CS-iGCSE-CIE-Notes
A Encryption
2.3 Encryption :It is a process of taking a message of plain text and using a key or algorithm to encrypt it into ciphertext, altering it so that it cannot be read.Without encrypting data, cyber criminals can easily read that data as it transmits through the internet. * Protects private data from being read by unwanted parties
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It does NOT prevent hacking
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The data is meaningless unless the recipient has the decryption tools (e.g encryption algorithm, key), a middleman will not be able to read the dataThere are two forms of encryption:* Symmetric encryption
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Asymmetric encryptionHow can you tell if your data is encrypted online?Secure:
Not secure:
SSL (secure sockets layer) is an encryption Internet security protocol. It establishes secure connections through networks and computers, preventing cyber criminals from stealing data. This is done through methods of encryption.Passwords on databases are stored in hashed format.**
Methods of encryption
- Caesar cypher, +3 letters,A B C D E F G H I J K L M N O P Q R S T U V W X Y ZD E F G H I J K L M N O P Q R S T U V W X Y Z A B CPlain text:“I love you, will you go out with me”Cypher text:“L ORYH BRX, ZLOO BRX JR RXW ZLWK PH”
Symmetric Encryption
The key/algorithm to encrypt and decrypt the message are the same. Anyone with the key can decrypt the data.Symmetric encryption is used in phone and computer login passwords.
Asymmetric Encryption
Also known as public key encryption gives the user a private and public key. Only the user with the private key may unlock and read (decrypt) anything locked (encrypted) with their public key. The private key can only be accessed by the user. The public key is shared so that it can be used to encrypt data being sent to the user.Only messages encrypted using the public key can be decrypted by the private key. This makes it much more secure than symmetric encryption where anyone can decrypt the ciphertext if they have access to the key.Hashing This is an irreversible mathematical process that is used to protect encryption keys. This is because many different values and inputs can become the same hashed value. They are usually stored as hexadecimal values. This makes it essentially impossible for hackers to find the encrypted key.The RSA algorithm (Rivest-Shamir-Adleman) utilises prime numbers. 1) Choose two large prime numbers P, Q
2) N is the product and P and Q
3) The encryption key is calculated by (P-1) * (Q-1) = E
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