mirror of
https://salsa.debian.org/gnuk-team/gnuk/gnuk.git
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153 lines
4.2 KiB
Python
153 lines
4.2 KiB
Python
from binascii import hexlify, unhexlify
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from time import time
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from struct import pack
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from hashlib import sha1, sha256
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import string
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from os import urandom
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def read_key_from_file(file):
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f = open(file)
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n_str = f.readline()[:-1]
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e_str = f.readline()[:-1]
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p_str = f.readline()[:-1]
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q_str = f.readline()[:-1]
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f.close()
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e = int(e_str, 16)
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p = int(p_str, 16)
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q = int(q_str, 16)
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n = int(n_str, 16)
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if n != p * q:
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raise ValueError("wrong key", p, q, n)
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return (unhexlify(n_str), unhexlify(e_str), unhexlify(p_str), unhexlify(q_str), e, p, q, n)
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def calc_fpr(n,e):
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timestamp = int(time())
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timestamp_data = pack('>I', timestamp)
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m_len = 6 + 2 + 256 + 2 + 4
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m = '\x99' + pack('>H', m_len) + '\x04' + timestamp_data + '\x01' + \
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pack('>H', 2048) + n + pack('>H', 17) + e
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fpr = sha1(m).digest()
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return (fpr, timestamp_data)
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key = [ None, None, None ]
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fpr = [ None, None, None ]
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timestamp = [ None, None, None ]
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key[0] = read_key_from_file('rsa-sig.key')
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key[1] = read_key_from_file('rsa-dec.key')
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key[2] = read_key_from_file('rsa-aut.key')
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(fpr[0], timestamp[0]) = calc_fpr(key[0][0], key[0][1])
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(fpr[1], timestamp[1]) = calc_fpr(key[1][0], key[1][1])
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(fpr[2], timestamp[2]) = calc_fpr(key[2][0], key[2][1])
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def build_privkey_template(openpgp_keyno, keyno):
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n_str = key[keyno][0]
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e_str = '\x00' + key[keyno][1]
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p_str = key[keyno][2]
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q_str = key[keyno][3]
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if openpgp_keyno == 1:
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keyspec = '\xb6'
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elif openpgp_keyno == 2:
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keyspec = '\xb8'
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else:
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keyspec = '\xa4'
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key_template = '\x91\x04'+ '\x92\x81\x80' + '\x93\x81\x80'
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exthdr = keyspec + '\x00' + '\x7f\x48' + '\x08' + key_template
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suffix = '\x5f\x48' + '\x82\x01\x04'
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t = '\x4d' + '\x82\01\16' + exthdr + suffix + e_str + p_str + q_str
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return t
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def build_privkey_template_for_remove(openpgp_keyno):
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if openpgp_keyno == 1:
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keyspec = '\xb6'
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elif openpgp_keyno == 2:
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keyspec = '\xb8'
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else:
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keyspec = '\xa4'
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return '\x4d\02' + keyspec + '\0x00'
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def compute_digestinfo(msg):
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digest = sha256(msg).digest()
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prefix = '\x30\31\x30\x0d\x06\x09\x60\x86\x48\x01\x65\x03\x04\x02\x01\x05\x00\x04\x20'
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return prefix + digest
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# egcd and modinv are from wikibooks
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# https://en.wikibooks.org/wiki/Algorithm_Implementation/Mathematics/Extended_Euclidean_algorithm
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def egcd(a, b):
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if a == 0:
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return (b, 0, 1)
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else:
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g, y, x = egcd(b % a, a)
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return (g, x - (b // a) * y, y)
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def modinv(a, m):
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g, x, y = egcd(a, m)
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if g != 1:
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raise Exception('modular inverse does not exist')
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else:
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return x % m
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def pkcs1_pad_for_sign(digestinfo):
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byte_repr = '\x00' + '\x01' + string.ljust('', 256 - 19 - 32 - 3, '\xff') \
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+ '\x00' + digestinfo
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return int(hexlify(byte_repr), 16)
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def pkcs1_pad_for_crypt(msg):
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padlen = 256 - 3 - len(msg)
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byte_repr = '\x00' + '\x02' \
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+ string.replace(urandom(padlen),'\x00','\x01') + '\x00' + msg
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return int(hexlify(byte_repr), 16)
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def compute_signature(keyno, digestinfo):
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e = key[keyno][4]
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p = key[keyno][5]
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q = key[keyno][6]
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n = key[keyno][7]
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p1 = p - 1
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q1 = q - 1
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h = p1 * q1
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d = modinv(e, h)
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dp = d % p1
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dq = d % q1
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qp = modinv(q, p)
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input = pkcs1_pad_for_sign(digestinfo)
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t1 = pow(input, dp, p)
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t2 = pow(input, dq, q)
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t = ((t1 - t2) * qp) % p
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sig = t2 + t * q
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return sig
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def integer_to_bytes_256(i):
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s = hex(i)[2:]
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s = s.rstrip('L')
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if len(s) & 1:
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s = '0' + s
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return string.rjust(unhexlify(s), 256, '\x00')
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def encrypt(keyno, plaintext):
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e = key[keyno][4]
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n = key[keyno][7]
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m = pkcs1_pad_for_crypt(plaintext)
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return '\x00' + integer_to_bytes_256(pow(m, e, n))
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def encrypt_with_pubkey(pubkey_info, plaintext):
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n = int(hexlify(pubkey_info[0]), 16)
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e = int(hexlify(pubkey_info[1]), 16)
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m = pkcs1_pad_for_crypt(plaintext)
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return '\x00' + integer_to_bytes_256(pow(m, e, n))
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def verify_signature(pubkey_info, digestinfo, sig):
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n = int(hexlify(pubkey_info[0]), 16)
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e = int(hexlify(pubkey_info[1]), 16)
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di_pkcs1 = pow(sig,e,n)
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m = pkcs1_pad_for_sign(digestinfo)
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return di_pkcs1 == m
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