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rc4 implementation in ACME_Lib seems to work

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git-svn-id: https://svn.code.sf.net/p/acme-crossass/code-0/trunk@313 4df02467-bbd4-4a76-a152-e7ce94205b78
This commit is contained in:
marcobaye 2020-12-27 00:23:13 +00:00
parent 98e8ae453a
commit b09b484a90
1 changed files with 10 additions and 8 deletions
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18
ACME_Lib/6502/rc4.a
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@ -1,22 +1,22 @@
;ACME 0.97
; this is an implementation of the stream cipher algorithm known as RC4.
; UNFINISHED - DO NOT USE!
; you need to define these symbols in your code:
; rc4_length a single byte to hold key/chunk lengths
; rc4_count a single byte (iteration counter)
; rc4_count a single byte (tmp var for iteration counter)
; rc4_ii a single byte to hold state
; rc4_jj a single byte to hold state
; rc4_state a full page of memory (256 bytes)
; rc4_key key buffer
; rc4_in input buffer
; rc4_out output buffer
; the size of the buffers limits how much data you can pass to the functions.
; the two buffer addresses may be identical, in that case the output will
; overwrite the input.
; all three buffer addresses may be identical, in that case the output will
; overwrite the input (and/or the key).
; functions you can then call:
; rc4_init initialise state
; rc4_key_X use key (in input buffer, length in X) to change state
; rc4_usekey_X use key (in key buffer, length in X) to change state
; rc4_reset reset ii and jj (call between keying and processing)
; rc4_process_X de/encrypt a chunk of data buffer-to-buffer (length in X)
@ -27,6 +27,7 @@
.ii = rc4_ii
.jj = rc4_jj
.state = rc4_state
.keybuf = rc4_key
.inbuf = rc4_in
.outbuf = rc4_out
@ -44,8 +45,9 @@ rc4_reset ldx #0
stx .jj
rts
; use key (in input buffer, length in X) to change permutation in state array
rc4_key_X
; use key (in key buffer, length in X) to change permutation in state array
; X==0 means 256!
rc4_usekey_X
; X holds .ii (but we count from 0 to 255 and so do not use the real .ii at all)
; Y holds .jj or .count (.jj is then in A)
stx .length
@ -61,7 +63,7 @@ rc4_key_X
adc .state, x
ldy .count
clc
adc .inbuf, y
adc .keybuf, y
;sta .jj
;if (++count == length)
; count = 0;