pascal.txt

一个我自用的BLOWFISH源码VC++环境.有不完善的地方还请各位大侠指点~!

                                    BF-SDK
                                    ~~~~~~
                                     V1.1

                               Pascalinterface
                               ~~~~~~~~~~~~~~~

                    (c) 1996 Cedric Reinartz & Markus Hahn


This documentation helps you to use the pascal interface in your own 
program. You need to include the unit BLOWFISH.TPU in your programm. 
It should be sufficient to use the provided one which was compiled with
the default parameters. For changing the parameters please see ASM.TXT.

The following type declarations are made in BLOWFISH.TPU:

  ULONG = Longint;     { unsigned 32bit }
  UINT  = Word;        { unsigned 16bit }
  UCHAR = Byte;        { unsigned 8bit }
  BOOL  = Word;        { 16bit boolean }
  P_UCHAR_Buffer = ^T_UCHAR_Buffer;
  T_UCHAR_Buffer = array[0..MAXDATA-1] of UCHAR;
  P_UINT_Buffer  = ^T_UINT_Buffer;
  T_UINT_Buffer  = array[0..(MAXDATA div 2)-1] of UINT;
  P_ULONG_Buffer = ^T_ULONG_Buffer;
  T_ULONG_Buffer = array[0..(MAXDATA div 4)-1] of ULONG;

You need this declarations to understand and use the following 
descriptions. See also PAS_DEMO.PAS for reference.



