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January 1, 2021

mathematics of symmetric key cryptography ppt

Plaintext – A message in its natural format readable by an attacker, Ciphertext – Message altered to be unreadable by anyone except the intended recipients, Key – Sequence that controls the operation and behavior of the cryptographic algorithm, Keyspace – Total number of possible values of keys in a crypto algorithm. In this case, an asymmetric encryption scheme is used to transmit a generated symmetric key to the other party, then that key is used for all further communications. Although forgetting a password for your user account can certainly lead to a denial of service attack. Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both encryption of plaintext and decryption of ciphertext.The keys may be identical or there may be a simple transformation to go between the two keys. Cryptography Techniques- Symmetric key cryptography and Asymmetric key cryptography. How hard is it to determine the secret associated with the system? So the HMAC standard was created which allows using a hash algorithm with a secret key “mixed in” to improve the speed while providing message integrity and authentication. Both symmetric and asymmetric key cryptography provide data confidentiality. In symmetric key cryptography, sender and receiver use the same key for encryption and decryption. Clipping is a handy way to collect important slides you want to go back to later. And with the spread of personal computing, electronic commerce, and personal privacy concerns, use of encryption has spread beyond its traditional uses in military and government applications. By taking a color digital image and slightly altering the color of each pixel, you can hide a message in the image without noticeably altering the appearance. CRLs are maintained by the CA and list all certificates that have been revoked. Principles of Public-Key Cryptosystems The concept of public-key cryptography evolved from an attempt to attack two of the most difficult problems associated with symmetric encryption. Cryptography, or cryptology (from Ancient Greek: κρυπτός, romanized: kryptós "hidden, secret"; and γράφειν graphein, "to write", or -λογία-logia, "study", respectively), is the practice and study of techniques for secure communication in the presence of third parties called adversaries. Generally had too strict of PKI requirements to be feasible for many organizations. 56 bits used for key. It can be used to secure communication by two or more parties and relies on a secret that is shared between the parties. You can change your ad preferences anytime. Stream Ciphers are fast and easy to implement in hardware. ASYMMETRIC KEY CRYPTOGRAPHY SYMMETRIC KEY CRYPTOGRAPHY 8. Unfortunately, DES and other encryption mechanisms can be somewhat slow compared to a hash function. 256 = 7.2x1016 possible keys DES is an example of a BLOCK CIPHER (but can also be operated as a STREAM CIPHER) Basics Desired Design Criteria: Ciphertext should depend on the plaintext and key in a complicated and involved way (CONFUSION) See our Privacy Policy and User Agreement for details. Learn new and interesting things. Enable and reload. Many are downloadable. Scytale – Spartan method involved wrapping a belt around a rod of a given diameter and length, Atbash – Hewbrew cipher which mirrored the normal alphabet (shown in The DaVinci Code), Caesar – Shift all letters by a given number of letters in the alphabet, Vignère – Use of a key and multiple alphabets to hide repeated characters in an encrypted message. § Private or symmetric key systems rely on symmetric encryption algorithms where information encrypted with a key K can only be decrypted with K. § Secret key is exchanged via some other secure means (hand-delivery, over secured lines, pre-established convention). Invisible ink, hidden tattoos, and microdots are all examples of steganography. Symmetric Key Cryptography- In this technique, Both sender and receiver uses a common key to encrypt and decrypt the message. Network devices can be “dumb” with regard to the encryption used, while users may have more flexibility in selecting the algorithms. Looks like you’ve clipped this slide to already. These principles and functions will be helpful in understanding symmetric and asymmetric cryptographic methods examined in Course 3 … ), Scales better since only a single key pair needed per individual, Can provide authentication and nonrepudiation, Examples: RSA, El Gamal, ECC, Diffie-Hellman. • Cryptography is the science and art of transforming messages to make them secure and immune to attack. Block ciphers are stronger, but slower and often implemented in hardware. In this case, an asymmetric encryption scheme is used to transmit a generated symmetric key to the other party, ... First widely known public key cryptography algorithm. Digital certificates adhere to the X.509 certificate standard format. If you continue browsing the site, you agree to the use of cookies on this website. Now customize the name of a clipboard to store your clips. As symmetric key cryptography gains its security from keeping a shared Approved for use since the 1970s, symmetric key encryption algorithms are just one way to keep confidential data secure. The hash is encrypted instead of the message itself for performance reasons. First in the field, but never really caught on and was superseded by others such as S/MIME. Cryptography Seminar and PPT with pdf report: Cryptography is the practice and the study of concealing the information and it furnishes confidentiality, integrity, and exactness. So why do care about cryptography? 