A cryptographic key is a small amount of information, without which encrypted data will not in practice be convertible back to its original form -- at least for high quality encryption algorithms. Most cryptographic algorithms use a single key which is used both to encrypt and decrypt the data: they are known as symmetric algorithms. An attacker who obtains the key can recover the original message from the encrypted data, since as a matter of principle the details of the cryptographic algorithm used is assumed to be already available to the attacker. This design assumption is usually known in crypto circles as Kerchoff's Law, or in more colloquial form, Shannon's Maxim. |
A cryptographic key is a small amount of information that is used by an algorithm that encrypts or decrypts a message, or "plaintext". If the decryption key is lost, encrypted data will not in practice be convertible back to its original form -- at least for high quality encryption algorithms and large enough key sizes. Most cryptographic algorithms use a single key which is used both to encrypt and decrypt the data: they are known as symmetric algorithms. An attacker who obtains the key can recover the original message from the encrypted data, since as a matter of principle the details of the cryptographic algorithm used is assumed to be already available to the attacker. This design assumption is usually known in crypto circles as Kerchoff's Law, or in more colloquial form, Shannon's Maxim. |