In this video, you will learn to; describe the purpose or use of cryptography in cybersecurity, describe how cryptography is used to assure the key cybersecurity tenants of confidentiality, integrity, authentication, and non-repudiation. One key concept of security cryptography we'll discuss this now. Cryptography it's basically a way of secret writing. Its a secure communication between two parties, and only the intended recipient can understand this communication. That is the key task of cryptography. One thing that we need to understand for cryptography is that there's data at motion and data at rest, and both of them need to be secure. Cryptography is nothing new it has been used for thousands of years. Examples are Egyptian Hieroglyphics, the Spartan Scytale, Ceasar Cipher, those are just a few examples of the ancient cryptography. Nowadays is just more evolved. We have encrypting data, and with the rise of computers, cryptography has evolved over the years. To understand better cryptography and why it is important, we need to discuss some key concepts. We'll start with confidentiality. Basically, confidentiality is the process of assuring that only the intended parties can read and understand the message. Integrity is the process of actually detecting if the message has been changed, where the message shouldn't be altered in any way in the process of being transmitted. Authentication it's the process of identifying are authenticated with someone or something it's actually not allowed to do something or some message is actually correct. Non-repudiation is the process of detecting if something or someone has done something, and that someone one cannot deny that action or that message which was sent by him or her. Cryptonalysis is basically the process of analyzing ciphers in cryptographic algorithms. Cryptonalysis is a key factor to cryptography because it allows scientists and mathematicians to actually determine if a cryptographic algorithm is secure or not. Cipher is the actual algorithm that encrypts a message. For example, the Caesar Cipher was an engineers' cryptography algorithm that basically shifted the alphabet or shifted specific letters either to the right to the left in amount of kinds. Plaintext like the word says it's just plain text can be human readable. The Ciphertext basically refers to the plaintext gone through the cipher, which is basically, the cipher has been applied to a plaintext and the ciphertext is something that it's not humanly readable. Encryption is the process of transforming plaintext into ciphertext. Decryption is the process of transforming the ciphertext into a plaintext using the cipher as well on those two key concept. Let's talk about cryptographic strength a little bit now. Cryptographic strength relies on math not secrecy. Keeping something secret does not make a cryptographic algorithm anymore secure. Actually, the most secure algorithms out there they have stood the test of time are public algorithms. Modern ciphers use modular math. On the left side of the screen, you will see some exclusive XOR table. You will see column A, B and the column A XOR B. So trying to explain this would be better. Column A will be the plaintext, column B will be the key that we'll use to encrypt the information, and column C will be the resulting ciphertext. If you did the other way around, you'll have the column A XOR B, meaning you have the ciphertext, and you run that on another XOR based on column B, which will be the key, you will end up having column A will choose plan through the plaintext. Now let's talk little bit about two type of ciphers. There is stream cipher and there's the block cipher. Stream cipher encrypt or decrypt the information bit per bit, meaning one bit at a time on a stream manner. Block ciphers they encrypt or decrypt information differently. They actually use blocks of bits or bits to encrypt information. Some algorithms use 64 bits of information to encrypt at a time. So block cipher will encrypt the message 64 bits at a time.
