Attack model

Attack models or attack types specify how much information a cryptanalyst has access to when cracking an encrypted message (also known as ciphertext). Some common attack models are:

• Ciphertext-only attack
• Known-plaintext attack
  • During World War II, the Allies used known-plaintexts ("cribs") in their successful Cryptanalysis of the Enigma machine cipher.
• Chosen-plaintext attack
• Chosen-ciphertext attack
  • Adaptive chosen-ciphertext attack
  • Indifferent chosen-ciphertext attack

The ciphertext-only attack model is the weakest because it implies that the cryptanalyst has just the encoded message. Modern ciphers rarely fail under this attack type.

Different attack models are used for other cryptographic primitives, or more generally for all kind of security systems. Examples for such attack models are:

• Adaptive chosen-message attack for digital signatures

References

• ^ Information Security Laboratory (powerpoint)
• ^ Bruce Schneier (2000). "Cryptography". Secrets & Lies: Digital Security in a Networked World (Hardcover ed.). Wiley Computer Publishing Inc. pp. 90–91. ISBN 0-471-25311-1. 
• Niels Ferguson; Bruce Schneier (2003). "Introduction to Cryptography: Attacks". In Carol A. Long. Practical Cryptography (Hardcover ed.). Wiley Publishing Inc. pp. 30–32. ISBN 0-471-22894-X. 

Further reading

• Susan Hansche; John Berti, Chris Hare (2004). "6 - Cryptography: Cryptoanalysis and attacks". Official (ISC)² Guide to the CISSP Exam (Hardcover ed.). Auerbach Publications. pp. 389–393. ISBN 0-8493-1707-X. 

External links

• University of Waterloo paper that discusses attack models (PostScript file) html version