Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Detailed action
Claims 1-2, 4-10, 12-13, 15-21 are pending and being considered.
Claims 3, 11, 14 and 22 have been cancelled.
Claims 1, 9, 10, 12, 20 and 21 have been amended.
Response to 103
Applicant’s arguments filed on 03/02/2026 have been fully considered and are persuasive but are moot in view of new grounds of rejections. The arguments do not apply to current art being used.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 9 and 20 rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention. The claims recite “wherein the key share refresh operation results in generation of a second plurality of key shares, including the new private key share, that replace the respective key shares of the cryptographic key” the new private key share cannot replace the respective key shares of the cryptographic key, since the key share refresh operation is for the private threshold decryption key and not for the cryptographic key. It appears that the claim should read as “wherein the key share refresh operation results in generation of a second plurality of key shares, including the new private key share, that replace
Dependent claims 10 and 21 are also rejected under the same rationales as set forth above.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1, 2, 4-9, 12, 13 and 15-20 are rejected under 35 U.S.C. 103 as being unpatentable over TOMLINSON et al (hereinafter TOMLINSON) (US 20210099290) in view of RAJU et al (hereinafter RAJU) (US 20250055684).
Regarding claim 1 TOMLINSON teaches a method for key management, comprising: (TOMLINSON on [0036] teaches system and method for quorum-based data processing using keys);
encrypting a key share via a public threshold encryption key (TOMLINSON on [0009] teaches public encryption key is utilized to encrypt key fragments as ciphertext. See also on [0038] teaches session key fragments 2′, which are each encrypted by a key fragment ciphertext generator 10 into respective key fragment ciphertexts 11, denoted as C.sub.1 to C.sub.n, using an encryption key 30a of a corresponding fragment holder 8. The quorum key fragments 2′ may be encrypted using any known public encryption algorithm, for example based on a public key cipher);
wherein the key share is of a plurality of key shares associated with a cryptographic key (TOMLINSON on [0009-0010] teaches plurality of key fragments of a key. See also on [0038] teaches session key fragments 2′, which are each encrypted by a key fragment ciphertext generator 10 into respective key fragment ciphertexts 11, denoted as C.sub.1 to C.sub.n, using an encryption key 30a of a corresponding fragment holder 8. The quorum key fragments 2′ may be encrypted using any known public encryption algorithm, for example based on a public key cipher or a symmetric key cipher);
transmitting, (TOMLINSON on [0010] teaches ciphertexts (i.e., one or more request) distributed to fragment holders, any fragment holder participating in a quorum is termed an active fragment holder. When a quorum of k active fragment holders is formed, each active fragment holder decrypts their respective ciphertext to retrieve their key fragment. See also on [0038-0040] teaches distributing ciphertext containing key fragment to plurality of fragment holder device. See on [0004, 0081 and 0146] teaches distributing ciphertext containing key fragments to plurality of key fragment holder and wherein each key fragment holder uses respective private key to decrypt ciphertext containing key fragment);
receiving, in response to the one or more requests, a plurality of partial decryption results from at least a subset of the plurality of parties having the respective private key (TOMLINSON on [0010, 0040 and claim 1-2] teaches when a quorum of k active fragment holders is formed, each active fragment holder device 8′ decrypts their respective quorum key fragment ciphertext 11 to recover the corresponding session key fragment 2′ (i.e., partial decryption result). Each decrypted session key fragment 2′ is multiplied by a factor, a multiplicative constant to form a weighted key fragment. The weighting computation may be performed by each respective device 8′ or by the quorum processor system 50 i.e., decrypting respective ciphertext containing key fragment using their respective private key);
combining the plurality of partial decryption results to generate the key share (TOMLINSON on [0010 and 0040] teaches summing all k weighted key fragments together to reconstruct session key. See also Fig 4 and text on [0065] teaches the session key 2 may be reconstructed by receiving from k fragment holders their respective key fragments multiplied by the weighting factors above and then summing these together);
executing a (TOMLINSON Fig 4 and text on [0040 and 0065] teaches executing decryption operation using the reconstructed session key);
obtaining, (TOMLINSON on [0144] teaches the new key fragment is produced by the sum of three weighted key fragments using appropriate weighting factors. See on [0145] teaches a new session key derived from a new, randomly generated key polynomial of degree k−1 and a minimal number k key fragments are generated from the key polynomial and encrypted using k administration keys into k ciphertexts C.sub.al to C.sub.ak. Further teaches new index x.sub.k+1 the quorum extender can produce the new key fragment. See on [0150-0151 and 0155] teaches periodically update the key fragments by replacing old key fragments with new key fragments);
wherein the first key share refresh operation results in generation of a second plurality of key shares that replace the plurality of key shares of the cryptographic key (TOMLINSON on [0150-0151 and 0155] teaches periodically update the key fragments by replacing old key fragments with new key fragments);
and encrypting the new key share using the public threshold encryption key (TOMLINSON on [0155 and claim 9] teaches encrypting the new key fragment into a new key fragment ciphertext using public key).
