Public Key


A public key is a key used in the public cryptographic system.

The public key is often saved in a cer format.


The public key distribution can be done:

  • through public key servers. When a person creates a key-pair, they keep one key private and the other, known as the public-key, is uploaded to a server where it can be accessed by anyone to send the user a private, encrypted, message.
  • by publishing it in a public directory such as with a certification authority.
  • through an algorithm: See for instance: Diffie–Hellman key exchange and RSA

I judged it most important for military use … if you can share your key rapidly and electronically, you have a major advantage over your opponent.


A public key is created from a private key.

Example: create a rsa public key from a rsa private key

openssl rsa -in key.pem -pubout -out pubkey.pem

See also: Keypair (public and a private key)




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