Patent ID: 8046584

Claim:
An authentication device of a message comprising: a message storage device for storing the message, an encrypted signature, and a certificate, wherein the encrypted signature is created using a private key associated with a sender of the message, and wherein the certificate is created using a private key associated with a reliable third party; a protected device comprising: a microprocessor card; and a box configured to receive the microprocessor card; and a display device, wherein, when the box receives the microprocessor card, the microprocessor card is provided with input/output I 1 /O 1 of commands/data for a first link with the message storage device and input/output I 2 /O 2 of display for a second link with the display device, wherein the first link and the second link are physically separate, and wherein the microprocessor card is configured to: load the message, the encrypted signature, and the certificate from the message storage device onto the microprocessor card; obtain result data by verifying the certificate using a public key associated with the reliable third party, wherein the result data is displayed using the display device; when the certificate is verified: hash the message to obtain a reduction of the message; send the reduction of the message to the display device; obtain a decrypted signature using the encrypted signature and a public key associated with the sender; compare the decrypted signature with the reduction of the message; and when the decrypted signature matches the reduction of the message, send a result message to the display device indicating that the signature is valid.