Process for generating DSA signatures with low-cost portable apparatuses
First Claim
1. Process for generating digital signatures with a portable apparatus of the microprocessor-based integrated-circuit card type, the portable apparatus including a microprocessor, a communication device, and an electrically programmable non-volatile memory, the method comprising the steps ofpreparing a plurality of original coupons, the plurality of original coupons being prepared externally to the portable apparatus, the plurality of original coupons being formed of precomputed data useful in the generation of the digital signatures, wherein different coupons correspond to different individual signatures such that the generation of an individual signature involves the use of only a single coupon, and wherein the plurality of original coupons each correspond to an intermediate step in the calculation of the different individual signatures;
- loading the plurality of original coupons into the portable apparatus after the plurality of original coupons have been prepared;
using the plurality of original coupons to generate the digital signatures; and
periodically reloading the apparatus with pluralities of additional coupons after the apparatus has been issued to an end user and after the plurality of original coupons has been substantially exhausted, each performance of the reloading step comprising the steps ofestablishing a connection between a signature verification device and the apparatus, the signature verification device being formed of one of a verifier and a certified central authority,preparing a plurality of additional coupons,enciphering the plurality of additional coupons, andsending the plurality of additional coupons from the signature verification device to the apparatus in enciphered format, the plurality of additional coupons enabling the apparatus to generate a plurality of additional digital signatures.
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Accused Products
Abstract
The invention relates to a process for generating digital signatures from portable apparatuses (A1, A2, . . . Ai . . . An) of the microprocessor-based card type, including means for computation, communication and retention of data, which means comprise at least one electrically programmable non-volatile memory, consisting in preparing enciphered data constituting coupons and loading these coupons into the non-volatile memories so as later to use these coupons in order to sign a message sent by a verifier device. According to the process, the preparation of the coupons is carried out by a certified central authority B or by the card itself.
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Citations
20 Claims
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1. Process for generating digital signatures with a portable apparatus of the microprocessor-based integrated-circuit card type, the portable apparatus including a microprocessor, a communication device, and an electrically programmable non-volatile memory, the method comprising the steps of
preparing a plurality of original coupons, the plurality of original coupons being prepared externally to the portable apparatus, the plurality of original coupons being formed of precomputed data useful in the generation of the digital signatures, wherein different coupons correspond to different individual signatures such that the generation of an individual signature involves the use of only a single coupon, and wherein the plurality of original coupons each correspond to an intermediate step in the calculation of the different individual signatures; -
loading the plurality of original coupons into the portable apparatus after the plurality of original coupons have been prepared; using the plurality of original coupons to generate the digital signatures; and periodically reloading the apparatus with pluralities of additional coupons after the apparatus has been issued to an end user and after the plurality of original coupons has been substantially exhausted, each performance of the reloading step comprising the steps of establishing a connection between a signature verification device and the apparatus, the signature verification device being formed of one of a verifier and a certified central authority, preparing a plurality of additional coupons, enciphering the plurality of additional coupons, and sending the plurality of additional coupons from the signature verification device to the apparatus in enciphered format, the plurality of additional coupons enabling the apparatus to generate a plurality of additional digital signatures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 17, 18, 19, 20)
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15. ri =(gk i mod p) mod q 4. the signature verification device computing the Certificate (R, S) corresponding to the n coupons:
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X being the secret key of the signature verification device 1. the signature verification device generating a random number K, 2. M=Hash (Control-- Datum, r1, r2, . . . , rn), 3. R=(gk mod p) mod q, ##EQU25##
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16. 5. the signature verification device sending the Certificate (R, S), the control data and the ri to the apparatus, andthe apparatus recording the Certificate (R,S), the control data and the ri in the non-volatile memory.
Specification