Abstract
TPypy is a tweaked version of the Py stream cipher algorithm submitted to eSTREAM. Py uses a kind of processing referred to as a ‘rolling array’, the mixing of two types of array and one variable, to generate the keystream. TPypy is proposed as a highly secure stream cipher that fixes all of the previously identified weaknesses of Py.
This paper reports a significant bias in the pseudo-random generation algorithm of TPypy that can be exploited to distinguish the keystream obtained from multiple arbitrary secret key and initial vector pairs from a truly random number sequence using about 2199 words.
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eSTREAM, the ECRYPT Stream Cipher Project, available at http://www.ecrypt.eu.org/stream/
Baignères, T., Junod, P., Vaudenay, S.: How Far Can We Go Beyond Linear Cryptanalysis? In: Lee, P.J. (ed.) ASIACRYPT 2004. LNCS, vol. 3329, pp. 432–450. Springer, Heidelberg (2004)
Biham, E., Seberry, J.: Py (Roo): A Fast and Secure Stream Cipher Using Rolling Arrays. eSTREAM, the ECRYPT Stream Cipher Project, Report 2005/023 (2005)
Biham, E., Seberry, J.: Pypy: Another Version of Py. eSTREAM, the ECRYPT Stream Cipher Project, Report 2006/038 (2006)
Biham, E., Seberry, J.: Tweaking the IV Setup of the Py Family of Stream Ciphers – The Ciphers TPy, TPypy, and TPy6. eSTREAM, the ECRYPT Stream Cipher Project, Report 2007/038 (2007)
Crowley, P.: Improved Cryptanalysis of Py. In: SASC 2006 - Stream Ciphers Revisited, Workshop Record, pp. 52–60 (2006)
Isobe, T., Ohigashi, T., Kuwakado, H., Morii, M.: How to Break Py and Pypy by a Chosen-IV Attack. In: SASC 2007 - The State of the Art of Stream Ciphers, Workshop Record, pp. 340–352 (2007)
Kogiso, M., Shimoyama, T.: A Distinguishing Attack on the Stream Cipher Pypy. In: Symposium on Cryptography and Information Security - SCIS, IEICE Technical Report, 2A2-2 (2007) (in Japanese)
Paul, S., Preneel, B., Sekar, G.: Distinguishing Attacks on the Stream Cipher Py. In: Robshaw, M. (ed.) FSE 2006. LNCS, vol. 4047, pp. 405–421. Springer, Heidelberg (2006)
Paul, S., Preneel, B.: On the (In)security of Stream Ciphers Based on Arrays and Modular Addition. In: Lai, X., Chen, K. (eds.) ASIACRYPT 2006. LNCS, vol. 4284, pp. 69–83. Springer, Heidelberg (2006)
Schneier, B.: Applied Cryptography, 2nd edn. John Wiley & Sons, Chichester (1996)
Sekar, G., Paul, S., Preneel, B.: Weaknesses in the Pseudorandom Bit Generation Algorithms of the Stream Ciphers TPypy and TPy. eSTREAM, the ECRYPT Stream Cipher Project, Report 2007/037 (2007)
Wu, H., Preneel, B.: Attacking the IV Setup of Py and Pypy. eSTREAM, the ECRYPT Stream Cipher Project, Report 2006/050 (2006)
Wu, H., Preneel, B.: Key Recovery Attack on Py and Pypy with Chosen IVs. eSTREAM, the ECRYPT Stream Cipher Project, Report 2006/052 (2006)
Wu, H., Preneel, B.: Differential Cryptanalysis of the Stream Ciphers Py, Py6 and Pypy. In: Naor, M. (ed.) EUROCRYPT 2007. LNCS, vol. 4515, pp. 276–290. Springer, Heidelberg (2007)
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Tsunoo, Y., Saito, T., Kawabata, T., Nakashima, H. (2007). Distinguishing Attack Against TPypy. In: Adams, C., Miri, A., Wiener, M. (eds) Selected Areas in Cryptography. SAC 2007. Lecture Notes in Computer Science, vol 4876. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-77360-3_25
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DOI: https://doi.org/10.1007/978-3-540-77360-3_25
Publisher Name: Springer, Berlin, Heidelberg
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