/*****************************************************************************

 Advanced Encryption Standard (AES) Include Header for 
   cipher feeback (CFB) mode

****************************************************************************
 FileName:      AES_CFB.h
 Dependencies:  AES.h
 Processor:		PIC24F, PIC24H, dsPIC30F, or dsPIC33F
 Compiler:		MPLAB C30 2.02 or later
 Linker:			MPLAB LINK30 2.02 or later
 Company:		Microchip Technology Incorporated

 Software License Agreement

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 (the “Company”) for its PICmicro® Microcontroller is intended and
 supplied to you, the Company’s customer, for use solely and
 exclusively on Microchip PICmicro Microcontroller products. The
 software is owned by the Company and/or its supplier, and is
 protected under applicable copyright laws. All rights are reserved.
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 license.

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 by Microchip and is protected under applicable copyright laws.  
 All rights reserved.

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 INDEMNITY OR CONTRIBUTION, OR OTHER SIMILAR COSTS. 

 Rev    Comment
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 v1.0   Original release - released with AN1044

 v2.0   Updated to support 192-bit and 256-bit modes.  API change to be
        compatible with PIC32 implementation.  This increases RAM usage but
        decreases the decode time.
****************************************************************************/
#ifndef AES_CFB_H
#define AES_CFB_H

// ****************************************************************************
// ****************************************************************************
// Section: Includes
// ****************************************************************************
// ****************************************************************************

#include <GenericTypeDefs.h>

// ****************************************************************************
// ****************************************************************************
// Section: Constants & Data Types
// ****************************************************************************
// ****************************************************************************

/* AES_CFB_STATE_DATA, *P_AES_CFB_STATE_DATA

  Summary:
    State information that must be maintained between blocks and initialization
    data.

  Description:
    The AES_CFB_STATE_DATA structure contains state information that needs to be
    retained between blocks of CFB data.  This structure is also used to pass
    some initialization data to the first block of a new stream.
*/
typedef struct
{
    /* The initialization vector must be loaded before the first call to the 
       encrypt or decrypt functions.  After that point this variable should
       not be touched.  This buffer is used to hold intermediate data. */
    UINT8 __attribute__((aligned)) initial_vector[16];

    /* The number of bytes left in the key stream before a new block encryption
       needs to occur */
    UINT8 bytes_in_buffer;

} AES_CFB_STATE_DATA, *P_AES_CFB_STATE_DATA;

// *****************************************************************************
// *****************************************************************************
// Section: AES Interface Routines
// *****************************************************************************
// *****************************************************************************

/*******************************************************************************
  Function:  void AESCFBEncrypt(	UINT8 * cipher_text,
                                    UINT8 * plain_text, 
									UINT32 num_bytes, 
                                    void* round_keys,
									AES_CFB_STATE_DATA *p_cfb_state_data,
                                    UINT32 options
								);

  Summary:
    Encrypts a specified amount of data using cipher feedback (CFB) mode.

  Description:
    Encrypts a specified amount of data using cipher feedback (CFB) mode.

  Precondition:
    * p_cfb_state_data->intial_vector must be populated with the initialization vector before the first call of this function on a new data stream.
    * p_cfb_state_data->round_keys must be initialized to point to the round_keys before the first call of this function on a new data stream.
    * round_keys must be properly generated using AESCreateRoundKeys().
  Parameters:
    cipher_text      - [out] pointer to the buffer where the encrypted data sould reside.  It must also be the same length as the plain_text buffer.
    plain_text       - [in]  pointer to the data that needs to be encrypted.
    num_bytes        - [in]  the number of bytes in the plain_text and cipher_text buffers
    round_keys       - [in]  pointer to the round key buffer that will be used
                       for this encryption cycle.
    p_cfb_state_data - [in]  pointer to an instance of the AES_CFB_STATE_DATA for this stream.  The first call of this function should have the p_cfb_state_data->initial_vector set to the initialization vector.
    options          - [in]  Set of options that are ORed together (e.g. - AES_CIPHER_TEXT_POINTER_ALIGNED | AES_STREAM_START).  Valid options are\: 
                            * AES_STREAM_START
                            * AES_STREAM_COMPLETE
                            * AES_STREAM_CONTINUE
                            * AES_CIPHER_TEXT_POINTER_ALIGNED
                            * AES_PLAIN_TEXT_POINTER_ALIGNED
  Returns:
    None

  Example:
    <code>
    //Example variables.  The key and initialization vector information
    //  should be customized for the target application.
    static const UINT8 AESKey128[]              = { 0x95, 0xA8, 0xEE, 0x8E,
                                                    0x89, 0x97, 0x9B, 0x9E, 
                                                    0xFD, 0xCB, 0xC6, 0xEB, 
                                                    0x97, 0x97, 0x52, 0x8D
                                                  };
    static const UINT8 initialization_vector[]  = { 0x00, 0x01, 0x02, 0x03, 
                                                    0x04, 0x05, 0x06, 0x07, 
                                                    0x08, 0x09, 0x0A, 0x0B, 
                                                    0x0C, 0x0D, 0x0E, 0x0F
                                                  };
    AES_ROUND_KEYS_128_BIT round_keys;
    AES_CFB_STATE_DATA current_stream;
    
    //Create the round keys.  This only needs to be done once for each key.
    //  This example is here for completeness.
    AESCreateRoundKeys(     &round_keys,
                            AESKey128,
                            AES_KEY_SIZE_128_BIT
                       );
    
    //Before the first call of AESCFBEncrypt() for a stream of data, the
    //  p_cfb_state_data->initial_vector must be loaded with the initialization
    //  vector information for that specific stream of data.
    memcpy(current_stream.initial_vector,initialization_vector,16);

    //Encrypt 128 bytes of of the current stream.  The num_bytes field must
    //  be a multiple of 16 unless the options field specifies that it is the
    //  end of the stream.
    AESCFBEncrypt(  cipher_text,
                    plain_text,
                    128,                    //num_bytes
                    &round_keys,
                    &current_stream,
                    AES_STREAM_START,       //options
                 );
    
    //At some point later we need to encrypt the rest of the stream.  The
    //  entire stream could have been encrypted in the first call if it was all
    //  available at the time.  Otherwise it can be done in sections, like this
    //  example.
    
