Bit-Flipping Attack

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Bit-flipping attack is an attack against stream ciphers in which the attacker changes one or several bits in the ciphertext, at specific position, such that the plaintext changes at the same positions.

• attacker cannot control the resulting plaintext,
  • if he/she does not know the original plaintext format
• but if you know the message format and the content of the bits to change,
  • then can control the modified plaintext
  • because the ciphertext in stream ciphers is yielded by XORing the plaintext with the key
• e.g. if the attacker knows the format of a bank transaction, which contains the value 50 in bits at positions 100 to 120,
  • then can change the value to