Class: CryptoToolchain::Tools::CbcBitflipAttack

Inherits:
Object
  • Object
show all
Defined in:
lib/crypto_toolchain/tools/cbc_bitflip_attack.rb

Instance Method Summary collapse

Constructor Details

#initialize(target: CryptoToolchain::BlackBoxes::CbcBitflipTarget.new) ⇒ CbcBitflipAttack

Returns a new instance of CbcBitflipAttack.



5
6
7
 
# File 'lib/crypto_toolchain/tools/cbc_bitflip_attack.rb', line 5

def initialize(target: CryptoToolchain::BlackBoxes::CbcBitflipTarget.new)
  @target = target
end

Instance Method Details

#execute ⇒ Object 



14
15
16
17
18
19
20
21
22
 
# 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) ⇒ Object 



9
10
11
12
 
# 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