DETAILED ACTION
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 .
EXAMINER’S COMMENT
Regarding the claims, it is noted by the Examiner here that under the broadest reasonable interpretation, given a list of options joined by the conjunction “or” such as a list of A, B, or C, the prior art need only teach one of the listed options to read upon the claim. In particular, independent claims 52 and 59 recite the phrase “either… or…”, such as on page 7 of Claims for Claim 52. That is, on page 7 of Claims, Claim 52 recites “and either: if not in possession of the group key: agreeing… or: if in possession of the group key: iteratively distributing …” Under the broadest reasonable interpretation, only one of these options need to be met.
Drawings
The drawings are objected to because the unlabeled rectangular boxes shown in Figure 1 should be provided with descriptive labels. Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Claim Objections
Claims 52-59 are objected to because of the following informalities:
Claim 52 recites the limitation “optionally, determining a group key, K0” in line 8 of page 7 of Claims. It is recommended by the Examiner to amend the limitation to read as “optionally, determining a group key, K0” for consistency with Claim 40.
Claims 53-58 are objected to by virtue of depending upon Claim 52.
Claim 59 is objected to for the same reasons as above as in Claim 52 as it also recites this limitation.
It is further recommended by the Examiner that the indentation of Claim 59 be amended to match that of Claim 52 for consistency.
Appropriate correction is required.
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 52-59 are 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.
Claims 52-58 recite multiple instances of “the further endpoint device” and other variations. There is insufficient antecedent basis for this limitation in the claims. Claim 52 recites “a further endpoint device” in line 11 of Page 7 of Claims corresponding to the case of the endpoint device not being in possession of the group key, and “respectively further endpoint devices” in the case of the endpoint device being in possession of the group key. This means that further mentions of “the further endpoint device” are ambiguous as to referring the first or the second case, such as in lines 2 and 4 of Claim 54, rendering the claims indefinite. It is recommended by the Examiner to clearly delineate the two situations and preferably distinguish the endpoint devices between the two cases.
Claim 52 recites the limitation “optionally, determining a group key, K0” in line 8 of page 7 of Claims. The recitation of the word “optionally” in this context is ambiguous as to whether this step is being performed or not in such a manner which creates confusion over the scope of the claim, therefore rendering the claim indefinite.
Claim 52 recites the limitations “the respective sets of transmitting bases”, “the respective sets of receiving bases”, and “the respective encryption keys” in lines 22-28 of page 7 of Claims as part of agreeing on a pairwise encryption key. There is insufficient antecedent basis for these limitations in the claim. These limitations, i.e. “sets of transmitting bases”, “sets of receiving bases” and “encryption keys”, with regards to the endpoint device not in possession of the group key are not previously recited, therefore it is unclear as to what is being referred to, rendering the claim indefinite.
Claims 54-58 are rejected for similar reasons as above by virtue of depending on Claim 52.
Claim 59 is rejected for similar reasons as listed above regarding Claim 52 as Claim 59 recites similar limitations as Claim 52.
Claim 54 recites the limitation "a further set of bits of the further encryption key" in line 7 of Claim 54. There is insufficient antecedent basis for this limitation in the claim. The claim does not previously recite “a further encryption key”, therefore it is ambiguous as to which key is being referred to, rendering the claim indefinite.
Claims 55-58 are rejected for similar reasons as above by virtue of depending on Claim 54.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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 40-59 are rejected under 35 U.S.C. 103 as being unpatentable over Childe et al. (WO 2021/090025 A1) hereinafter referred to as “Childe” and in view of Ko et al. (U.S. Pub. No. 2022/0006627 A1) hereinafter referred to as “Ko”.
