Why cryptography ppt

Presented by. 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. What was originally used almost exclusively by governments for espionage has become a powerful tool for personal privacy today. Every modern computer system uses modern cryptographic methods to secure passwords stored and provides the trusted backbone for e-commerce think lock icon.

Cryptography fits into the CIA triad, as it can be used to ensure confidentiality and integrity of a message. Some forms also provide for sender authenticity and proof of delivery. Although forgetting a password for your user account can certainly lead to a denial of service attack. However, cryptography is used in many access control systems.

History — The Manual Era. The history of cryptography begins where many stories of history do…. Scytale — Spartan method involved wrapping a belt around a rod of a given diameter and length. Caesar — Shift all letters by a given number of letters in the alphabet.

History — The Mechanical Era. The history of cryptography begins where many old tales do…. These were not meant to hide messages so much as to give a formal and ceremonial touch to stories of everyday events. During the industrial age, cryptography was moved from a manual exercise to one done by machines. The invention of cipher disks and rotors for this use allowed for the creation of much more complex algorithms. History — The Modern Era. Modern computing gave cryptographers vast resources for improving the complexity of cryptosystems as well as for attacking them.

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. Speak Like a Crypto Geek. 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. Just like with many technical topics, Cryptography has its own lingo. Learning and using these terms and their definitions are the key to speaking like a crypto geek. Speak Like a Crypto Geek 2. 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. Cryptosystem Services. So why do care about cryptography? 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. Types of Cryptography. Stream Ciphers are fast and easy to implement in hardware. Block ciphers are stronger, but slower and often implemented in hardware. Encryption Systems.

Substitution Cipher: Replacing one letter with another. Transposition Cipher: World Jumble. 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. Polyalphabetic Cipher: Algorithm that substitutes a letter from two or more ciphertext alphabets for each plaintext alphabet letter based on position in the message.

Referred to as modulo N. One-time Pads: Offer perfect secrecy if a true source of randomness is used, but is very difficult to use in practice. Invisible ink, hidden tattoos, and microdots are all examples of steganography. 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.

The receiver can then extract the message if they have the original, unaltered image. Cryptographic Methods. I have also explained about the various classes which. The SlideShare family just got bigger. Home Explore Login Signup. Successfully reported this slideshow. We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

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