Intel has decided that AES encryption feature of the 520 Series SSD (Cherryville) does not actually feature 256-bit encryption. It turns out that the SSD actually only supports 128-bit encryption, which should be plenty for most users. These details have come to light after Intel published an updated specification document for the series.

Intel is doing the right thing and offering a refund for users who feel 128-bit isn't enough:

Intel stands behind its products and is committed to product quality, and is working to bring AES 256-bit encryption to future products. If, however, our customers are not satisfied with the 128-bit encryption in an Intel 520 Series SSD purchased before July 1, 2012, they can contact Intel customer support prior to October 1, 2012 to return their product and Intel is offering to provide a full refund of the purchase price. For further information or questions about this specification change, consumers should contact Intel Customer Support.

Intel asserts that 128-bit is enough for most consumers, and I have to agree. The bit number refers to the length of the key and 128-bit keys are pretty hard to crack. The longer the key, the longer it takes to crack due to a larger keyspace. 256-bit is only really needed for military and super secret applications. But then again, if you aren't careful with the password, a huge key doesn't matter.