warcrypttext.h

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/** 
*/

#ifndef WAR_CRYPT_TEXT_H
#define WAR_CRYPT_TEXT_H

#if WAR_CRYPTO

/* SYSTEM INCLUDES */

#if WAR_CRYPTO && !defined(WAR_OPENSSL_EVP_H_INCLUDED)
#   define WAR_OPENSSL_EVP_H_INCLUDED
#   include <openssl/evp.h>
#endif

/* PROJECT INCLUDES */

#ifndef WAR_EXCEPTION_H
#   include "WarException.h"
#endif

#ifndef WAR_COLLECTOR_H
#   include "WarCollector.h"
#endif

/* LOCAL INCLUDES */


/* FORWARD REFERENCES */



#ifdef __cplusplus
extern "C" 
{
#endif
/****************** BEGIN OLD STYLE C spesific ********/


/****************** END OLD STYLE C spesific **********/
#ifdef __cplusplus 
}
#endif

/****************** BEGIN C++ spesific ****************/

#ifdef __cplusplus

class WarCryptText 
{
public:
    typedef WarCollector<char> passwd_t;
    typedef unsigned char * byteptr_t;
    typedef std::vector<unsigned char> buffer_t;
    // LIFECYCLE
    
    /**
    * Default constructor.
    */
    WarCryptText(war_ccstr_t secretPasswd = NULL);
    
    /**
    * Copy constructor.
    *
    * @param from The value to copy to this object.
    */
    WarCryptText(const WarCryptText& from);
    
    /**
    * Destructor.
    */
    ~WarCryptText();
    
    // OPERATORS
    
    /**
    * Assignment operator.
    *
    * @param from THe value to assign to this object.
    *
    * @return A reference to this object.
    */
    WarCryptText& operator = (const WarCryptText& from);
    
    // OPERATIONS

    /** Set the password */
    void SetPassword(war_ccstr_t newPasswd)
    {
        mPasswd = newPasswd;
    }

    /** High-level encryption, from a text string, to 
      * a hex-string with a 4 char header that identifies
      * the encryption method (version) used.
      */
    template <class charT>
        void Encrypt(std::basic_string<charT>& toHexStr,
        const std::basic_string<charT>& fromPlainStr) 
        const throw(WarException)
    {
        size_t bytes_to_encrypt = fromPlainStr.size() * sizeof(TCHAR);
        buffer_t encr_buffer;

        EncryptBytes(encr_buffer, (byteptr_t)fromPlainStr.c_str(), 
            bytes_to_encrypt);

        bytes_to_encrypt = encr_buffer.size();
        vector<TCHAR> hex_bytes((bytes_to_encrypt * 2) + 5);
        charT *pp = (charT *)&hex_bytes[0];

        // Header "0x01"
        *pp++ = '0'; *pp++ = 'x'; *pp++ = '0'; *pp++ = '1';
        
        byteptr_t p = (byteptr_t)&encr_buffer[0];
        for(size_t index = 0; index < bytes_to_encrypt; index++, p++)
        {
            static const unsigned char hexmap[] = {"0123456789abcdef"};
            
            *pp++ = hexmap[(((*p & 0xf0) >> 4) & 0x0f)];
            *pp++ = hexmap[(*p & 0x0f)];
        }
        *pp = 0;
        toHexStr = (const charT *)&hex_bytes[0];
    }

    /** High-level decryption, from a hex-string with a 4 char 
      * header that identifies the encryption method (version) used
      * to a text string.
      * 
      */
    template <class charT>
        void Decrypt(std::basic_string<charT>& toPlainStr,
        const std::basic_string<charT>& fromHexStr)
        const throw(WarException)
    {
        toPlainStr.erase();
        
        size_t num_chars = fromHexStr.size();
        if (num_chars < 4)
            WarThrow(WarError(WAR_ERR_INVALID_ARGUMENT), NULL);
        num_chars -= 4; // skip header
        
        if (!num_chars)
            return; // Nothing to do

        // Hex digits must be aligned to two chars
        if (num_chars % 2)
            WarThrow(WarError(WAR_ERR_INVALID_ARGUMENT), NULL);

        size_t bytes_to_decrypt = (num_chars / 2); 

        // Check header
        const charT *ph = fromHexStr.c_str();
        if ((*ph++ != '0') 
            || (*ph++ != 'x') 
            || (*ph++ != '0') 
            || (*ph++ != '1'))
            WarThrow(WarError(WAR_ERR_INVALID_ARGUMENT), NULL);

        vector<char> encrypted_bytes(bytes_to_decrypt);
        byteptr_t encr_value = (byteptr_t)&encrypted_bytes[0];

        // Decode the hex string
        for(unsigned int index = 0
            ; index < bytes_to_decrypt
            ; index++, encr_value++)
        {
            *encr_value = ((Atoh(*ph++) << 4) & 0xf0)
                | (Atoh(*ph++) & 0x0f);
        }

        encr_value = (byteptr_t)&encrypted_bytes[0];
        buffer_t decr_buf;
        toPlainStr.resize(bytes_to_decrypt / sizeof(TCHAR));
        byteptr_t plain_value = (byteptr_t)&toPlainStr[0];

        DecryptBytes(decr_buf, encr_value, bytes_to_decrypt);
        decr_buf.resize(decr_buf.size() + sizeof(TCHAR));
        charT *term_p = (charT *)&decr_buf[0];
        term_p[(decr_buf.size() / sizeof(TCHAR)) - 1] = 0;
        toPlainStr = (const charT *)&decr_buf[0];
        memset(&decr_buf[0], 0, decr_buf.size());
    }

    /* Low-level encrypt function. Block cipher. */
    void EncryptBytes(buffer_t& toBuf, 
        const byteptr_t fromBuf,
        const size_t bufferLength)
        const throw(WarException);

    /* Low-level Decrypt function. Block cipher.*/
    void DecryptBytes(buffer_t& toBuf, 
        const byteptr_t fromBuf,
        const size_t bufferLength)
        const throw(WarException);

    // CALLBACK
    // ACCESS
    // INQUIRY
    
protected:
private:
    inline unsigned char Atoh(unsigned int val)
        const throw(WarException)
    {
        if ((val >= '0') && (val <= '9'))
            return val - '0';
        if ((val >= 'a') && (val <= 'f'))
            return (val - 'a') + 10;
        if ((val >= 'A') && (val <= 'F'))
            return (val - 'A') + 10;
        WarThrow(WarError(WAR_ERR_INVALID_ARGUMENT), NULL);
    }

    passwd_t mPasswd;
};

/* INLINE METHODS */

/* EXTERNAL REFERENCES */

#endif /* __cplusplus */

/****************** END C++ spesific ******************/

#endif /* WAR_CRYPTO */

#endif  /* WAR_CRYPT_TEXT_H_ */