- Added a generic entropy accumulator that provides support for adding custom entropy sources and added some generic and platform dependent entropy sources

library/CMakeLists.txt

@@ -14,6 +14,8 @@ set(src
      debug.c
      des.c
      dhm.c
+     entropy.c
+     entropy_poll.c
      error.c
      havege.c
      md.c

library/Makefile

@@ -22,18 +22,18 @@ DLEXT=so
 # Windows shared library extension:
 # DLEXT=dll
 
-OBJS=	aes.o		arc4.o		asn1parse.o	\
-		base64.o	bignum.o	camellia.o	\
+OBJS=	aes.o		arc4.o		asn1parse.o		\
+		base64.o	bignum.o	camellia.o		\
 		certs.o		cipher.o	cipher_wrap.o	\
-		ctr_drbg.o	debug.o	\
-		des.o		dhm.o		havege.o	\
-		error.o \
-		md.o		md_wrap.o	md2.o		\
-		md4.o		md5.o		net.o		\
-		padlock.o	pem.o		pkcs11.o	\
-		rsa.o		sha1.o		sha2.o		\
-		sha4.o		ssl_cli.o	ssl_srv.o	\
-		ssl_tls.o	timing.o	version.o	\
+		ctr_drbg.o	debug.o		des.o			\
+		dhm.o		entropy.o	entropy_poll.o	\
+		error.o		havege.o					\
+		md.o		md_wrap.o	md2.o			\
+		md4.o		md5.o		net.o			\
+		padlock.o	pem.o		pkcs11.o		\
+		rsa.o		sha1.o		sha2.o			\
+		sha4.o		ssl_cli.o	ssl_srv.o		\
+		ssl_tls.o	timing.o	version.o		\
 		x509parse.o	xtea.o
 	
 

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

library/entropy_poll.c

@@ -0,0 +1,135 @@
+/*
+ *  Platform-specific and custom entropy polling functions
+ *
+ *  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"
+
+#if defined(POLARSSL_TIMING_C)
+#include "polarssl/timing.h"
+#endif
+#if defined(POLARSSL_HAVEGE_C)
+#include "polarssl/havege.h"
+#endif
+
+#if !defined(POLARSSL_NO_PLATFORM_ENTROPY)
+#if defined(_WIN32)
+
+#include <windows.h>
+#if !defined(_WIN32_WINNT)
+#define _WIN32_WINNT 0x0400
+#endif
+#include <wincrypt.h>
+
+int platform_entropy_poll( void *data, unsigned char *output, size_t len,
+                           size_t *olen )
+{
+    HCRYPTPROV provider;
+    *olen = 0;
+
+    if( CryptAcquireContext( &provider, NULL, NULL,
+                              PROV_RSA_FULL, CRYPT_VERIFYCONTEXT ) == FALSE )
+    {
+        return POLARSSL_ERR_ENTROPY_SOURCE_FAILED;
+    }
+
+    if( CryptGenRandom( provider, len, output ) == FALSE )
+        return POLARSSL_ERR_ENTROPY_SOURCE_FAILED;
+
+    CryptReleaseContext( provider, 0 );
+    *olen = len;
+
+    return( 0 );
+}
+#else
+
+#include <stdio.h>
+
+int platform_entropy_poll( void *data,
+                           unsigned char *output, size_t len, size_t *olen )
+{
+    FILE *file;
+    size_t ret;
+    ((void) data);
+
+    *olen = 0;
+
+    file = fopen( "/dev/urandom", "rb" );
+    if( file == NULL )
+        return POLARSSL_ERR_ENTROPY_SOURCE_FAILED;
+    
+    ret = fread( output, 1, len, file );
+    if( ret != len )
+    {
+        fclose( file );
+        return POLARSSL_ERR_ENTROPY_SOURCE_FAILED;
+    }
+
+    fclose( file );
+    *olen = len;
+
+    return( 0 );
+}
+#endif
+#endif
+
+#if defined(POLARSSL_TIMING_C)
+int hardclock_poll( void *data,
+                    unsigned char *output, size_t len, size_t *olen )
+{
+    unsigned long timer = hardclock();
+    ((void) data);
+    *olen = 0;
+
+    if( len < sizeof(unsigned long) )
+        return( 0 );
+
+    memcpy( output, &timer, sizeof(unsigned long) );
+    *olen = sizeof(unsigned long);
+
+    return( 0 );
+}
+#endif
+
+#if defined(POLARSSL_HAVEGE_C)
+int havege_poll( void *data,
+                 unsigned char *output, size_t len, size_t *olen )
+{
+    havege_state *hs = (havege_state *) data;
+    *olen = 0;
+
+    if( havege_random( hs, output, len ) != 0 )
+        return POLARSSL_ERR_ENTROPY_SOURCE_FAILED;
+
+    *olen = len;
+
+    return( 0 );
+}
+#endif
+
+#endif /* POLARSSL_ENTROPY_C */

library/error.c

@@ -59,6 +59,10 @@
 #include "polarssl/dhm.h"
 #endif
 
+#if defined(POLARSSL_ENTROPY_C)
+#include "polarssl/entropy.h"
+#endif
+
 #if defined(POLARSSL_MD_C)
 #include "polarssl/md.h"
 #endif
@@ -391,6 +395,13 @@ void error_strerror( int ret, char *buf, size_t buflen )
         snprintf( buf, buflen, "DES - The data input has an invalid length" );
 #endif /* POLARSSL_DES_C */
 
+#if defined(POLARSSL_ENTROPY_C)
+    if( use_ret == -(POLARSSL_ERR_ENTROPY_SOURCE_FAILED) )
+        snprintf( buf, buflen, "ENTROPY - Critical entropy source failure" );
+    if( use_ret == -(POLARSSL_ERR_ENTROPY_MAX_SOURCES) )
+        snprintf( buf, buflen, "ENTROPY - No more sources can be added" );
+#endif /* POLARSSL_ENTROPY_C */
+
 #if defined(POLARSSL_NET_C)
     if( use_ret == -(POLARSSL_ERR_NET_UNKNOWN_HOST) )
         snprintf( buf, buflen, "NET - Failed to get an IP address for the given hostname" );