Message authentication device
View Patent ↗Method for checking the signature of a message. The message, signature, and a certificate are sent by a signer having a public key to a recipient having a message storage device. The certificate is checked by a protected device connected to the message storage device and a checking result data element is sent for checking to a display device connected to the protected 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. The signature is decrypted using the public key in the protected device, and the decrypted signature is compared with the reduction carried out. According to the comparison, a message is sent from the protected device to the display device indicating whether the signature conforms or does not conform to the message or to the public key of the signer put forward.
1. 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.
2. The authentication device according to claim 1 , wherein a single logic link between the commands/data circulating between the microprocessor card and the message storage device on one hand and data circulating between the microprocessor card and the display device on the other hand is a software of the microprocessor card.
3. The authentication device according to claim 1 , wherein the display device is one selected from a group consisting of a printer, a screen, and a filing device.
4. A microprocessor card is configured to be connected to a message storage device and to a display device,
wherein 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 message storage device is configured to store a 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, 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.
5. The microprocessor card according to claim 4 , wherein a single logic link between the commands/data circulating between the microprocessor card and the message storage device on one hand and data circulating between the microprocessor card and the display device on the other hand, is a software of the microprocessor card.
6. The microprocessor card according to claim 4 , wherein the microprocessor card comprises a physically separate inlet to enter a confidential code.
7. A box configured to receive a microprocessor card and further configured to be connected to a message storage device and to a display device,
wherein the message storage device is configured to store a message, an encrypted signature, and a certificate, wherein the encrypted signature is created using a private key associated with a sender of the message, wherein the certificate is created using a private key associated with a reliable third party,
wherein, when the box receives the microprocessor card, the microprocessor card is provided with a data/command circuit for a first link with the message storage device and a display circuit for a second link with the display device, wherein an inlet/outlet of the data/command circuit and the display circuit being electrically independent, 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 received 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.
8. The box according to claim 7 , wherein a single logic link between the data circulating in the data/commands and display circuits is the software of the microprocessor card.
9. The box according to claim 7 , wherein the box comprises a keyboard allowing to enter data, such as a confidential code.