Asymmetrical encryption

The public key can be freely shared with any party. It is associated with its paired key, but the private key cannot be derived from the public key. The mathematical relationship between the public key and the private key allows the public key to encrypt messages that can only be decrypted by the private key. This is a one-way ability, meaning that the public key has no ability to decrypt the messages it writes, nor can it decrypt anything the private key may send it.

The private key should be kept entirely secret and should never be shared with another party. This is a key requirement for the public key paradigm to work. The private key is the only component capable of decrypting messages that were encrypted using the associated public key. By virtue of this fact, any entity capable of decrypting these messages has demonstrated that they are in control of the private key.