From 79fecc456499cc12e56e373871991cf804468a9d Mon Sep 17 00:00:00 2001 From: Robey Pointer Date: Sun, 9 Nov 2003 20:59:51 +0000 Subject: [project @ Arch-1:robey@lag.net--2003-public%secsh--dev--1.0--patch-4] change kex-gex server code to generate primes by hand added a util function "generate_prime" to compare to the incredibly slow C version, but it's no faster of course. i think kex-gex from the server is just not going to be feasible without having a separate thread generate some primes in the background to have handy when a request comes in. so in short, this still doesn't work. also i put bit_length into util and a tb_strings function which gets stack traceback info and splits it into a list of strings. --- util.py | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) (limited to 'util.py') diff --git a/util.py b/util.py index 28349721..fd78af38 100644 --- a/util.py +++ b/util.py @@ -1,6 +1,7 @@ #!/usr/bin/python -import struct +import sys, struct, traceback +from Crypto.Util import number def inflate_long(s, always_positive=0): "turns a normalized byte string into a long-int (adapted from Crypto.Util.number)" @@ -87,3 +88,30 @@ def safe_string(s): return out # ''.join([['%%%02X' % ord(c), c][(ord(c) >= 32) and (ord(c) <= 127)] for c in s]) + +def bit_length(n): + norm = deflate_long(n, 0) + hbyte = ord(norm[0]) + bitlen = len(norm) * 8 + while not (hbyte & 0x80): + hbyte <<= 1 + bitlen -= 1 + return bitlen + +def generate_prime(bits, randpool): + hbyte_mask = pow(2, bits % 8) - 1 + x = randpool.get_bytes((bits+7) // 8) + if hbyte_mask > 0: + x = chr(ord(x[0]) & hbyte_mask) + x[1:] + n = inflate_long(x, 1) + n |= 1 + n |= (1 << (bits - 1)) + while 1: + # loop catches the case where we increment n into a higher bit-range + while not number.isPrime(n): + n += 2 + if bit_length(n) == bits: + return n + +def tb_strings(): + return ''.join(traceback.format_exception(*sys.exc_info())).split('\n') -- cgit v1.2.3