Although TOMLINSON teaches multiple participants in quorum for performing operation such decrypting key fragment using respective private key, but fails to explicitly teach executing operation of the multiparty computation utilizing private key shares and obtaining, triggered by executing the portion of the multi-party computation operation and in accordance with a first key share refresh operation for the cryptographic key, a new key share of the cryptographic key, however RAJU from analogous art teaches
obtaining, triggered by executing the portion of the multi-party computation operation and in accordance with a first key share refresh operation for the cryptographic key, a new key share of the cryptographic key (RAJU on [0007-0008] teaches each backup MPC node in the backup MPC cluster may be configured to generate a new backup private key share different from and to replace its corresponding backup private key share. i.e., generation of new key share is triggered by MPC. See on [0086-0087 and 0095-0096] teaches the primary MPC nodes 1-3 110a, 120a, 130a may communicate with the primary MPC client 1 140a in the primary asset custody subsystem 104a to generate new key shares. Further teaches during or shortly after deployment of the primary MPC node cluster 1 in example embodiments), the primary MPC client 1 140a may communicate with the primary MPC nodes 1-3 110a-110c so that they generate and store in respective primary MPC node secure databases or other type of data storage new private key shares).
Thus, it would have been obvious to one ordinary skill in the art before the effective filing date to implement the teaching of RAJU into the teaching of TOMLINSON by generating new key share based on execution of multi-party computation. One would be motivated to do so in order to collectively perform encryption/decryption operation using refreshed private key shares triggered by MPC without revealing their respective key shares to other party in multi-party computation environment (RAJU on [0007-0014]).
Regarding claim 9 TOMLINSON teaches a method for key management, comprising: (TOMLINSON on [0036] teaches system and method for quorum-based data processing using keys);
receiving, (TOMLINSON on [0010] teaches ciphertexts (i.e., one or more request) distributed to fragment holders, any fragment holder participating in a quorum is termed an active fragment holder. When a quorum of k active fragment holders is formed, each active fragment holder decrypts their respective ciphertext to retrieve their key fragment. See also on [0038-0040] teaches distributing ciphertext containing key fragment to plurality of fragment holder device. See on [0004, 0081 and 0146] teaches distributing ciphertext containing key fragments to plurality of key fragment holder and wherein each key fragment holder uses respective private key to decrypt ciphertext containing key fragment. See on [0009] teaches public encryption key is utilized to encrypt key fragments as ciphertext. See also on [0038] teaches session key fragments 2′, which are each encrypted by a key fragment ciphertext generator 10 into respective key fragment ciphertexts 11, denoted as C.sub.1 to C.sub.n, using an encryption key 30a of a corresponding fragment holder 8. The quorum key fragments 2′ may be encrypted using any known public encryption algorithm, for example based on a public key cipher);
decrypting, based at least in part on receiving the request and via a private key share of a private threshold decryption key corresponding to the public threshold encryption key, one or more ciphertexts associated with the request (TOMLINSON on [0010] teaches ciphertexts distributed to fragment holders, any fragment holder participating in a quorum is termed an active fragment holder. When a quorum of k active fragment holders is formed, each active fragment holder decrypts their respective ciphertext to retrieve their key fragment. See on [0004, 0081 and 0146] teaches distributing ciphertext containing key fragments to plurality of key fragment holder and wherein each key fragment holder uses respective private key to decrypt ciphertext containing key fragment);
transmitting, in response to the request and after decrypting the one or more ciphertexts, one or more partial decryption results to the one or more parties (TOMLINSON on [0010, 0040 and claim 1-2] teaches when a quorum of k active fragment holders is formed, each active fragment holder device 8′ decrypts their respective quorum key fragment ciphertext 11 to recover the corresponding session key fragment 2′ (i.e., partial decryption result). Each decrypted session key fragment 2′ is multiplied by a factor, a multiplicative constant to form a weighted key fragment. The weighting computation may be performed by each respective device 8′ or by the quorum processor system 50 i.e., decrypting respective ciphertext containing key fragment using their respective private key to generate partial decryption result).
