Entropy collector and CTR-DRBG now also work on SHA-256 if SHA-512 not available
diff --git a/include/polarssl/config.h b/include/polarssl/config.h
index 84b36b6..5aee165 100644
--- a/include/polarssl/config.h
+++ b/include/polarssl/config.h
@@ -1326,7 +1326,7 @@
// CTR_DRBG options
//
-#define CTR_DRBG_ENTROPY_LEN 48 /**< Amount of entropy used per seed by default */
+#define CTR_DRBG_ENTROPY_LEN 48 /**< Amount of entropy used per seed by default (48 with SHA-512, 32 with SHA-256) */
#define CTR_DRBG_RESEED_INTERVAL 10000 /**< Interval before reseed is performed by default */
#define CTR_DRBG_MAX_INPUT 256 /**< Maximum number of additional input bytes */
#define CTR_DRBG_MAX_REQUEST 1024 /**< Maximum number of requested bytes per call */
@@ -1382,9 +1382,18 @@
#error "POLARSSL_ECP_C defined, but not all prerequisites"
#endif
-#if defined(POLARSSL_ENTROPY_C) && !defined(POLARSSL_SHA512_C)
+#if defined(POLARSSL_ENTROPY_C) && (!defined(POLARSSL_SHA512_C) && \
+ !defined(POLARSSL_SHA256_C))
#error "POLARSSL_ENTROPY_C defined, but not all prerequisites"
#endif
+#if defined(POLARSSL_ENTROPY_C) && defined(POLARSSL_SHA512_C) && \
+ defined(POLARSSL_CONFIG_OPTIONS) && (CTR_DRBG_ENTROPY_LEN > 64)
+#error "CTR_DRBG_ENTROPY_LEN value too high"
+#endif
+#if defined(POLARSSL_ENTROPY_C) && !defined(POLARSSL_SHA512_C) && \
+ defined(POLARSSL_CONFIG_OPTIONS) && (CTR_DRBG_ENTROPY_LEN > 32)
+#error "CTR_DRBG_ENTROPY_LEN value too high"
+#endif
#if defined(POLARSSL_GCM_C) && !defined(POLARSSL_AES_C)
#error "POLARSSL_GCM_C defined, but not all prerequisites"
diff --git a/include/polarssl/ctr_drbg.h b/include/polarssl/ctr_drbg.h
index b47d389..4c0fc17 100644
--- a/include/polarssl/ctr_drbg.h
+++ b/include/polarssl/ctr_drbg.h
@@ -43,7 +43,11 @@
/**< The seed length (counter + AES key) */
#if !defined(POLARSSL_CONFIG_OPTIONS)
-#define CTR_DRBG_ENTROPY_LEN 48 /**< Amount of entropy used per seed by default */
+#if defined(POLARSSL_SHA512_C)
+#define CTR_DRBG_ENTROPY_LEN 48 /**< Amount of entropy used per seed by default (48 with SHA-512, 32 with SHA-256) */
+#else
+#define CTR_DRBG_ENTROPY_LEN 32 /**< Amount of entropy used per seed by default (48 with SHA-512, 32 with SHA-256) */
+#endif
#define CTR_DRBG_RESEED_INTERVAL 10000 /**< Interval before reseed is performed by default */
#define CTR_DRBG_MAX_INPUT 256 /**< Maximum number of additional input bytes */
#define CTR_DRBG_MAX_REQUEST 1024 /**< Maximum number of requested bytes per call */
diff --git a/include/polarssl/entropy.h b/include/polarssl/entropy.h
index 69d5b3b..ea27848 100644
--- a/include/polarssl/entropy.h
+++ b/include/polarssl/entropy.h
@@ -31,7 +31,16 @@
#include "config.h"
+#if defined(POLARSSL_SHA512_C)
#include "sha512.h"
+#define POLARSSL_ENTROPY_SHA512_ACCUMULATOR
+#else
+#if defined(POLARSSL_SHA256_C)
+#define POLARSSL_ENTROPY_SHA256_ACCUMULATOR
+#include "sha256.h"
+#endif
+#endif
+
#if defined(POLARSSL_HAVEGE_C)
#include "havege.h"
#endif
@@ -45,7 +54,11 @@
#define ENTROPY_MAX_GATHER 128 /**< Maximum amount requested from entropy sources */
#endif /* !POLARSSL_CONFIG_OPTIONS */
+#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
