diff options
Diffstat (limited to 'arcfour.c')
-rw-r--r-- | arcfour.c | 53 |
1 files changed, 49 insertions, 4 deletions
@@ -34,7 +34,52 @@ RCSID("$Id$"); #define SWAP(a,b) do { int _t = a; a = b; b = _t; } while(0) -void arcfour_set_key(struct arcfour_ctx *ctx, const UINT8 *key, UINT32 len) +void arcfour_init(struct arcfour_ctx *ctx) +{ + unsigned i; + + /* Initialize context */ + + for (i = 0; i<256; i++) + ctx->S[i] = i; +} + +void arcfour_update_key(struct arcfour_ctx *ctx, + UINT32 length, const UINT8 *key) +{ + register UINT8 i = ctx->i; + register UINT8 j = ctx->j; + + unsigned k; + + for (k = 0; k<length; k++) + { + i++; i &= 0xff; + j += ctx->S[i] + key[k]; j &= 0xff; + SWAP(ctx->S[i], ctx->S[j]); + } + ctx->i = i; ctx->j = j; +} + +void arcfour_stream(struct arcfour_ctx *ctx, + UINT32 length, UINT8 *dest) +{ + register UINT8 i = ctx->i; + register UINT8 j = ctx->j; + unsigned k; + + for (k = 0; k<length; k++) + { + i++; i &= 0xff; + j += ctx->S[i]; j &= 0xff; + SWAP(ctx->S[i], ctx->S[j]); + dest[k] = ctx->S[ (ctx->S[i] + ctx->S[j]) & 0xff ]; + } + + ctx->i = i; ctx->j = j; +} + +void arcfour_set_key(struct arcfour_ctx *ctx, UINT32 length, const UINT8 *key) { register UINT8 j; /* Depends on the eight-bitness of these variables. */ unsigned i; @@ -49,19 +94,19 @@ void arcfour_set_key(struct arcfour_ctx *ctx, const UINT8 *key, UINT32 len) do { j += ctx->S[i] + key[k]; SWAP(ctx->S[i], ctx->S[j]); - k = (k+1) % len; /* Repeat key if needed */ + k = (k+1) % length; /* Repeat key if needed */ } while(++i < 256); ctx->i = ctx->j = 0; } void arcfour_crypt(struct arcfour_ctx *ctx, UINT8 *dest, - const UINT8 *src, UINT32 len) + UINT32 length, const UINT8 *src) { register UINT8 i, j; i = ctx->i; j = ctx->j; - while(len--) + while(length--) { i++; i &= 0xff; j += ctx->S[i]; j &= 0xff; |