Cryptography (or cryptology) is the practice and study of hiding secret information by encryption. Encryption is the conversion of data into a form, called a ciphertext. Decryption is the reverse, in other words, moving from the unintelligible ciphertext back to plaintext. Modern cryptography intersects the disciplines of mathematics, computer science, and electrical/electronics engineering. Applications of cryptography include credit cards, laptop data security, computer passwords, computer network security solutions & software systems, and online/internet data security in electronic commerce.

Cryptographic techniques are needed for privacy and authentication of digital data. There are two types of encryption algorithms used in cryptography, namely Symmetric-Key Encryption (also known as symmetric-key encryption, single-key encryption, one-key encryption and private key encryption) and Asymmetric Encryption (Public Key Encryption).

Cryptanalysis is the study of methods for obtaining the meaning of encrypted information without access to the key normally required to do so; i.e., it is the study of how to crack encryption algorithms or their implementations.

Applications of Cryptography (Encryption & Decryption Algorithms)

• Secure messaging/mail
• Secure network communications
• Network authentication
• Electronic voting
• Electronic notary
• Digital money (digital wallet) or Electronic Cashcards (credit cards, ATM/debit cards)
• Data distribution
• Credentialing Systems
• Electronic Signatures
• Systems Using Changing Keys
• Covert communication using Steganogrphy
• Security mechanisms for secure ID cards, smartcards, biometrics

Advantages of Cryptography (Encryption & Decryption Algorithms)

• Message privacy
• Sender and recipient authentication
• Non-repudiation
• Anonymity
• Fairness
• Accountability
• Untraceability
• Dividability
• Transferability
• Off-line operations
• Universality
• Data distribution operation (TV, CD-ROM)
• Selective reception
• Secrecy in Transmission
• Secrecy in Storage
• Integrity in Storage
• Authentication of Identity