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Discard first 256 bytes of keystream, as per recommendation in

"Weaknesses in the Key Scheduling Algorithm of RC4", Fluhrer, Mantin and
Shamir. ok itojun@
OPENBSD_3_5
djm 21 years ago
parent
commit
826f436391
1 changed files with 10 additions and 1 deletions
  1. +10
    -1
      src/lib/libc/crypt/arc4random.c

+ 10
- 1
src/lib/libc/crypt/arc4random.c View File

@ -1,4 +1,4 @@
/* $OpenBSD: arc4random.c,v 1.9 2003/08/16 19:07:40 tedu Exp $ */
/* $OpenBSD: arc4random.c,v 1.10 2003/11/26 21:40:08 djm Exp $ */
/*
* Arc4 random number generator for OpenBSD.
@ -48,6 +48,8 @@ static int rs_initialized;
static struct arc4_stream rs;
static pid_t arc4_stir_pid;
static inline u_int8_t arc4_getbyte(struct arc4_stream *);
static inline void
arc4_init(struct arc4_stream *as)
{
@ -98,6 +100,13 @@ arc4_stir(struct arc4_stream *as)
arc4_stir_pid = getpid();
arc4_addrandom(as, (void *) &rdat, sizeof(rdat));
/*
* Discard early keystream, as per recommendations in:
* http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
*/
for (i = 0; i < 256; i++)
(void) arc4_getbyte(as);
}
static inline u_int8_t


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