It's simply not necessary.
Signed-off-by: George Spelvin <linux@xxxxxxxxxxx>
---
crypto/ansi_cprng.c | 28 +++++++++++-----------------
1 file changed, 11 insertions(+), 17 deletions(-)
diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index c9e1684b..c0a27288 100644
--- a/crypto/ansi_cprng.c
+++ b/crypto/ansi_cprng.c
@@ -46,7 +46,6 @@
struct prng_context {
spinlock_t prng_lock;
unsigned char rand_data[DEFAULT_BLK_SZ];
- unsigned char last_rand_data[DEFAULT_BLK_SZ];
unsigned char DT[DEFAULT_BLK_SZ];
unsigned char I[DEFAULT_BLK_SZ];
unsigned char V[DEFAULT_BLK_SZ];
@@ -89,8 +88,6 @@ static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test)
{
int i;
unsigned char tmp[DEFAULT_BLK_SZ];
- unsigned char *output = NULL;
-
dbgprint(KERN_CRIT "Calling _get_more_prng_bytes for context %p\n",
ctx);
@@ -103,6 +100,7 @@ static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test)
* This algorithm is a 3 stage state machine
*/
for (i = 0; i < 3; i++) {
+ unsigned char *output;
switch (i) {
case 0:
@@ -115,23 +113,23 @@ static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test)
hexdump("tmp stage 0: ", tmp, DEFAULT_BLK_SZ);
break;
case 1:
-
/*
- * Next xor I with our secret vector V
- * encrypt that result to obtain our
- * pseudo random data which we output
+ * Next xor I with our secret vector V.
+ * Encrypt that result to obtain our pseudo random
+ * data which we output. It is kept temporarily
+ * in (no longer used) V until we have done the
+ * anti-repetition compare.
*/
xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ);
hexdump("tmp stage 1: ", tmp, DEFAULT_BLK_SZ);
- output = ctx->rand_data;
+ output = ctx->V;
break;
case 2:
/*
* First check that we didn't produce the same
- * random data that we did last time around through this
+ * random data that we did last time around.
*/
- if (!memcmp(ctx->rand_data, ctx->last_rand_data,
- DEFAULT_BLK_SZ)) {
+ if (!memcmp(ctx->V, ctx->rand_data, DEFAULT_BLK_SZ)) {
if (cont_test) {
panic("cprng %p Failed repetition check!\n",
ctx);
@@ -144,15 +142,13 @@ static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test)
ctx->flags |= PRNG_NEED_RESET;
return -EINVAL;
}
- memcpy(ctx->last_rand_data, ctx->rand_data,
- DEFAULT_BLK_SZ);
+ memcpy(ctx->rand_data, ctx->V, DEFAULT_BLK_SZ);
/*
* Lastly xor the random data with I
* and encrypt that to obtain a new secret vector V
*/
- xor_vectors(ctx->rand_data, ctx->I, tmp,
- DEFAULT_BLK_SZ);
+ xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ);
output = ctx->V;
hexdump("tmp stage 2: ", tmp, DEFAULT_BLK_SZ);
break;
@@ -161,7 +157,6 @@ static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test)
/* do the encryption */
crypto_cipher_encrypt_one(ctx->tfm, output, tmp);
-
}
/*
@@ -299,7 +294,6 @@ static int reset_prng_context(struct prng_context *ctx,
memset(ctx->DT, 0, DEFAULT_BLK_SZ);
memset(ctx->rand_data, 0, DEFAULT_BLK_SZ);
- memset(ctx->last_rand_data, 0, DEFAULT_BLK_SZ);
ctx->rand_read_pos = DEFAULT_BLK_SZ; /* Force immediate refill */
--
2.1.3
--
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