lib/kruptos/blowfish.rb
# blowfish.rb Richard Kernahan <kernighan_rich@rubyforge.org>
#
# Blowfish algorithm by Bruce Schneider
# Ported by Richard Kernahan from the reference C code
module Kruptos
class Blowfish
require 'kruptos/cbc'
include Kruptos::CBC
require 'kruptos/blowfish-tables'
include Kruptos::BlowfishTables
ULONG = 0x100000000
def block_size
return(8)
end
def initialize(key)
@key = key
raise "Bad key length: the key must be 1-56 bytes." unless (key.length.between?(1,56))
@pArray = []
@sBoxes = []
setup_blowfish()
end
def f(x)
a, b, c, d = [x].pack('N').unpack('CCCC')
y = (@sBoxes[0][a] + @sBoxes[1][b]) % ULONG
y = (y ^ @sBoxes[2][c]) % ULONG
y = (y + @sBoxes[3][d]) % ULONG
return(y)
end
def setup_blowfish()
@sBoxes = Array.new(4) { |i| INITIALSBOXES[i].clone }
@pArray = INITIALPARRAY.clone
keypos = 0
0.upto(17) { |i|
data = 0
4.times {
data = ((data << 8) | @key[keypos].ord) % ULONG
keypos = (keypos.next) % @key.length
}
@pArray[i] = (@pArray[i] ^ data) % ULONG
}
l = 0
r = 0
0.step(17, 2) { |i|
l, r = encrypt_pair(l, r)
@pArray[i] = l
@pArray[i+1] = r
}
0.upto(3) { |i|
0.step(255, 2) { |j|
l, r = encrypt_pair(l, r)
@sBoxes[i][j] = l
@sBoxes[i][j+1] = r
}
}
end
def encrypt_pair(xl, xr)
0.upto(15) { |i|
xl = (xl ^ @pArray[i]) % ULONG
xr = (xr ^ f(xl)) % ULONG
xl, xr = [xl, xr].reverse
}
xl, xr = [xl, xr].reverse
xr = (xr ^ @pArray[16]) % ULONG
xl = (xl ^ @pArray[17]) % ULONG
return([xl, xr])
end
def decrypt_pair(xl, xr)
17.downto(2) { |i|
xl = (xl ^ @pArray[i]) % ULONG
xr = (xr ^ f(xl)) % ULONG
xl, xr = [xl, xr].reverse
}
xl, xr = [xl, xr].reverse
xr = (xr ^ @pArray[1]) % ULONG
xl = (xl ^ @pArray[0]) % ULONG
return([xl, xr])
end
def encrypt_block(block)
xl, xr = block.unpack('NN')
xl, xr = encrypt_pair(xl, xr)
encrypted = [xl, xr].pack('NN')
return(encrypted)
end
def decrypt_block(block)
xl, xr = block.unpack('NN')
xl, xr = decrypt_pair(xl, xr)
decrypted = [xl, xr].pack('NN')
return(decrypted)
end
end
end