Although TOMLINSON teaches refreshing key fragments and refreshing session key, but fails to explicitly teach a key share refresh operation for the private threshold decryption key, a new private key share of the private threshold decryption key in multi-party computation, however Gryb from analogous art teaches obtaining, in accordance with a key share refresh operation for the private threshold decryption key and based at least in part on transmitting the one or more partial decryption results, a new private key share of the private threshold decryption key, (RAJU on [0095-0096 and 0117] teaches after receiving and decrypting the private key share from its primary MPC node 1-3 110a-130a, each backup MPC node 1-3 110b-130b either automatically, or in response to a message from the backup MPC client 1 140b in step 324 to generate a new private key share);
wherein the key share refresh operation results in generation of a second plurality of key shares, including the new private key share, that replace the respective key shares of the cryptographic key (RAJU on [0007-0008] teaches generate a new backup private key share different from and to replace its corresponding backup private key share).
Thus, it would have been obvious to one ordinary skill in the art before the effective filing date to implement the teaching of RAJU into the teaching of TOMLINSON by generating new key share based on execution of multi-party computation. One would be motivated to do so in order to collectively perform encryption/decryption operation using refreshed private key shares triggered by MPC without revealing their respective key shares to other party in multi-party computation environment (RAJU on [0007-0014]).
Regarding claim 12 TOMLINSON teaches an apparatus for key management, comprising: (TOMLINSON on [0036] teaches system and method for quorum-based data processing using keys);
one or more memories storing processor-executable code; and one or more processors coupled with the one or more memories and individually or collectively operable to execute the code to cause the apparatus to (TOMLINSON on [0158-0160] teaches one or more processor executing instruction stored in memory);
encrypt a key share via a public threshold encryption key (TOMLINSON on [0009] teaches public encryption key is utilized to encrypt key fragments as ciphertext. See also on [0038] teaches session key fragments 2′, which are each encrypted by a key fragment ciphertext generator 10 into respective key fragment ciphertexts 11, denoted as C.sub.1 to C.sub.n, using an encryption key 30a of a corresponding fragment holder 8. The quorum key fragments 2′ may be encrypted using any known public encryption algorithm, for example based on a public key cipher);
wherein the key share is of a plurality of key shares associated with a cryptographic key (TOMLINSON on [0009-0010] teaches plurality of key fragments of a key. See also on [0038] teaches session key fragments 2′, which are each encrypted by a key fragment ciphertext generator 10 into respective key fragment ciphertexts 11, denoted as C.sub.1 to C.sub.n, using an encryption key 30a of a corresponding fragment holder 8. The quorum key fragments 2′ may be encrypted using any known public encryption algorithm, for example based on a public key cipher or a symmetric key cipher);
transmit, (TOMLINSON on [0010] teaches ciphertexts (i.e., one or more request) distributed to fragment holders, any fragment holder participating in a quorum is termed an active fragment holder. When a quorum of k active fragment holders is formed, each active fragment holder decrypts their respective ciphertext to retrieve their key fragment. See also on [0038-0040] teaches distributing ciphertext containing key fragment to plurality of fragment holder device. See on [0004, 0081 and 0146] teaches distributing ciphertext containing key fragments to plurality of key fragment holder and wherein each key fragment holder uses respective private key to decrypt ciphertext containing key fragment);
receive, in response to the one or more requests, a plurality of partial decryption results from at least a subset of the plurality of parties having the respective private key (TOMLINSON on [0010, 0040 and claim 1-2] teaches when a quorum of k active fragment holders is formed, each active fragment holder device 8′ decrypts their respective quorum key fragment ciphertext 11 to recover the corresponding session key fragment 2′ (i.e., partial decryption result). Each decrypted session key fragment 2′ is multiplied by a factor, a multiplicative constant to form a weighted key fragment. The weighting computation may be performed by each respective device 8′ or by the quorum processor system 50 i.e., decrypting respective ciphertext containing key fragment using their respective private key);
combine the plurality of partial decryption results to generate the key share (TOMLINSON on [0010 and 0040] teaches summing all k weighted key fragments together to reconstruct session key. See also Fig 4 and text on [0065] teaches the session key 2 may be reconstructed by receiving from k fragment holders their respective key fragments multiplied by the weighting factors above and then summing these together);
execute a portion (TOMLINSON Fig 4 and text on [0040 and 0065] teaches executing decryption operation using the reconstructed session key);
obtain, (TOMLINSON on [0144] teaches the new key fragment is produced by the sum of three weighted key fragments using appropriate weighting factors. See on [0145] teaches a new session key derived from a new, randomly generated key polynomial of degree k−1 and a minimal number k key fragments are generated from the key polynomial and encrypted using k administration keys into k ciphertexts C.sub.al to C.sub.ak. Further teaches new index x.sub.k+1 the quorum extender can produce the new key fragment. See on [0150-0151 and 0155] teaches periodically update the key fragments by replacing old key fragments with new key fragments);
wherein the first key share refresh operation results in generation of a second plurality of key shares that replace the plurality of key shares of the cryptographic key (TOMLINSON on [0150-0151 and 0155] teaches periodically update the key fragments by replacing old key fragments with new key fragments);
and encrypt the new key share using the public threshold encryption key (TOMLINSON on [0155 and claim 9] teaches encrypting the new key fragment into a new key fragment ciphertext using public key).
