History of cryptography and cryptanalysis. Questions that wish to ask about the history of cryptography should use this tag; if you're asking about historical ciphers you may also wish to use the classical-cipher tag.

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6
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1answer
678 views

How were the AES key and block length subsets of Rijndael selected?

My intuition tells me it's a trade off between speed and security, but how did the standardisation process select these three seemingly arbitrary key lengths (namely, AES-128, AES-192, AES-256).
10
votes
0answers
697 views

Who first published the interest of more than two prime factors in RSA?

Multi-prime RSA is now a well known technique (described here): it uses $k>2$ distinct secret prime factors in the public RSA modulus, with the advantage that, using the CRT, we can gain a speed ...
20
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3answers
13k views

How cryptographically secure was the original WW2 Enigma machine, from a modern viewpoint?

If cryptanalysts today were to crack the original Enigma machine, “how fast” or “how easily” could they do it? What methods would they use? The original cracking was significantly helped by operator ...
29
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1answer
2k views

How is the MD2 hash function S-table constructed from Pi?

For fun, I'm learning more about cryptography and hashing. I'm implementing the MD2 hash function following RFC 1319 (http://tools.ietf.org/html/rfc1319). I'll preface by saying I know there are ...
28
votes
1answer
4k views

Examples of modern, widely used ciphers that suddenly fell?

RC4 and GOST are two major ciphers (defined as being widely used to encrypt large amounts of data) that fell to cryptanalysis (relatively) suddenly. The first becoming totally broken and the second ...
7
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3answers
553 views

Did non-military cryptography appear in 50's and 60's only due to NSA leaks?

I'm not talking about scytale, but encryption like RSA, DES, etc... How did exactly civil cryptography evolve after World War II?
6
votes
2answers
132 views

Purpose of DES parity bits

DES has a 64-bit key size, but only 56 of those are used during encryption. The other 8 are "parity bits". What was the intended purpose of the party bits, and why are they no longer used in modern ...