From fc754a91781bdb80268191385cc1343603cb2d2d Mon Sep 17 00:00:00 2001
From: Paul Bakker <p.j.bakker@polarssl.org>
Date: Mon, 5 Dec 2011 13:23:51 +0000
Subject: [PATCH]  - Addedd writing and updating of seedfiles as functions to
 CTR_DRBG

---
 include/polarssl/ctr_drbg.h           | 26 +++++++++++-
 library/ctr_drbg.c                    | 57 +++++++++++++++++++++++++++
 programs/random/gen_random_ctr_drbg.c | 21 ++++++++++
 programs/random/gen_random_havege.c   |  2 +
 4 files changed, 105 insertions(+), 1 deletion(-)

diff --git a/include/polarssl/ctr_drbg.h b/include/polarssl/ctr_drbg.h
index 01a58e1b23..b2014c27b0 100644
--- a/include/polarssl/ctr_drbg.h
+++ b/include/polarssl/ctr_drbg.h
@@ -152,7 +152,7 @@ int ctr_drbg_reseed( ctr_drbg_context *ctx,
  * \param add_len       Length of additional data
  */
 void ctr_drbg_update( ctr_drbg_context *ctx,
-                     const unsigned char *additional, size_t add_len );
+                      const unsigned char *additional, size_t add_len );
 
 /**
  * \brief               CTR_DRBG generate random with additional update input
@@ -189,6 +189,30 @@ int ctr_drbg_random_with_add( void *p_rng,
 int ctr_drbg_random( void *p_rng,
                      unsigned char *output, size_t output_len );
 
+#if defined(POLARSSL_FS_IO)
+/**
+ * \brief               Write a seed file
+ *
+ * \param path          Name of the file
+ *
+ * \return              0 if successful, 1 on file error, or
+ *                      POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED
+ */
+int ctr_drbg_write_seed_file( ctr_drbg_context *ctx, const char *path );
+
+/**
+ * \brief               Read and update a seed file. Seed is added to this
+ *                      instance
+ *
+ * \param path          Name of the file
+ *
+ * \return              0 if successful, 1 on file error,
+ *                      POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or
+ *                      POLARSSL_ERR_CTR_DRBG_INPUT_TOO_BIG
+ */
+int ctr_drbg_update_seed_file( ctr_drbg_context *ctx, const char *path );
+#endif
+
 /**
  * \brief               Checkup routine
  *
diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index e3796a0771..6611c3d7b7 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -34,6 +34,10 @@
 
 #include "polarssl/ctr_drbg.h"
 
+#if defined(POLARSSL_FS_IO)
+#include <stdio.h>
+#endif
+
 int ctr_drbg_init( ctr_drbg_context *ctx,
                    int (*f_entropy)(void *, unsigned char *, size_t),
                    void *p_entropy,
@@ -329,6 +333,59 @@ int ctr_drbg_random( void *p_rng, unsigned char *output, size_t output_len )
     return ctr_drbg_random_with_add( p_rng, output, output_len, NULL, 0 );
 }
 
+#if defined(POLARSSL_FS_IO)
+int ctr_drbg_write_seed_file( ctr_drbg_context *ctx, const char *path )
+{
+    int ret;
+    FILE *f;
+    unsigned char buf[ CTR_DRBG_MAX_INPUT ];
+
+    if( ( f = fopen( path, "wb" ) ) == NULL )
+        return( 1 );
+
+    if( ( ret = ctr_drbg_random( ctx, buf, CTR_DRBG_MAX_INPUT ) ) != 0 )
+        return( ret );
+
+    if( fwrite( buf, 1, CTR_DRBG_MAX_INPUT, f ) != CTR_DRBG_MAX_INPUT )
+    {
+        fclose( f );
+        return( 1 );
+    }
+
+    fclose( f );
+    return( 0 );
+}
+
+int ctr_drbg_update_seed_file( ctr_drbg_context *ctx, const char *path )
+{
+    FILE *f;
+    size_t n;
+    unsigned char buf[ CTR_DRBG_MAX_INPUT ];
+
+    if( ( f = fopen( path, "rb" ) ) == NULL )
+        return( 1 );
+
+    fseek( f, 0, SEEK_END );
+    n = (size_t) ftell( f );
+    fseek( f, 0, SEEK_SET );
+
+    if( n > CTR_DRBG_MAX_INPUT )
+        return( POLARSSL_ERR_CTR_DRBG_INPUT_TOO_BIG );
+
+    if( fread( buf, 1, n, f ) != n )
+    {
+        fclose( f );
+        return( 1 );
+    }
+
+    ctr_drbg_update( ctx, buf, n );
+    
+    fclose( f );
+    
+    return( ctr_drbg_write_seed_file( ctx, path ) );
+}
+#endif /* POLARSSL_FS_IO */
+
 #if defined(POLARSSL_SELF_TEST)
 
 #include <stdio.h>
diff --git a/programs/random/gen_random_ctr_drbg.c b/programs/random/gen_random_ctr_drbg.c
index 5eed520fb7..fb3a34051c 100644
--- a/programs/random/gen_random_ctr_drbg.c
+++ b/programs/random/gen_random_ctr_drbg.c
@@ -64,6 +64,26 @@ int main( int argc, char *argv[] )
     ctr_drbg_init( &ctr_drbg, entropy_func, &entropy, (unsigned char *) "RANDOM_GEN", 10 );
     ctr_drbg_set_prediction_resistance( &ctr_drbg, CTR_DRBG_PR_OFF );
 
+#if defined(POLARSSL_FS_IO)
+    ret = ctr_drbg_update_seed_file( &ctr_drbg, "seedfile" );
+
+    if( ret == 1 )
+    {
+        printf("Failed to open seedfile. Generating one.\n");
+        ret = ctr_drbg_write_seed_file( &ctr_drbg, "seedfile" );
+        if( ret != 0 )
+        {
+            printf("failed in ctr_drbg_write_seed_file: %d\n", ret );
+            goto cleanup;
+        }
+    }
+    else if( ret != 0 )
+    {
+        printf("failed in ctr_drbg_update_seed_file: %d\n", ret );
+        goto cleanup;
+    }
+#endif
+
     for( i = 0, k = 768; i < k; i++ )
     {
         ret = ctr_drbg_random( &ctr_drbg, buf, sizeof( buf ) );
@@ -83,6 +103,7 @@ int main( int argc, char *argv[] )
     ret = 0;
 
 cleanup:
+    printf("\n");
 
     fclose( f );
 
diff --git a/programs/random/gen_random_havege.c b/programs/random/gen_random_havege.c
index 20246fec19..9d3b560583 100644
--- a/programs/random/gen_random_havege.c
+++ b/programs/random/gen_random_havege.c
@@ -83,6 +83,8 @@ int main( int argc, char *argv[] )
     if( t == time( NULL ) )
         t--;
 
+    printf(" \n ");
+
     fclose( f );
     return( 0 );
 }