[rng] Add dummy entropy source

Cryptographic random number generation requires an entropy source,
which is used as the input to a Deterministic Random Bit Generator
(DRBG).

iPXE does not currently have a suitable entropy source.  Provide a
dummy source to allow the DRBG code to be implemented.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 48 insertions, 0 deletions

diff --git a/src/crypto/entropy.c b/src/crypto/entropy.c
new file mode 100644
index 000000000..86fa89783
--- /dev/null
+++ b/src/crypto/entropy.c
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** @file
+ *
+ * Entropy source
+ *
+ */
+
+#include <string.h>
+#include <ipxe/entropy.h>
+
+/**
+ * Obtain entropy input
+ *
+ * @v entropy_bits	Minimum amount of entropy, in bits
+ * @v data		Data buffer
+ * @v min_len		Minimum length of entropy input, in bytes
+ * @v max_len		Maximum length of entropy input, in bytes
+ * @ret len		Length of entropy input, in bytes
+ */
+int get_entropy_input ( unsigned int entropy_bits, void *data, size_t min_len,
+			size_t max_len ) {
+
+	/* Placeholder to allow remainder of RBG code to be tested */
+	( void ) entropy_bits;
+	( void ) min_len;
+	memset ( data, 0x01, max_len );
+
+	return max_len;
+}