Implementation SHA512 Hash Function And Boyer-Moore String Matching Algorithm For Jpeg/exif Message Digest Compilation

Abstract

Security information method for JPEG/exif documents generally aims to prevent security attacks by protecting documents with password and watermark. Both methods cannot be used to determine the condition of data integrity at the detection stage of the information security cycle. Message Digest is the essence of a file that has a function as a digital fingerprint to represent data integrity. This study aims to compile digital fingerprints to detect changes that occurred in JPEG / exif documents in information security. The research phase consists of five stages. The first stage, identification of the JPEG / exif document structure conducted using the Boyer-Moore string matching algorithm to find JPEG/exif segments location. The Second stage is segment content acquisition, conducted based on segment location and length obtained. The Third step, computing message digest for each segment using SHA512 hash function. Fourth stage, JPEG / exif document modification experiments to identified affected segments. The fifth stage is selecting and combining the hash value of the segment into the message digest. The obtained result shows the message digest for JPEG/exif documents composed of three hash values. The SOI segment hash value used to detect modifications for JPEG to png conversion and image editing. The APP1 hash value used to detect metadata editing. The SOF0 hash values use to detect modification for image recoloring, cropping and resizing — the combination from three hash values as JPEG/exif’s message digest.

Comparison of search algorithms in Javanese-Indonesian dictionary application

“…The Boyer-Moore algorithm becomes one of the most frequently used string-lookup algorithms or is implemented into a document or data search feature in the database because it is considered the most efficient in typical applications and is best compared to other string search algorithms [24,25]. The Boyer-Moore algorithm starts matching a character from the right direction of the pattern or the right-to-left direction of the text [16,26,27]. Adequately systematic, the stages that the Boyer-Moore algorithm performed at the time of matching the following strings [26,28]: a. Boyer-Moore's algorithm starts matching the pattern at the beginning of the text.…”

Similarity Identification Based on Word Trigrams Using Exact String Matching Algorithms

“…The Horspool Boyer-Moore is one of the simplified versions of the Boyer-Moore algorithm [4], [14]. The Boyer-Moore algorithm is a character-based algorithm that applies a heuristic approach in the string matching process [4], [13], [15]. Pattern matching in this algorithm starts from right to left with two heuristic approaches wrong character heuristic and good suffix heuristic.…”