diff --git a/arcfour.c b/arcfour.c index 100f9cc01447f88638e91cd61d6adee172da8783..1c0e717e120f19c20af25de02d0bb17316717a00 100644 --- a/arcfour.c +++ b/arcfour.c @@ -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; diff --git a/include/arcfour.h b/include/arcfour.h index 8287cc3a5bd4b0e39d6c15a36ac0abb5477d419c..300987b3fcf26b628aade286589824d5e37263f3 100644 --- a/include/arcfour.h +++ b/include/arcfour.h @@ -16,8 +16,17 @@ struct arcfour_ctx { void arcfour_init(struct arcfour_ctx *ctx); #endif -void arcfour_set_key(struct arcfour_ctx *ctx, const UINT8 *key, UINT32 len); +/* Encryption functions */ +void arcfour_set_key(struct arcfour_ctx *ctx, UINT32 length, const UINT8 *key); void arcfour_crypt(struct arcfour_ctx *ctx, UINT8 *dest, - const UINT8 *src, UINT32 len); + UINT32 length, const UINT8 *src); + +/* Using arcfour as a randomness generator. */ +void arcfour_init(struct arcfour_ctx *ctx); +void arcfour_update_key(struct arcfour_ctx *ctx, + UINT32 length, const UINT8 *key); +void arcfour_stream(struct arcfour_ctx *ctx, + UINT32 length, UINT8 *dest); + #endif /* ARCFOUR_H_INCLUDED */