Traditionally, encode meant to use one word/symbol to represent another, while encipher meant to transform one (usually mathematically) into another.
For example, "Tora, Tora, Tora" was a code that had no intrinsic meaning, but was the signal to proceed with the Pearl Harbor attack. No way to reverse that.
Meanwhile, "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG" can be transformed with a Caesar cipher to "QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD". It can easily be reversed.
Funny but also thought-provoking! When did the verb "encipher" give way to "encrypt," and why? I might enjoy reading a well-researched piece on that subject.
So basically encipher was never used in the context of the web. And the web is what made encrypt popular separate from encipher. It does look like maybe encipher was possibly going to take off but encrypt stepped on its head.
Interestingly, the basis of web encryption does use the term "encipherment" -- the `KeyUsage` field of X.509 certificates has `keyEncipherment` and `dataEncipherment` flags.
An interesting data point is that Kahn's The codebreakers, from 1967, uses "encipher" everywhere except for various US goverment agency quotes, which use "encrypt."
I remember reading in Bruce Schneier's Applied Cryptography that in some cultures "encrypt" refers to the process of entombing bodies for burial and that "encipher" did not have that baggage.
Similar connotation to "decrypt" which would be exhumation.
For example in Spanish, there's been always a fight between using "cifrar" instead of "encriptar". I like "cifrar" a bit more, but it's true that we've always had the prefix "cripto-" for hidden or mysterious things. Anyway, the difference is "cifra" is the Latin root for "digit", and "kryptos" is the Greek root for "hidden".
