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Tag Archives: .net

Digital Signature

digital signature

An essential purpose of cryptography would be  to ensure nonrepudiation of a delivered message. This is where the receiver of the message cannot deny that the message is genuine. A digital signature is a technique used to help demonstrate this authenticity and the integrity of the message. It is useful for …

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Hybrid Encryption with Integrity

hybrid-encryption

In this article, we will build on the previous hybrid encryption example by adding message integrity. This will mean that, once the encrypted data block has been created, you can check whether or not it has been tampered with or corrupted while in transit to its recipient. Before looking at …

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Hybrid Encryption (RSA+AES)

hybrid-encryption

With RSA you cannot encrypt data that is bigger than the length of the asymmetric key. If you want to encrypt a bigger block of information, what exactly would you do? Preferably, you’d wish to make use of symmetric encryption algorithm such as AES, but the issue you encounter is that …

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Asymmetric Encryption – RSA

rsa

The main problem with symmetric encryption is that of securely sharing keys. For a recipient to decrypt a message, they need the same key as the sender, and this exchange of keys can be very difficult to do securely. A good solution to this problem is to use asymmetric cryptography …

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Advanced Encryption Standard (AES)

AES

The Advanced Encryption Standard (AES) is the latest encryption standard adopted by NIST in 2001 for the symmetric encryption of messages. The AES algorithm was selected as part of a contest to find a replacement for the Data Encryption Standard (DES). This algorithm was based on the Rijndael cipher developed …

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Data Encryption Standard (DES)

encryption

The Data Encryption Standard (DES) used to be the default standard for symmetric encryption of data. DES was based on an earlier design by Horst Feistel and developed by IBM in the early 1970s. DES was submitted to the National Bureau of Standards as part of a drive to propose …

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Symmetric Encryption

encryption

A symmetric encryption algorithm is a two-way encryption procedure that employs the same key for both encryption and decryption of the information. Theoretically, this seems straightforward as both the sender and receiver of the message should know the key, however in practice safely sharing a key is very hard to …

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Password Storage

password

Using Hashes to Store Passwords A common usage scenario for hashes is to encode passwords for storing in a database. With the rise of modern processors and graphical processing units (GPUs), it is not recommended you take this approach as hashes can be brute force attacked or attacked by using …

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Cryptographic Random Numbers

cryptography

Random numbers are essential in cryptography as you need them for generating encryption keys for symmetric algorithms such as AES, as well as for adding entropy into hashing functions and key derivation functions. Usually in .NET, when you want to generate a random number or a pseudorandom number, you would make …

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What is Cryptography?

cryptography

Throughout history, cryptography has been used to confidentially complete messages to various recipients. This has been specifically beneficial in times of war. Up until World War II, with the use of the German enciphering machine Enigma, communications that have been encrypted were text-based. With the advent of modern computing, cryptography …

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