Although TOMLINSON teaches multiple participants in quorum for performing operation such decrypting key fragment using respective private key, but fails to explicitly teach executing operation of the multiparty computation utilizing private key shares and obtaining, triggered by executing the portion of the multi-party computation operation and in accordance with a first key share refresh operation for the cryptographic key, a new key share of the cryptographic key, however RAJU from analogous art teaches
obtaining, triggered by executing the portion of the multi-party computation operation and in accordance with a first key share refresh operation for the cryptographic key, a new key share of the cryptographic key (RAJU on [0007-0008] teaches each backup MPC node in the backup MPC cluster may be configured to generate a new backup private key share different from and to replace its corresponding backup private key share. i.e., generation of new key share is triggered by MPC. See on [0086-0087 and 0095-0096] teaches the primary MPC nodes 1-3 110a, 120a, 130a may communicate with the primary MPC client 1 140a in the primary asset custody subsystem 104a to generate new key shares. Further teaches during or shortly after deployment of the primary MPC node cluster 1 in example embodiments), the primary MPC client 1 140a may communicate with the primary MPC nodes 1-3 110a-110c so that they generate and store in respective primary MPC node secure databases or other type of data storage new private key shares).
Thus, it would have been obvious to one ordinary skill in the art before the effective filing date to implement the teaching of RAJU into the teaching of TOMLINSON by generating new key share based on execution of multi-party computation. One would be motivated to do so in order to collectively perform encryption/decryption operation using refreshed private key shares triggered by MPC without revealing their respective key shares to other party in multi-party computation environment (RAJU on [0007-0014]).
Regarding claim 20 TOMLINSON teaches an apparatus for key management, comprising: (TOMLINSON on [0036] teaches system and method for quorum-based data processing using keys);
one or more memories storing processor-executable code; and one or more processors coupled with the one or more memories and individually or collectively operable to execute the code to cause the apparatus to: (TOMLINSON on [0158-0160] teaches one or more processor executing instruction stored in memory);
receive, in accordance with a multi-party computation operation at one or more parties of a plurality of parties having respective key shares of a cryptographic key, a request to decrypt a respective key share of the cryptographic key that is encrypted using a public threshold encryption key (TOMLINSON on [0010] teaches ciphertexts (i.e., one or more request) distributed to fragment holders, any fragment holder participating in a quorum is termed an active fragment holder. When a quorum of k active fragment holders is formed, each active fragment holder decrypts their respective ciphertext to retrieve their key fragment. See also on [0038-0040] teaches distributing ciphertext containing key fragment to plurality of fragment holder device. See on [0004, 0081 and 0146] teaches distributing ciphertext containing key fragments to plurality of key fragment holder and wherein each key fragment holder uses respective private key to decrypt ciphertext containing key fragment. See on [0009] teaches public encryption key is utilized to encrypt key fragments as ciphertext. See also on [0038] teaches session key fragments 2′, which are each encrypted by a key fragment ciphertext generator 10 into respective key fragment ciphertexts 11, denoted as C.sub.1 to C.sub.n, using an encryption key 30a of a corresponding fragment holder 8. The quorum key fragments 2′ may be encrypted using any known public encryption algorithm, for example based on a public key cipher);
decrypt, based at least in part on receiving the request and via a private key share of a private threshold decryption key corresponding to the public threshold encryption key, one or more ciphertexts associated with the request (TOMLINSON on [0010] teaches ciphertexts distributed to fragment holders, any fragment holder participating in a quorum is termed an active fragment holder. When a quorum of k active fragment holders is formed, each active fragment holder decrypts their respective ciphertext to retrieve their key fragment. See on [0004, 0081 and 0146] teaches distributing ciphertext containing key fragments to plurality of key fragment holder and wherein each key fragment holder uses respective private key to decrypt ciphertext containing key fragment);
transmit, in response to the request and after decrypting the one or more ciphertexts, one or more partial decryption results to the one or more parties (TOMLINSON on [0010, 0040 and claim 1-2] teaches when a quorum of k active fragment holders is formed, each active fragment holder device 8′ decrypts their respective quorum key fragment ciphertext 11 to recover the corresponding session key fragment 2′ (i.e., partial decryption result). Each decrypted session key fragment 2′ is multiplied by a factor, a multiplicative constant to form a weighted key fragment. The weighting computation may be performed by each respective device 8′ or by the quorum processor system 50 i.e., decrypting respective ciphertext containing key fragment using their respective private key to generate partial decryption result).
