- 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/library/entropy.c b/library/entropy.c
new file mode 100644
index 0000000..0ece345
--- /dev/null
+++ b/library/entropy.c
@@ -0,0 +1,173 @@
+/*
+ * 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.
+ */
+
+#include "polarssl/config.h"
+
+#if defined(POLARSSL_ENTROPY_C)
+
+#include "polarssl/entropy.h"
+#include "polarssl/entropy_poll.h"
+
+#define ENTROPY_MAX_LOOP 256 /**< Maximum amount to loop before error */
+
+void entropy_init( entropy_context *ctx )
+{
+ memset( ctx, 0, sizeof(entropy_context) );
+
+ sha4_starts( &ctx->accumulator, 0 );
+
+#if !defined(POLARSSL_NO_PLATFORM_ENTROPY)
+ entropy_add_source( ctx, platform_entropy_poll, NULL );
+#endif
+#if defined(POLARSSL_TIMING_C)
+ entropy_add_source( ctx, hardclock_poll, NULL );
+#endif
+}
+
+int entropy_add_source( entropy_context *ctx,
+ f_source_ptr f_source, void *p_source )
+{
+ if( ctx->source_count >= ENTROPY_MAX_SOURCES )
+ return( POLARSSL_ERR_ENTROPY_MAX_SOURCES );
+
+ ctx->f_source[ctx->source_count] = f_source;
+ ctx->p_source[ctx->source_count] = p_source;
+
+ ctx->source_count++;
+
+ return( 0 );
+}
+
+/*
+ * Entropy accumulator update
+ */
+int entropy_update( entropy_context *ctx, unsigned char source_id,
+ const unsigned char *data, size_t len )
+{
+ unsigned char header[2];
+ unsigned char tmp[ENTROPY_BLOCK_SIZE];
+ size_t use_len = len;
+ const unsigned char *p = data;
+
+ if( use_len > ENTROPY_BLOCK_SIZE )
+ {
+ sha4( data, len, tmp, 0 );
+
+ p = tmp;
+ use_len = ENTROPY_BLOCK_SIZE;
+ }
+
+ header[0] = source_id;
+ header[1] = use_len & 0xFF;
+
+ sha4_update( &ctx->accumulator, header, 2 );
+ sha4_update( &ctx->accumulator, p, use_len );
+
+ ctx->size += use_len;
+
+ return( 0 );
+}
+
+int entropy_update_manual( entropy_context *ctx,
+ const unsigned char *data, size_t len )
+{
+ return entropy_update( ctx, ENTROPY_SOURCE_MANUAL, data, len );
+}
+
+/*
+ * Run through the different sources to add entropy to our accumulator
+ */
+int entropy_gather( entropy_context *ctx )
+{
+ int ret, i;
+ unsigned char buf[ENTROPY_MAX_GATHER];
+ size_t olen;
+
+ /*
+ * Run through our entropy sources
+ */
+ for( i = 0; i < ctx->source_count; i++ )
+ {
+ olen = 0;
+ if ( ( ret = ctx->f_source[i]( ctx->p_source[i],
+ buf, ENTROPY_MAX_GATHER, &olen ) ) != 0 )
+ {
+ return( ret );
+ }
+
+ /*
+ * Add if we actually gathered something
+ */
+ if( olen > 0 )
+ entropy_update( ctx, (unsigned char) i, buf, olen );
+ }
+
+ return( 0 );
+}
+
+int entropy_func( void *data, unsigned char *output, size_t len )
+{
+ int ret, count = 0;
+ entropy_context *ctx = (entropy_context *) data;
+ unsigned char buf[ENTROPY_BLOCK_SIZE];
+
+ if( len > ENTROPY_BLOCK_SIZE )
+ return( POLARSSL_ERR_ENTROPY_SOURCE_FAILED );
+
+ /*
+ * Always gather extra entropy before a call
+ */
+ do
+ {
+ if( count++ > ENTROPY_MAX_LOOP )
+ return( POLARSSL_ERR_ENTROPY_SOURCE_FAILED );
+
+ if( ( ret = entropy_gather( ctx ) ) != 0 )
+ return( ret );
+ }
+ while( ctx->size < ENTROPY_MIN_POOL );
+
+ memset( buf, 0, ENTROPY_BLOCK_SIZE );
+
+ sha4_finish( &ctx->accumulator, buf );
+
+ /*
+ * Perform second SHA-512 on entropy
+ */
+ sha4( buf, ENTROPY_BLOCK_SIZE, buf, 0 );
+
+ /*
+ * Reset accumulator
+ */
+ memset( &ctx->accumulator, 0, sizeof( sha4_context ) );
+ sha4_starts( &ctx->accumulator, 0 );
+ ctx->size = 0;
+
+ memcpy( output, buf, len );
+
+ return( 0 );
+}
+
+#endif