Penyandian File Gambar dengan Metode Substitusi dan Transposisi

Abstract

Cryptography is a science which studying about safety of messages, so it makes the
messages cannot be read by unauthorized persons. Cryptography have two kinds of algorithm
first is encryption algorithm, that is algorithm altering plaintext become the ciphertext, and the
second is decryption algorithm that is algorithm altering ciphertext become the plaintext,  that
conducive of message can only be made and read by authorized persons. Plaintext represent the
message able to be read,  while ciphertext is message which have pass by the encryption process,
so that order the ciphertext difficult to be translated or read. And method of substitution and
transpotition method are some of conventional technique able to be used to protect the pictures
files, so that produce the pictures files which do not easy to to be read. The conventional
technique basically use a same key to do the encryption  and decryption process.