text: /* MD5
  converted to C++ class by Frank Thilo (thilo@unix-ag.org)
  for bzflag (http://www.bzflag.org)
  
  based on:
  
  md5.h and md5.c
  reference implementation of RFC 1321
  
  Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
  rights reserved.
  
  License to copy and use this software is granted provided that it
  is identified as the "RSA Data Security, Inc. MD5 Message-Digest
  Algorithm" in all material mentioning or referencing this software
  or this function.
  
  License is also granted to make and use derivative works provided
  that such works are identified as "derived from the RSA Data
  Security, Inc. MD5 Message-Digest Algorithm" in all material
  mentioning or referencing the derived work.
  
  RSA Data Security, Inc. makes no representations concerning either
  the merchantability of this software or the suitability of this
  software for any particular purpose. It is provided "as is"
  without express or implied warranty of any kind.
  
  These notices must be retained in any copies of any part of this
  documentation and/or software.
  
  */
  
  #ifndef BZF_MD5_H
  #define BZF_MD5_H
  
  #include <cstring>
  #include <iostream>
  
  
  // a small class for calculating MD5 hashes of strings or byte arrays
  // it is not meant to be fast or secure
  //
  // usage: 1) feed it blocks of uchars with update()
  //      2) finalize()
  //      3) get hexdigest() string
  //      or
  //      MD5(std::string).hexdigest()
  //
  // assumes that char is 8 bit and int is 32 bit
  class MD5
  {
  public:
      typedef unsigned int size_type; // must be 32bit
  
      MD5();
      MD5(const std::string& text);
      void update(const unsigned char *buf, size_type length);
      void update(const char *buf, size_type length);
      MD5& finalize();
      std::string hexdigest() const;
      friend std::ostream& operator<<(std::ostream&, MD5 md5);
  
  private:
      void init();
      typedef unsigned char uint1; //  8bit
      typedef unsigned int uint4;  // 32bit
      enum { blocksize = 64 }; // VC6 won't eat a const static int here
  
      void transform(const uint1 block[blocksize]);
      static void decode(uint4 output[], const uint1 input[], size_type len);
      static void encode(uint1 output[], const uint4 input[], size_type len);
  
      bool finalized;
      uint1 buffer[blocksize]; // bytes that didn't fit in last 64 byte chunk
      uint4 count[2];   // 64bit counter for number of bits (lo, hi)
      uint4 state[4];   // digest so far
      uint1 digest[16]; // the result
  
      // low level logic operations
      static inline uint4 F(uint4 x, uint4 y, uint4 z);
      static inline uint4 G(uint4 x, uint4 y, uint4 z);
      static inline uint4 H(uint4 x, uint4 y, uint4 z);
      static inline uint4 I(uint4 x, uint4 y, uint4 z);
      static inline uint4 rotate_left(uint4 x, int n);
      static inline void FF(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
      static inline void GG(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
      static inline void HH(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
      static inline void II(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
  };
  
  std::string md5(const std::string str);
  
  #endif
  