It is a bit technical, but should explain the system we use and why we like it.

"Using Catalog's built-in encryption, the order is encrypted and the credit card details are twice encrypted. As the entire order is encrypted, Catalog orders are more secure than those using SSL. Within Catalog, for the java encryption, we use Diffie-Hellman Public and Private key encryption.

As an expert on encryption, one of our founders wrote the following:

Actinic Catalog uses the Diffie-Hellman key exchange (which is a public/private key or asymmetric key system) to generate a 256 bit key. Then 128 bits of this key is used in the symmetrical encryption protocol called SAFER.

A 128-bit symmetrical protocol is generally regarded as not crackable. The only known approach is by brute force and requires around 10^40 operations. If you could do 100 billion operations per second (10^11), then it would still take 10^29 seconds or 10^21 years. That's
1,000,000,000,000,000,000,000 years. If you use a 256 bit symmetrical key, it's thermodynamically impossible to crack (i.e there isn't enough energy in the universe). However, 128 bits is considered by most people to be safe."

Actinic Catalog

What that means is your data is safe with us!