cryptography and one deals with formal approaches to protocol design. In other terms, Data is encrypted and decrypted using the same key. 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. ), Scales better since only a single key pair needed per individual, Can provide authentication and nonrepudiation, Examples: RSA, El Gamal, ECC, Diffie-Hellman. Every modern computer system uses modern cryptographic methods to secure passwords stored and provides the trusted backbone for e-commerce (think lock icon). Symmetric cryptography : Symmetric cryptography is the most widely used form of cryptography. 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. Offered by University of Colorado System. – A message in its natural format readable by an attacker, – Message altered to be unreadable by anyone except the intended recipients, – Sequence that controls the operation and behavior of the cryptographic algorithm, Total number of possible values of keys in a crypto algorithm, Random values used with ciphers to ensure no patterns are created during encryption, – The combination of algorithm, key, and key management functions used to perform cryptographic operations, Hiding a message within another medium, such as an image, Mathematically related key pairs for encryption and decryption, Change location of plaintext in ciphertext, Hash algorithms should be resistant to this attack, Small block of data generated with a secret key and appended to a message, Hash of message encrypted with private key, All components needed to enable secure communication, Verifies identity for certificate requests, Process to establish a trust relationship between CAs, Allows each CA to validate certificates issued by the other CA, Used in large organizations or business partnerships, The study of methods to break cryptosystems, The only secrecy involved with a cryptosystem should be the key. JavaScript isn't enabled in your browser, so this file can't be opened. Modern cryptography relies on cryptographic keys, usually a short string of text, for encoding and decoding messages in combination with cryptographic algorithms. As symmetric key cryptography gains its security from keeping a shared Stream Ciphers are fast and easy to implement in hardware. Symmetric Key Cryptography- In this technique, Both sender and receiver uses a common key to encrypt and decrypt the message. MD-5 is based on MD-4 and was created to address vulnerabilities found in MD-4. Let us know about both of them in details: Symmetric Key Encryption. RIPEMD-160 performs 5 paired rounds with 16 steps each. 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. Symmetric cryptography: it is the technique for convert plaintext into ciphertext using a same key for both sides (sender/recipient). This can be appended to the plaintext to be used as a MAC. 2. Cryptography Mathematical Foundations, Algorithms, and Protocols Klaus Köhler Munich University of … See our User Agreement and Privacy Policy. HAVAL was developed at the University of Wollongong in Australia. DSS is a US government standard and is used in e-commerce, e-mail, and financial transactions on a daily basis. 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. If you continue browsing the site, you agree to the use of cookies on this website. 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. Satellite TV is an example of a medium that uses link encryption. Looks like you’ve clipped this slide to already. Symmetric cryptography algorithms are AES, DES, Blowfish, RC5, etc. 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. 1 Encryption and Cryptography Using Encryption a message in its original form (plaintext) is encrypted into an unintelligible form (ciphertext) by a set of procedures known as an encryption algorithm and a variable, called a key; and the ciphertext is transformed (decrypted) back into plaintext using the encryption algorithm and a key. Introduction; 2 Public Key Cryptography. The history of cryptography begins where many old tales do…. To do the same for all students would require over half a billion key pairs! DES takes 64 bit plain text as input and produce 64 bit cipher text as output. Cryptographic Algorithms generally fall into one of two different categories, or are a combination of both. Additionally, the fact that only one key gets used (versus two for asymmetric cryptography) also makes the entire process faster. Get ideas for your own presentations. Public key schemes encrypt large blocks of data 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. Symmetric cryptography uses symmetric-key algorithms for the encryption and decryption of data. Symmetric-key cryptography is sometimes called secretkey cryptography. ASYMMETRIC KEY CRYPTOGRAPHY SYMMETRIC KEY CRYPTOGRAPHY 8. Modern computing gave cryptographers vast resources for improving the complexity of cryptosystems as well as for attacking them. 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. The mathematics of cryptology Paul E. Gunnells Department of Mathematics and Statistics University of Massachusetts, Amherst Amherst, MA 01003 ... Public Key Cryptography Each user has an encryption function and a decryption function. These ciphers are used in symmetric key cryptography.A symmetric algorithm uses the same key to encrypt data as it does to decrypt data. 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. RIPEMD-160 was developed by the European RACE integrity Primitives Evaluation Project. The history of cryptography begins where many stories of history do…. The output size is 160 bits and operates on 512-bit blocks. This combines the scalability and key management features of the asymmetric algorithms with the speed of symmetric ones. In symmetric key cryptography a single key is used for encryption of the data as well as decryption. This kind of encryption procedure is known as public-key cryptography, correspondingly symmetric encrypting is called secret-key cryptography. Large mathematical operations make it slower than symmetric algorithms, No need for out of band key distribution (public keys are public! Key management headaches from large number of key pairs to maintain N(N-1)/2, That’s over 6.3 million key pairs to let all 3556 Purdue A/P staff members exchange encrypted messages. So why do care about cryptography? The keys, in practice, represent a shared secret between two or more parties that can be used to maintain a private information link. Unfortunately, DES and other encryption mechanisms can be somewhat slow compared to a hash function. 