Public Key

Definition

A public key is a cryptographic key that can be shared openly and is used in asymmetric encryption to encrypt data or verify digital signatures. It forms part of a key pair, which includes a private key that must be kept secret. This system allows secure communication and authentication without requiring the exchange of sensitive information.

5 Must Know Facts For Your Next Test

1. Public keys are used in various cryptographic protocols, including SSL/TLS, which secure online communications.
2. The strength of security using public keys relies on the mathematical difficulty of deriving the private key from the public key.
3. Public keys are typically distributed via digital certificates, which help establish trust by associating keys with specific identities.
4. Public-key cryptography enables secure transactions and communications over untrusted networks, such as the internet.
5. Public keys can also facilitate secure multi-party computations and decentralized applications within blockchain technology.

Review Questions

• How does the relationship between public keys and private keys enhance security in digital communications?
  • The relationship between public keys and private keys is foundational to the security of digital communications. The public key can be freely distributed and used to encrypt messages, while only the holder of the corresponding private key can decrypt those messages. This ensures that even if the public key is widely known, only someone with access to the private key can read the encrypted content, effectively protecting sensitive information from unauthorized access.
• Discuss the role of public keys in creating digital signatures and how they contribute to verifying authenticity.
  • Public keys play a crucial role in creating digital signatures, which are used to ensure the authenticity and integrity of digital messages. When a sender signs a message using their private key, anyone with access to the sender's public key can verify that the signature is valid. This means that the message has not been altered and confirms that it truly comes from the claimed sender, thereby facilitating trust in electronic communications.
• Evaluate how public key infrastructure (PKI) supports the effective use of public keys in securing online transactions.
  • Public Key Infrastructure (PKI) supports effective use of public keys by providing a framework for managing digital certificates and associated encryption keys. PKI establishes trust through certificate authorities (CAs) that issue certificates linking public keys to verified identities. This system helps prevent man-in-the-middle attacks and enables secure online transactions by ensuring users can trust that they are communicating with legitimate parties. As such, PKI is vital for maintaining security in modern internet communications.

Related terms

Private Key:

A private key is a secret key in asymmetric cryptography that is used to decrypt data encrypted with the corresponding public key or to create digital signatures.

Asymmetric Encryption: Asymmetric encryption is a type of encryption that uses a pair of keys – a public key for encryption and a private key for decryption – making it distinct from symmetric encryption, which uses the same key for both processes.

Digital Signature:

A digital signature is a cryptographic technique used to validate the authenticity and integrity of a message, file, or software by applying the signer's private key to create a unique signature that can be verified with the corresponding public key.