[Cryptography] What is the difference between a code and a cipher?
Dave Horsfall
dave at horsfall.org
Fri Sep 5 00:01:13 EDT 2014
On Thu, 4 Sep 2014, Richard Outerbridge wrote:
> Codes can have variable length plaintext symbols, and also variable
> length ciphertext symbols.
>
> Ciphers have same length plaintext symbols, but can have variable length
> ciphertext symbols.
And coming as I do from a military family, it's also a way of abbreviating
your message. Look at ships' flags, for example.
"I am carrying explosives" i.e. try not to ram me.
"I have lost control of all steering" i.e. I might ram you in turn.
"I am carrying infectious diseases" i.e. don't even think about it.
And of course, there's the "England expects" truncation.
It's crypto, in a way.
-- Dave
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