Patent ID: 7039808

Claim:
Method for checking the signature of a message, the message, signature and a certificate having been sent by a signer having a public key to a recipient having a message storage device, characterised in that it comprises stages according to which: the message, signature and certificate are loaded from the storage device onto a protected device connected to said storage device of the recipient, the certificate in the protected device is checked within the protected device by means of a public key of a reliable third party associated with said certificate, and at least one data element of the result of checking is transmitted to a display device connected directly to the protected device, the result data element is checked on the display device, when the certificate is verified, a reduction of the message is calculated in the protected device and the message is recopied onto the display device during the reduction operation, the signature with the public key of the signer are decrypted in said protected device, the signature decrypted is compared with the carried out reduction, and according to the result of this comparison, a message is sent from the protected device to the display device indicating that the signature conforms/does not conform to the message or the public key of the signer put forward.