What is Symmetric Algorithm

A symmetric algorithm utilizes a similar key for encrypting and decrypting data, and everybody that is permitted to encrypt and decrypt the data has a duplicate of the key. his is also known as a shared secret.  Symmetric algorithms provide confidentiality by encrypting data or messages. Some of the past and current symmetric key encryption algorithms include Data Encryption Standard (DES), Triple DES (3DES), Advanced Encryption Standard (AES), International Data Encryption Algorithm (IDEA), Blowfish, and RC4.

There are advantages and disadvantages to using symmetric keys. Some of the advantages are as follows:

Speed
The algorithms used with symmetric encryption are relatively fast, so they impact system performance less and are good for encrypting large amounts of data (for instance, data on a hard disk or data being transmitted across a remote access link).

Strength
Symmetric algorithms are difficult to decipher without the correct algorithm; therefore they are not easy to break. Well-tested symmetric algorithms such as 3DES and AES are nearly impossible to decipher without the correct key. Also, a technique can be used in which encrypted data can be encrypted a second or even third time. This way, if someone does break the encryption, he or she will have access to only more encrypted information.

Some of the disadvantages of using symmetric keys are as follows:

Poor key distribution mechanism
There is no easy way to securely distribute a shared secret; therefore wide-scale deployment of symmetric keys is difficult.

Single key
There is a single key (single shared secret); therefore if the secret is compromised, the impact is widespread. Because there is a single key that can be shared with some or many, symmetric keys are not suited to provide integrity, authentication, or nonrepudiation.

Some of the characteristics of specific symmetric keys are as follows:

DES
56-bit key, U.S. Government standard until 1998, but not considered strong enough for today's standards, relatively slow.

Triple DES
Performs 3DES operations, equivalent of 168-bit keys, more secure than DES, widely used, relatively slow.

AES
Variable key lengths, latest standard for U.S. Government use, replacing DES.

IDEA
128-bit key, requires licensing for commercial use.

Blowfish
Variable key length, free algorithm, extremely fast.

RC4
Variable key length, stream cipher, effectively in public domain.

What is Asymmetric Algorithm

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