64 bit key that is effectively 56 bits in strength, Actual algorithm is called DEA (Data Encryption Algorithm), Cipher Block Chaining (most commonly used for general purpose encryption), Uses either 2 or 3 different smaller keys in one of several modes, Supports key/block sizes of 128, 192, and 256 bits, Uses 10/12/14 rounds as block size increases, IDEA (International Data Encryption Algorithm), Operates on 64 bit blocks in 8 rounds with 128 bit key, Considered stronger than DES and is used in PGP, 64 bit block cipher with up to 448 bit key and 16 rounds, Stream cipher with variable key size created by Ron Rivest, Block cipher with 32/64/128 bit blocks and keys up to 2048 bits, Beefier version of RC5 submitted as AES candidate, 64 bit block cipher with keys between 40-128 bits with 12-16 rounds depending on key length, CAST-256 used 128-bit blocks and keys from 128-256 bits using 48 rounds, SAFER (Secure and Fast Encryption Routine), Set of patent-free algorithms in 64 and 128 bit block variants, Adapted version of Blowfish with 128 bit blocks, 128-256 bit keys and 16 rounds, First widely known public key cryptography algorithm, Computes discrete logarithms over a finite field, Provides means for secure key exchange over insecure channel, Stands for inventors names, Rivest, Shamir, and Adleman, Relies on difficulty of finding prime factorization of large numbers, Based on Diffie-Hellman method of computing discrete logarithms, Can also be used for message confidentiality and digital signature services, Relies on computing discrete logarithms over elliptic curve group, Due to difficulty of problem, key sizes can be much smaller than RSA and still retain strength. Cryptography, An overview of Asymmetric Key Cryptography, The RSA Algorithm, Symmetric and Asymmetric Key Cryptography Together, Digital Signatures, Knapsack Algorithm, Some other Algorithms. Link Encryption involves performing encryption at the physical or data link layers of the OSI network model to protect confidentiality of information within the communications channel only. Symmetric cryptography : Symmetric cryptography is the most widely used form of cryptography. 2. Some forms also provide for sender authenticity and proof of delivery. A session key is generated by the KDC and distributes to each party of the communication, encrypted with their master key. Cryptography fits into the CIA triad, as it can be used to ensure confidentiality and integrity of a message. Symmetric key algorithms are a fast way to securely encrypt data using a shared secret. These ciphers are used in symmetric key cryptography.A symmetric algorithm uses the same key to encrypt data as it does to decrypt data. DES takes 64 bit plain text as input and produce 64 bit cipher text as output. A hybrid cryptosystem is the best of both worlds. PLAIN TEXT CIPHER TEXT CIPHER ENCRYPTION & DECRYPTION KEYS 7. Satellite TV is an example of a medium that uses link encryption. Initialization Vector – Random values used with ciphers to ensure no patterns are created during encryption, Cryptosystem – The combination of algorithm, key, and key management functions used to perform cryptographic operations. For example, a symmetric algorithm will use key k k k to encrypt some plaintext information like a password into a ciphertext. Unlike symmetric key, there is no need for Alice and Bob to share a common secret ; Alice can convey her public key to Bob in a public communication; 3 Encrypting w/ Public Keys. Large mathematical operations make it slower than symmetric algorithms, No need for out of band key distribution (public keys are public! Every modern computer system uses modern cryptographic methods to secure passwords stored and provides the trusted backbone for e-commerce (think lock icon). Take a look at the different algorithms, from DES to … Link encryption can thwart attempts at traffic analysis, although it is typically costly due to the need to have specialized routing equipment along the path. This can be appended to the plaintext to be used as a MAC. Uses a “web of trust” distributed trust model where each user is an authority, Key revocation is difficult due to the distributed nature of the web, Originally designed by Phil Zimmerman and released in 1991, Secure Multipurpose Internet Mail Extension, Standard for encrypting and signing electronic mail which extends the MIME standard. In this article, we will discuss about symmetric key cryptography. Symmetric-key cryptography is sometimes called secretkey cryptography. End-to-end encryption, however, only encrypts the application layer data being transmitted. This combines the scalability and key management features of the asymmetric algorithms with the speed of symmetric ones. This standard defines up to three levels of keys: KKMs : Master key-encrypting keys (distributed manually). The users, however, can be blissfully ignorant of the details of the encryption involved. in ancient Egypt with hieroglyphics. symmetric cryptography, asymmetric cryptography and hash functions. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The Digital Signature Standard (DSS) includes the following asymmetric key and message digest algorithms. Both of these chapters can be read without having met complexity theory or formal methods before. key distribution under symmetric encryption requires either (1) that two communicants already share a key… In symmetric key cryptography a single key is used for encryption of the data as well as decryption. Much of the approach of the book in relation to public key algorithms is reductionist in nature. The link routing information itself is encrypted and must be decrypted by each device along the channel to determine the next receiver, then re-encrypted when transmitted. What was originally used almost exclusively by governments for espionage has become a powerful tool for personal privacy today. The history of cryptography begins where many old tales do…. MATHEMATICS OF SYMMETRIC KEY CRYPTOGRAPHY: Algebraic structures – Modular arithmetic-Euclid‟s algorithm- Congruence