Patent ID: 7178027

Claim:
A method of securely copying a cryptographic key from one smart device to another smart device, comprising: mutually authenticating a smart source device and a host with respect to each other; mutually authenticating a smart destination device and the host with respect to each other; authenticating the destination device through the host by the source device; and sending a cryptographic key stored in the source device to the destination device, wherein the step of authenticating the destination device includes sending to the destination device a challenge encrypted with a symmetric key and signed with a private key of the source device, the symmetric key being common to the source and destination devices, decrypting the challenge with the symmetric key by the destination device, verifying the signature of the challenge by the destination device, sending to the source device a response encrypted with the public key of the source device and signed with the private key of the destination device, verifying the signature of the response by the source device, and decrypting the response with the private key of the source device, wherein the step of sending to the destination device a challenge includes sending the challenge to the host, signing the challenge with the private key of the host, and sending the signed challenge to the destination device.