Legal Definitions - public-key encryption

Public-key encryption, also known as asymmetric encryption, is a sophisticated method of securing digital communications and data. It relies on a pair of mathematically linked keys: a public key and a private key.

• The public key can be freely shared with anyone. It is used to encrypt messages or verify digital signatures.
• The private key must be kept secret and is known only to its owner. It is used to decrypt messages that were encrypted with the corresponding public key, or to create digital signatures.

This system ensures that information encrypted with a public key can only be decrypted by the person holding the corresponding private key, and that a digital signature created with a private key can be verified by anyone using the corresponding public key. This allows for secure communication and authentication without the need for parties to share a secret key beforehand.

Examples:

• Secure Online Transactions: When you make a purchase on an e-commerce website, your web browser often uses public-key encryption to protect your payment information.

  How it illustrates the term: The online store provides its public key to your browser. Your browser then uses this public key to encrypt your credit card number and other sensitive details before sending them over the internet. Only the online store, which possesses the corresponding private key, can decrypt and read your payment information. This prevents unauthorized individuals from intercepting and understanding your data.

• Confidential Email Exchange: Imagine a lawyer needs to send highly sensitive client information to a colleague via email, ensuring only that specific colleague can read it.

  How it illustrates the term: The lawyer obtains their colleague's public key. They then use this public key to encrypt the email message. Once encrypted, the email can only be decrypted by the colleague using their unique private key. Even if the email is intercepted by a third party, its contents remain unreadable, protecting client confidentiality.

• Verifying Software Downloads: When you download software from a reputable vendor, they often provide a digital signature to assure you the software is authentic and hasn't been tampered with.

  How it illustrates the term: The software vendor uses their private key to create a digital signature for the software package. When you download the software, your computer can use the vendor's widely available public key to verify this signature. If the signature is valid, it confirms that the software genuinely came from the vendor and that its contents have not been altered since it was signed, providing assurance of its integrity and origin.