// Copyright (c) 2013-2015 IONU Security, Inc. All rights reserved.
//
// DRBG class for deterministic random bit generation and predictable RSA keys

#ifndef eyedrbg_h
#define eyedrbg_h

#include <vector>
#include <openssl/evp.h>

#ifdef WIN32
#  ifdef DLLEXPORT
#    define LIBEYE_DLL __declspec(dllexport)
#  else
#    define LIBEYE_DLL __declspec(dllimport)
#  endif
#else
#define LIBEYE_DLL
#endif

#define IONU_DRBG_BUFFER_LEN 32768

namespace sequencelogic {


class EyeDRBG {
 public:
    /**
     * @constructor
     * @param seed value for DRBG
     * @param seed length
     */
    LIBEYE_DLL EyeDRBG (const unsigned char* seed, size_t seedlen);

    LIBEYE_DLL ~EyeDRBG ();

    /**
     * Generate an RSA key
     * @param rsa pointer to OpenSSL RSA structure
     * @return true for success
     */
    LIBEYE_DLL bool GenerateDRBGRSAKey (RSA* rsa);

    /**
     * Generate an EC key
     * @param eckey pointer to OpenSSL EC_KEY structure
     * @return true for success
     */
    LIBEYE_DLL bool GenerateDRBGECKey (EC_KEY *eckey);

    /**
     * Get bytes from pseudo random number generator
     * @param bytes buffer to fill
     * @param len number of bytes to get
     */
    LIBEYE_DLL bool RandBytes (unsigned char* bytes, size_t len);

 private:
    unsigned char* _data;  // Random data buffer
    unsigned char _ctr;    // Wrapping counter
    size_t _pos;           // Current position in buffer
    void FillBuffer();
    bool GenerateRSAPrime (BIGNUM *rsap);
};


} //namespce ionu
#endif