# Cryptography

2021.03.17 13:45

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# Cryptography

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## Sidharth Mohapatra

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Published on Sep 19, 2013

Cryptography is the science of using mathematics to encrypt and decrypt data.

Cryptography enables you to store sensitive information or transmit it across insecure networks so that it cannot be read by anyone except the intended recipient.

*Published in: Education , Technology*

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### * * Cryptography

1. Presented By : Shibani Sarangi IT Branch, Regd no. 1001289324 Guided By : Prof. X 1 2. 2 Cryptography Vocabulary Encryption & Decryption Transmission Technique Symmetric Cryptography Asymmetric Cryptography 3. 3 Cryptography is the science of using mathematics to encrypt and decrypt data. Cryptography enables you to store sensitive information or transmit it across insecure networks so that it cannot be read by anyone except the intended recipient. 4. 4 Plaintext: Data that can be read and understood without any special measures. Encryption: The method of disguising plaintext in such a way as to hide its substance is called encryption. Cipher text: Encrypting plaintext results in unreadable gibberish called cipher text. Decryption: The process of reverting cipher text to its original plaintext is called decryption. Key: some secret piece of information 5. 5 Cryptanalysis: The art of breaking ciphers, i.e. retrieving the plaintext without knowing the proper key. Cryptographers: People who do cryptography Cryptanalysts: Practitioners of cryptanalysis. Cryptology: The branch of mathematics that studies the mathematical foundations of cryptographic methods. 6. 6 7. 7 For “secret writing” To establish a shared secret when other people (eavesdroppers) are listening. TYPES Mainly classified into two types : 1. Symmetric key cryptography 2. Asymmetric key cryptography 8. 8 encoder decoder (plaintext in - ciphertext out) ciphertextciphertext msgmsg (ciphertext in - plaintext out) (should understand nothingnothing about the msg) eavesdropper bla-blabla-bla cmbcmb--cmbcmb bla-blabla-bla Cipher msg Plain text – in Cipher text - out Should understand NOTHING about the message Cipher text – in Plain text - out 9. Cryptography Symmetric key Asymmetric key cryptography cryptography (Public key cryptography) Classical Modern cryptography cryptography Transposition Substitution Stream Block cipher cipher cipher cipher 9 10. BOTH SHOULD KNOWTHE KEY 10 11. 11 In classical cryptography, a transposition cipher changes one character from the plaintext to another i.e. the order of the characters is changed. 12. 12 Substitution cipher is a method of encryption by which units of plaintext are substituted with ciphertext according to a regular system. 13. 13 A Stream Cipher is a symmetric or secret- key encryption algorithm that encrypts a single bit at a time. With a Stream Cipher, the same plaintext bit or byte will encrypt to a different bit or byte every time it is encrypted. e.g. : Plain text: Pay 100 Binary of plain text: 010111101 (hypothetical) Key: 100101011 ----- Perform XOR ____________________ Cipher text 110010110 ----- 14. 14 Block cipher technique involves encryption of one block of text at a time .Decryption also takes one block of encrypted text at a time. Length of the block is usually 64 or 128 bits. e.g. : Plain text: four and five Four and five Key Key Key wvfa ast wvfa --- 15. 15 Public key cryptography is an asymmetric scheme that uses a Pair of keys for encryption: a Public key, which encrypts data, and a corresponding Private key (secret key) for decryption. 16. 16 Cryptanalysis refers to the study of ciphers, cipher text, or cryptosystems (that is, to secret code systems) with a view to finding weaknesses in them that will permit retrieval of the plain text from the cipher text, without necessarily knowing the key or the algorithm. This is known as breaking the cipher, cipher text, or cryptosystem. Unlike cryptography which is a clearly 17. 17 Known - plain text analysis Chosen – plain text analysis (Differential cryptanalysis) Cipher text - only analysis Man – in – the - middle attack 18. 18 It is a side channel attack which exploits sounds emitted by computers or machines. Modern acoustic cryptanalysis mostly focuses on sounds emitted by computer keyboards and internal computer components Historically it has also been applied to impact printers and electromechanical cipher machines. 19. 19 Use rubber keyboard or virtual keyboards to prevent keystroke sounds. Use acoustic printers. Use Acoustic case for CPU. 20. 20 Cryptography, being an art of encrypting and decrypting confidential information and private messages, should be implemented in the network security to prevent any leakage and threat. It can be done by using any of these techniques discussed above for fortifying the personal data transmission as well as for secure transaction. Acoustic cryptanalysis, being an art of 21. Yang, Sarah (14 September 2005), Researchers recover typed text using audio recording of keystrokes , UC Berkeley News. Adi Shamir & Eran Tromer. Acoustic cryptanalysis . Blavatnik School of Computer Science, Tel Aviv University. Retrieved 1 November 2011. http://en.wikipedia.org/wiki/Cryptography 21 22. 22 Recommended **Explore professional development books with Scribd**Scribd -

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Clipping is a handy way to collect important slides you want to go back to later. Now customize the name of a clipboard to store your clips.- Cryptography Tutorial - Tutorialspoint
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Definition: Cryptography is associated with the process of converting ordinary plain text into unintelligible text and vice-versa. It is a method of storing and transmitting data in a particular form so that only those for whom it is intended can read and process it.
- Cryptography | Computer science | Computing | Khan Academy

Cryptography is used in all fields to secure data and prevent it from getting hacked. For example, for securing passwords, authenticating banking transactions, etc. Nowadays, various new cryptographic techniques are developed and cracked; hence, it is important always to be aware of computer threats and take precautions to avoid them as best as we can.
- What is Cryptography? Definition of Cryptography ...