Regarding Claim 40:
Childe teaches the following limitations:
A computer-implemented method of generating a group key for a group of endpoint devices in a communication system comprising the group of endpoint devices and an intermediary device, the intermediary device being communicatively linked to each of the endpoint devices by a respective quantum communication channel and a respective classical communication channel, the method comprising (Fig. 1, Par. [0007], Par. [0068], Par. [0108]). Regarding a high-level overview of the claimed invention, the invention can be divided into roughly two parts: 1. an intermediary device facilitating pairwise communication between endpoint devices in having them agree on a pairwise encryption key and 2. iteratively distributing a group key. The first concept and its corresponding solution, as the issue is described in the Applicant’s specification at Par. [0005], is described nearly exactly in Childe et al. (WO 2021/090025 A1, see Par. [0003]), a prior art reference with common inventorship which address this same issue and was published more than a year before the effective filing date of the claimed invention. Therefore, the invention can be seen as a variation of this protocol, dubbed the ARQ19 protocol by the inventors (see Par. [0004] of U.S. Pub. No. 2025/0365140 A1 or correspondingly Application 18/874,018), in which this variation further adds communication of a group key, i.e. the second concept. This is also the conclusion found in the Written Opinion of the International Searching Authority regarding this application (i.e. with regards to PCT/GB2023/051530). Childe teaches an intermediary device being connected to endpoint devices through both a quantum/classical channel for each endpoint device. Furthermore, note that under the broadest reasonable interpretation, there is no restriction on the number of endpoint devices within this group, so a group can consist of two endpoint devices.
sending, from the intermediary device to each of the endpoint devices, over the corresponding quantum communication channel a respective encryption key [symbol string], said respective encryption key being defined by a string of bits (Par. [0007], Par. [0101], Par. [0110], Par. [0119], Par. [0125]). Childe teaches the intermediary device sending a secret symbol string to endpoint devices. This symbol string can be considered to be an encryption key as it is a string of bits which the claim itself defines an encryption key as. These strings are further usable for OTP encryption.
wherein each bit of each encryption key is transmitted in a randomly selected basis state such that for each encryption key there is a corresponding set of transmitting bases indicative of the basis in which each bit of said encryption key was sent to the corresponding endpoint device (Par. [0008], Par. [0110]-[0112], Par. [0119]). Childe further teaches transmitting bits modulated by randomly selected basis states.
receiving, at each endpoint device, the respective encryption key, wherein each bit of the respective received encryption key is received in a randomly selected basis state such that there is a corresponding set of receiving bases indicative of the basis in which each bit of the respective received encryption key was received by the corresponding endpoint device (Par. [0021], Par. [0113], Par. [0119]). The endpoint devices receive the symbols and demodulate the symbols by randomly selecting basis states.
sending, from the intermediary device to each of the endpoint devices, over the corresponding classical communication channel the respective set of transmitting bases corresponding to the respective encryption key (Par. [0008], Par. [0118], Par. [0123]). Childe teaches the intermediary device transmitting the basis states that it used before.
determining, by each endpoint device, a set of bits of the encryption key that were validly received based on a combination of the respective set of transmitting bases and the respective set of receiving bases (Par. [0030], Par. [0113], Par. [0123]). Childe teaches the endpoint devices determining which bits were validly received by determining whether the bases states used were the same.
(taught by Ko below)
(taught by Ko below)
agreeing, between an endpoint device in possession of the group key and another endpoint device not in possession of the group key, a respective pairwise encryption key [common set of symbols] (Par. [0008], Par. [0019], Par. [0130]-[0134]). Childe teaches that two endpoint devices can agree on a shared set of symbols which form a cryptographic key.
wherein the agreeing of the pairwise encryption key is based on: the respective sets of transmitting bases corresponding to each of the endpoint device in possession of the group key and the endpoint device not in possession of the group key (Par. [0008], Par. [0019], Par. [0130]-[0134]). This set of symbols is based on the transmitting sets of bases.
the respective sets of receiving bases corresponding to each of the endpoint device in possession of the group key and the endpoint device not in possession of the group key (Par. [0008], Par. [0019], Par. [0130]-[0134]). This set of symbols is also based on the receiving sets of bases.
and the respective encryption keys received by each of the endpoint device in possession of the group key and the endpoint device not in possession of the group key (Par. [0008], Par. [0019], Par. [0130]-[0134]). Finally, this set of symbols is also dependent on the keys received, i.e. the symbols received by the endpoint device from the intermediary device, as these symbols together were sifted.
