-- Michael D. Schroeder, October 30, 1981  3:11 PM

-- MESA access the DES encryption facilities


DESDefs: DEFINITIONS = BEGIN


  -- Public types and constants

Block: TYPE = ARRAY [0 .. 3] OF UNSPECIFIED;
Key: TYPE = PACKED ARRAY [0 .. 7] OF
                              MACHINE DEPENDENT RECORD[b: [0 .. 127], p: [0 .. 1]];

nullKey: Key = ALL[[b:0, p:0]];


  -- Key generation and conversion

GetRandomKey: PROC RETURNS [Key];

MakeKey: PROC [source: LONG STRING]  RETURNS [Key];

BadKey: ERROR; -- key parity bad


  -- To, From must point to segments containing an integral number of Blocks 
  -- The segments must be totally disjoint or fully congruent!
  -- For speed, try to align to and from segments on quadword boundaries.


  -- Electronic Code Book.
  -- No state kept between 64-bit blocks.

ECBEncrypt: PROC [ key: Key, nBlks: CARDINAL, from, to: LONG POINTER] =
  INLINE {CryptData[@key, nBlks, from, to, encrypt, ecb, NIL, NIL]};

ECBDecrypt: PROC [ key: Key, nBlks: CARDINAL, from, to: LONG POINTER] =
  INLINE {CryptData[@key, nBlks, from, to, decrypt, ecb, NIL, NIL]};


  -- Cipher Block Chaining.
  -- 64-bits of state kept between blocks. 
  -- This state is XOR'd with the next incoming clear text block before encryption.
  -- seed is the 64-bit initial value of this state.

CBCEncrypt: PROC [ key: Key, seed: Block, nBlks: CARDINAL,
        from, to: LONG POINTER]
    RETURNS [newSeed: Block] =
  INLINE {CryptData[@key, nBlks, from, to, encrypt, cbc, @seed, @newSeed];};

CBCDecrypt: PROC [ key: Key, seed: Block, nBlks: CARDINAL,
        from, to: LONG POINTER] 
    RETURNS [newSeed: Block]=
  INLINE {CryptData[@key, nBlks, from, to, decrypt, cbc, @seed, @newSeed];};


  -- ???

CBCCheksum: PROC [key: Key, seed: Block, nBlks: CARDINAL,
        from: LONG POINTER ] RETURNS [Key];



  -- Internal types and procedures

Direction: PRIVATE TYPE = {encrypt, decrypt};
Mode: PRIVATE TYPE = {ecb, cbc};

CryptData: PRIVATE PROC [keyP: POINTER TO Key, nBlks: CARDINAL,
        from, to: LONG POINTER, direction: Direction, mode: Mode,
        seedP, newSeedP: LONG POINTER TO Block];

END. --DESDefs--(635)\f1 99b7B57b5B40b3B119b7B63b12B23b7B46b6B316b10B132b10B343b10B190b10B201b10B