Hash Data column size

Mon, 01 Jan 0001 00:00:00 +0000

A hash value is always 160 bits / 20 bytes (SHA1) or 256 bits / 32 bytes (SHA256) long regardless of what data it’s calculated on. Basically you should have a table with a binary column of 20 bytes or 32 bytes for the hash value.

Here is an example of an Oracle table with hash value instead of name:

CREATE TABLE NAMETABLE ( ident NUMBER PRIMARY KEY, 
 name RAW(32));

Using Hashing Triggers and View

Mon, 01 Jan 0001 00:00:00 +0000

Oracle example:

CREATE OR REPLACE TRIGGER SCOTT.NAMETABLE_INS
INSTEAD OF INSERT ON SCOTT.NAMETABLE
FOR EACH ROW
DECLARE
NAME_ RAW(2000) := NULL;

BEGIN
 **NAME\_:=PTY.INS\_HASH\_VARCHAR2\('HashDE', :new.NAME, 0\)**;

 INSERT INTO SCOTT.NAMETABLE_ENC(IDENT, NAME)
 VALUES(:new.IDENT, NAME_);
END;


CREATE OR REPLACE TRIGGER SCOTT.NAMETABLE_UPD
INSTEAD OF UPDATE ON SCOTT.NAMETABLE
FOR EACH ROW
DECLARE
NAME_ RAW(2000) := NULL;

BEGIN
 **PTY.SEL\_CHECK\('HashDE'\);

 NAME\_:=PTY.UPD\_HASH\_VARCHAR2\('HashDE', :new.NAME, 0\)**;

 IF: old.IDENT = :new.IDENT THEN
 UPDATE NAMETABLE_ENC SET 
 NAME= NAME_,
 WHERE IDENT=:old.IDENT;
 ELSE
 UPDATE NAMETABLE_ENC SET 
 IDENT=:new.IDENT, 
 NAME= NAME_,
 WHERE IDENT=:old.IDENT;
 END IF;
END;

The view selects the hash value directly from the table instead of running a decrypt function. To make this work as a normal trigger/view solution, the binary data type is cast into the original data type. In Oracle it should be VARCHAR2. The data type must be cast to insert data through the view as usual.

Hashing Functions and Examples on

Hash Data column size

Using Hashing Triggers and View