    //Encrypt the remaining data of this stream.
    AESCFBEncrypt(  cipher_text_part2,
                    plain_text_part2,
                    53,                                     //num_bytes
                    &round_keys,
                    &current_stream,
                    AES_PAD_NULLS | AES_STREAM_COMPLETE     //options
                 );
    </code>

 *****************************************************************************/
void AESCFBEncrypt(UINT8 * cipher_text, UINT8 * plain_text, UINT32 num_bytes, void * round_keys, AES_CFB_STATE_DATA *p_cfb_state_data, UINT32 options);

/*******************************************************************************
  Function:  void AESCFBDecrypt(	UINT8 * plain_text,
									UINT8 * cipher_text, 
									UINT32 num_bytes, 
                                    void * round_keys,
									AES_CFB_STATE_DATA *p_cfb_state_data,
                                    UINT32 options
								);

  Summary:
    Decrypts a specified amount of data using cipher feedback (CFB) mode.

  Description:
    Decrypts a specified amount of data using cipher feedback (CFB) mode.

  Precondition:
    Round keys must be create by AESCreateRoundKeys before calling this routine.
    p_cfb_state_data->intial_vector must be populated with the initialization vector before the first call of this function on a new data stream.

  Parameters:
    plain_text       - [out] pointer to the buffer where the decrypted data sould reside.  This buffer must be a muliple of 16 bytes and must be equal to or larger than the cipher_text buffer.
    cipher_text      - [in]  pointer to the data that needs to be decrypted.
    num_bytes        - [in]  the number of bytes in the cipher_text buffer
    round_keys       - [in]  pointer to the round key buffer that will be used
                             for this encryption cycle.
    p_cfb_state_data - [in]  pointer to an instance of the AES_CFB_STATE_DATA for this stream.  The first call of this function should have the p_cfb_state_data->initial_vector set to the initialization vector.
    options          - [in]  Set of options that are ORed together (e.g. - AES_PAD_NONE | AES_STREAM_START).  Valid options are\: 
                            * AES_STREAM_START
                            * AES_STREAM_COMPLETE
                            * AES_STREAM_CONTINUE
                            * AES_CIPHER_TEXT_POINTER_ALIGNED
                            * AES_PLAIN_TEXT_POINTER_ALIGNED
  Returns:
    None

  Example:
    <code>
    //Example variables.  The key and initialization vector information
    //  should be customized for the target application.
    static const UINT8 AESKey128[]              = { 0x95, 0xA8, 0xEE, 0x8E,
                                                    0x89, 0x97, 0x9B, 0x9E, 
                                                    0xFD, 0xCB, 0xC6, 0xEB, 
                                                    0x97, 0x97, 0x52, 0x8D
                                                  };
    static const UINT8 initialization_vector[]  = { 0x00, 0x01, 0x02, 0x03, 
                                                    0x04, 0x05, 0x06, 0x07, 
                                                    0x08, 0x09, 0x0A, 0x0B, 
                                                    0x0C, 0x0D, 0x0E, 0x0F
                                                  };
    AES_ROUND_KEYS_128_BIT round_keys;
    AES_CFB_STATE_DATA current_stream;
    
    //Create the round keys.  This only needs to be done once for each key.
    //  This example is here for completeness.
    AESCreateRoundKeys(     &round_keys,
                            AESKey128,
                            AES_KEY_TYPE_128_BIT
                       );
    
    //Before the first call of AESCFBDecrypt() for a stream of data, the
    //  p_cfb_state_data->initial_vector must be loaded with the initialization
    //  vector information for that specific stream of data.
    memcpy(current_stream.initial_vector,initialization_vector,16);
    
    //Decrypt 128 bytes of of the current stream.  The num_bytes field must
    //  be a multiple of 16 unless the options field specifies that it is the
    //  end of the stream.
    AESCFBDecrypt(  plain_text,
                    cipher_text,
                    128,                    //num_bytes
                    &round_keys,
                    &current_stream,
                    AES_STREAM_START,       //options
                 );
    
    //At some point later we need to decrypt the rest of the stream.  The
    //  entire stream could have been decrypted in the first call if it was all
    //  available at the time.  Otherwise it can be done in sections, like this
    //  example.
    
    //Decrypt the remaining data of this stream.
    AESCFBDecrypt(  plain_text_part2,
                    cipher_text_part2,
                    53,                     //num_bytes
                    &round_keys,
                    &current_stream,
                    AES_STREAM_COMPLETE     //options
                 );
    </code>

 *****************************************************************************/
void AESCFBDecrypt(UINT8 * plain_text, UINT8 * cipher_text, UINT32 num_bytes, void * round_keys, AES_CFB_STATE_DATA *p_cfb_state_data, UINT32 options);

#endif //AES_CFB_H
