Dual Encryption Method for File Security

Lots of important, confidential and personal information are stored on the computer and sent on the internet need to be protected. Cryptography is one of technique to protect the file. This research proposes a cryptography method by combining the RSA algorithm and the RC4 algorithm. The power of the RSA method dependent on the key quality, which is obtained from the computation of two different prime numbers of p and q. The encryption result can encrypt the file byte but beyond the limit of the byte. RSA algorithm needs to be modified, so the key is more various and works on file byte. Encrypt file from RSA algorithm, combined with RC4 algorithm to get the higher security of file. To test the performance of the proposed algorithm, entropy measuring, avalanche effect counting, and bit error ratio (BER) measuring, and time required for the computation process were performed. Based on the proposed method, proved that file security has improved because the testing method produces a satisfying result.