Cryptography Archives – Practical Networking .net

Authentication

Ed Harmoush — Fri, 06 Nov 2015 09:48:38 +0000

In Cryptography, the concept of Authentication serves to provide proof that the other side of a communication is indeed who they claim to be, and who you intend for them to be. There are multiple ways to verify the opposing party’s Authentication. We will look at three of the most common: Username and Password Pre-Shared-Key… Read More »Authentication

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Diffie-Hellman Key Exchange

Ed Harmoush — Wed, 04 Nov 2015 08:40:54 +0000

How can two people in a crowded room derive a secret that only the pair know, without revealing the secret to anyone else that might be listening? That is exactly the scenario the Diffie-Hellman Key Exchange exists to solve. The Diffie-Hellman Key Exchange is a means for two parties to jointly establish a shared secret over… Read More »Diffie-Hellman Key Exchange

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Anti-Replay

Ed Harmoush — Tue, 20 Oct 2015 06:04:42 +0000

The Problem Before we can describe the solution, we must first adequately describe the problem Anti-Replay is trying to solve. Imagine your local bank branch office. Imagine someone going to that branch location, and depositing $100 in cash into their account. At some point following the transaction, that branch location will send some packets to the bank headquarters… Read More »Anti-Replay

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Using Asymmetric Keys

Ed Harmoush — Wed, 30 Sep 2015 07:35:34 +0000

We’ve established how Asymmetric encryption makes use of two mathematically linked keys: One referred to as the Public Key, and the other referred to as the Private Key. We’ve also established that what one key encrypts, only the other can decrypt. These two attributes allow us to perform two separate operations with a Key Pair. Asymmetric Encryption Below is… Read More »Using Asymmetric Keys

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RSA Example

Ed Harmoush — Sat, 26 Sep 2015 09:02:34 +0000

The RSA algorithm is the most widely used Asymmetric Encryption algorithm deployed to date. The acronym is derived from the last names of the three mathematicians who created it in 1977: Ron Rivest, Adi Shamir, Leonard Adleman. In order to understand the algorithm, there are a few terms we have to define: Prime – A number… Read More »RSA Example

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Asymmetric Encryption

Ed Harmoush — Fri, 25 Sep 2015 09:20:20 +0000

Earlier, we learned that Symmetric encryption is an encryption scheme that uses the same key to encrypt and decrypt. Conversely, Asymmetric encryption, uses different keys to encrypt and decrypt. Lets take a look at a simple example. For the sake of simplicity, let us pretend for this example that there are only the lower case letters a -… Read More »Asymmetric Encryption

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Hashing Algorithm

Ed Harmoush — Tue, 22 Sep 2015 05:42:27 +0000

The first concept we need to discuss in our exploration of Cryptography is that of a Hashing Algorithm. A Hashing Algorithm is a mathematical formula that takes a Message of arbitrary length as input and produces as output a representational sample of the original data. For instance, a rudimentary example of a hashing algorithm is simply adding… Read More »Hashing Algorithm

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Message Integrity

Ed Harmoush — Fri, 18 Sep 2015 09:09:29 +0000

In the world of secured communications, Message Integrity describes the concept of ensuring that data has not been modified in transit. This is typically accomplished with the use of a Hashing algorithm. We learned earlier what a Hashing Algorithm does. Now we can take a look at how they are actually used to provide Message Integrity. The basic premise is… Read More »Message Integrity

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Symmetric Encryption

Ed Harmoush — Wed, 16 Sep 2015 21:06:17 +0000

We learned earlier that Symmetric encryption is an encryption scheme that encrypts and decrypts using the same secret key. Now we will explore a bit further into what that involves. Let’s start with a simple example: As pictured, if we start with the plain text hello, and use a Symmetric encryption algorithm of simply rotating the… Read More »Symmetric Encryption

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Confidentiality

Ed Harmoush — Wed, 16 Sep 2015 03:18:51 +0000

Confidentiality is the concept of hiding or scrambling your data so that only the intended recipient has access. This is typically accomplished by some means of Encryption. Data before it has been encrypted is referred to as Plain text, or Clear text. After the data has been encrypted, it is referred to as Cipher text. The Cipher text should be completely… Read More »Confidentiality

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