Terminology Index
Glossary
2953 terms
Private Key
The secret half of an asymmetric key pair, kept strictly confidential by its owner, used to decrypt or sign. Its secrecy is the foundation of identity and trust in public-key cryptography.
In asymmetric cryptography, the private key is the secret companion of a public key: only the private key can decrypt what its public key encrypted, and only it can produce a signature its public key verifies. Protecting it absolutely is non-negotiable, exposure breaks everything that depended on it. Private keys live in hardware security modules, key vaults, secure enclaves, and devices, with controls preventing extraction. Understanding their role is foundational to PKI, TLS, signatures, and modern authentication.
Introduced in: Cryptography Essentials
Examples
- Signing with a private key so a public-key holder can verify origin.
- Decrypting messages that were encrypted with the matching public key.
- Protecting a private key in a hardware security module.
