Cryptography

Importance of cryptography

Cryptography is important to secure data and communication over the internet.

Some important terms

CypherText

The result of encrypting a plaintext

Cipher

A method of encrypting or decrypting data. Modern cipher are cryptographic, but there are many non-cryptographic cipher like Caesar cipher.

Plaintext

Data before encryption, often text but not always. Could be a photograph or other file.

Encryption

Transforming plaintext into ciphertext, using a cipher

Encoding

Not a form of encryption, just a form of data representation. Example - Base64

Key

Soem information that is needed to correctly decrypt the ciphertext and obtain the plaintext.

Passphrase

Seperate to the key, a passphrase is a password to protect the key

Cryptanalysis

Attacking cryptography by finding a weakness in unerlying maths.

Usage of cryptography with examples

Cryptography is used to protect confidentiality, ensure integrity and ensure authenticity

Examples

1. When you connect to SSH, your client and server establish an encrypted tunnel so that no one can snoop on your sessio.

2. When you connect to your bank, there is a certificate that uses cryptography to prove that it actually your bank.

3. When you download a file, you can use cryptography here to verify a checksum of data