#define ENTROPY_BLOCK_SIZE 64 /**< Block size of entropy accumulator (SHA-512) */
+#else
+#define ENTROPY_BLOCK_SIZE 32 /**< Block size of entropy accumulator (SHA-256) */
+#endif
#define ENTROPY_SOURCE_MANUAL ENTROPY_MAX_SOURCES
@@ -83,7 +96,11 @@
*/
typedef struct
{
+#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
sha512_context accumulator;
+#else
+ sha256_context accumulator;
+#endif
int source_count;
source_state source[ENTROPY_MAX_SOURCES];
#if defined(POLARSSL_HAVEGE_C)
diff --git a/include/polarssl/ssl.h b/include/polarssl/ssl.h
index bf6b10c..8383b7f 100644
--- a/include/polarssl/ssl.h
+++ b/include/polarssl/ssl.h
@@ -439,7 +439,9 @@
md5_context fin_md5;
sha1_context fin_sha1;
sha256_context fin_sha256;
+#if defined(POLARSSL_SHA512_C)
sha512_context fin_sha512;
+#endif
void (*update_checksum)(ssl_context *, const unsigned char *, size_t);
void (*calc_verify)(ssl_context *, unsigned char *);
diff --git a/library/entropy.c b/library/entropy.c
index a6704d7..2352bcf 100644
--- a/library/entropy.c
+++ b/library/entropy.c
@@ -40,7 +40,11 @@
{
memset( ctx, 0, sizeof(entropy_context) );
+#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
sha512_starts( &ctx->accumulator, 0 );
+#else
+ sha256_starts( &ctx->accumulator, 0 );
+#endif
#if defined(POLARSSL_HAVEGE_C)
havege_init( &ctx->havege_data );
#endif
@@ -91,8 +95,11 @@
if( use_len > ENTROPY_BLOCK_SIZE )
{
+#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
sha512( data, len, tmp, 0 );
-
+#else
+ sha256( data, len, tmp, 0 );
+#endif
p = tmp;
use_len = ENTROPY_BLOCK_SIZE;
}
@@ -100,8 +107,13 @@
header[0] = source_id;
header[1] = use_len & 0xFF;
+#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
sha512_update( &ctx->accumulator, header, 2 );
sha512_update( &ctx->accumulator, p, use_len );
+#else
+ sha256_update( &ctx->accumulator, header, 2 );
+ sha256_update( &ctx->accumulator, p, use_len );
+#endif
return( 0 );
}
@@ -179,6 +191,7 @@
memset( buf, 0, ENTROPY_BLOCK_SIZE );
+#if defined(POLARSSL_ENTROPY_SHA512_ACCUMULATOR)
sha512_finish( &ctx->accumulator, buf );
/*
@@ -192,6 +205,21 @@
memset( &ctx->accumulator, 0, sizeof( sha512_context ) );
sha512_starts( &ctx->accumulator, 0 );
sha512_update( &ctx->accumulator, buf, ENTROPY_BLOCK_SIZE );
+#else /* POLARSSL_ENTROPY_SHA512_ACCUMULATOR */
+ sha256_finish( &ctx->accumulator, buf );
+
+ /*
+ * Perform second SHA-256 on entropy
+ */
+ sha256( buf, ENTROPY_BLOCK_SIZE, buf, 0 );
+
+ /*
+ * Reset accumulator and counters and recycle existing entropy
+ */
+ memset( &ctx->accumulator, 0, sizeof( sha256_context ) );
+ sha256_starts( &ctx->accumulator, 0 );
+ sha256_update( &ctx->accumulator, buf, ENTROPY_BLOCK_SIZE );
+#endif /* POLARSSL_ENTROPY_SHA512_ACCUMULATOR */
for( i = 0; i < ctx->source_count; i++ )
ctx->source[i].size = 0;
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 625cafd..033c9fa 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2318,7 +2318,7 @@
const ssl_ciphersuite_t *ciphersuite_info )
{
#if !defined(POLARSSL_SHA512_C)
- ((void) ciphersuite);
+ ((void) ciphersuite_info);
#endif
if( ssl->minor_ver < SSL_MINOR_VERSION_3 )
