===== Private Key =====
[[dido:public:ra:xapend:xapend.a_glossary:start| Return to Glossary ]]

==== Definition 1 ====

A **Private Key**((
Elaine Barker,
NIST,
__Recommendation for Key Management: Part 1 - General__,
NIST Special Publication 800-57 Part 1, Revision 5,
May 2020,
Accessed 18 January 2022,
[[https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-57pt1r5.pdf]]
)) is a Cryptographic Key used with a [[dido:public:ra:xapend:xapend.a_glossary:p:public_key#definition_1| Public Key]] [[dido:public:ra:xapend:xapend.a_glossary:c:cryptographic_algorithm]]
that is uniquely associated with an entity and is not made public. In an
asymmetric-key ([[dido:public:ra:xapend:xapend.a_glossary:p:public_key#definition_1| Public Key]]) cryptosystem, the private key has a
corresponding [[dido:public:ra:xapend:xapend.a_glossary:p:public_key#definition_1| Public Key]]. Depending on the algorithm, the private key
may be used, for example:

  - Compute the corresponding [[dido:public:ra:xapend:xapend.a_glossary:p:public_key#definition_1| Public Key]],
  - Compute a digital signature that may be verified by the corresponding [[dido:public:ra:xapend:xapend.a_glossary:p:public_key#definition_1| Public Key]],
  - Decrypt keys that were encrypted by the corresponding [[dido:public:ra:xapend:xapend.a_glossary:p:public_key#definition_1| Public Key]], or
  - Compute a shared secret during a key-agreement transaction.

==== Definition 2 ====

A **Private Key**, also known as a secret [[dido:public:ra:xapend:xapend.a_glossary:k:key|key]], is a variable in [[dido:public:ra:xapend:xapend.a_glossary:c:cryptography|cryptography]] that is used with an algorithm to encrypt and decrypt code. Secret keys are only shared with the key’s generator, making it highly secure. **Private Keys** play an important role in symmetric cryptography, asymmetric cryptography, and cryptocurrencies.

The complexity and length of the private key determine how feasible it is for an interloper to carry out a brute force attack and try out different keys until the right one is found.

[[dido:public:ra:xapend:xapend.a_glossary:p:public_key]] are for encrypting data by anyone with access to the Public Key. The **Private Key** is required to decrypt the data, which is why the Private key needs to be kept secret.

Source: [[https://searchsecurity.techtarget.com/definition/private-key]]


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