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DesignersX. Yi, C.H. Tan, C.K. Siew, and M.R. Syed
First published2001
Cipher detail
Key sizesabout 4094.2 bits
Block sizes4096 bits
Best public cryptanalysis
Youssef and Tavares break it with 1 known plaintext and 2 chosen plaintexts

In cryptography, FEA-M (Fast Encryption Algorithm for Multimedia) is a block cipher developed in 2001 by X. Yi, C. H. Tan, C. K. Siew, and M. R. Syed.

With the unusually large block size of 4096 bits, all of FEA-M's calculations operate on 64×64 binary matrices. Unlike most block ciphers, FEA-M does not use multiple rounds of encryption. Each block is encrypted using just two multiplications and two additions. The data is encrypted using a pair of session keys chosen for just that message. The key is an invertible matrix used to encrypt the session keys, and the encrypted session keys must be sent along with the ciphertext. Since only invertible matrices can be used for the key, the effective key size is about 4094.2 bits.

FEA-M is insecure; an attack found by Youssef and Tavares (2003) recovers the secret key using only 1 known plaintext and 2 chosen plaintexts.[1]


  • Hongjun Wu; Feng Bao; Robert H. Deng (October 2003). An Efficient Known Plaintext Attack on FEA-M (PDF). 5th International Conference on Information and Communication Security (ICICS 2003). Huhehaote: Springer-Verlag. pp. 34–46. Retrieved 31 December 2006.[permanent dead link]
  1. ^ Li, Shujun; Lo, Kwok-Tung (14 June 2006). "Security problems with improper implementations of improved FEA-M". Journal of Systems and Software. 80 (5): 791–794. arXiv:cs.cr/0509036. CiteSeerX doi:10.1016/j.jss.2006.05.002. S2CID 2381494.

Further reading[edit]

  • Mihaljevic, M.J. (November 2003). "On vulnerabilities and improvements of fast encryption algorithm for multimedia FEA-M". IEEE Transactions on Consumer Electronics. 49 (4): 1199–1207. doi:10.1109/TCE.2003.1261217.