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. Many are downloadable. Approved for use since the 1970s, symmetric key encryption algorithms are just one way to keep confidential data secure. Share yours for free! Among those who are not entirely familiar with the mathematics of cryptography, key length is a topic of continuing confusion. • Also known as secret key. 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. Symmetric and asymmetric key cryptography is based on the number of keys and the way these keys work. 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 key algorithms can be divided into two categories: block and stream. 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. The problem with symmetric encrypting is the secret key distribution to all parties, as keys must also be updated every now and then. Both symmetric and asymmetric key cryptography provide data confidentiality. No public clipboards found for this slide. Currently in version 3. § 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). A hybrid cryptosystem is the best of both worlds. Although forgetting a password for your user account can certainly lead to a denial of service attack. A session key is generated by the KDC and distributes to each party of the communication, encrypted with their master key. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The Secure Sockets Layer (SSL) protocol negotiates which asymmetric and symmetric algorithms to use in a hybrid system to protect TCP connections, such as an HTTP connection between a web browser and web server. login). SHA-1 also operates on 512-bit blocks, but produces a 160-bit hash value in 4 rounds of 20 steps each. MD5 generates 128-bit hash values over 512-bit blocks in 4 rounds of 16 steps each. Now customize the name of a clipboard to store your clips. Clipping is a handy way to collect important slides you want to go back to later. The hash is encrypted instead of the message itself for performance reasons. Master key pairs are generated for each user and the KDC. Clients are supposed to check if a certificate has been revoked before using it, but this is not always the case in practice. However, cryptography is used in many access control systems. Guess values based on frequency of occurrence, Secures a number of popular network services. 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) Cryptography is used to defend the data and to defend the data and to define it in the simple and easy words, it is an art of writing and solving the codes. key distribution under symmetric encryption requires either (1) that two communicants already share a key… View Arcada.ppt from CS MISC at Faculty of Sciences and Technology. DES- DATA ENCRYPTION STANDARDS DES, Data Encryption Standards is a symmetric key block cipher. It was published by National Institute of Standard and Technology (NIST) . CRLs are maintained by the CA and list all certificates that have been revoked. Strong encryption uses a combination of both of these attributes to attain a sufficiently complex algorithm. PLAIN TEXT CIPHER TEXT CIPHER ENCRYPTION & DECRYPTION KEYS 7. Cryptography, An overview of Asymmetric Key Cryptography, The RSA Algorithm, Symmetric and Asymmetric Key Cryptography Together, Digital Signatures, Knapsack Algorithm, Some other Algorithms. Learning and using these terms and their definitions are the key to speaking like a crypto geek. sessions 15, 16.ppt - Free download as Powerpoint Presentation (.ppt), PDF File (.pdf), Text File (.txt) or view presentation slides online. 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. The primary benefit promised by elliptic curve cryptography is a smaller key size , reducing storage and transmission requirements, i.e. Title: Public Key Cryptography 1 Public Key Cryptography. Cryptography fits into the CIA triad, as it can be used to ensure confidentiality and integrity of a message. In this article, we will discuss about symmetric key cryptography. The two most commonly used algorithms to date are Triple DES and AES. 6. Cryptography – Greek for hidden and writing is a means of transforming data in a way that renders it unreadable by anyone except the intended recipient. In asymmetric key cryptography there would be two separate keys. They are used to secure bulk data, provide a foundation for message authentication codes, and provide support for password-based encryption as well. Generally had too strict of PKI requirements to be feasible for many organizations. Well, here’s what it can do for us. Symmetric cryptography is faster to run (in terms of both encryption and decryption) because the keys used are much shorter than they are in asymmetric cryptography. Network devices can be “dumb” with regard to the encryption used, while users may have more flexibility in selecting the algorithms. 56 bits used for key. 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. 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. End-to-end encryption, however, only encrypts the application layer data being transmitted. 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. Symmetric key encryption technique uses a straight forward method of encryption. HAVAL operates on 1024-bit blocks. These principles and functions will be helpful in understanding symmetric and asymmetric cryptographic methods examined in Course 3 … • Alice makes her encryption function E A publicly Traditional MAC is generated using DES-CBC and is just the last block of ciphertext created when encrypting the message itself. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Hence, this … During the industrial age, cryptography was moved from a manual exercise to one done by machines. IBM designed the DES based on their Lucifer cipher. Take a look at the different algorithms, from DES to … Learn new and interesting things. It has a number of different modes of operation based on the chosen output size and number of rounds. Symmetric Key Cryptography (3.5) Plaintext encrypted 64-bits at a time. Polyalphabetic Cipher: Algorithm that substitutes a letter from two or more ciphertext alphabets for each plaintext alphabet letter based on position in the message. These were not meant to hide messages so much as to give a formal and ceremonial touch to stories of everyday events. Invisible ink, hidden tattoos, and microdots are all examples of steganography. On this website over half a billion key pairs one done by machines is called secret-key cryptography separate keys 2. 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