The Work of Asymmetric Encryption and Decryption

Subject: Tech & Engineering
Pages: 3
Words: 669
Reading time:
3 min

With symmetric encryption, the key used for encryption has to be shared over the internet. This creates a high risk in terms of the security of the encrypted data and the possibility of the key falling into the wrong hands. As a result in order to waive such risks, asymmetric encryption is used. Asymmetric encryption makes use of private keys. A key pair is formed where the public key is available to the sender freely over the internet while the second key, the private key is kept secret.

Any message (text, binary files, or documents) that are encrypted by using the public key can only be decrypted by applying the same algorithm, but by using the matching private key. Any message that is encrypted by using the private key can only be decrypted by using the matching public key. This means that you do not have to worry about passing public keys over the Internet (the keys are supposed to be public). A problem with asymmetric encryption, however, is that it is slower than symmetric encryption. It requires far more processing power to both encrypt and decrypt the content of the message.

The advantage of the asymmetric form of encryption is that it is possible to transmit the public keys to other parties freely over mass and public communication mediums like the internet. Simultaneously, the second key involved in the encryption is kept secretly with the sender and the receiver. The secret key can be communicated amongst the receiver and the sender through their public keys, and the asymmetric encryption on their secret key. In asymmetric systems the key used to encrypt a message is not the same as that used to decrypt it. If a message has been encrypted using one key of a pair it cannot be decrypted even by someone else who has that key (crucially, knowing one key doesn’t provide knowledge of the other). Only the matching key of the pair can be used for decryption.

The following message traded however can be performed using symmetric encryption only making way for faster processing of information and less computerization as compared if the entire communication was conducted in asymmetric encryption. Moreover, the use of asymmetric encryption also provides proof of origin. The disadvantage of asymmetric encryption is that its performance is slow due to the high level of computation involved and the double keys being utilized for encryption and decryption. The asymmetric form of encryption works on the basis of making multiples of factors of a given variable that are so large that it is not possible to factorize the variable in a reasonable amount of time. Therefore for complete security 1024 bits are used for asymmetric encryption. However, the processing of such large numbers is very complex and time-consuming making the processing time for asymmetric encryptions thousands of times slower.

Raising such very large numbers to very large exponents is computationally much more demanding than the bit shifting and XOR’ing of symmetric cryptosystems such as DES, so asymmetric encryption is really only practical for short messages. A common workaround when encrypting long messages is to use RSA to encrypt a short preamble containing a DES or AES key selected at random, then send the main body of the message encrypted with that key. A recipient with the corresponding private key can decrypt the preamble and use the key it contains to decipher the rest of the message. Modern web browsers use exactly this method to conduct secure communications. The dynamic nature and characteristics of the asymmetric encryption, and the hybrid utilization of both public and private keys as well as the combined use of symmetric and asymmetric encryption sessions management has enabled the internet to provide increasingly secure and unique options for the and transfer of data ranging form emails to shorted messages, pictures, videos, and multimedia material.