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List Info
Thread: rc4 for m_utils?
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| rc4 for m_utils? |
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2007-06-12 22:26:01 |
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Hi All,
just knocked this up (and tested) - i was looking through the code for the gaim myspace plugin and noticed that it uses RC4 during authentication - thought it might be a candidate for inclusion in the utils module? i followed the format used there for MD5 and SHA1 as closely as i could
(note: called 'ARC4' for 'Alleged RC4' since apparently actual RC4 was never publically released - not sure it makes any difference anymore)
typedef struct {
char lookup[256];
int x, y;
} mir_arc4_ctx;
struct ARC4_INTERFACE {
int cbSize;
void (*arc4_init)(mir_arc4_ctx *ctx, char *key, int keylen);
void (*arc4_crypt)(mir_arc4_ctx *ctx, char *dataIn, char *dataOut, int datalen);
};
void swap(char *b1, char *b2) {
char b = *b1;
;*b1 = *b2;
;*b2 = b;
}
void arc4_init(mir_arc4_ctx *ctx, char *key, int keylen) {
int i;
for(i = 0; i < 256; i++)
; ctx->lookup[i] = i;
ctx->x = 0;
for(i = 0; i < 256; i++) {
; ctx->x = (key[i % keylen] + ctx->lookup[i] + ctx->x) & 0xFF;
swap(&ctx->lookup[ctx->;x], &ctx->lookup[i]);
; }
ctx->x = 0;
ctx->y = 0;
}
void arc4_crypt(mir_arc4_ctx *ctx, char *dataIn, char *dataOut, int datalen) {
for(int i = 0; i < datalen; i++) {
ctx->x = (ctx->x + 1) & 0xFF;
ctx->y = (ctx->lookup[ctx->x] + ctx->y) & 0xFF;
swap(&ctx->lookup[ctx->;x], &ctx->lookup[ctx->y]);
dataOut[i] = (dataIn[i] ^ ctx->lookup[(ctx->lookup[ctx->x] + ctx->lookup[ctx->y]) & 0xFF]);
; }
}
int GetARC4Interface(WPARAM wParam, LPARAM lParam) {
struct ARC4_INTERFACE *arc4i = (struct ARC4_INTERFACE*) lParam;
if ( arc4i == NULL )
return 1;
if ( arc4i->cbSize != sizeof( struct ARC4_INTERFACE ))
; return 1;
arc4i->arc4_init = arc4_init;
arc4i->arc4_crypt = arc4_crypt;
return 0;
}
Scott
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