Computer and Cryptography

Computers have transformed the Cryptography. Before the computer era, cryptography was used only to encrypt messages. Once the team began in the cryptography uses higher mathematics important to make strong encryption. Computers and the Internet have also expanded cryptography for authentication and digital signing.

Encryption on the computer can be divided into two categories, symmetric and asymmetric encryption. An encryption key is also called because uses the same key to both encrypt and decrypt the symmetric encrypted message. Asymmetric encryption uses two different keys, a private and a public key. Public key encryption is called asymmetric encryption.

Symmetric encryption can be done very quickly and safely. The biggest drawback with the symmetric cipher is the distribution. Before using the symmetric encryption key safe for all participants it must be distributed. This a logistical nightmare included quickly, if it increases the number of people. The password should be changed regularly to minimize the risk of using a key of sustained serious damage. Symmetric encryption is not a viable option for encryption on the Internet. This is also not only because of the wide range of keys, which would be necessary before it can begin to communicate with someone, it is necessary to agree on a secret key.

Asymmetric encryption is typically slower than symmetric encryption, but is much more suitable for the Internet. Key distribution security isn't a problem, all those involved have a private and a public key. It is known only from the holder of the private key, is familiar with the corresponding key on all sides.

The private and public keys are related mathematically, if a message with a private key encrypted with the corresponding public key can decrypt the text. In this way you can be sure that the message was encrypted by the owner of the private key. In addition to a message with a public key to encrypt and send the message on unsafe roads. Because no one can decode the message of the corresponding private key except the owner, regardless of whether others maintain the ciphertext. This also means that you will ensure that you communicate with the person who is the owner of the private key.

But you can be sure that you have the public key right? Someone could tell a fake key and you, which is the public key of your bank. If you choose to accept the key, it could end by giving their banking details and credit card fraudsters. The solution is simple, Web browsers have a pre-installed number of certification authorities that trust. These CA certificates which prove that a site really the page that claims to be. If a Web site certificate from a certification authority trust browser that does not appear a warning, saying that the certificate was not issued by a trusted certification authority.