Private key

Definitions

A private key is

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[t]he secret part of an asymmetric key pair that is typically used to digitally sign or decrypt data.

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“

a cryptographic key, used with a public key cryptographic algorithm, that is uniquely associated with an entity and is not made public. In an asymmetric (public) cryptosystem, the private key is associated with a public key. Depending on the algorithm, the private key may be used to — 1) Compute the corresponding public key, 2) Compute a digital signature that may be verified by the corresponding public key, 3) Decrypt data that was encrypted by the corresponding public key, or 4) Compute a piece of common shared data, together with other information.

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Overview

For digital signatures, the private key is uniquely associated with the owner and is not made public. The private key is used to compute a digital signature that may be verified using the corresponding public key.

The integrity of even the most secure digital signature rests on the continuing confidentiality of the private key.

Source

• "Overview" section: FIPS 186-3, at 4.