Cryptograms can often be classified by being either of:

form. Asymmetric cryptograms make use of two keys, one for encryption (often called the *public key*) and another for decryption (often called the *private key*), while the symmetric ones only use one key (i.e. the same in both directions). The public and private keys are related to each other, but despite this, knowledge about the public key in not enough to calculate the private key (in a reasonable amount of time). Hence, the public key can be made *public*, allowing people to encrypt data using this key, while the private key is kept *private*, and is necessary for the decryption. Because symmetric algorithms use the same key for both directions, this has to be delivered to the "encryptioneers'', while keeping it secret to others.

Having this disadvantage, symmetric cryptograms are still often more practical than the asymmetric algorithms, because of their speed. While the latter are inherently slow, the former can be very fast, and hence, much more practical. If encrypted data is often sent between the same partners, an initial setup of a secret common key is not a big deal, but if the data is always sent to different places, then asymmetric cryptograms are in favour.

NB! Although *Power Crypto* is symmetric, there exists actually a safe way to distribute the secret key, using for example e-mail. Therefore, *Power Crypto* does not suffer notably from the disadvantage most symmetric cryptos have in comparison with the asymmetric ones. For detailed information about this, read here.