GROUP 11 Dhita Puspita Larasati Topan Firmansyah Dimas Kurnia Ayatullah Galih Purwanti Rahma Aprilia Handayani Sindy Wulandari CLASS: 11.2A.05 MAJORS: COMPUTERIZED ACCOUNTING

MEETING 11 CRYPTOGRAPHY CRYPTOGRAPHY

DISCUSSION : Cryptography Cryptography The Concept of Cryptography The Concept of Cryptography Classical Cryptography Classical Cryptography Basic Processes In Cryptography Basic Processes In Cryptography Types Of Cryptography Types Of Cryptography Symmetric Cryptography Symmetric Cryptography Asymmetric algorithms Asymmetric algorithms Hybrid Cryptography Hybrid Cryptography Classification of cryptography Classification of cryptography Criterias Of Cryptography Criterias Of Cryptography Conclusion Conclusion

Cryptography Is ? Cryptography (cryptography) of Greece, consists of two syllables that Crypto and graphia. Crypto meaning hide, whereas graphia means writing. Cryptography is the study of mathematical techniques related to aspects of information security, data confidentiality, the validity of such data, data integrity, and data authentication.But not all aspects of information security can be solved by Cryptography. Cryptography may also be interpreted as a science or art to maintain the security of the message.

The Concept of Cryptography The concept of cryptography has long been used by humans for example in Egypt and Roman civilization, though still very modest. There is also the underlying principles of cryptography, i.e. : Confidelity Confidelity Data integrity Data integrity Authentication Authentication Non-repudiation Non-repudiation

Classical Cryptography In contrast to classical cryptography that focuses the power on confidentiality algorithms used (meaning when the algorithms used were known then the message has been clear "leaked" and its contents can be known by anyone who knows the algorithm), focuses on more modern cryptographic confidentiality keys are used in the algorithms (by the wearer) so that the algorithm can be disseminated to the community without fear of loss of confidentiality for the wearer.

Basic Processes In Cryptography The process of which will be discussed in this article include two basic processes in cryptography, namely : 1.Encryption 2.Depcryption With the same key is used for both the above processes. The used of the same key for both encryption and depcription process is also called the Secret Key, Shared Key or Symetric Key Cryptosystem

Types Of Cryptography Cryptographic algorithm is divided into three sections based on keywords are used: 1.Symmetric Cryptography 2.Asymmetric Cryptography 3.Hybrid Cryptography

Symmetric Cryptography Symmetric cryptography is: code Hill or better known as the Hill cipher is a symmetric key cryptographic algorithms, and is one of the crypto polyalphabetic. Hill cipher was invented by Lester s. Hill in Cryptographic techniques was created with the intention to create ciphers that can not be solved using frequency analysis techniques. In contrast to the caesar cipher, the hill cipher does not replace any of the same alphabet at plainteks with other alphabets on the same cipherteks as using matrix multiplication on basic encryption and decryption. Pros: Operating speed is higher when compared with the asymmetric algorithm. Due to a fairly high speed, it can be used in real-time systems Weaknesses: For each delivery of messages with different user needs different keys as well, so there will be difficulties in the key management. Problems in the delivery of the key itself is called "key distribution problem" Examples of algorithms: Twofish, Rijndael, Camellia

Asymmetric algorithms Asymmetric algorithms (asymmetric algorithm) is an algorithm where the encryption key being used is not the same with the decryption key. The algorithm uses two keys: a public key (the public key) and a private key (the private key). The public key is distributed generally whereas the private key is kept secret by the user. While the public key is known but will be very difficult to know the private key is used. Pros: Security issues on the key distribution can be better The problem of key management is better because fewer number of keys Weaknesses: The speed is lower when compared with symmetric algorithms For the same security level, the key being used longer than symmetric algorithms. Examples of algorithms: RSA, DSA, ElGamal

Hybrid Cryptography Interesting problems in the field of information security is a trade off between speed and convenience. The more secure the more uncomfortable, apply vice versa the more comfortable the more insecure. One example is the field of Cryptography. But this can be overcome by the use of hybrid Cryptography. Hybrid Cryptography is often used because it utilizes the advantages of data- processing speed by symmetric algorithms and ease the transfer of key using an asymmetric algorithm. This has resulted in increased speed without reducing comfort and security. Hybrid cryptographic applications that exist today are generally intended for public use or the mainstream computer users.

Classification of cryptography Classification of cryptographic algorithms based on the length of the data used in a single process: A.Block cipher Algorithm: information/data to be sent in the form of large blocks (for example, 64-bit) where blocks is operated with the same encryption function and will result in confidential information in the blocks of the same size also. Example: RC4, It Seals, A5, The Oryx. B.Stream cipher Algorithm: information/data to be sent in the form of block-operated smaller blocks (bytes or bits), usually one character per unit time-process, using tranformasi encryption that changes every time. For Example: DES, Blowfish, Gost, Idea, RC5, Safer, Square, Twofish, RC6, Loki97.

Criterias Of Cryptography A cryptographic algorithm is said to be safe (computationally secure) when you meet the following three criteria: a)Mathematical Equations that describe the operations of the cryptographic algorithms are very complex so that the algorithm is unlikely be solved in analytic. b)Costs to break ciphertext beyond the value of the information contained in the ciphertext. c)The time required to break ciphertext beyond the length of time that information must be kept confidential.

Cryptography is one of the ancient communication and information media that are still used to this day. Cryptography in Indonesia called a passcode that is briefly may mean the art of protecting data and information from parties who are not desired either while it is transmitted or when stored. While the science of cryptology called passcodes. cryptology is the science that studies of how technical data and protecting that information. Conclusion

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