Instrument for making secure data exchanges

• US 6,493,823 B1
• Filed: 03/03/1999
• Issued: 12/10/2002
• Est. Priority Date: 09/04/1996
• Status: Expired due to Fees

• Current Assignee: ATOS Origin Integration (Atos SE)
• Original Assignee: Atos IT Services Ltd. (Atos SE)
• Inventors: Bourdin, Michel Paul
• Primary Examiner(s): Peeso, Thomas R.
• Application Number:
  US09/254,270
• Time in Patent Office: 1,378 Days
• Field of Search: 713/153, 713/161, 713/168
• US Class Current: 713/153
• CPC Class Codes: H04L 2209/04 Masking or blinding
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04L 9/0825 using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates
• CPC Class Codes: H04L 9/083 involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]

Abstract

An instrument for making secure messages exchanged between each of the actors of a network having a plurality of actors, each being capable of acting as a sender or as an addressee of a message that is encoded or sealed, the instrument being characterized in that it comprises, for each actor, a respective device (E₁) including an integrated circuit with memory zones (2, 3) and a microprocessor (1) capable of executing at least one algorithm and of controlling access to said zones (2, 3) as a function of the nature of the operation requested thereof by the operator holding the device (E₁), the operations being selected from the following: encoding (6, 7); calculating a key to be communicated (8); and decoding (9, 10); the memory zones (2 and 3) containing two types of base key that are masked, including a base key (T₁) of a first type which is specific to each device (E₁), and at least one base key (U) of a second type which is common to all of the devices.

Claims

1. An instrument for making secure messages exchanged between each of the actors of a network having a plurality of actors, each being capable of acting as a sender or as an addressee of a message that is encoded or sealed, the instrument being characterized in that it comprises, for each actor, a respective device (E₁) including an integrated circuit with memory zones (2, 3) and a microprocessor (1) capable of executing at least one algorithm and of controlling access to said zones (2, 3) as a function of the nature of the operation requested thereof by the operator holding the device (E₁), the operations being selected from the following:

encoding (6, 7);

calculating a key to be communicated (8); and

decoding (9, 10);

the memory zones (2 and 3) containing two types of base key that are masked, including a base key (T₁) of a first type which is specific to each device (E₁), and at least one base key (U) of a second type which is common to all of the devices.

2. An instrument for making secure according to claim 1, characterized in that it has a memory zone (11) that is accessible in reading only an that contains a key (I) identifying the holder.

3. An instrument for making secure according to claim 1, characterized in that it includes a memory zone (12) that is accessible in reading only, containing a key (D) for writing to a domain of the network, the base key (U_D) of the second type being common to all of the actors of the domain.

4. A method of calculating a key to be communicated by means of the instrument of claim 1, the method being characterized in that it consists in implementing a first symmetrical encoding algorithm (A) applied to a signature key (S) selected by the actor acting as a sender while using the base key (T₁) of the first type, and in implementing a second symmetrical encoding algorithm which is applied to the results of the preceding encoding operation while using at least one base key (U) of the second type.

5. A method of encoding a message by means of the instrument of claim 1, characterized in that it consists in generating an ephemeral encoding key (K) by implementing a first symmetrical algorithm (A) applied to a signature key (S) selected by the actor acting as a sender while using the base key (T₁) of the first type, and in implementing a second algorithm applied to at least a portion of the method while using the encoding key (K).

6. A method to decode a message encoded by the method of claim 5, the decoding method being characterized in that it consists in applying, to a key to be communicated (V) as received from the sender of the message, an algorithm that is the inverse of the algorithm used for generating said key while using the key (U) of the second type, and in using the result that is obtained as the key (K) for decoding the message.

7. A method of sealing a message characterized in that it consists in adding to the message, at least a portion thereof encoded by the method according to claim 5.

8. A method to verify a message seal made by the method of claim 7, the verification method being characterized in that it consists in generating the decoding key (K) by the method of claim 6, in encoding at least the above-mentioned portion of said message by means of said key (K), and in comparing the value that is obtained with the value of the seal accompanying the received message.

9. A method of calculating a key to be communicated in accordance with claim 4, the method being characterized in that it consists in the corresponding algorithms using at least one base key of the second type as obtained by the microprocessor making a combination of the identity keys of the two actors concerned by the exchange of messages.

10. A method of sealing a message according to claim 7, the method of sealing a message being characterized in that the seal is made by encoding the message (M), the domain inscription key (D), identity keys (I₁, I₂) of the two actors concerned by the exchange, and the value of at least one base key (U_D) of the second type common to all of the actors of the domain.

11. A method of sealing according to claim 10, characterized in that the message (M) concerned has previously been encoded (M′

).

12. A method of encoding a message according to claim 5, the method being characterized in that it consists in transmitting the public key to be communicated to one of the actors of the network acting as a trusted third party and in presenting the seal of said public key as calculated by the trusted third party to the instrument, said seal constituting authorization to execute the encoding function.