What are the differences between these encryption algorithms?

Question

What are the difference between MCRYPT_RIJNDAEL_128, MCRYPT_RIJNDAEL_256, MCRYPT_BLOWFISH, etc. Which one is best suitable for data trans

Answer 1

Both Rijndael and Blowfish are considered to be secure.

MCRYPT_RIJNDAEL_128 vs MCRYPT_RIJNDAEL_256:
The only difference is the block size. You can use either with 128 bit, 192 bit, or 256 bit keys.
Bigger keys take longer to brute-force.
The 256-bit version is therefor more secure.
Note: The 128-bit version still takes lots of time time to brute-force.

Currently Rijndael is the Advanced Encryption Standard:
http://en.wikipedia.org/wiki/Advanced_Encryption_Standard

AES is generally faster then Blowfish because:
- The algorithm itself is more efficient for processors (bit vs byte blocks).
- Manny processors support hardware acceleration for AES.

Conclusions:
- All three options are secure enough for data transfer.
- The choice depends on how 'secret' the data is.
- Rijndael is wider used and therefore easier to implement is some situations.