Functions
~~~~~~~~~

Blowfish_Init(pKey : P_UCHAR_Buffer; unKeySize : UINT);

 Function   : Initialises the Boxes
 Argument   : Pointer to the Password (which is NOT a string)
              Length of the Password
 Return     : none
 Description: A Password with a maximum of 56 Bytes is used to encrypt the
              Boxes. These encrypted boxes are vital for the further encryption
              process with Blowfish_(CBC)Encrypt and Blowfish_(CBC)Decrypt.
              If you want to change the password at runtime you have to restore
              the original contents of the boxes before you can use this
              function again (See Blowfish_GetBoxes and Blowfish_SetBoxes).

-------------------------------------------------------------------------------

Blowfish_WeakKey : BOOL;

 Function   : Test if the generated Boxes are weak
 Argument   : none
 Return     : Status (1=weak, 0=good)
 Description: After "Blowfish_InitCrypt" you should test the Boxes with this 
              function. If they provide a weakness which a cryptoanalyst could
              use to break the cipher a "1" is returned. In this case you
              should reload the original boxes and let the user choose a
              different password.

-------------------------------------------------------------------------------

Blowfish_ECBEncrypt(pBuffer : P_ULONG_Buffer; unCount : UINT);

 Function   : Encrypts a plaintext string using the ECB method
 Argument   : Pointer to the plaintext
              Length of the plaintext
 Return     : none
 Description: This function encrypts (multiple) blocks of 8 Bytes of plaintext
              using the ECB method (blocks are not chained). The generated 
              ciphertext will overwrite the plaintext. Thus the plaintext-
              pointer will point to the ciphertext after the encryption. The 
              length of the plaintext must be a multiple of 8. If it is not,
              plaintext bytes will be left at the end of the ciphertext.

-------------------------------------------------------------------------------

Blowfish_ECBDecrypt(pBuffer : P_ULONG_Buffer; unCount : UINT);

 Function   : Decrypts a ciphertext string using the ECB method
 Argument   : Pointer to the ciphertext
              Length of the ciphertext
 Return     : none
 Description: This function decrypts (multiple) blocks of 8 Bytes of cipher-
              text using the ECB method (blocks are not chained). The generated
              plaintext will overwrite the ciphertext. Thus the ciphertext-
              pointer will point to the plaintext after the decryption. The 
              length of the ciphertext must be a multiple of 8. If it is not, 
              ciphertext bytes will be left at the end of the plaintext.

-------------------------------------------------------------------------------

Blowfish_CBCEncrypt(pBuffer : P_ULONG_Buffer; unCount : UINT;
                              var ulCBCLeft, ulCBCRight : ULONG);

 Function   : Encrypts a plaintext string using the CBC method
 Argument   : Pointer to the plaintext
              Length of the plaintext
              Lower part of the IV
              Upper part of the IV
 Return     : none
 Description: This function encrypts (multiple) blocks of 8 Bytes of plaintext
              using the CBC method (blocks are chained using an initialisation
	      vector IV). The generated ciphertext will overwrite the plain-
	      text. Thus the plaintext-pointer will point to the ciphertext 
	      after the encryption. The length of the plaintext must be a
	      multiple of 8. If it is not, plaintext bytes will be left at the
	      end of the ciphertext. The IV must not be secret. For different
	      encryptions you can choose the same IV but if possible you should
	      use different ones to improve security. 
	      Note: you need the original IV for decryption.


-------------------------------------------------------------------------------

Blowfish_CBCDecrypt(pBuffer : P_ULONG_Buffer; unCount : UINT;
                              var ulCBCLeft, ulCBCRight : ULONG);

 Function   : Decrypts a ciphertext string using the CBC method
 Argument   : Pointer to the ciphertext
              Length of the ciphertext
              Lower part of the IV
              Upper part of the IV
 Return     : none
 Description: This function decrypts (multiple) blocks of 8 Bytes of ciphertext
              using the CBC method (blocks are chained using an initialisation
	      vector IV). The generated plaintext will overwrite the cipher-
	      text. Thus the ciphertext-pointer will point to the plaintext 
	      after the decryption. The length of the ciphertext must be a
	      multiple of 8. If it is not, ciphertext bytes will be left at the
	      end of the plaintext.
	      Note: The IV is the same used on encryption.

-------------------------------------------------------------------------------

Blowfish_Done;

 Function   : Clears the Boxes
 Argument   : none
 Return     : none
 Description: Clears the contents of the P- and S-Boxes. This should be used
              before you exit your program to make sure that no one can get
              your Key.

-------------------------------------------------------------------------------

Blowfish_SetRounds(Rounds : UINT): UINT;

 Function   : Set number of rounds. Returns number of rounds.
 Argument   : # of rounds = 16, 32 or 2-32. See variable RNDS in ASM.TXT
 Return     : number of rounds
 Description: You always have to give a Argument. If BFENG386.ASM was compiled
              with "rnds equ 3" you are able to set the number of rounds 
              between 2 and 32. This function always returns the number of
              rounds actual used. If you supply an invalid argument nothing
              is changed and the currently used number of rounds is returned.
              For more details see variable RNDS in ASM.TXT.

-------------------------------------------------------------------------------

Blowfish_GetBoxes(pBuffer : P_ULONG_Buffer);

 Function   : Copies the actual P- and S-Boxes to a user buffer
 Arguments  : Pointer to the user buffer
 Return     : none
 Description: Use this to save the original Boxes. If you want to change the
              Password at runtime you have to restore these Boxes first. 
              You can also save the encrypted Boxes and restore them if needed.
              In this way you are able to swap Passwords at high speed.
              The needed buffer size is 1042 for rnds=1 and 1058 for rnds=2 or 
              rnds=3 (see ASM.TXT for the meaning of "rnds").

-------------------------------------------------------------------------------

Blowfish_SetBoxes(pBuffer : P_ULONG_Buffer);

 Function   : Copies a user buffer to the P- and S-Boxes
 Arguments  : Pointer to the user buffer
 Return     : none
 Description: Use this to restore the Boxes with previously saved ones.
              See description of "Blowfish_GetBoxes".

-------------------------------------------------------------------------------

Blowfish_GetBoxPointer : Pointer;

 Function   : Returns a Pointer to the beginning of PBox in DX:AX
 Arguments  : none
 Return     : pointer to the Boxes
 Description: For a reason I do not know the pointer is sometimes wrong,
              so verify this! Normaly there is no need to use this function.


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