D. Kahn, The Codebreakers; The Story of Secret Writing, Macmillan Publishing CO., INC.
[The Comprehensive History of Secret Communication from Ancient to the Modern Times.
A generation of cryptographers was raised by this book. A great history book.]

Handbook of Applied Cryptography (On-line!)
[A very concise book. Both for newbies and professionals. Chapter 2 provides some useful "Mathematical Background".
Chapter 7 is a very fast run through "Block Ciphers".]
 

Eli Biham, Adi Shamir, Differential Cryptanalysis of the Data Encryption Standard, Springer-Verlag, 1993 Older version online!
[Development of the method of differential cryptanalysis and its application to DES and other ciphers. THE book.]
 

MAIN REFERENCES

• Marian Rejewski "Mathematical Solution of the Enigma Cipher", Cryptologia, Vol.VI, No.1, 1982. (can be found here)
• Claude Shannon, "Theory of Secrecy Systems", Bell Systems Technical J., Vol 28, pp. 656-715, October 1949 (can also be found here).
• H.Feistel, W.A.Notz, J.L. Smith, "Cryptographic Techniques for Machine to Machine Data Communications", RC 3663 (#16560), December 27, 1971,  Communications, IBM T.J.Watson RC. (Popular version in: Horst Feistel, "Cryptography and Computer Privacy", Scientific American, Vol. 228, No.5 , 1973.)
• Philippe Flajolet, Andrew Odlyzko, "Random Mapping Statistics", Lecture Notes in Computer Science 434, EUROCRYPT'89, pp.329-354,1989.
• Martin Hellman, "A Cryptanalytic Time-Memory Trade-Off",  IEEE Transactions on Information Theory, Vol. IT-26, No.4, July 1980.
• Don Coppersmith, "The Data Encryption Standard and its Strength Against Attacks", IBM Journal of Research and Development, vol. 38, no. 3, p. 243-50, May 1994.
• Eli Biham, Adi Shamir, "Differential Cryptanalysis of the Full 16-Round DES",Proceedings of Crypto'92, LNCS 740.
• Mitsuru Matsui, "Linear Cryptanalysis Method of DES Cipher",  Eurocrypt'93, LNCS 765, pp.386-397, Springer-Verlag 1994.

Advanced Reading

Tonns of various grey books. Proceedings of FSE, Eurocrypt, Crypto, Asiacrypt, SAC, etc. Here are just a few, for example.

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