Cryptography – Communication system using cryptography – Pseudo-random sequence scrambling
Reexamination Certificate
1996-06-26
2001-04-17
Buczinski, Stephen C. (Department: 3662)
Cryptography
Communication system using cryptography
Pseudo-random sequence scrambling
C705S037000, C705S053000, C705S067000, C705S075000
Reexamination Certificate
active
06219423
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of communications. More particularly, the present invention relates to a system and method for creating a remote digital agreement formulated through an execution procedure.
2. Description of Art Related to the Invention
Over hundreds of years, written agreements have been used as a vehicle for a variety of purposes, among which is to establish certainty and clarity in business, legal and other types of arrangements between two or more parties to the agreement. In general, one type of an agreement is a “contract”, which is defined as a promise or set of promises between two or more parties by which the law allows the party or parties that abide by the terms of the contract to recover damages (e.g., monetary compensation) from the party or parties that breach the contract. Another type of agreement is a stipulation agreement used during litigation in which the parties agree to material facts not in dispute. Although there exists a wide variety of execution schemes, one type of scheme is where the parties to the contract negotiate “at arm's length” to formulate terms of the written agreement (e.g., contract) which are mutually agreeable to the parties.
After agreeing to the terms of the written agreement, the parties select an execution procedure for signing the agreement. The nature of that execution procedure may depend on the importance of the agreement, past dealings between the parties, and many other factors. The execution procedure may be overseen by a “non-signing party” acting as an arbitrator (referred to as “independently-arbitrated agreement execution”), or by the parties themselves in a localized setting (referred to as “mutually-arbitrated agreement execution”).
Referring to
FIG. 1
, mutually-arbitrated agreement execution is generally preferred when all of the parties or the signatories of the agreement
110
can meet at a selected location to execute one or more printed copies of the agreement
120
. This guarantees that each party possesses an original copy of the agreement upon adjournment of the meeting. Such meetings are costly and difficult to arrange, especially when the agreement involves a large number of parties.
In the event that the simultaneous assembly of all parties is not feasible or undesirable, an alternative approach may include an independently-arbitrated execution procedure utilizing human arbitration as shown in FIG.
2
. For this execution procedure, each signatory
110
1
and
110
2
separately executes one or more copies of the agreement and provides the partially-signed agreements
130
1
and
130
2
to the arbitrator
140
(e.g., a third party who is not a signatory of the agreement). When receiving partially-signed agreements
130
1
and
130
2
from all of the parties, the arbitrator
140
provides a copy of the fully-signed agreement
150
1
and
150
2
back to each signatory
110
1
and
110
2
. The disadvantage associated with this execution procedure is that it is entirely dependent on the integrity of the arbitrator
140
to properly follow a static procedure. However, it is apparent that it is quite difficult and costly, especially for parties situated in other countries and/or in different states, to check the integrity of the arbitrator. Likewise, the cost of the arbitration service itself and the time delay in execution of the written agreement may be unacceptable.
Referring now to
FIG. 3
, another execution procedure (referred to as “non-arbitrated execution”) is applicable when the written agreement is of lesser value or when a sufficient degree of trust exists between the “an” signatories (“n” being a whole number, n≧3 in this example). One signatory
110
1
starts the execution process by signing the agreement and forwarding the partially-signed agreement
160
1
on to the next signatory
110
2
. As each successive signatory receives the partially-signed agreement, it applies its own signature and forwards it to another signatory until the agreement is fully executed. The last signatory
110
n
has the responsibility to return copies of the fully-executed agreement
170
1
,
170
2
, . . .
170
n-1
to all signatories, as did the arbitrator in FIG.
2
. This method has the advantage of cost reduction, since the signatories need not be assembled nor is an arbitration fee incurred. The significant disadvantage is that the success of the process is dependent on the integrity of the last signatory who is a party to the agreement. The last signatory is not compelled to redistribute copies of the signed agreement, especially if a business advantage can be gained by being in possession of the only signed agreement.
Recently, a number of states have passed legislation that recognizes private key-based digital signature as legally binding a party to the terms of a digital agreement. A “digital agreement” is an electronic document representing an agreement that is to be digitally signed by all parties to the agreement through their respective private keys. Like written agreements, digital agreements may be executed through independent-arbitration, mutual-arbitration, or non-arbitration execution procedures. However, it is evident that cost and time saving advantages offered by digital agreements would be greatly reduced by following an independently-arbitrated execution procedure or a mutually-arbitrated execution procedure. Thus, it has been desirable for digital agreements to undergo non-arbitrated execution as shown in FIG.
4
.
Referring to
FIG. 4
, after negotiating the terms of the digital agreement
205
, a first party at a first node
200
(e.g., computer) normally signs the digital agreement
205
by (i) applying a hash algorithm (e.g., “MD5” algorithm developed by RSA Data Security of Redwood City, Calif.) to the digital agreement
205
to obtain its unique hash value
210
, and (ii) encrypting the hash value
210
with an asymmetric cryptographic algorithm (e.g., RSA algorithm) under its private key (“PrKA”) to produce a “first digital signature”
215
. It is contemplated that such hashing is not necessary, but may be used to reduce the amount of data thereby preserving bandwidth during transmission and memory during storage. Thereafter, at least the first digital signature
215
is transferred to another party at a second node
220
. Additional information may be transferred in combination with the first digital signature
215
such as the digital agreement
205
or its hash value
210
. Optionally, some or all of this information may be protected during transfer (for privacy purposes) by encrypting with a previously chosen symmetric key.
The execution procedure can be continued in a serial manner by the party at the second node
220
creating its own digital signature
230
(e.g., in this embodiment, hash value
225
encrypted under a private key “PrKB” of the party at the second node
220
). Thereafter, an aggregate signature set
235
(including the first and second digital signatures
215
and
230
and possibly additional information) to the next party of the agreement. This procedure may continue for an arbitrary number of parties with the final party at node
240
being responsible for returning the fully-signed digital agreement
250
(i.e., in this case, a hash value of the agreement individually encrypted with the private keys of each party to the digital agreement) to all of the other signatories.
Referring now to
FIG. 5
, if the first digital signature
215
is created by encrypting the hash value
210
under the private key PrKA, the first digital signature
215
may be validated by any party with access to the hash value
210
or the original digital agreement
205
. Such validation is accomplished by decrypting the first digital signature
215
with a well-known public key (“PuKA”) associated with the first party at node
200
to produce a resultant value
260
. Thereafter, the resultant value
260
is compared to a previously obtained or computed hash value
210
of the digital agreement
205
as s
Blakely , Sokoloff, Taylor & Zafman LLP
Buczinski Stephen C.
Intel Corporation
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