Wrapper functions added to generate non-zero random bytes

2 files changed, 68 insertions, 0 deletions

diff --git a/src/libstrongswan/crypto/rngs/rng.c b/src/libstrongswan/crypto/rngs/rng.c
index 67fd76910..f8fd50d3f 100644
--- a/src/libstrongswan/crypto/rngs/rng.c
+++ b/src/libstrongswan/crypto/rngs/rng.c
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2012 Tobias Brunner
  * Copyright (C) 2008 Martin Willi
  * Hochschule fuer Technik Rapperswil
  *
@@ -20,3 +21,43 @@ ENUM(rng_quality_names, RNG_WEAK, RNG_TRUE,
 	"RNG_STRONG",
 	"RNG_TRUE",
 );
+
+/*
+ * Described in header.
+ */
+bool rng_get_bytes_not_zero(rng_t *rng, size_t len, u_int8_t *buffer, bool all)
+{
+	u_int8_t *pos = buffer, *check = buffer + (all ? len : min(1, len));
+
+	if (!rng->get_bytes(rng, len, pos))
+	{
+		return FALSE;
+	}
+
+	for (; pos < check; pos++)
+	{
+		while (*pos == 0)
+		{
+			if (!rng->get_bytes(rng, 1, pos))
+			{
+				return FALSE;
+			}
+		}
+	}
+	return TRUE;
+}
+
+/*
+ * Described in header.
+ */
+bool rng_allocate_bytes_not_zero(rng_t *rng, size_t len, chunk_t *chunk,
+								 bool all)
+{
+	*chunk = chunk_alloc(len);
+	if (!rng_get_bytes_not_zero(rng, len, chunk->ptr, all))
+	{
+		chunk_clear(chunk);
+		return FALSE;
+	}
+	return TRUE;
+}
diff --git a/src/libstrongswan/crypto/rngs/rng.h b/src/libstrongswan/crypto/rngs/rng.h
index 48ca52dd8..c72509b54 100644
--- a/src/libstrongswan/crypto/rngs/rng.h
+++ b/src/libstrongswan/crypto/rngs/rng.h
@@ -75,4 +75,31 @@ struct rng_t {
 	void (*destroy) (rng_t *this);
 };
 
+/**
+ * Wrapper around rng_t.get_bytes() ensuring that either all bytes or at least
+ * the first byte is not zero.
+ *
+ * @param rng			rng_t object
+ * @param len			number of bytes to get
+ * @param buffer		pointer where the generated bytes will be written
+ * @param all			TRUE if all bytes have to be non-zero
+ * @return				TRUE if bytes successfully written
+ */
+bool rng_get_bytes_not_zero(rng_t *rng, size_t len, u_int8_t *buffer, bool all);
+
+/**
+ * Wrapper around rng_t.allocate_bytes() ensuring that either all bytes or at
+ * least the first byte is not zero.
+ *
+ * @param rng			rng_t object
+ * @param len			number of bytes to get
+ * @param buffer		pointer where the generated bytes will be written
+ * @param all			TRUE if all bytes have to be non-zero
+ * @return				TRUE if bytes successfully written
+ */
+bool rng_allocate_bytes_not_zero(rng_t *rng, size_t len, chunk_t *chunk,
+								 bool all);
+
+
+
 #endif /** RNG_H_ @}*/