Today, lossless data compression (LDC) used on personal computers to increase their storage capacity. If we take an example, we can get double the normal capacity by using LDC algorithms. This is necessary to indicate compressed data of variable length in a fixed length block with little fragmentation as much as possible. Binary Coded Decimal is a digital encoding system in which each decimal number is represented in four bits binary. It represents the decimal range 0 through 9. Unpacked BCD consumes a byte for each represented numeral, but in packed BCD typically consumes a single byte for two numerals. Because we can represent a BCD number by using only four bits, so another four bits are free, so by using packed BCD technique we can store another numeral in remaining four bits. In this paper, we are going to apply security mechanism to the packed BCD numerals.