Cryptography is the science of using mathematics to encrypt and decrypt data. Cryptography enables you to store sensitive information or transmit it across insecure networks so that it cannot be read by anyone except the intended recipient.
- Cryptography Techniques | Learn Main Types Of Cryptography ...

This is called 'decryption.' Cryptography begins when we abandon physical locks and use 'ciphers' instead. Think of [ciphers] as virtual locks. Ciphers allow Alice and Bob to scramble and descramble their messages so that they would appear meaningless if Eve intercepted them. Cryptography has been around for thousands of years.
- Cryptography - SlideShare

Cryptography is the study of secure communications techniques that allow only the sender and intended recipient of a message to view its contents. The term is derived from the Greek word kryptos ...
- cryptography · PyPI

This tutorial covers the basics of the science of cryptography. It explains how programmers and network professionals can use cryptography to maintain the privacy of computer data. Starting with the origins of cryptography, it moves on to explain cryptosystems, various traditional and modern ciphers, public key encryption, data integration, message authentication, and digital signatures.
- Real Life Applications of CRYPTOGRAPHY | by Prashanth ...

Block Cipher. An encryption method that applies a deterministic algorithm along with a symmetric key to encrypt a block of text, rather than encrypting one bit at a time as in stream ciphers. Example: A common block cipher, AES, encrypts 128-bit blocks with a key of predetermined length: 128, 192, or 256 bits.
- Cryptography and its Types - GeeksforGeeks

cryptography is a package which provides cryptographic recipes and primitives to Python developers. Our goal is for it to be your “cryptographic standard library”. It supports Python 3.6+ and PyPy3 7.2+. cryptography includes both high level recipes and low level interfaces to common cryptographic algorithms such as symmetric ciphers, message ...
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Cryptography is technique of securing information and communications through use of codes so that only those person for whom the information is intended can understand it and process it. Thus preventing unauthorized access to information.
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Unit: Cryptography. Lessons. Ancient cryptography. Learn. What is cryptography? (Opens a modal) The Caesar cipher (Opens a modal) Caesar Cipher Exploration (Opens a modal) Frequency Fingerprint Exploration (Opens a modal) Polyalphabetic cipher (Opens a modal) Polyalphabetic Exploration (Opens a modal)

Definition: Cryptography is associated with the process of converting ordinary plain text into unintelligible text and vice-versa. It is a method of storing and transmitting data in a particular form so that only those for whom it is intended can read and process it.

Cryptography is used in all fields to secure data and prevent it from getting hacked. For example, for securing passwords, authenticating banking transactions, etc. Nowadays, various new cryptographic techniques are developed and cracked; hence, it is important always to be aware of computer threats and take precautions to avoid them as best as we can.

Cryptography is the science of using mathematics to encrypt and decrypt data. Cryptography enables you to store sensitive information or transmit it across insecure networks so that it cannot be read by anyone except the intended recipient.

This is called 'decryption.' Cryptography begins when we abandon physical locks and use 'ciphers' instead. Think of [ciphers] as virtual locks. Ciphers allow Alice and Bob to scramble and descramble their messages so that they would appear meaningless if Eve intercepted them. Cryptography has been around for thousands of years.

Cryptography is the study of secure communications techniques that allow only the sender and intended recipient of a message to view its contents. The term is derived from the Greek word kryptos ...

This tutorial covers the basics of the science of cryptography. It explains how programmers and network professionals can use cryptography to maintain the privacy of computer data. Starting with the origins of cryptography, it moves on to explain cryptosystems, various traditional and modern ciphers, public key encryption, data integration, message authentication, and digital signatures.

Block Cipher. An encryption method that applies a deterministic algorithm along with a symmetric key to encrypt a block of text, rather than encrypting one bit at a time as in stream ciphers. Example: A common block cipher, AES, encrypts 128-bit blocks with a key of predetermined length: 128, 192, or 256 bits.

cryptography is a package which provides cryptographic recipes and primitives to Python developers. Our goal is for it to be your “cryptographic standard library”. It supports Python 3.6+ and PyPy3 7.2+. cryptography includes both high level recipes and low level interfaces to common cryptographic algorithms such as symmetric ciphers, message ...

Cryptography is technique of securing information and communications through use of codes so that only those person for whom the information is intended can understand it and process it. Thus preventing unauthorized access to information.

Unit: Cryptography. Lessons. Ancient cryptography. Learn. What is cryptography? (Opens a modal) The Caesar cipher (Opens a modal) Caesar Cipher Exploration (Opens a modal) Frequency Fingerprint Exploration (Opens a modal) Polyalphabetic cipher (Opens a modal) Polyalphabetic Exploration (Opens a modal)