I wanted to see the speed of the methods, the final results of each are from encrypting 1 sentance 300,000 times in a loop.

Round 1
MD5 generated in 0.350 seconds.
Base64 generated in 0.007 seconds.
CRC32 generated in 0.006 seconds.
SHA1 generated in 0.012 seconds.

Round 2
MD5 generated in 0.360 seconds.
Base64 generated in 0.008 seconds.
CRC32 generated in 0.006 seconds.
SHA1 generated in 0.012 seconds.

Round 3
MD5 generated in 0.362 seconds.
Base64 generated in 0.007 seconds.
CRC32 generated in 0.007 seconds.
SHA1 generated in 0.012 seconds.

Feel free to discuss :)