Matakuliah
Tahun
Versi
: M0284/Teknologi & Infrastruktur E-Business
: 2005
: <<versi/revisi>>
Pertemuan 11
Authentication, Encryption,
Digital Payments, and Digital
Money
1
Learning Objectives
• Understand the importance of
authentication.
• Understand the various encryption
alternatives.
• Differentiate between symmetric and
asymmetric encryption.
2
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”
3
Methods of Encrypting Data
• Translation Table
– Simplest method.
– Easy to program
– Easy to break
– Refinements
• Table rotation
• Using several tables
A
C I
B
C D E
D G A
F
B
G H I
E F H
4
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.
5
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.
6
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
7