Cryptography
- 2. INTRODUCTION the practice and study of techniques for constructing and analyzing protocols that overcome the influence of adversaries and which are related to various aspects in information such as data confidentiality data integrity and authentication Applications of cryptography include ATM cards, computer passwords, and electronic commerce
- 3. REQUIREMENTS OF A SECURE NETWORKS Authentication: The process of proving one's identity. (The primary forms of host-to-host authentication on the Internet today are name-based or address-based, both of which are notoriously weak.) Privacy/confidentiality: Ensuring that no one can read the message except the intended receiver. Integrity: Assuring the receiver that the received message has not been altered in any way from the original. Non-repudiation: A mechanism to prove that the sender really sent this message
- 6. COMPUTER ERA The development of digital computers and electronics after WWII made possible much more complex ciphers. Furthermore, computers allowed for the encryption of any kind of data Represent able in any binary format, unlike classical ciphers which only encrypted written language texts; this was new and significant. Computer use has thus supplanted linguistic cryptography, both for cipher design and cryptanalysis.
- 8. SECRET KEY CRYPTOGRAPHY Uses a single key for both encryption and decryption With this type of cryptography, both the sender and the receiver know the same secret code, called the key This method works well if you are communicating with only a limited number of people, but it becomes impractical to exchange secret keys with large numbers of people. In addition, there is also the problem of how you communicate the secret key securely.
- 9. PUBLIC KEY CRYPTOGRAPHY Uses one key for encryption and another for decryption. uses a pair of keys for encryption and decryption The public key can be freely distributed without compromising the private key, which must be kept secret by its owner.
- 10. HASH FUNCTION CRYPTOGRAPHY A hash function is any algorithm or subroutine that maps large data cells, called keys, to smaller data sets. For example, a single integer can serve as an index to an array. Hash functions are mostly used to accelerate table lookup or data comparison tasks such as finding items in database, detecting duplicated or similar records in a large file, finding similar stretches in DNA sequences, and so on.
- 11. PURPOSE OF CRYPTOGRAPHY Cryptography is the science of writing in secret code and is an ancient art; the first documented use of cryptography in writing dates back to circa 1900 B.C. It provides more efficient way of security by encrypting our data. It allows the sender and receiver to communicate more securily It is used in armies from older ages to modern ages. It allows the armies for exchanging information in the efficient and secured way.
- 12. CONCLUSION Some experts argue that cryptography appeared spontaneously sometime after writing was invented, with applications ranging from diplomatic missives to war-time battle plans. It is no surprise, then, that new forms of cryptography came soon after the widespread development of computer communications. In data and telecommunications, cryptography is necessary when communicating over any untrusted medium, which includes just about any network, particularly the Internet.