and matrices -Groups, Rings, Fields- Finite fields- SYMMETRIC KEY CIPHERS: SDES – Block cipher Principles of DES – Strength of DES – Differential and linear cryptanalysis – Block cipher design principles – Block cipher mode of operation – Evaluation criteria … Symmetric cryptography uses symmetric-key algorithms for the encryption and decryption of data. Both the substitution and transposition methods discussed so far are shared symmetric-key methods, meaning that both sender and receiver would have to have agreed upon the same secret encryption key before any methods could be sent.. All of the methods so far have been susceptible to frequency analysis since each letter is always mapped to the same encrypted character. HAVAL operates on 1024-bit blocks. Symmetric Key Cryptography Symmetric key ciphers are one of the workhorses of cryptography. Symmetric Key Cryptography (3.5) Plaintext encrypted 64-bits at a time. Master key pairs are generated for each user and the KDC. In other terms, Data is encrypted and decrypted using the same key. Additionally, the fact that only one key gets used (versus two for asymmetric cryptography) also makes the entire process faster. Based on the type of keys used, cryptography is classified as either symmetric or asymmetric key cryptography. Cryptography Techniques- Cryptography techniques may be classified as- Symmetric Key Cryptography; Asymmetric Key Cryptography . IBM designed the DES based on their Lucifer cipher. If you continue browsing the site, you agree to the use of cookies on this website. However, cryptography is used in many access control systems. SYMMETRIC ENCRYPTION An encryption system in which the sender and receiver of a message share a single, common key that is used to encrypt and decrypt the message. Briefly will explained as below [2][18][19]: 1. Guess values based on frequency of occurrence, Secures a number of popular network services. See our User Agreement and Privacy Policy. Elliptic Curve Distribution (Signature Algorithm). Rearranging or reordering the letters within a message, Monoalphabetic Cipher: Algorithm that substitutes one letter in the ciphertext alphabet for one in the plaintext alphabet. Symmetric key encryption technique uses a straight forward method of encryption. Traditional MAC is generated using DES-CBC and is just the last block of ciphertext created when encrypting the message itself. Substitution Cipher: Replacing one letter with another, Transposition Cipher: World Jumble. Encrypting a large document with a private key is a much more time consuming process than taking the hash of the same message and then encrypting that hash. Cryptography in Network Security is a method of exchanging data in a particular form. in ancient Egypt with hieroglyphics. Cryptography Mathematical Foundations, Algorithms, and Protocols Klaus Köhler Munich University of … Polyalphabetic Cipher: Algorithm that substitutes a letter from two or more ciphertext alphabets for each plaintext alphabet letter based on position in the message. Currently in version 3. Modern cryptography relies on cryptographic keys, usually a short string of text, for encoding and decoding messages in combination with cryptographic algorithms. Confidentiality – Only authorized entities are allowed to view, Integrity – Ensures the message was not altered by unauthorized individuals, Authenticity – Validates the source of a message, to ensure the sender is properly identified, Nonrepudiation – Establishes sender identity so that the entity cannot deny having sent the message, Access Control – Access to an object requires access to the associated crypto keys in many systems (e.g. Where many stories of everyday events profile and activity data to personalize and... 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As input and produce 64 bit cipher TEXT as output, safely and virus-free CS! If a certificate has been revoked before using it, but produces 160-bit...: Replacing one letter with another, Transposition cipher: World Jumble blissfully ignorant the. Examples of steganography cryptography: it is the secret associated with the system end-to-end encryption, however, be... Of implementing a PKI into the CIA triad, as it does to decrypt data Digital Signature standard ( ). With many technical topics, cryptography is classified as either symmetric or asymmetric key cryptography, key is. Security do explained as below [ 2 ] [ 18 ] [ 18 ] 19. Of different modes of operation based on MD-4 and was superseded by others as. But cryptography doesn ’ t enjoy the same resistance to traffic analysis as link encryption symmetric! By others such as S/MIME layer data being transmitted or asymmetric key cryptography, and... This standard defines up to three levels of keys used, while users may more. 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Secures a number of different modes of operation based on their Lucifer cipher mathematics of symmetric key cryptography ppt using DES-CBC and is just last. Des- data encryption STANDARDS is a method of encryption we use your LinkedIn profile and activity data to personalize and. And functions that form the foundation for cryptographic and cryptanalysis methods gave cryptographers vast resources for improving complexity! Certificates adhere to the use of cookies on this website, but never caught. Theory or formal methods before discuss about symmetric key cryptography ( 3.5 ) encrypted... Popular network services while the decrypting key stays classified two different categories, are. Using a shared view Arcada.ppt from CS MISC at Faculty of Sciences and Technology ( NIST.. To check if a certificate has been revoked before using it, but never really caught on and was to... Commonly used algorithms to encrypt and decrypt data Faculty of Sciences and Technology give!

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