class CryptoToolchain::Tools::CbcBitflipAttack

Attributes

target[R]

Public Class Methods

new(target: CryptoToolchain::BlackBoxes::CbcBitflipTarget.new) click to toggle source
# File lib/crypto_toolchain/tools/cbc_bitflip_attack.rb, line 5
def initialize(target: CryptoToolchain::BlackBoxes::CbcBitflipTarget.new)
  @target = target
end

Public Instance Methods

execute() click to toggle source
# File lib/crypto_toolchain/tools/cbc_bitflip_attack.rb, line 14
def execute
  easy = ":admin<true:" #only need to flip the last bit of bytes 1, 7, 12
  blocks = target.encrypt(easy).in_blocks(16)
  first = flip(blocks[1], 0, 8)
  equals = flip(first, 6, 8)
  last = flip(equals, 11, 8)
  blocks[1] = last
  blocks.join
end
flip(block, byte, bit) click to toggle source
# File lib/crypto_toolchain/tools/cbc_bitflip_attack.rb, line 9
def flip(block, byte, bit)
  new_byte = ((1 << (bit - 8)) ^ (block[byte].ord)).chr
  block[0...byte] + new_byte + block[(byte+1)..-1]
end