stevefan1999 9 hours ago

> In my 6502 hacking days, the presence of an exclusive OR was a sure-fire indicator you’d either found the encryption part of the code, or some kind of sprite routine.

Correct. Most ciphers of that era should be Feistel cipher in the likes of DES/3DES, or even RC4 uses XOR too. Later AES/Rijndael, CRC and ECC (Elliptic Curve Cryptography) also make heavy use of XOR but in finite field terms which is based on modular arithmetic over GF(2), that effectively reduces to XOR (while in theory should be mod 2).

▲

OhMeadhbh 8 hours ago | parent | next [-]

I was going to say "but RC4 and AES were published well after the 6502's heyday," but NESes were completely rocking it in '87 (and I'm told 65XX cores were used as the basis for several hard drive controllers of the era.) Alas, the closest I ever came to encryption on a (less than 32-bit system) was lucifer on an IBM channel controller in the forever-ago and debugging RC5 on an 8085.

▲

kjs3 7 hours ago | parent [-]

I'm told 65XX cores were used as the basis for several hard drive controllers of the era

Western Design Center is still (apparently) making a profit at least in part licensing 6502 core IP for embedded stuff. There's probably a 6502 buried and unrecognized in all sorts of low-cost control applications laying around you.

RC5 on an 8085

Oof. Well played.

▲

PaulHoule 6 hours ago | parent [-]

I dunno. The 6502 has been a $2 part for a long time but needs RAM and some glue logic, for a similar price you can get an AVR-8 [1] or ESP-32 [2] and get some RAM and GPIO.

[1] faster, more registers than the IBM 360, << 64k RAM

[2] much faster, 32bit, >> 64k RAM

	▲	rzzzt 6 hours ago \| parent \| next [-]
		There are uC versions like the W65C134S: https://www.westerndesigncenter.com/wdc/w65c134s-chip.php
	▲	kjs3 5 hours ago \| parent \| prev [-]
		I dunno. You don't know what, exactly? You can go to the web site and see what they are selling. The 6502 has been a $2 part for a long time I doubt that for an IP license at any volume such a thing would make sense. but needs RAM and some glue logic Sure? Embedded in whatever you're building. for a similar price you can get... Oh, sorry...my bad. You were doing it the HN way: "Don't actually read what was written for comprehension...just take your first knee jerk and tell them how you would obviously do it better.".

▲

ASalazarMX 6 hours ago | parent | prev [-]

Reading cryptography was that advanced at that time, I'm even more surprised that the venerable Norton Utilities for MS-DOS required a password, that was simply XORed with some constant and embedded in the executables. If the reserved space was zeroes, it considered it a fresh install and demanded a new password.

If it had been properly encrypted my young cracker self would have had no opportunity.