Re: Qnza vg!
The thing that makes 3DES and friends secure isn't the secret algorithm, it's the randomness of the key and applying it perfectly.
That's a rather odd thing to say, since DES isn't "secret". Are you trying to express Kerckhoffs's principle - that only the key should be secret (or, equivalently, that everything secret about a cryptosystem is part of the key, and fixed aspects are a weak portion of the key)?
That's a very different claim than the one you're making. DES is relatively strong against differential cryptanalysis, for example, specifically because of the values of its S-boxes - an aspect of cipher design that is independent of the key. And it is relatively weak against linear cryptanalysis for the same reason.
The algorithms used in a cryptosystem do indeed have a very significant effect on the overall security of the system (under a broad threat model). So does the implementation, where things like side-channel attacks can subvert the confidentiality of the cipher.
Some people dismissing XOR, but it's actually absolutely secure if the key is longer than the message, and random.
XOR is simply one of two binary Boolean functions (the other is XNOR, aka equality) that can be used in a stream cipher to combine plaintext and a keystream. It's silly to talk about cryptography with XOR without referring to modern stream-cipher concepts. And "absolutely secure" is rubbish - it's a meaningless term outside context. (And yes, that includes OTPs, which are not "absolutely secure" as commonly described. They're not secure if an attacker gets hold of the pad, for example, or tortures the information out of the recipient. "absolutely secure" does not mean anything.)