Abstract: Various embodiments include composite security interconnect devices and methods. One method embodiment that may be performed by a composite security interconnect device, also referred to herein as a security controller, includes decrypting a first encrypted input received from a peripheral device with a first encryption key to obtain clear text. The first encryption key may be an encryption key established between the security controller and the peripheral device. The method further includes encrypting the clear text with a second encryption key to obtain second encrypted input, the second encryption key being a key of an encryption key pair established with a transaction processing host.