(taught by Ko below)
(taught by Ko below)
Ko teaches the following limitations:
determining, by one of the endpoint devices, a group key, K0 (Par. [0018], Par. [0031], Par. [0168]). Ko teaches generating a group key.
and iteratively distributing the group key, wherein each iteration of the distributing comprises (Par. [0018], Par. [0031], Par. [0169]-[0177]). Ko then teaches iteratively distributing a group key along a path.
encrypting, by said endpoint device in possession of the group key, a copy of the group key with the respective pairwise encryption key (Par. [0018], Par. [0031], Par. [0169]-[0177]). Ko teaches encrypting the group key for transmission.
and sending, from said endpoint device in possession of the group key to said endpoint device not in possession of the group key, the encrypted copy of the group key (Par. [0018], Par. [0031], Par. [0169]-[0177]).
Childe teaches a quantum key distribution for agreeing on a pairwise encryption key, but does not teach distributing a group key. Ko however teaches that a group key can be iteratively distributed along nodes by encrypting a group key for each pair of endpoint devices. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to combine the quantum key distribution system (QKD) of Childe with the group key distribution of Ko in order to gain the predictable result of the group key being iteratively distributed by means of pairwise encryption keys between nodes. One of ordinary skill in the art would have recognized that the QKD system of Childe ultimately amounts to two endpoint devices agreeing upon a shared encryption key for further communication between the two devices. On the other hand, Ko teaches a group key distribution system in which endpoint devices transmit and receive a group key in a pairwise manner. Therefore, one of ordinary skill in the art would have recognized that the QKD system of Childe is compatible with Ko, as the shared encryption key can be used to implement the secure communication of the group key in Ko, and gain the predictable result of the group key being iteratively distributed through negotiated pairwise encryption keys as in Childe.
Regarding Claim 41:
Childe teaches the following limitation:
wherein determining the set of bits of the encryption key that were validly received comprises: combining the respective set of transmitting bases and the respective set of receiving bases by performing an XOR operation between the set of transmitting bases and the set of receiving bases (Par. [0050], Par. [0113], Par. [0118], Par. [0123]). Childe teaches calculating a set of basis flags representing validly received bits by combining the transmitting and receiving bases. In Childe, validly received bits are in positions where both the transmitting and receiving basis used for a particular bit match. For example, given bit string 1100 and bit string 0101, the combination of these bit strings must reflect that in both respective positions of the above bit strings, a valid bit occurs when both symbols match while an invalid bit occurs when the symbols do not match. This is logically equivalent to an XOR operation if 0 represents a valid bit and 1 represents an invalid bit, i.e. the combination would result in 1001 in the example above (positions 2/3 have matching bits, therefore 0 is in those positions in the combined string).
Regarding Claim 42:
Childe teaches the following limitations:
wherein agreeing, between a first and second endpoint device, a pairwise encryption key comprises: receiving, at the second endpoint device from the intermediary device, pairwise key information [third secret symbol string] based on: information associated with the encryption key sent from the intermediary device to the first endpoint device and information associated with the encryption key sent from the intermediary device to the second endpoint device [combining first and second set of secret symbols] (Par. [0017]-[0018], Par. [0124]-[0127]). Childe teaches the intermediary device creating a third secret symbol string by combining the first/second secret symbol strings, i.e. encryption keys corresponding to the first and second endpoint devices. Childe further teaches an example of using XOR to combine these strings to produce the third string.
