QuickCrypt Library

C++ Interface

CCFBMode::Init

void Init( SL_CIPHER_DIR dir, const unsigned char* pIV, const unsigned char* pKey, unsigned int nKeyLen = DEFAULTKEYSIZE, unsigned int fs = 0 );

void Init( SL_CIPHER_DIR dir, const unsigned char* pIV, unsigned int fs = 0 );

Parameters

dir

    [in] Cipher direction. It can be SLC_ENCRYPT or SLC_DECRYPT.

 pIV

    [in] Pointer to the initialization vector.

 pKey

    [in] Pointer to the secret key.

 nKeyLen

    [in] Length in bytes of the secret key.

 fs

    [in] Feedback size in bytes. By default fs is 0 which means to use the maximum feedback size. This size is the mostly used feedback size.

Remarks

Both member functions initialize the CCFBMode object. A brief description of both of them follows.

• void Init( SL_CIPHER_DIR dir, const unsigned char* pIV, const unsigned char* pKey, unsigned int nKeyLen = DEFAULTKEYSIZE, unsigned int fs = 0 );

Call this member function to initialize the CCFBMode object with the initialization vector pointed by pIV, and the secret key pointed by pKey.

Notes. 

• The first CCFBMode<T>::BLOCKSIZE bytes of the memory buffer pointed by pIV are used as the initialization vector.

• nKeyLen can be CCFBMode<T>::DEFAULTKEYSIZE bytes. For Rijndael (AES) algorithm it can also be 24 or 32 bytes. For Blowfish algorithm it can be in the range 1 through 72 bytes.

• void Init( SL_CIPHER_DIR dir, const unsigned char* pIV, unsigned int fs = 0 );

Call this member function to initialize the CCFBMode object with the initialization vector pointed by pIV without changing the key set by previous initialization. Note that the first CCFBMode<T>::BLOCKSIZE bytes of the memory buffer pointed by pIV are used as the initialization vector.

 

The CCFBMode object is initialized for encryption if dir is SLC_ENCRYPT, or it is initialized for decryption if dir is SLC_DECRYPT.

Example

//Define the key
char key[CDES::DEFAULTKEYSIZE] = 
{
    'p', 'a', 's', 's', 'w', 'o', 'r', 'd'
};

//Define the initialization vector
unsigned char iv[CDES::BLOCKSIZE] = 
{
    0x41, 0x3E, 0xF0, 0xA1, 0xC6, 0x11, 0xE5, 0x50
};

//Instantiate a CCFBMode object that will use DES encryption algorithm  
CCFBMode<CDES> cipher( SLC_ENCRYPT, iv, (const unsigned char*)key );

//...

//Change cipher direction
cipher.Init( SLC_DECRYPT, iv );

CCFBMode Overview   |   Class Members   |   Useful Links

See Also    CCFBMode::Process