- Added a generic entropy accumulator that provides support for adding custom entropy sources and added some generic and platform dependent entropy sources
diff --git a/include/polarssl/entropy.h b/include/polarssl/entropy.h
new file mode 100644
index 0000000..46df929
--- /dev/null
+++ b/include/polarssl/entropy.h
@@ -0,0 +1,129 @@
+/**
+ * \file entropy.h
+ *
+ * \brief Entropy accumulator implementation
+ *
+ * Copyright (C) 2006-2011, Brainspark B.V.
+ *
+ * This file is part of PolarSSL (http://www.polarssl.org)
+ * Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
+ *
+ * All rights reserved.
+ *
+ * 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
+ * (at your option) 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#ifndef POLARSSL_ENTROPY_H
+#define POLARSSL_ENTROPY_H
+
+#include <string.h>
+
+#include "sha4.h"
+
+#define POLARSSL_ERR_ENTROPY_SOURCE_FAILED -0x003A /**< Critical entropy source failure. */
+#define POLARSSL_ERR_ENTROPY_MAX_SOURCES -0x003C /**< No more sources can be added. */
+
+#define ENTROPY_MIN_POOL 128 /**< Minimum amount of pool entropy needed for release */
+#define ENTROPY_MAX_SOURCES 20 /**< Maximum number of sources supported */
+#define ENTROPY_MAX_GATHER 128 /**< Maximum amount requested from entropy sources */
+#define ENTROPY_BLOCK_SIZE 64 /**< Block size of entropy accumulator (SHA-512) */
+
+#define ENTROPY_SOURCE_MANUAL ENTROPY_MAX_SOURCES
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief Entropy poll callback pointer
+ *
+ * \param data Callback-specific data pointer
+ * \param output Data to fill
+ * \param len Maximum size to provide
+ * \param olen The actual amount of bytes put into the buffer (Can be 0)
+ *
+ * \return 0 if no critical failures occurred,
+ * POLARSSL_ERR_ENTROPY_SOURCE_FAILED otherwise
+ */
+typedef int (*f_source_ptr)(void *, unsigned char *, size_t, size_t *);
+
+/**
+ * \brief Entropy context structure
+ */
+typedef struct
+{
+ sha4_context accumulator;
+ size_t size;
+ int source_count;
+ f_source_ptr f_source[ENTROPY_MAX_SOURCES];
+ void * p_source[ENTROPY_MAX_SOURCES];
+}
+entropy_context;
+
+/**
+ * \brief Initialize the context
+ *
+ * \param ctx Entropy context to initialize
+ */
+void entropy_init( entropy_context *ctx );
+
+/**
+ * \brief Adds an entropy source to poll
+ *
+ * \param ctx Entropy context
+ * \param f_source Entropy function
+ * \param p_source Function data
+ *
+ * \return 0 is successful or POLARSSL_ERR_ENTROPY_MAX_SOURCES
+ */
+int entropy_add_source( entropy_context *ctx,
+ f_source_ptr f_source, void *p_source );
+
+/**
+ * \brief Trigger an extra gather poll for the accumulator
+ *
+ * \param ctx Entropy context
+ *
+ * \return 0 if successful, or POLARSSL_ERR_ENTROPY_SOURCE_FAILED
+ */
+int entropy_gather( entropy_context *ctx );
+
+/**
+ * \brief Retrieve entropy from the accumulator (Max ENTROPY_BLOCK_SIZE)
+ *
+ * \param data Entropy context
+ * \param output Buffer to fill
+ * \param len Length of buffer
+ *
+ * \return 0 if successful, or POLARSSL_ERR_ENTROPY_SOURCE_FAILED
+ */
+int entropy_func( void *data, unsigned char *output, size_t len );
+
+/**
+ * \brief Add data to the accumulator manually
+ *
+ * \param ctx Entropy context
+ * \param data Data to add
+ * \param len Length of data
+ *
+ * \return 0 if successful
+ */
+int entropy_update_manual( entropy_context *ctx,
+ const unsigned char *data, size_t len );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* entropy.h */