INTRODUCTION

The transmission of information through an electronic network requires a process that ensures safety and integrity of the transmitted information [1] [2] [3]. The information must remain confidential during delivery and must continue to be original upon receipt at destination [3] [4] [5], to fulfill this condition, the process of encryption and decryption of information to be sent [6]. Encryption is made at the time of transmission by converting the original information into encrypted information while decryption process at the moment of receipt by converting encrypted information into original information [5] [7], the information transmitted during the sending process already encrypted so the unauthorized parties cannot know the original information. The recipient can only know the original information by using a secret key [7] [8].
In addition to information security, now users are also trying to reduce the size of data (compression of data). The purpose of this compression is to speed up the transmission of data or information [9]. Data compression also aims to reduce the size of data and can be stored on storage media that has a relatively small size due to security and speed is important in communication using computers and networks [9] [10].
Many algorithms that can be used to perform data security such as Twofish, IDEA, MMB, GOST, AES and Blowfish, Blowfish algorithm is an algorithm that uses in this research. Blowfish algorithm is a modern symmetry algorithm by using S-Box table for the key as a decryption encryption process [11], the compression process also has a variety of algorithms used, one of which is the algorithm LZW. The LZW algorithm is a lossless compression algorithm and uses the dictionary method [9]. The compression principle will occur when the bit value for the specified dictionary replaces the sequence of characters or strings formed while in the decompression process to obtain the same result with the file before compression LZW recreates the dictionary during the decompression process [9] [12] [13] [15]. The combination of Blowfish and Lempel-Ziv-Welch (LZW) algorithms in this study is expected to be a good security solution with compressed ciphertext results so that ciphertext will be much safer and with a smaller message length.

METHODOLOGY

Encryption is a crucial thing in cryptography which is the security of data sent secreted [8]. The original message is called plaintext which transformed into codes that are not understood [1] [6] [8]. Encryption could be described as a cipher or code. Unlike the case with decryption can be interpreted as a process to convert the ciphertext into plaintext [1] [2] [3], the process of encryption decryption could be described as below: