Diff: mbedtls/source/ctr_drbg.c

Revision:

11:cada08fc8a70

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbedtls/source/ctr_drbg.c	Thu Jun 09 17:08:36 2016 +0000
@@ -0,0 +1,593 @@
+/*
+ *  CTR_DRBG implementation based on AES-256 (NIST SP 800-90)
+ *
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+/*
+ *  The NIST SP 800-90 DRBGs are described in the following publucation.
+ *
+ *  http://csrc.nist.gov/publications/nistpubs/800-90/SP800-90revised_March2007.pdf
+ */
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#if defined(MBEDTLS_CTR_DRBG_C)
+
+#include "mbedtls/ctr_drbg.h"
+
+#include <string.h>
+
+#if defined(MBEDTLS_FS_IO)
+#include <stdio.h>
+#endif
+
+#if defined(MBEDTLS_SELF_TEST)
+#if defined(MBEDTLS_PLATFORM_C)
+#include "mbedtls/platform.h"
+#else
+#include <stdio.h>
+#define mbedtls_printf printf
+#endif /* MBEDTLS_PLATFORM_C */
+#endif /* MBEDTLS_SELF_TEST */
+
+/* Implementation that should never be optimized out by the compiler */
+static void mbedtls_zeroize( void *v, size_t n ) {
+    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
+}
+
+/*
+ * CTR_DRBG context initialization
+ */
+void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx )
+{
+    memset( ctx, 0, sizeof( mbedtls_ctr_drbg_context ) );
+
+#if defined(MBEDTLS_THREADING_C)
+    mbedtls_mutex_init( &ctx->mutex );
+#endif
+}
+
+/*
+ * Non-public function wrapped by ctr_crbg_init(). Necessary to allow NIST
+ * tests to succeed (which require known length fixed entropy)
+ */
+int mbedtls_ctr_drbg_seed_entropy_len(
+                   mbedtls_ctr_drbg_context *ctx,
+                   int (*f_entropy)(void *, unsigned char *, size_t),
+                   void *p_entropy,
+                   const unsigned char *custom,
+                   size_t len,
+                   size_t entropy_len )
+{
+    int ret;
+    unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];
+
+    memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE );
+
+    mbedtls_aes_init( &ctx->aes_ctx );
+
+    ctx->f_entropy = f_entropy;
+    ctx->p_entropy = p_entropy;
+
+    ctx->entropy_len = entropy_len;
+    ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
+
+    /*
+     * Initialize with an empty key
+     */
+    mbedtls_aes_setkey_enc( &ctx->aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS );
+
+    if( ( ret = mbedtls_ctr_drbg_reseed( ctx, custom, len ) ) != 0 )
+        return( ret );
+
+    return( 0 );
+}
+
+int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx,
+                   int (*f_entropy)(void *, unsigned char *, size_t),
+                   void *p_entropy,
+                   const unsigned char *custom,
+                   size_t len )
+{
+    return( mbedtls_ctr_drbg_seed_entropy_len( ctx, f_entropy, p_entropy, custom, len,
