TIme of encryption and decryption of 500MB ramdisk using 256-bit AES in CBC mode

Benchmark
$openssl speed

Here is the script to calculate how long the encryption and decryption will take:
#!/bin/bash
ENCSTART=$(date +%s:%N)
echo "start = $ENCSTART"
openssl enc -aes-256-cbc -salt -in /dev/ram0 -out ramdisk.enc -pass pass:password
ENCEND=$(date +%s:%N)
echo "end = $ENCEND"
DECSTART=$(date +%s:%N)
echo "start = $DECSTART"
openssl enc -d -aes-256-cbc -in ramdisk.enc -out ramdisk -pass pass:password
DECEND=$(date +%s:%N)
echo "end = $DECEND"


More info, please see:
http://www.madboa.com/geek/openssl/