Class: Forgers::StreamCipher::ForgeGenerator

Inherits:
Object
  • Object
show all
Defined in:
lib/crypto-toolbox/forgers/stream_ciphers/forge_generator.rb

Overview

This class generates a forged ciphertext that has been constructed to decipher to a specific and specified forged plaintext. It receives a observed orginal ciphertext c, its (partial or full) plaintext and the plaintext the attacker would like to have. It returns the ciphertext that correcponds to the forged message

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.forge(ciphertext, plaintext, target_plaintext) ⇒ Object 



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# File 'lib/crypto-toolbox/forgers/stream_ciphers/forge_generator.rb', line 21

def self.forge(ciphertext,plaintext,target_plaintext)
  new.forge(ciphertext,plaintext,target_plaintext)
end

Instance Method Details

#forge(ciphertext, plaintext, target_plaintext) ⇒ Object

Create the xor of the two plaintext messages, that can also just be a part of the real message or have some pseudo padding for any unknown position finally xor that difference of the plaintexts at the correct position of the ciphertext



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# File 'lib/crypto-toolbox/forgers/stream_ciphers/forge_generator.rb', line 15

def forge(ciphertext,plaintext,target_plaintext)
  diff = CryptBuffer(plaintext).xor(target_plaintext)
  c    = CryptBuffer.from_hex(ciphertext)
  c.xor(diff)
end