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Secret key

(also private key)

Secret key definition

A secret key is a parameter that can be used to encrypt and decrypt data in symmetric and asymmetric encryption. It could be a password or a phrase, but usually, it's a random sequence of bits. The longer and more random the key is, the more challenging it is for a cybercriminal to use brute force to crack it. Because of their length and randomness, secret keys are less likely to be cracked by a brute-force or dictionary attack.

How does a secret key work in asymmetric encryption?

Secret keys are used in asymmetric cryptography as part of the private and public key pair. Here’s how the process works:

  • The sender obtains the receiver’s public key (from a public database or directly from the receiver).
  • The sender uses the public key to encrypt the message, data, or file and turn it into ciphertext.
  • The sender transmits the encrypted data over to the receiver.
  • The receiver uses their secret key to decrypt the message.

How does a secret key work in symmetric encryption?

Symmetric encryption uses only secret keys. Here’s how it works:

  • The sender and receiver decide on a key they will be using.
  • The sender transmits the secret key to the receiver (or vice versa).
  • The sender uses the secret key to encrypt the message, data, or file and turn it into ciphertext.
  • The sender transmits the encrypted data over to the receiver.
  • The receiver uses their secret key to decrypt the message.