Asymmetric encryption

Asymmetric encryption is also called public key encryption. Two keys are required a private key and a public key. Usually the sender encrypts the data with the public key and the receiver decrypts the data with a private key but it can also be the other way arormd. Public keys are frequently located on the Internet. Private keys are located in a secure area of the owner s computer. 

This can be done by using so-called mix servers [58], [57]. A mix server makes tracing of data packets nearly impossible. It receives a packet (which has to be encrypted), re-codes it, and forwards it with some delay. This delay causes several packets received by the mix server to be permuted in their order in the sending process. The re-coding is done with an asymmetric encryption method. The sender encrypts the packet with the public key of the mix server, the mix server decrypts it with the corresponding private key and forwards it. It is also possible to create a chain of mix servers for increased security. Due to the delay caused for decrypting and also for forwarding the packets in a different order, this techniques is unsuited for sjmchronous communication. 

For asymmetric encryption the sender sets the padding scheme it requires setPaddingScheme) and verifies the receiver s certificate if it is not already known. Finally, the encryption algorithm encryptAlgorithm) is executed on the message msg) with the public key of the receiver (P(R)). 

Breaking asymmetric encryption is also an extremely hard problem, which is why it forms the basis of much information transmission security. The asymmetric cr3rptosystem is RSA (Cormen et ah, 2001). The genetic algorithm uses a multiobjective fitness function to measure how close a solution is to the correct set of primes. To find the primes, the fitness function is given access to a true plaintext and true cyphertext. The two objectives are ... 

E. Fujisaki and T. Okamoto, Secure Integration of Asymmetric and Symmetric Encryption Schemes, Advances in Cryptology - CRYPTO 1999, Lecture Notes in Computer Science, Vol. 1666, 1999, pp. 537-554. 

The same idea with key pairs was first introduced for secrecy schemes in [DiHe76] In this case, the first, more powerful, key is needed to decrypt messages, whereas with the second key, one can only encrypt. As before, the second key is published. Thus everybody can encrypt messages for the owner of a key pair and only the owner can decrypt them with the secret key. These schemes are called asymmetric secrecy schemes. ... 

This asymmetric cryptography approach also protects the existence of the electronic record by storing the record identifier in an encrypted format. This is achieved by encrypting the electronic record identifier with the record owner s private key. Therefore only the ones who have access to the public key of the record owner can access the record identifier. 

Often, Ke = that is, the encryption and decryption keys are identical, and in this case we refer to it simply as the key or the secret key. This is called symmetric or secret key cryptography. In contrast, in asymmetric or public key cryptography, the encryption keys and decryption keys are different from each other, and only the decryption key needs to be kept secret. In public key cryptography, the decryption key is also sometimes called the secret key. 

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