diff --git a/include/polarssl/ctr_drbg.h b/include/polarssl/ctr_drbg.h
new file mode 100644
index 0000000..da70611
--- /dev/null
+++ b/include/polarssl/ctr_drbg.h
@@ -0,0 +1,199 @@
+/**
+ * \file ctr_drbg.h
+ *
+ * \brief CTR_DRBG based on AES-256 (NIST SP 800-90)
+ *
+ *  Copyright (C) 2006-2010, 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.
+ */
+#ifndef POLARSSL_CTR_DRBG_H
+#define POLARSSL_CTR_DRBG_H
+
+#include <string.h>
+
+#include "aes.h"
+
+#define POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED        -0x0034  /**< The entropy source failed. */
+#define POLARSSL_ERR_CTR_DRBG_REQUEST_TOO_BIG              -0x0036  /**< Too many random requested in single call. */
+#define POLARSSL_ERR_CTR_DRBG_INPUT_TOO_BIG                -0x0038  /**< Input too large (Entropy + additional). */
+
+#define CTR_DRBG_SEEDLEN            48      /**< The seed length (counter + AES key)            */
+#define CTR_DRBG_ENTROPY_LEN        32      /**< Amount of entropy used per seed by default     */
+#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        500     /**< Maximum number of requested bytes per call     */
+#define CTR_DRBG_MAX_SEED_INPUT     384     /**< Maximum size of (re)seed buffer                */
+
+#define CTR_DRBG_PR_OFF             0       /**< No prediction resistance       */
+#define CTR_DRBG_PR_ON              1       /**< Prediction resistance enabled  */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief          CTR_DRBG context structure
+ */
+typedef struct
+{
+    unsigned char counter[16];  /*!<  counter (V)       */
+    int reseed_counter;         /*!<  reseed counter    */
+    int prediction_resistance;  /*!<  enable prediction resistance (Automatic
+                                      reseed before every random generation)        */
+    size_t entropy_len;         /*!<  amount of entropy grabbed on each (re)seed    */
+    int reseed_interval;        /*!<  reseed interval   */
+
+    aes_context aes_ctx;        /*!<  AES context       */
+
+    /*
+     * Callbacks (Entropy)
+     */
+    int (*f_entropy)(void *, unsigned char *, size_t);
+
+    void *p_entropy;            /*!<  context for the entropy function */
+}
+ctr_drbg_context;
+
+/**
+ * \brief               CTR_DRBG initialization
+ * 
+ * Note: Personalization data can be provided in addition to the more generic
+ *       entropy source to make this instantiation as unique as possible.
+ *
+ * \param ctx           CTR_DRBG context to be initialized
+ * \param f_entropy     Entropy callback (p_entropy, buffer to fill, buffer
+ *                      length)
+ * \param p_entropy     Entropy context
+ * \param custom        Personalization data (Device specific identifiers)
+ * \param len           Length of personalization data
+ *
+ * \return              0 if successful, or
+ *                      POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED
+ */
+int ctr_drbg_init( ctr_drbg_context *ctx,
+                   int (*f_entropy)(void *, unsigned char *, size_t),
+                   void *p_entropy,
+                   unsigned char *custom,
+                   size_t len );
+
+/**
+ * \brief               Enable / disable prediction resistance (Default: Off)
+ *
+ * Note: If enabled, entropy is used for ctx->entropy_len before each call!
+ *       Only use this if you have ample supply of good entropy!
+ *
+ * \param ctx           CTR_DRBG context
+ * \param resistance    CTR_DRBG_PR_ON or CTR_DRBG_PR_OFF
+ */
+void ctr_drbg_set_prediction_resistance( ctr_drbg_context *ctx,
+                                         int resistance );
+
+/**
+ * \brief               Set the amount of entropy grabbed on each (re)seed
+ *                      (Default: CTR_DRBG_ENTROPY_LEN)
+ *
+ * \param ctx           CTR_DRBG context
+ * \param len           Amount of entropy to grab
+ */
+void ctr_drbg_set_entropy_len( ctr_drbg_context *ctx,
+                               size_t len );
+
+/**
+ * \brief               Set the reseed interval
+ *                      (Default: CTR_DRBG_RESEED_INTERVAL)
+ *
+ * \param ctx           CTR_DRBG context
+ * \param interval      Reseed interval
+ */
+void ctr_drbg_set_reseed_interval( ctr_drbg_context *ctx,
+                                   int interval );
+
+/**
+ * \brief               CTR_DRBG reseeding (extracts data from entropy source)
+ * 
+ * \param ctx           CTR_DRBG context
+ * \param additional    Additional data to add to state
+ * \param len           Length of additional data
+ *
+ * \return              0 if successful, or
+ *                      POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED
+ */
+int ctr_drbg_reseed( ctr_drbg_context *ctx,
+                     unsigned char *additional, size_t len );
+
+/**
+ * \brief               CTR_DRBG update state
+ *
+ * \param ctx           CTR_DRBG context
+ * \param data          Data to update with
+ *
+ * \return              0 if successful
+ */
+int ctr_drbg_update( ctr_drbg_context *ctx,
+                     unsigned char data[CTR_DRBG_SEEDLEN] );
+
+/**
+ * \brief               CTR_DRBG generate random with additional update input
+ *
+ * Note: Automatically reseeds if reseed_counter is reached.
+ *
+ * \param p_rng         CTR_DRBG context
+ * \param output        Buffer to fill
+ * \param output_len    Length of the buffer
+ * \param additional    Additional data to update with
+ * \param add_len       Length of additional data
+ *
+ * \return              0 if successful, or
+ *                      POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED, or
+ *                      POLARSSL_ERR_CTR_DRBG_REQUEST_TOO_BIG
+ */
+int ctr_drbg_random_with_add( void *p_rng,
+                              unsigned char *output, size_t output_len,
+                              unsigned char *additional, size_t add_len );
+
+/**
+ * \brief               CTR_DRBG generate random
+ *
+ * Note: Automatically reseeds if reseed_counter is reached.
+ *
+ * \param p_rng         CTR_DRBG context
+ * \param output        Buffer to fill
+ * \param output_len    Length of the buffer
+ *
+ * \return              0 if successful, or
+ *                      POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED, or
+ *                      POLARSSL_ERR_CTR_DRBG_REQUEST_TOO_BIG
+ */
+int ctr_drbg_random( void *p_rng,
+                     unsigned char *output, size_t output_len );
+
+/**
+ * \brief               Checkup routine
+ *
+ * \return              0 if successful, or 1 if the test failed
+ */
+int ctr_drbg_self_test( int verbose );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ctr_drbg.h */