The last paragraph:

Most modern ciphers fall into three main categories: ... (followed by a list of four categories)

needs work.

I do not know for sure but suspect that: block vs stream and symmetric key vs asymmetric key are orthogonal categorizations. If that is the case, changing three to four (in the offending paragraph) does not really fix the problem.

Yep, they're orthogonal. I tidied up the last paragraph to reflect that. The rest of the article should probably be re-worked a bit for clarity as well.

Encryption and Cipher are currently too similar. They should be merged, or Cipher should be specialized to the customary (though vague) subset of private-key encryption.

While I'm a crypto-head and so probably biased, I do think there's a case for primary disambiguation here. I think any user typing in "cipher" is most likely to be looking for the encryption algorithm meaning, as opposed to a synonym for zero, or a Pokemon team of villains, or any of the other meanings. — Matt Crypto 11:33, 15 November 2006 (UTC)[reply]

In hebrew "sifra" ספרה means "numerical digit". Thus, given the the fact that Hebrew culture has always had interest in such subjects as Numerology, the source of the word may have also come from that direction. Bilbobugginz (talk) 05:15, 14 July 2008 (UTC)[reply]

Encipherment does not contain enough information to stand on its own. It should be merged into this article.

Neelix (talk) 01:07, 6 May 2008 (UTC)[reply]

Huh? It's a redirect to this page. --84.250.188.136 (talk) 03:24, 9 May 2008 (UTC)[reply]

It wasn't when Neelix wrote the above. — Matt Crypto 05:22, 9 May 2008 (UTC)[reply]

Hello, hope I'm doing this right, am new at it. Just writing to suggest something. Ciphers are often said to be either transposition, or substitution, or both; but there's also one appearing in Dorothy Sayers mystery novel, "The Nine Tailors," that, strictly speaking, is neither, for it embeds the plaintext message - without substitution, and without rearrangement - within a cover message (the key being a "change ringing" method for church bells). Can't stay to pursue this, but anyone's welcome to take it up. Boinkles (talk) 17:52, 24 August 2009 (UTC)[reply]

Steganography? — Matt Crypto 20:15, 24 August 2009 (UTC)[reply]

The article describes "codes" in the cryptographic sense as operating on the level of meaning, e.g. words; versus "ciphers", which operate on the level of characters, groups of characters, or bits. It then gives telegraphic code as an example of a code. But our article on telegraphic codes points to Morse code, which operates on the level of characters, as the most common one. Is something meant by "telegraphic code" here other than the kind that telegraphic code describes? --Delirium (talk) 01:25, 5 September 2009 (UTC)[reply]