From 34abb9209e4781f9c273284b1d81c5279163e93c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niels=20M=C3=B6ller?= <nisse@lysator.liu.se>
Date: Mon, 8 Oct 2001 22:36:10 +0200
Subject: [PATCH] * yarrow256.c (yarrow_fast_reseed): New function.
(yarrow_slow_reseed): New function. (yarrow256_update): Check seed/reseed
thresholds. (yarrow_gate): New function, extracted from
yarrow_generate_block_with_gate which was deleted.
(yarrow_generate_block_with_gate): Deleted function. (yarrow256_random):
Don't buffer any output, instead gate after each request.
Rev: src/nettle/yarrow256.c:1.4
---
yarrow256.c | 60 +++++++++++------------------------------------------
1 file changed, 12 insertions(+), 48 deletions(-)
diff --git a/yarrow256.c b/yarrow256.c
index de924c35..3be5b29a 100644
--- a/yarrow256.c
+++ b/yarrow256.c
@@ -61,9 +61,6 @@ yarrow256_init(struct yarrow256_ctx *ctx,
ctx->seeded = 0;
- /* Means that we have no buffered output */
- ctx->index = sizeof(ctx->buffer);
-
ctx->nsources = n;
ctx->sources = s;
}
@@ -144,9 +141,6 @@ yarrow256_update(struct yarrow256_ctx *ctx,
sha256_update(&ctx->pools[current], length, data);
- /* FIXME: Use different counters for fast and slow poll? Or a total
- * for fast poll, and individual for slow poll? */
-
/* NOTE: We should be careful to avoid overflows in the estimates. */
if (source->estimate[current] < YARROW_MAX_ENTROPY)
{
@@ -215,30 +209,16 @@ yarrow_generate_block(struct yarrow256_ctx *ctx,
}
}
-/* FIXME: According to Niels Ferguson, it's better to gate after each
- * request for random data. */
static void
-yarrow_generate_block_with_gate(struct yarrow256_ctx *ctx,
- uint8_t *block)
+yarrow_gate(struct yarrow256_ctx *ctx)
{
- if (ctx->block_count < YARROW_GATE_THRESHOLD)
- {
- yarrow_generate_block(ctx, block);
- ctx->block_count++;
- }
- else
- {
- uint8_t key[AES_MAX_KEY_SIZE];
- unsigned i;
-
- for (i = 0; i < sizeof(key); i+= AES_BLOCK_SIZE)
- yarrow_generate_block(ctx, key + i);
+ uint8_t key[AES_MAX_KEY_SIZE];
+ unsigned i;
- aes_set_key(&ctx->key, sizeof(key), key);
+ for (i = 0; i < sizeof(key); i+= AES_BLOCK_SIZE)
+ yarrow_generate_block(ctx, key + i);
- yarrow_generate_block(ctx, block);
- ctx->block_count = 1;
- }
+ aes_set_key(&ctx->key, sizeof(key), key);
}
void
@@ -246,35 +226,19 @@ yarrow256_random(struct yarrow256_ctx *ctx, unsigned length, uint8_t *dst)
{
assert(ctx->seeded);
- if (ctx->index < AES_BLOCK_SIZE)
- {
- unsigned left = AES_BLOCK_SIZE - ctx->index;
-
- if (length <= left)
- {
- memcpy(dst, ctx->buffer + ctx->index, length);
- ctx->index += length;
- return;
- }
-
- memcpy(dst, ctx->buffer + ctx->index, left);
- dst += left;
- length -= left;
-
- assert(length);
- }
-
while (length > AES_BLOCK_SIZE)
{
- yarrow_generate_block_with_gate(ctx, dst);
+ yarrow_generate_block(ctx, dst);
dst += AES_BLOCK_SIZE;
length -= AES_BLOCK_SIZE;
}
if (length)
{
+ uint8_t buffer[AES_BLOCK_SIZE];
+
assert(length < AES_BLOCK_SIZE);
- yarrow_generate_block_with_gate(ctx, ctx->buffer);
- memcpy(dst, ctx->buffer, length);
- ctx->index = length;
+ yarrow_generate_block(ctx, buffer);
+ memcpy(dst, buffer, length);
}
+ yarrow_gate(ctx);
}
--
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