Cryptography has several important aspects in supporting the security of the data, which guarantees confidentiality, integrity and the guarantee of validity (authenticity) data. One of the public-key cryptography is the RSA cryptography. The greater the size of the modulus n, it will be increasingly difficult to factor the value of n. But the flaws in the RSA algorithm is the time required in the decryption process is very long. Theorem used in this research is the Chinese Remainder Theorem (CRT). The goal is to find out how much time it takes RSA-CRT on the size of modulus n 1024 bits and 4096 bits to perform encryption and decryption process and its implementation in Java programming. This implementation is intended as a means of proof of tests performed and generate a cryptographic system with the name “RSA and RSA-CRT Text Security”. The results of the testing algorithm is RSA-CRT 1024 bits has a speed of approximately 3 times faster in performing the decryption. In testing the algorithm RSA-CRT 4096 bits, the conclusion that the decryption process is also effective undertaken more rapidly. However, the flaws in the key generation process and the RSA 4096 bits RSA-CRT is that the time needed is longer to generate the keys. Keywords: Encryption and Decryption, RSA, RSA-CRT, 1024 bit and 4096 bit

http://www.cscjournals.org/manuscript/Journals/IJCSS/Volume10/Issue5/IJCSS-1289.pdf