Although TOMLINSON teaches refreshing key fragments and refreshing session key, but fails to explicitly teach a key share refresh operation for the private threshold decryption key, a new private key share of the private threshold decryption key in multi-party computation, however Gryb from analogous art teaches obtain, in accordance with a key share refresh operation for the private threshold decryption key, wherein transmitting the one or more partial decryption results triggers the key share refresh operation for the private threshold decryption key, (RAJU on [0095-0096 and 0117] teaches after receiving and decrypting the private key share from its primary MPC node 1-3 110a-130a, each backup MPC node 1-3 110b-130b either automatically, or in response to a message from the backup MPC client 1 140b in step 324 to generate a new private key share);
wherein the key share refresh operation results in generation of a second plurality of key shares, including the new private key share, that replace the respective key shares of the cryptographic key (RAJU on [0007-0008] teaches generate a new backup private key share different from and to replace its corresponding backup private key share).
Thus, it would have been obvious to one ordinary skill in the art before the effective filing date to implement the teaching of RAJU into the teaching of TOMLINSON by generating new key share based on execution of multi-party computation. One would be motivated to do so in order to collectively perform encryption/decryption operation using refreshed private key shares triggered by MPC without revealing their respective key shares to other party in multi-party computation environment (RAJU on [0007-0014]).
Regarding claim 2 and 13 the combination of TOMLINSON and RAJU teaches all the limitations of claims 1 and 12 respectively, TOMLINSON further teaches generating, as a result of encrypting the key share via the public threshold encryption key, a first ciphertext, wherein the one or more requests comprise the first ciphertext (TOMLINSON on [0009] teaches public encryption key is utilized to encrypt key fragments as ciphertext. See also on [0038] teaches session key fragments 2′, which are each encrypted by a key fragment ciphertext generator 10 into respective key fragment ciphertexts 11, denoted as C.sub.1 to C.sub.n, using an encryption key 30a of a corresponding fragment holder 8. The quorum key fragments 2′ may be encrypted using any known public encryption algorithm, for example based on a public key cipher).
Regarding claim 4 and 15 the combination of TOMLINSON and RAJU teaches all the limitations of claims 1 and 12 respectively, RAJU further teaches wherein the key share refresh operation for the respective private key shares of the private threshold decryption key comprises generation of a second plurality of private key shares replacing the respective private key shares of the private threshold decryption key (RAJU on [0007-0008] teaches generate a new backup private key share different from and to replace its corresponding backup private key share).
Thus, it would have been obvious to one ordinary skill in the art before the effective filing date to implement the teaching of RAJU into the teaching of TOMLINSON by generating new key share based on execution of multi-party computation. One would be motivated to do so in order to collectively perform encryption/decryption operation using refreshed private key shares triggered by MPC without revealing their respective key shares to other party in multi-party computation environment (RAJU on [0007-0014]).
