Compute a hash value from a BDL string

How to compute a hash value of a BDL string using the security.Digest API.

Program Example

This retrieves the hash value from the signature and returns it. The computed hash value is encoded in Base64, so you may have additional conversion to do.

Program example ComputeHash.4gl :

IMPORT SECURITY

MAIN

  DEFINE result STRING

  IF num_args() != 2 THEN
    DISPLAY "Usage: ComputeHash <string> <hashcode>"
    DISPLAY "  string: the string to digest"
    DISPLAY "  hashcode: SHA1, SHA512, SHA384, SHA256, SHA224, MD5"
  ELSE
    LET result = ComputeHash(arg_val(1), arg_val(2))
    IF result IS NOT NULL THEN
      DISPLAY "Hash value is: ",result
    ELSE
      DISPLAY "Error"
    END IF
  END IF

END MAIN

FUNCTION ComputeHash(toDigest, algo)

  DEFINE toDigest, algo, result STRING
  DEFINE dgst security.Digest

  TRY
    LET dgst = security.Digest.CreateDigest(algo)
    CALL dgst.AddStringData(toDigest)
    LET result = dgst.DoBase64Digest()
  CATCH
    DISPLAY "ERROR : ", status, " - ", sqlca.sqlerrm
    EXIT PROGRAM(-1)
  END TRY

  RETURN result
END FUNCTION

Example execution:

$ fglrun ComputeHash "Hello World" SHA1

$ Hash value is: Ck1VqNd45QIvq3AZd8XYQLvEhtA=