+                                       MBEDTLS_CTR_DRBG_ENTROPY_LEN ) );
+}
+
+void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+#if defined(MBEDTLS_THREADING_C)
+    mbedtls_mutex_free( &ctx->mutex );
+#endif
+    mbedtls_aes_free( &ctx->aes_ctx );
+    mbedtls_zeroize( ctx, sizeof( mbedtls_ctr_drbg_context ) );
+}
+
+void mbedtls_ctr_drbg_set_prediction_resistance( mbedtls_ctr_drbg_context *ctx, int resistance )
+{
+    ctx->prediction_resistance = resistance;
+}
+
+void mbedtls_ctr_drbg_set_entropy_len( mbedtls_ctr_drbg_context *ctx, size_t len )
+{
+    ctx->entropy_len = len;
+}
+
+void mbedtls_ctr_drbg_set_reseed_interval( mbedtls_ctr_drbg_context *ctx, int interval )
+{
+    ctx->reseed_interval = interval;
+}
+
+static int block_cipher_df( unsigned char *output,
+                            const unsigned char *data, size_t data_len )
+{
+    unsigned char buf[MBEDTLS_CTR_DRBG_MAX_SEED_INPUT + MBEDTLS_CTR_DRBG_BLOCKSIZE + 16];
+    unsigned char tmp[MBEDTLS_CTR_DRBG_SEEDLEN];
+    unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];
+    unsigned char chain[MBEDTLS_CTR_DRBG_BLOCKSIZE];
+    unsigned char *p, *iv;
+    mbedtls_aes_context aes_ctx;
+
+    int i, j;
+    size_t buf_len, use_len;
+
+    if( data_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT )
+        return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );
+
+    memset( buf, 0, MBEDTLS_CTR_DRBG_MAX_SEED_INPUT + MBEDTLS_CTR_DRBG_BLOCKSIZE + 16 );
+    mbedtls_aes_init( &aes_ctx );
+
+    /*
+     * Construct IV (16 bytes) and S in buffer
+     * IV = Counter (in 32-bits) padded to 16 with zeroes
+     * S = Length input string (in 32-bits) || Length of output (in 32-bits) ||
+     *     data || 0x80
+     *     (Total is padded to a multiple of 16-bytes with zeroes)
+     */
+    p = buf + MBEDTLS_CTR_DRBG_BLOCKSIZE;
+    *p++ = ( data_len >> 24 ) & 0xff;
+    *p++ = ( data_len >> 16 ) & 0xff;
+    *p++ = ( data_len >> 8  ) & 0xff;
+    *p++ = ( data_len       ) & 0xff;
+    p += 3;
+    *p++ = MBEDTLS_CTR_DRBG_SEEDLEN;
+    memcpy( p, data, data_len );
+    p[data_len] = 0x80;
+
+    buf_len = MBEDTLS_CTR_DRBG_BLOCKSIZE + 8 + data_len + 1;
+
+    for( i = 0; i < MBEDTLS_CTR_DRBG_KEYSIZE; i++ )
+        key[i] = i;
+
+    mbedtls_aes_setkey_enc( &aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS );
+
+    /*
+     * Reduce data to MBEDTLS_CTR_DRBG_SEEDLEN bytes of data
+     */
+    for( j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE )
+    {
+        p = buf;
+        memset( chain, 0, MBEDTLS_CTR_DRBG_BLOCKSIZE );
+        use_len = buf_len;
+
+        while( use_len > 0 )
+        {
+            for( i = 0; i < MBEDTLS_CTR_DRBG_BLOCKSIZE; i++ )
+                chain[i] ^= p[i];
+            p += MBEDTLS_CTR_DRBG_BLOCKSIZE;
+            use_len -= ( use_len >= MBEDTLS_CTR_DRBG_BLOCKSIZE ) ?
