Cryptography: What Exactly is Cryptography? (Intro)

Cryptography: What Exactly is Cryptography? (Intro)

In this lesson, we’re going to start with an overview of what cryptography is, how it works and the benefits it offers.


We need cryptography for:

  1. password storage
  2. secure authentication
  3. data transmissions
  4. data security
  5. signing messages to prove whom they came from

Cryptography concepts

  1. symmetric versus asymmetric encryption,
  2. digital signatures,
  3. non-repudiation encryption

Decryption methods

  1. block ciphers stream
  2. ciphers
  3. elliptic curve cryptography (ECC)
  4. quantum cryptography


cryptographic hashing

  1. transport
  2. encryption
  3. steganography

Then, at the end of this lesson, we will discuss using only proven cryptographic technologies.

What is Cryptography?

This all falls under cryptography

It is the science and study of hiding any text so that only the intended recipients or authorized people can read it and that is any text even using things like invisible ink or the mechanical cryptography machines of the past.


These steps together are cryptography.

Sender > Encryption (Plaintext + Public Key) = Ciphertext
Decryption (Ciphertext + Private Key) = Plaintext > Recipient



This is the encryption step

What we are concerned with for IT security is obscuring information by converting plaintext to ciphertext.

So, if we look at the diagram, we have our plain text. This is put through the encryption algorithm. Now, many encryption algorithms are publicly known. So, what makes the encryption unique is the key. You can think of this as kind of a password, the plaintext and the key are put through the mathematical algorithm, and the result is the ciphertext.

For this to be considered strong Encryption, we shouldn’t be able to figure out the key from the ciphertext and we shouldn’t be able to get plaintext back from the ciphertext without the key.

Then the decryption step

Converting the information back from ciphertext to plaintext.

Then, when we need to use this text again or once it is being sent to the recipient, the opposite happens with a decryption algorithm and key. This time, the ciphertext and key are run through the algorithm and results back to our plaintext again.

There’s also cryptographic hashing

Cannot get plaintext back from the ciphertext, but we will cross that bridge we come to it.

Benefits of Cryptography

Now, let us talk about some benefits of cryptography

  1. The most obvious goal and benefit of cryptography is confidentiality. We use transport encryption protocols to protect data in transit. We also encrypt data to protect it while it is being stored at rest. This keeps unauthorized people out of our sensitive data.
  2. Cryptography can also offer non-repudiation and authentication a message encrypted with your private key or signed with your digital signature had to have come from you. Do not worry, private non-repudiation keys and digital signatures will all be covered later in this lesson.
  3. Another benefit is access control in a fundamental and limited way. Cryptography can offer access control with symmetric encryption. Only the secret key holders can decrypt the message with asymmetric encryption. A digital certificate can be used for authentication and thus access control.
  4. Cryptographic hashes are used to offer integrity message. Digests, like checksums, can be used to know if a message has been tampered with during transit or if data has been changed since the last message digest was taken. Hashing is super important to prove that evidence has not been tampered with.

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