Onion layer encryption scheme for secure multi-access with single card
A magnetic strip card includes a partial encrypted card payload encrypted with a long shared key to provide a final encrypted payload. A method for encoding the magnetic strip card includes encrypting a card payload with a code key of a access controls with a short key of the access control to generate a partial encrypted payload and encrypting the partial encrypted payload with a long shared key to provide a final encrypted payload.
1. A magnetic strip card of less than several hundred bits, comprising:
a card payload with a code key of an access control encrypted with a short key to generate a partial encrypted card payload, the partial encrypted card payload encrypted with a long shared key to provide a final encrypted payload.
2. The magnetic strip card as recited in claim 1 , wherein the partial encrypted card payload includes card contents unique to each access control encrypted with a short key.
3. The magnetic strip card as recited in claim 2 , wherein individual short key portion is different for each key/access control pair.
4. The magnetic strip card as recited in claim 3 , wherein the final encrypted payload contains individual short key portions for four different key/access control pair.
5. The magnetic strip card as recited in claim 2 , wherein the short key is 24 bits.
6. The magnetic strip card as recited in claim 2 , wherein the long shared key is 128 bits.
7. The magnetic strip card as recited in claim 1 , wherein the partial encrypted card payload is encrypted with a code key of an access control with the short key of the access control.
8. The magnetic strip card as recited in claim 7 , wherein the access control is a lock.
9. The magnetic strip card as recited in claim 8 , wherein the partial encrypted card payload is associated with a single lock.
10. A method for encoding a magnetic strip card of less than several hundred bits, the method comprising:
encrypting a card payload with a code key of an access control with a short key of the access control to generate a partial encrypted payload; and
encrypting the partial encrypted payload with a long shared key to provide a final encrypted payload.
11. The method as recited in claim 10 , wherein the short key is 24 bits.
12. The method as recited in claim 10 , wherein the long shared key is 128 bits.
13. The method as recited in claim 10 , wherein the short key is 24 bits and the long shared key is 128 bits.
14. The method as recited in claim 10 , further comprising encrypting a card payload with a code key for each of a multiple of access controls with a respective short key of the access control to generate the partial encrypted payload.
15. The method as recited in claim 14 , wherein the partial encrypted payload includes at least one code key.
16. The method as recited in claim 14 , wherein the partial encrypted payload includes four code keys.
17. The method as recited in claim 14 , wherein the partial encrypted payload includes a multiple of code keys.