1. 1 Pertemuan 11 Authentication, Encryption, Digital Payments, and Digital Money Matakuliah: M0284/Teknologi & Infrastruktur E-Business Tahun: 2005 Versi: >

2. 2 Learning Objectives Understand the importance of authentication. Understand the various encryption alternatives. Differentiate between symmetric and asymmetric encryption.

3. 3 Encryption “Encryption is the conversion of plain text or data into a unintelligible form by means of a reversible translation.” Decryption “The inverse operation to encryption”

4. 4 Methods of Encrypting Data Translation Table –Simplest method. –Easy to program –Easy to break –Refinements Table rotation Using several tables ABCDEFGHI CIDGABEFH

5. 5 Methods of Encrypting Data Word/byte rotation – XOR bit masking –Only computers can do it. –Can be used to detect code alterations through control redundancy check (CRC). –Better method than translation table but still weak.

6. 6 Methods of Encrypting Data Symmetric Key Encryption –Sender and receiver share the same key. –Highly efficient implementation. –Only the key decrypts the message, this assures authentication. –Security is compromised if the key is divulgated.

7. 7 Methods of Encrypting Data Asymmetric Key Encryption Most common Based on RSA Data Security Algorithm. Based on public keys. Composed by two keys, public and private. The public key is published. Private key encrypts the information. Public key decrypts the information. Requires more computation than symmetric method. High Security for short messages