# Public key cryptography

Public key cryptography |
---|

See also |

**Public key cryptography**, also known as asymmetric cryptography, is a form of cryptography that uses two different keys to encrypt and decrypt data. It involves the use of a public key, known and shared between two parties, to encrypt data and a private key, kept secret by the receiver, to decrypt the data. This type of cryptography is used to secure communications and verify the identities of two parties over the internet. It is an important component of cyber security, protecting data from malicious actors and ensuring that data is not tampered with during transmission.

## Example of Public key cryptography

- Public key cryptography is used to secure communication and verify identities over the internet. For example, when you send an email, the sender and receiver use public key cryptography to ensure that the message is encrypted and can only be decrypted by the intended recipient. Similarly, secure websites use public key cryptography to provide secure connections between the website and users. This is done by encrypting the data sent between the two parties with a shared public key and a private key known only to the receiver.
- Another example of public key cryptography is digital signatures. Digital signatures are used to prove that a document has not been tampered with and is from a specific source. In this case, the public key is used to encrypt the data and the private key is used to decrypt it. This ensures that the document is authentic and has not been modified.
- Public key cryptography is also used in cryptocurrency transactions. When a transaction is made, the sender and receiver use a public key to encrypt the transaction and a private key to decrypt it. This ensures that only the intended recipient can view the transaction and that the transaction is secure and untampered with.

## When to use Public key cryptography

Public key cryptography is an important tool for secure digital communication, and it is used in a variety of applications, including:

**Secure online communication**: Public key cryptography can be used to securely exchange messages between two parties over the internet, allowing them to communicate without fear of interception or tampering.**Digital signatures**: Public key cryptography can be used to create digital signatures, providing a secure way to digitally verify the identity of a sender and ensuring that the data has not been altered.**Secure file transfer**: Public key cryptography can be used to securely transfer files between two parties, ensuring that the files are not tampered with or intercepted during transmission.**Secure software updates**: Public key cryptography can be used to securely deliver software updates to users, preventing malicious actors from tampering with the updates.

## Types of Public key cryptography

Public key cryptography is an important component of cyber security and can be used to protect data from malicious actors and ensure that data is not tampered with during transmission. There are several types of public key cryptography, including:

- RSA (Rivest–Shamir–Adleman) is one of the oldest types of public key cryptography and is used to encrypt data and digitally sign documents. It is based on the difficulty of factoring large numbers.
- Diffie-Hellman is a type of public key cryptography that uses prime numbers to create a secure key exchange between two parties. It is used to establish secure communication channels over the internet.
- Elliptic Curve Cryptography (ECC) is a type of public key cryptography that uses elliptic curve equations to create a secure key exchange between two parties. It is more efficient and secure than RSA and Diffie-Hellman.
- Digital Signatures Algorithm (DSA) is a type of public key cryptography used to verify the authenticity of digital documents and data. It is based on the difficulty of calculating discrete logarithms.
- Quantum Key Distribution (QKD) is a type of public key cryptography that utilizes quantum mechanics to generate an unbreakable key exchange between two parties. It is the most secure type of public key cryptography available.

## Advantages of Public key cryptography

Public key cryptography offers several advantages for secure communication. The most important advantages include:

**Improved security**: As the private key is kept secret, public key cryptography provides a layer of security that is hard to breach. It also prevents data from being tampered with during transmission.**Increased convenience**: Public key cryptography makes it easy for two parties to securely communicate without having to manually exchange keys.**Authentication**: As each party can verify the identity of the other through the public key, public key cryptography can be used to authenticate the identities of two parties.**Flexibility**: Public key cryptography is versatile, allowing the same algorithm to be used for both encryption and digital signatures. This makes it useful for a variety of applications.

Public key cryptography is an important component of cyber security, providing a secure and reliable way to exchange information. Other approaches related to public key cryptography include:

**Digital signatures**: This is a type of electronic signature that uses public key cryptography to authenticate the identity of a sender or receiver. The sender encrypts a message with their private key, and the receiver decrypts the message with the sender's public key.**Certificate-based authentication**: This is a type of authentication that uses public key cryptography to verify the identity of a user. It involves a Certification Authority (CA) that issues digital certificates, which contain the user's public key. The CA then verifies the user's identity and signs the certificate, allowing the user to securely access information.**Secure Sockets Layer (SSL)**: This is a protocol used to securely transmit data over the internet. It uses public key cryptography to establish a secure connection between the server and the client, allowing them to exchange data securely.

In summary, public key cryptography is an important component of cyber security that provides a secure and reliable way to exchange information. Other approaches related to public key cryptography include digital signatures, certificate-based authentication, and Secure Sockets Layer (SSL). These approaches help to ensure that data is kept secure and confidential during transmission, making it an essential part of cyber security.

## Suggested literature

- Hellman, M. E. (2002).
*An overview of public key cryptography*. IEEE Communications Magazine, 40(5), 42-49. - Diffie, W. (1988).
*The first ten years of public-key cryptography*. Proceedings of the IEEE, 76(5), 560-577.