Public-key cryptography and related standards and techniques underlie the security features of many products such as signed and encrypted email, single sign-on, and Secure Sockets Layer (SSL) communications. This document introduces the basic concepts of public-key cryptography. For an overview of SSL, see "Introduction to SSL." For an overview of encryption and decryption, see "Encryption and Decryption." Information on digital signatures is available from "Digital Signatures."
Public-key cryptography is a set of well-established techniques and standards for protecting communications from eavesdropping, tampering, and impersonation attacks.
The sections that follow introduce the concepts of public-key cryptography that underlie these capabilities.
Public-key cryptography is a set of well-established techniques and standards for protecting communications from eavesdropping, tampering, and impersonation attacks.
- Encryption and decryption allow two communicating parties to disguise information they send to each other. The sender encrypts, or scrambles, information before sending it. The receiver decrypts, or unscrambles, the information after receiving it. While in transit, the encrypted information is unintelligible to an intruder.
- Tamper detection allows the recipient of information to verify that it has not been modified in transit. Any attempt to modify data or substitute a false message for a legitimate one will be detected.
- Authentication allows the recipient of information to determine its origin-that is, to confirm the sender's identity.
- Nonrepudiation prevents the sender of information from claiming at a later date that the information was never sent.
The sections that follow introduce the concepts of public-key cryptography that underlie these capabilities.