Public Key
Type of Cryptography where different keys are use, one for encryption and one for decryption
Private Key
- A private key is an unpublished key which has never been transmitted anywhere
- It has a matching public key
- It decrypts data its matching public key has encrypted
Plain text
Original data before encryption
Cipher Text
The result of encryption is transmitted to the recipient.
Encryption
Encryption alters the data to something unreadable by anybody for whom the data is not intended to
Symmetric key encryption
A single key is used for both encryption and decryption
Asymmetric key encryption
One key is used to encrypt the message, and the matching key is used to decrypt the message
Purpose of Asymmetric cryptography
- To provide better security by using two different keys, private and public
- One key is used to encrypt the message and the other is used to decrypt the message
How is asymmetric key cryptography used
- Uses matching pair of keys
- A public key is available for everyone, receivers public key is used to encrypt the data before being sent.
- A private key is only known to the owner of the keys, receiver’s private key is used for decrypting the message received.
Benefits of asymmetric key cryptography
- more secure as one key is private
- allows method authentication
- detects tampering
- allows non-repudiation
Drawbacks of symmetric key encryption
- Key has to be exchanged securely
- once compromised key can be used to decrypt both sent and received messages
- cannot ensure non-reputation
Differences between Symmetric and Asymmetric cryptography
- Symmetric cryptography uses a single key whereas asymmetric cryptography uses a pair of keys
- Symmetric key is shared whereas only the public key is shared in asymmetric cryptography. So the risk of compromise is higher in symmetric encryption so asymmetric is more secure
- Symmetric cryptography is a simple process that can be carried out quickly but asymmetric is much more complex, so slower.
- length of key of symmetric is shorter
Sending a private message
- Public key sent to sender
- Sender encrypts data with the public key and sends the cipher text
- Receiver decrypts data with the private key.
Reasons for using key cryptography
- To ensure the message is authentic
- To ensure only the intended receiver can understand the message
- To ensure the message has not been altered during transmission
- Non-repudiation, neither the sender nor receiver can deny that transmission has occurred
Purpose of Quantum Cryptography
- To produce a virtually unbreakable encryption system using the laws of quantum mechanics
- Eavesdropping can be detected as properties of photons change
- To protect the security of data over fiber optic cables to enable using longer keys.
Benefits of Quantum Cryptography
- Longer keys can be used
- Eavesdropping can be detected
- Virtually unbreakable
- Provides security based on laws of physics rather than mathematical algorithms so more secure
Drawbacks of Quantum Cryptography
- Limited range
- Polarized light may change during transmission
- High cost of purchasing required
- Lacks vital features such as digital signature.
