The Hashlet, a secure authentication device that performs SHA-256 in hardware, is now available for the Raspberry Pi! Like the BBB version, it slips on the expansion header and communicates over I2C. The Hashlet can provide a random number source, perform Message Authentication Codes, store up to 16 user programmable keys, and provide anti-counterfeiting features. The BBB version was recently featured on Atmel’s blog!
Support is via my IRC channel: #cryptotronix on Freenode (come hang out!), or via the Hashlet mailing lists.