Cipher

With an encryption method to clear text can be transformed into a ciphertext (encryption), and conversely the ciphertext again be converted back to the plaintext ( decryption ). Often this key is used. Cryptography has a long history, so encryption methods from ancient Egypt are already known. Important milestones in the development of new encryption methods are the invention of the telegraph, the computer and the asymmetric cryptosystems today Represents the result of digital communication most widely used method is the RSA method.

Principle

With encryption method, a source text, such as a message or a password to be encrypted. One such source text is plaintext, the ciphertext called ciphertext. In this way the source text can be protected against unauthorized access. Despite this encryption, a third party, usually called code breaker trying to decipher the incomprehensible for him text. In principle, a distinction is the classical symmetric cryptosystems from the known for only a few decades asymmetric cryptosystems.

Symmetric Encryption

For symmetric encryption and decryption procedures are performed with the same key. That is, the sender and receiver must have agreed in advance this secret key and the key must be kept secret, of course, to protect the information. A security problem to check out the handover of the secret key Represents the first known of this type represents the Caesar cipher

Asymmetric encryption

In asymmetric methods there is not a key to encrypt and decrypt, but two; a public key which is accessible to everyone, and a private key that must be kept secret. The text is encrypted with the public key and can only be decrypted with the private key. Here, the encryption key must not be kept secret, but it must be ensured that the public key actually belongs to the receiver. Asymmetric methods are also usually slow, and therefore most hybrid methods are used in practice.

ID - based encryption

ID -based encryption scheme is a special subset of the asymmetric method, in which there is only one secret decryption key. To encrypt only the public parameters of the process and the identity of the recipient must be known. The receiver can be in a central entity that has a kind of super key, can issue a decryption key corresponding to his identity. The special feature of this method is that no key is transmitted, the coding can be done even before the receiver knows his secret key.