+                       MBEDTLS_CTR_DRBG_BLOCKSIZE : use_len;
+
+            mbedtls_aes_crypt_ecb( &aes_ctx, MBEDTLS_AES_ENCRYPT, chain, chain );
+        }
+
+        memcpy( tmp + j, chain, MBEDTLS_CTR_DRBG_BLOCKSIZE );
+
+        /*
+         * Update IV
+         */
+        buf[3]++;
+    }
+
+    /*
+     * Do final encryption with reduced data
+     */
+    mbedtls_aes_setkey_enc( &aes_ctx, tmp, MBEDTLS_CTR_DRBG_KEYBITS );
+    iv = tmp + MBEDTLS_CTR_DRBG_KEYSIZE;
+    p = output;
+
+    for( j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE )
+    {
+        mbedtls_aes_crypt_ecb( &aes_ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+        memcpy( p, iv, MBEDTLS_CTR_DRBG_BLOCKSIZE );
+        p += MBEDTLS_CTR_DRBG_BLOCKSIZE;
+    }
+
+    mbedtls_aes_free( &aes_ctx );
+
+    return( 0 );
+}
+
+static int ctr_drbg_update_internal( mbedtls_ctr_drbg_context *ctx,
+                              const unsigned char data[MBEDTLS_CTR_DRBG_SEEDLEN] )
+{
+    unsigned char tmp[MBEDTLS_CTR_DRBG_SEEDLEN];
+    unsigned char *p = tmp;
+    int i, j;
+
+    memset( tmp, 0, MBEDTLS_CTR_DRBG_SEEDLEN );
+
+    for( j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE )
+    {
+        /*
+         * Increase counter
+         */
+        for( i = MBEDTLS_CTR_DRBG_BLOCKSIZE; i > 0; i-- )
+            if( ++ctx->counter[i - 1] != 0 )
+                break;
+
+        /*
+         * Crypt counter block
+         */
+        mbedtls_aes_crypt_ecb( &ctx->aes_ctx, MBEDTLS_AES_ENCRYPT, ctx->counter, p );
+
+        p += MBEDTLS_CTR_DRBG_BLOCKSIZE;
+    }
+
+    for( i = 0; i < MBEDTLS_CTR_DRBG_SEEDLEN; i++ )
+        tmp[i] ^= data[i];
+
+    /*
+     * Update key and counter
+     */
+    mbedtls_aes_setkey_enc( &ctx->aes_ctx, tmp, MBEDTLS_CTR_DRBG_KEYBITS );
+    memcpy( ctx->counter, tmp + MBEDTLS_CTR_DRBG_KEYSIZE, MBEDTLS_CTR_DRBG_BLOCKSIZE );
+
+    return( 0 );
+}
+
+void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,
+                      const unsigned char *additional, size_t add_len )
+{
+    unsigned char add_input[MBEDTLS_CTR_DRBG_SEEDLEN];
+
+    if( add_len > 0 )
+    {
+        /* MAX_INPUT would be more logical here, but we have to match
+         * block_cipher_df()'s limits since we can't propagate errors */
+        if( add_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT )
+            add_len = MBEDTLS_CTR_DRBG_MAX_SEED_INPUT;
+
+        block_cipher_df( add_input, additional, add_len );
+        ctr_drbg_update_internal( ctx, add_input );
+    }
+}
+
+int mbedtls_ctr_drbg_reseed( mbedtls_ctr_drbg_context *ctx,
+                     const unsigned char *additional, size_t len )
+{
+    unsigned char seed[MBEDTLS_CTR_DRBG_MAX_SEED_INPUT];
+    size_t seedlen = 0;
+
+    if( ctx->entropy_len + len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT )
+        return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );
+
+    memset( seed, 0, MBEDTLS_CTR_DRBG_MAX_SEED_INPUT );
+
+    /*
+     * Gather entropy_len bytes of entropy to seed state
