This is the last post of our Encryption series. You can read the rest of the posts by following the link on the side bar.
The following are the most common encryption algorithms:
1. AES (Advanced Encryption Standard): AES is a block cipher adopted as an encryption standard by the US government. AES was developed by two Belgian cryptographers, Joan Daemen and Vincent Rijmen, and is therefore also called ‘Rijndael’ (however, AES is not precisely Rijndael, as Rijndael supports a larger range of block and key sizes).
AES has a fixed block size of 128 bits and a key size of 128,192 or 256 bits. AES is fast in both software and hardware, is relatively easy to implement, and besides, it requires little memory. As a new encryption standard, it is currently being deployed on a large scale. 
2. Blowfish: Blowfish is another widely used encryption standard. It is a block cipher algorithm developed by Bruce Schneider. Blowfish is a variable-length key algorithm. The most common key lengths are 128-bit and 160-bit.
3. DES: DES has a fixed key length of 56 bits. DES is a block cipher algorithm developed by the National Institute of Standards and Technology (NIST) Data Encryption Standard.
4. Triple DES: Triple DES is a version of DES that encrypts a message or file three times using the DES 56-bit key. A plain text message or file is encrypted. The encrypted message is again encrypted, and the twice-encrypted message is encrypted a third time using DES.
5. RC4: RC4 is a stream cipher developed by RSA Data Security, Inc. The key-length is variable but typically limited to 40 bits. A 40-bit version of RC4 is also used by MS Office 97 for data encryption.
6. Message Digest (MD): MD is also sometimes referred to as a digital fingerprint. It is a number which is calculated from all the information in a message through the use of a cryptographic hash function, and which can be used to verify the data integrity of the message. Any change to the message, even of a single bit, typically results in a dramatically different message digest.
A message digest algorithm is considered ’secure’ if it is not computationally feasible to determine the content of a message from its message digest, nor to find ‘collisions’, wherein two different messages have the same message digest. In order to increase speed, most digital signature algorithms specify that only the digest of the message be ’signed’. Message digests can also be used in the generation of pseudorandom bits. SHA-1, MD5, and RIPEMD-160 are among the most commonly used message digest algorithms.
