callback object that will be invoked should the DSA public key be passphrase-protected. :return: instance of DSA_pub. """ dsapub = m2.dsa_read_pub_key(bio._ptr(), callback) return DSA_pub(dsapub, 1)