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: