diff options
| author |   damien <damien@openbsd.org> | 2007-07-24 19:35:20 +0000 |
|---|---|---|
| committer | damien <damien@openbsd.org> | 2007-07-24 19:35:20 +0000 |
| commit | c5823ff2899dc23bf01c945069e4bb125c7ccd19 (patch) | |
| tree | c05e796172cce0f2b9f8f6f26a4925d77652ba8c | |
| parent | reformat to 8 chars tab, zap unneeded comment (no binary change) (diff) | |
| download | wireguard-openbsd-c5823ff2899dc23bf01c945069e4bb125c7ccd19.tar.xz wireguard-openbsd-c5823ff2899dc23bf01c945069e4bb125c7ccd19.zip | |
add rc4_skip() function that can be used to discard bytes from
the arc4 key stream.
rc4_skip(ctx, len);
is equivalent to:
u_int8_t dummy[len];
rc4_crypt(ctx, dummy, dummy, len);
except that is does not require storage space and that it saves
some cpu cycles.
ok deraadt@
| -rw-r--r-- | sys/crypto/arc4.c | 12 | ||||
| -rw-r--r-- | sys/crypto/arc4.h | 3 |
2 files changed, 13 insertions, 2 deletions
diff --git a/sys/crypto/arc4.c b/sys/crypto/arc4.c index fe621dbcd9e..3bb3be4d78a 100644 --- a/sys/crypto/arc4.c +++ b/sys/crypto/arc4.c @@ -1,4 +1,4 @@ -/* $OpenBSD: arc4.c,v 1.1 2003/10/07 07:07:14 markus Exp $ */ +/* $OpenBSD: arc4.c,v 1.2 2007/07/24 19:35:20 damien Exp $ */ /* * Copyright (c) 2003 Markus Friedl <markus@openbsd.org> * @@ -57,3 +57,13 @@ rc4_crypt(struct rc4_ctx *ctx, u_char *src, u_char *dst, (ctx->state[ctx->x] + ctx->state[ctx->y]) % RC4STATE]; } } + +void +rc4_skip(struct rc4_ctx *ctx, u_int32_t len) +{ + for (; len > 0; len--) { + ctx->x = (ctx->x + 1) % RC4STATE; + ctx->y = (ctx->state[ctx->x] + ctx->y) % RC4STATE; + RC4SWAP(ctx->x, ctx->y); + } +} diff --git a/sys/crypto/arc4.h b/sys/crypto/arc4.h index 2bbf9227ceb..b4e96ea44b4 100644 --- a/sys/crypto/arc4.h +++ b/sys/crypto/arc4.h @@ -1,4 +1,4 @@ -/* $OpenBSD: arc4.h,v 1.1 2003/10/07 07:07:14 markus Exp $ */ +/* $OpenBSD: arc4.h,v 1.2 2007/07/24 19:35:20 damien Exp $ */ /* * Copyright (c) 2003 Markus Friedl <markus@openbsd.org> * @@ -25,3 +25,4 @@ struct rc4_ctx { void rc4_keysetup(struct rc4_ctx *, u_char *, u_int32_t); void rc4_crypt(struct rc4_ctx *, u_char *, u_char *, u_int32_t); +void rc4_skip(struct rc4_ctx *, u_int32_t); |