+     */
+    if( 0 != ctx->f_entropy( ctx->p_entropy, seed,
+                             ctx->entropy_len ) )
+    {
+        return( MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED );
+    }
+
+    seedlen += ctx->entropy_len;
+
+    /*
+     * Add additional data
+     */
+    if( additional && len )
+    {
+        memcpy( seed + seedlen, additional, len );
+        seedlen += len;
+    }
+
+    /*
+     * Reduce to 384 bits
+     */
+    block_cipher_df( seed, seed, seedlen );
+
+    /*
+     * Update state
+     */
+    ctr_drbg_update_internal( ctx, seed );
+    ctx->reseed_counter = 1;
+
+    return( 0 );
+}
+
+int mbedtls_ctr_drbg_random_with_add( void *p_rng,
+                              unsigned char *output, size_t output_len,
+                              const unsigned char *additional, size_t add_len )
+{
+    int ret = 0;
+    mbedtls_ctr_drbg_context *ctx = (mbedtls_ctr_drbg_context *) p_rng;
+    unsigned char add_input[MBEDTLS_CTR_DRBG_SEEDLEN];
+    unsigned char *p = output;
+    unsigned char tmp[MBEDTLS_CTR_DRBG_BLOCKSIZE];
+    int i;
+    size_t use_len;
+
+    if( output_len > MBEDTLS_CTR_DRBG_MAX_REQUEST )
+        return( MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG );
+
+    if( add_len > MBEDTLS_CTR_DRBG_MAX_INPUT )
+        return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );
+
+    memset( add_input, 0, MBEDTLS_CTR_DRBG_SEEDLEN );
+
+    if( ctx->reseed_counter > ctx->reseed_interval ||
+        ctx->prediction_resistance )
+    {
+        if( ( ret = mbedtls_ctr_drbg_reseed( ctx, additional, add_len ) ) != 0 )
+            return( ret );
+
+        add_len = 0;
+    }
+
+    if( add_len > 0 )
+    {
+        block_cipher_df( add_input, additional, add_len );
+        ctr_drbg_update_internal( ctx, add_input );
+    }
+
+    while( output_len > 0 )
+    {
+        /*
+         * Increase counter
+         */
+        for( i = MBEDTLS_CTR_DRBG_BLOCKSIZE; i > 0; i-- )
+            if( ++ctx->counter[i - 1] != 0 )
+                break;
+
+        /*
+         * Crypt counter block
+         */
+        mbedtls_aes_crypt_ecb( &ctx->aes_ctx, MBEDTLS_AES_ENCRYPT, ctx->counter, tmp );
+
+        use_len = ( output_len > MBEDTLS_CTR_DRBG_BLOCKSIZE ) ? MBEDTLS_CTR_DRBG_BLOCKSIZE :
+                                                       output_len;
+        /*
+         * Copy random block to destination
+         */
+        memcpy( p, tmp, use_len );
+        p += use_len;
+        output_len -= use_len;
+    }
+
+    ctr_drbg_update_internal( ctx, add_input );
+
+    ctx->reseed_counter++;
+
+    return( 0 );
+}
+
+int mbedtls_ctr_drbg_random( void *p_rng, unsigned char *output, size_t output_len )
+{
+    int ret;
+    mbedtls_ctr_drbg_context *ctx = (mbedtls_ctr_drbg_context *) p_rng;
+
+#if defined(MBEDTLS_THREADING_C)
+    if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
+        return( ret );
+#endif
+
+    ret = mbedtls_ctr_drbg_random_with_add( ctx, output, output_len, NULL, 0 );
+
+#if defined(MBEDTLS_THREADING_C)
