X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=bertos%2Fsec%2Fprng%2Fx917.c;h=d2c84f71f1a4ae8d0a5e0b2aab0208e7852188cc;hb=ae3571e0d7273f8642468c6a0958c29c05dc7b2a;hp=2ffba3aa8614334f131cd7f4dca1b8f3015183ca;hpb=075bcf453371e1b3f7b6ca72b4080eefbe1be3f7;p=bertos.git

diff --git a/bertos/sec/prng/x917.c b/bertos/sec/prng/x917.c
index 2ffba3aa..d2c84f71 100644
--- a/bertos/sec/prng/x917.c
+++ b/bertos/sec/prng/x917.c
@@ -103,17 +103,24 @@ static void x917_reseed(PRNG *ctx_, const uint8_t *seed)
 	//     of the seed, and use the result as new seed.
 	//   * Generate and throw away a block to update the state.
 	X917Context *ctx = (X917Context *)ctx_;
+	const size_t klen = sizeof(ctx->key);
+	const size_t blen = sizeof(ctx->state);
 
-	size_t klen = sizeof(ctx->key);
-	size_t blen = sizeof(ctx->state);
-
-	uint8_t buf[klen];
-	x917_generate(ctx_, buf, klen);
+	if (!ctx->rng.seeded)
+	{
+		memcpy(ctx->key, seed, klen);
+		memcpy(ctx->state, seed+klen, blen);
+	}
+	else
+	{
+		uint8_t buf[klen];
+		x917_generate(ctx_, buf, klen);
 
-	xor_block(ctx->key, buf, seed, klen);
-	xor_block(ctx->state, ctx->state, seed+klen, blen);
+		xor_block(ctx->key, buf, seed, klen);
+		xor_block(ctx->state, ctx->state, seed+klen, blen);
 
-	PURGE(buf);
+		PURGE(buf);
+	}
 }
 
 /*********************************************************************/
@@ -123,4 +130,5 @@ void x917_init(X917Context *ctx)
 	ctx->rng.reseed = x917_reseed;
 	ctx->rng.generate = x917_generate;
 	ctx->rng.seed_len = sizeof(ctx->key) + sizeof(ctx->state);
+	ctx->rng.seeded = 0;
 }