HMAC

*
* All this is based on the examples shown on the Wikipedia HMAC page
*
X.I.PAD = OCONV("36", "MCXD") ;** x36 = DECIMAL 54
X.O.PAD = OCONV("5C", "MCXD") ;** x5C = DECIMAL 92
X.THE.BLOCK.SIZE=64
X.THE.KEY=""
FOR I = 255 TO 250 STEP -1
  X.THE.KEY := CHAR(I)
NEXT I
X.TO.BE.HASHED="input"
X.I.KEY.FINAL=""
X.O.KEY.FINAL=""
IF X.THE.KEY = "" THEN
  X.THE.KEY = STR(CHAR(0) , X.THE.BLOCK.SIZE)
END ELSE
  IF LEN(X.THE.KEY) > X.THE.BLOCK.SIZE THEN
    X.HASHED.VAL=""
    X.ALGORITHM="MD5"
    X.DATA.LOC=1  ;** Return data in a string (2=to a file)
    X.ERROR.FLAG=DIGEST(X.ALGORITHM, X.THE.KEY, X.DATA.LOC, X.HASHED.VAL)  ;** "DIGEST" command actually does the MD5 hashing
*
    X.HASHED.VAL=OCONV(X.HASHED.VAL,"[[MX0C]]")  ;** convert binary to ascii hex string
    X.HASHED.VAL=DOWNCASE(X.HASHED.VAL)
    X.THE.KEY=X.HASHED.VAL
  END
END
*
FOR I = 1 TO LEN(X.THE.KEY)
  X.DEC.VAL=SEQ(X.THE.KEY[I,1])
  X.I.KEY.FINAL := CHAR(BITXOR(X.DEC.VAL , X.I.PAD))
  X.O.KEY.FINAL := CHAR(BITXOR(X.DEC.VAL , X.O.PAD))
NEXT I
*
FOR I = 1 TO (X.THE.BLOCK.SIZE - LEN(X.THE.KEY))
  X.I.KEY.FINAL := CHAR(BITXOR(0 , X.I.PAD))
  X.O.KEY.FINAL := CHAR(BITXOR(0 , X.O.PAD))
NEXT I
*
X.INNER.HASH = X.I.KEY.FINAL : X.TO.BE.HASHED
X.ERROR.FLAG=0
X.ERROR.MSG=''
*
X.HASHED.VAL=""
X.ALGORITHM="MD5"
X.DATA.LOC=1  ;** Return data in a string (2=to a file)
X.ERROR.FLAG=DIGEST(X.ALGORITHM, X.INNER.HASH, X.DATA.LOC, X.HASHED.VAL)
*
X.OUTER.HASH = X.O.KEY.FINAL : X.HASHED.VAL
X.ERROR.FLAG=0
X.ERROR.MSG=''
*
X.HASHED.VAL=""
X.ALGORITHM="MD5"
X.DATA.LOC=1
X.ERROR.FLAG=DIGEST(X.ALGORITHM, X.OUTER.HASH, X.DATA.LOC, X.HASHED.VAL)
*
X.HASHED.VAL=OCONV(X.HASHED.VAL,"[[MX0C]]")  ;** convert binary to ascii hex string
X.HASHED.VAL=DOWNCASE(X.HASHED.VAL)
*
CRT X.HASHED.VAL

STOP