+    if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
+        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
+#endif
+
+    return( ret );
+}
+
+#if defined(MBEDTLS_FS_IO)
+int mbedtls_ctr_drbg_write_seed_file( mbedtls_ctr_drbg_context *ctx, const char *path )
+{
+    int ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR;
+    FILE *f;
+    unsigned char buf[ MBEDTLS_CTR_DRBG_MAX_INPUT ];
+
+    if( ( f = fopen( path, "wb" ) ) == NULL )
+        return( MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR );
+
+    if( ( ret = mbedtls_ctr_drbg_random( ctx, buf, MBEDTLS_CTR_DRBG_MAX_INPUT ) ) != 0 )
+        goto exit;
+
+    if( fwrite( buf, 1, MBEDTLS_CTR_DRBG_MAX_INPUT, f ) != MBEDTLS_CTR_DRBG_MAX_INPUT )
+    {
+        ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR;
+        goto exit;
+    }
+
+    ret = 0;
+
+exit:
+    fclose( f );
+    return( ret );
+}
+
+int mbedtls_ctr_drbg_update_seed_file( mbedtls_ctr_drbg_context *ctx, const char *path )
+{
+    FILE *f;
+    size_t n;
+    unsigned char buf[ MBEDTLS_CTR_DRBG_MAX_INPUT ];
+
+    if( ( f = fopen( path, "rb" ) ) == NULL )
+        return( MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR );
+
+    fseek( f, 0, SEEK_END );
+    n = (size_t) ftell( f );
+    fseek( f, 0, SEEK_SET );
+
+    if( n > MBEDTLS_CTR_DRBG_MAX_INPUT )
+    {
+        fclose( f );
+        return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );
+    }
+
+    if( fread( buf, 1, n, f ) != n )
+    {
+        fclose( f );
+        return( MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR );
+    }
+
+    fclose( f );
+
+    mbedtls_ctr_drbg_update( ctx, buf, n );
+
+    return( mbedtls_ctr_drbg_write_seed_file( ctx, path ) );
+}
+#endif /* MBEDTLS_FS_IO */
+
+#if defined(MBEDTLS_SELF_TEST)
+
+static const unsigned char entropy_source_pr[96] =
+    { 0xc1, 0x80, 0x81, 0xa6, 0x5d, 0x44, 0x02, 0x16,
+      0x19, 0xb3, 0xf1, 0x80, 0xb1, 0xc9, 0x20, 0x02,
+      0x6a, 0x54, 0x6f, 0x0c, 0x70, 0x81, 0x49, 0x8b,
+      0x6e, 0xa6, 0x62, 0x52, 0x6d, 0x51, 0xb1, 0xcb,
+      0x58, 0x3b, 0xfa, 0xd5, 0x37, 0x5f, 0xfb, 0xc9,
+      0xff, 0x46, 0xd2, 0x19, 0xc7, 0x22, 0x3e, 0x95,
+      0x45, 0x9d, 0x82, 0xe1, 0xe7, 0x22, 0x9f, 0x63,
+      0x31, 0x69, 0xd2, 0x6b, 0x57, 0x47, 0x4f, 0xa3,
+      0x37, 0xc9, 0x98, 0x1c, 0x0b, 0xfb, 0x91, 0x31,
+      0x4d, 0x55, 0xb9, 0xe9, 0x1c, 0x5a, 0x5e, 0xe4,
+      0x93, 0x92, 0xcf, 0xc5, 0x23, 0x12, 0xd5, 0x56,
+      0x2c, 0x4a, 0x6e, 0xff, 0xdc, 0x10, 0xd0, 0x68 };
+
+static const unsigned char entropy_source_nopr[64] =
+    { 0x5a, 0x19, 0x4d, 0x5e, 0x2b, 0x31, 0x58, 0x14,
+      0x54, 0xde, 0xf6, 0x75, 0xfb, 0x79, 0x58, 0xfe,
+      0xc7, 0xdb, 0x87, 0x3e, 0x56, 0x89, 0xfc, 0x9d,
+      0x03, 0x21, 0x7c, 0x68, 0xd8, 0x03, 0x38, 0x20,
+      0xf9, 0xe6, 0x5e, 0x04, 0xd8, 0x56, 0xf3, 0xa9,
+      0xc4, 0x4a, 0x4c, 0xbd, 0xc1, 0xd0, 0x08, 0x46,
+      0xf5, 0x98, 0x3d, 0x77, 0x1c, 0x1b, 0x13, 0x7e,
+      0x4e, 0x0f, 0x9d, 0x8e, 0xf4, 0x09, 0xf9, 0x2e };
+
