Public-key cryptography

Public-key cryptography is a form of cryptography which generally allows users to communicate securely without having prior access to a shared secret key, by using a pair of cryptographic keys, designated as public key and private key, which are related mathematically.

Related Topics:
Cryptography - Key - Cryptographic key

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The term asymmetric key cryptography is a synonym for public key cryptography.

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In public key cryptography, the private key is generally kept secret, while the public key may be widely distributed. In a sense, one key "locks" a lock; while the other is required to unlock it. It should not be possible to deduce the private key of a pair given the public key.

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There are many forms of public-key cryptography, including:

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• public key encryption — keeping a message secret from anyone that does not possess a specific private key.
• public key digital signature — allowing anyone to verify that a message was created with a specific private key.
• key agreement — generally, allowing two parties that may not initially share a secret key to agree on one.

Typically, public-key techniques are much more computationally intensive than purely symmetric algorithms, but the judicious use of these techniques enables a wide variety of applications.

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