jcryption

1 files changed, 106 insertions, 0 deletions

diff --git a/lib/ayk/jcryption.rb b/lib/ayk/jcryption.rb
new file mode 100644
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+++ b/lib/ayk/jcryption.rb
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+#! /usr/bin/env ruby
+# -*- coding: UTF-8 -*-
+
+#----------------------------------------------------------------------------
+#
+# File     : jcryption.rb
+# Author   : Jérémy Zurcher <jeremy@asynk.ch>
+# Date     : 11/09/09 
+# License  :
+#
+#   Copyright (c) 2009 Jérémy Zurcher
+#
+#   Permission is hereby granted, free of charge, to any person obtaining
+#   a copy of this software and associated documentation files (the
+#   "Software"), to deal in the Software without restriction, including
+#   without limitation the rights to use, copy, modify, merge, publish,
+#   distribute, sublicense, and/or sell copies of the Software, and to
+#   permit persons to whom the Software is furnished to do so, subject to
+#   the following conditions:
+#
+#   The above copyright notice and this permission notice shall be
+#   included in all copies or substantial portions of the Software.
+#
+#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+#   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+#   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+#   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+#   LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+#   OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+#   WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+#
+#----------------------------------------------------------------------------
+#
+def Math.power_modulo(b, p, m)
+    if p == 1
+        b % m
+    elsif (p & 0x1) == 0
+        t = power_modulo(b, p >> 1, m)
+        (t * t) % m
+    else
+        (b * power_modulo(b, p-1, m)) % m
+    end
+end
+#
+class Bignum
+    #
+    class << self
+        def from_bytes bytes
+            val = 0
+            idx = 0
+            bytes.each_byte{ |b|
+                val += b << 8 * idx
+                idx += 1
+            }
+            val
+        end
+    end
+    #
+    def to_bytes
+        str = ''
+        bint = self
+        while bint!=0 do
+            bint,r = bint.divmod 256
+            str += r.chr
+        end
+        str
+    end
+    #
+    def bits
+        s = self.to_bytes
+        while s[-1].ord==0
+            s.slice!(-1)
+        end
+        bit_len = s.length * 8
+        tmp = s[-1].ord
+        while not tmp & 0x80
+            bit_len-=1
+            tmp <<=1
+        end
+        bit_len
+    end
+end
+#
+module JCryption
+    #
+    def decrypt data, d, n
+        s = data.split(' ').inject('') do |str,block| str += ( Math::power_modulo( block.to_i(16), d, n ) ).to_bytes end
+        sum,crc = 0,s.slice(0,2).to_i(16)
+        s.slice(2..-1).each_char do |char| sum += char.ord end
+        return ( crc == sum & 0xFF ) ? s : nil 
+    end
+    module_function :decrypt
+    #
+    def rsa_keys key, len
+        '{"e":"'+key.e.to_s(16)+'","n":"'+key.n.to_s(16)+'","maxdigits":"'+(len*2/16+3).to_s+'"}'
+    end
+    module_function :rsa_keys
+    #
+    def gen_keypair bits
+        # therese no point to try without using openssl
+        require 'openssl'
+        OpenSSL::PKey::RSA.generate( bits )
+    end
+    module_function :gen_keypair
+end
+