+static const unsigned char nonce_pers_pr[16] =
+    { 0xd2, 0x54, 0xfc, 0xff, 0x02, 0x1e, 0x69, 0xd2,
+      0x29, 0xc9, 0xcf, 0xad, 0x85, 0xfa, 0x48, 0x6c };
+
+static const unsigned char nonce_pers_nopr[16] =
+    { 0x1b, 0x54, 0xb8, 0xff, 0x06, 0x42, 0xbf, 0xf5,
+      0x21, 0xf1, 0x5c, 0x1c, 0x0b, 0x66, 0x5f, 0x3f };
+
+static const unsigned char result_pr[16] =
+    { 0x34, 0x01, 0x16, 0x56, 0xb4, 0x29, 0x00, 0x8f,
+      0x35, 0x63, 0xec, 0xb5, 0xf2, 0x59, 0x07, 0x23 };
+
+static const unsigned char result_nopr[16] =
+    { 0xa0, 0x54, 0x30, 0x3d, 0x8a, 0x7e, 0xa9, 0x88,
+      0x9d, 0x90, 0x3e, 0x07, 0x7c, 0x6f, 0x21, 0x8f };
+
+static size_t test_offset;
+static int ctr_drbg_self_test_entropy( void *data, unsigned char *buf,
+                                       size_t len )
+{
+    const unsigned char *p = data;
+    memcpy( buf, p + test_offset, len );
+    test_offset += len;
+    return( 0 );
+}
+
+#define CHK( c )    if( (c) != 0 )                          \
+                    {                                       \
+                        if( verbose != 0 )                  \
+                            mbedtls_printf( "failed\n" );  \
+                        return( 1 );                        \
+                    }
+
+/*
+ * Checkup routine
+ */
+int mbedtls_ctr_drbg_self_test( int verbose )
+{
+    mbedtls_ctr_drbg_context ctx;
+    unsigned char buf[16];
+
+    mbedtls_ctr_drbg_init( &ctx );
+
+    /*
+     * Based on a NIST CTR_DRBG test vector (PR = True)
+     */
+    if( verbose != 0 )
+        mbedtls_printf( "  CTR_DRBG (PR = TRUE) : " );
+
+    test_offset = 0;
+    CHK( mbedtls_ctr_drbg_seed_entropy_len( &ctx, ctr_drbg_self_test_entropy,
+                                (void *) entropy_source_pr, nonce_pers_pr, 16, 32 ) );
+    mbedtls_ctr_drbg_set_prediction_resistance( &ctx, MBEDTLS_CTR_DRBG_PR_ON );
+    CHK( mbedtls_ctr_drbg_random( &ctx, buf, MBEDTLS_CTR_DRBG_BLOCKSIZE ) );
+    CHK( mbedtls_ctr_drbg_random( &ctx, buf, MBEDTLS_CTR_DRBG_BLOCKSIZE ) );
+    CHK( memcmp( buf, result_pr, MBEDTLS_CTR_DRBG_BLOCKSIZE ) );
+
+    mbedtls_ctr_drbg_free( &ctx );
+
+    if( verbose != 0 )
+        mbedtls_printf( "passed\n" );
+
+    /*
+     * Based on a NIST CTR_DRBG test vector (PR = FALSE)
+     */
+    if( verbose != 0 )
+        mbedtls_printf( "  CTR_DRBG (PR = FALSE): " );
+
+    mbedtls_ctr_drbg_init( &ctx );
+
+    test_offset = 0;
+    CHK( mbedtls_ctr_drbg_seed_entropy_len( &ctx, ctr_drbg_self_test_entropy,
+                            (void *) entropy_source_nopr, nonce_pers_nopr, 16, 32 ) );
+    CHK( mbedtls_ctr_drbg_random( &ctx, buf, 16 ) );
+    CHK( mbedtls_ctr_drbg_reseed( &ctx, NULL, 0 ) );
+    CHK( mbedtls_ctr_drbg_random( &ctx, buf, 16 ) );
+    CHK( memcmp( buf, result_nopr, 16 ) );
+
+    mbedtls_ctr_drbg_free( &ctx );
+
+    if( verbose != 0 )
+        mbedtls_printf( "passed\n" );
+
+    if( verbose != 0 )
+            mbedtls_printf( "\n" );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_SELF_TEST */
+
+#endif /* MBEDTLS_CTR_DRBG_C */