Regarding claim 5 and 16 the combination of TOMLINSON and RAJU teaches all the limitations of claims 1 and 12 respectively, TOMLINSON further teaches wherein the multi-party computation operation is executed in accordance with execution of a threshold quantity of portions of the multi-party computation operation using at least a threshold quantity of key shares of the cryptographic key (TOMLINSON on [0005] teaches the number of ciphertexts, that are required to form a quorum is denoted by k. The system generates a plurality of ciphertexts from which an encryption or decryption key may be reconstructed. The total number of ciphertexts generated is usually equal to the total number of key fragment holders, denoted by n. Each ciphertext may be generated using the respective encryption key of each fragment holder but this does not have to be the case and ephemeral session keys may be employed. The fixed quorum number of ciphertexts required to reconstruct the key is k. The required quorum number k of ciphertexts is a smaller number than the total number of generated ciphertexts. The quorum ciphertexts can be any combination of k ciphertexts selected from all of the n ciphertexts. See also on [0036] teaches providing the predetermined minimum number of quorum key fragments, the quorum participants can be authenticated to be allowed access to the secured assets. In further examples the secret key would be used for generating a digital signature, where by coming together and providing the predetermined minimum number of quorum key fragments. See on [0065] teaches the session key 2 may be reconstructed by receiving from k fragment holders their respective key fragments multiplied by the weighting factors above and then summing these together as depicted in FIG. 4. The recipient of the sum, the session key, may alternatively receive the key fragments directly from the fragment holders and carry out the weighting of the key fragments before the summation. The fragment holders may or may not send the key fragments, already weighted. Considering as an example that fragment holders 1, 4, and 5 form a quorum and contribute their weighted key fragments, which sum to produce the session key).
Regarding claim 6 and 17 the combination of TOMLINSON and RAJU teaches all the limitations of claims 1 and 12 respectively, TOMLINSON further teaches wherein a quantity of the subset of the plurality of parties satisfies a threshold quantity of decryption results combinable to generate the key share (TOMLINSON on [0011 and 0040] teaches a different quorum size with a different number of fragment holders may be used to generate a key to be used for encryption compared to the size of quorum of fragment holders used to generate the same key to be used for decryption. This is in the case of the cipher being a symmetric key encryption cipher. See on [0065] teaches the session key 2 may be reconstructed by receiving from k fragment holders their respective key fragments multiplied by the weighting factors above and then summing these together as depicted in FIG. 4. The recipient of the sum, the session key, may alternatively receive the key fragments directly from the fragment holders and carry out the weighting of the key fragments before the summation. The fragment holders may or may not send the key fragments, already weighted. Considering as an example that fragment holders 1, 4, and 5 form a quorum and contribute their weighted key fragments, which sum to produce the session key).
Regarding claim 7 and 18 the combination of TOMLINSON and RAJU teaches all the limitations of claims 1 and 12 respectively, TOMLINSON further teaches wherein executing the portion of the multi-party computation operation comprises: executing a signing operation using the key share resulting from the combination of the plurality of partial decryption results (TOMLINSON on [0012] teaches digital signature keys may be derived by additional application of a Key Derivation Function (KDF) using the reconstructed key as input).
Regarding claim 8 and 19 the combination of TOMLINSON and RAJU teaches all the limitations of claims 1 and 12 respectively, TOMLINSON further teaches wherein executing the portion of the multi-party computation operation comprises: executing a decryption operation using the key share resulting from the combination of the plurality of partial decryption results (TOMLINSON Fig 4 and text on [0040 and 0065] teaches executing decryption operation using the reconstructed session key).
Claims 10 and 21 are rejected under 35 U.S.C. 103 as being unpatentable over TOMLINSON et al (hereinafter TOMLINSON) (US 20210099290) in view of RAJU et al (hereinafter RAJU) (US 20250055684) and further in view of Gryb et al (hereinafter Gryb) (US 20200410113).
Regarding claim 10 and 21 the combination of TOMLINSON and RAJU teaches all the limitations of claims 9 and 20 respectively, the combination fails to explicitly teach
Gryb teaches obtaining a second new private key share in accordance with the key share refresh operation, wherein the key share refresh operation occurs periodically for the private threshold decryption key (Gryb on [0093] the private key shares may be periodically refreshed (e.g., daily, after every decryption). This can increase security as two private key shares stolen at different times (e.g., before and after the keys are refreshed) may not be usable by an attacker).
Thus, it would have been obvious to one ordinary skill in the art before the effective filing date to implement the teaching of Gryb into the combined teaching of TOMLINSON and RAJU by refreshing private key shares in multi-party computation. One would be motivated to do so in order to collectively perform encryption/decryption operation using private key shares without revealing their respective key shares to other party in multi-party computation environment, thereby protecting the key from unauthorized access (Gryb on [0042-0043 and 0093]).
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/MOEEN KHAN/Primary Examiner, Art Unit 2436