determining, at the second endpoint device, an intermediate key [fourth symbol string] based on the pairwise key information and the respective encryption key received from the intermediary device by the second endpoint device (Par. [0124]-[0127]). Childe then teaches the second endpoint device creating a fourth symbol string by combining the third secret symbol string with the second secret symbol string, such as through an XOR operation again.
exchanging, between the first and second endpoint devices, over a communication channel communicatively linking the first and second endpoint devices, the respectively determined set of bits of the corresponding encryption key that were validly received by each of the endpoint devices (Par. [0008], Par. [0019], Par. [0130]-[0134]). Childe then teaches the endpoint devices negotiating the common set of symbols, i.e. encryption key based on validly received bits.
discarding, by the first endpoint device, bits from the respective encryption key received from the intermediary device that are in positions within the respective encryption key corresponding to the positions of the bits in their respective encryption keys that were not validly received by either the first endpoint device or the second endpoint device to obtain a first copy of the pairwise encryption key [first common set of secret symbols] (Par. [0008], Par. [0019], Par. [0130]-[0134]). Childe teaches the first endpoint device discarding bits according to basis flags that each endpoint devices sends to the other endpoint device.
and discarding, by the second endpoint device, bits from the intermediate key that are in positions within the intermediate key corresponding to the positions of the bits in their respective encryption keys that were not validly received by either the first endpoint device or the second endpoint device to obtain a second copy of the pairwise encryption key [second common set of secret symbols] (Par. [0008], Par. [0019], Par. [0130]-[0134]). Similarly, Childe teaches the second endpoint device discarding bits according to basis flags that each endpoint devices sends to the other endpoint device.
Regarding Claim 43:
Childe teaches the following limitation:
wherein the pairwise key information comprises a combination of information indicative of the encryption key sent to the first endpoint device by the intermediary device and information indicative of the encryption key sent to the second endpoint device by the intermediary device (Par. [0017]-[0018], Par. [0124]-[0127]). This pairwise key information was previously shown to be a possible XOR combination of first/second secret symbol strings or encryption keys.
Regarding Claim 44:
Childe teaches the following limitation:
wherein the combination of information indicative of the encryption key sent to the first endpoint device by the intermediary device and information indicative of the encryption key sent to the second endpoint device by the intermediary device comprises a bit string obtainable by performing an XOR operation between the encryption key sent to the first endpoint device and the encryption key sent to the second endpoint device (Par. [0017]-[0018], Par. [0124]-[0127]). This pairwise key information was previously shown to be a possible XOR combination of first/second secret symbol strings or encryption keys.
Regarding Claim 45:
Childe teaches the following limitation:
wherein determining the intermediate key, by the second endpoint device, comprises combining the respective encryption key received from the intermediary device with the pairwise key information received from the intermediary device (Par. [0124]-[0127]). The intermediate key was previously shown to be a possible XOR combination of second and third secret symbol strings or encryption keys.
Regarding Claim 46:
Childe teaches the following limitation:
wherein combining the respective encryption key received by the second endpoint device with the pairwise key information received from the intermediary device comprises performing an XOR operation between said encryption key and the pairwise key information (Par. [0124]-[0127]). The intermediate key was previously shown to be a possible XOR combination of second and third secret symbol strings or encryption keys.
Regarding Claim 47:
Childe teaches the following limitations:
after exchanging the respectively determined set of bits of the corresponding encryption key that were validly received by each of the endpoint devices: determining, by each of the first and second endpoint device, a set of positions [compare basis flags] within the respective encryption key or intermediate key (Par. [0133]-[0134]). Childe teaches the endpoint devices comparing basis flag sets to determine valid positions.
corresponding to one or both of:(i) positions within the encryption key received by the first endpoint device from the intermediary device that are the positions of bits in said encryption key that were not validly received by the first endpoint device; and(ii) positions within the encryption key received by the second endpoint device from the intermediary device that are the positions of bits in said encryption key that were not validly received by the second endpoint device (Par. [0130]-[0134]). Childe teaches the first endpoint device, Bob in their example, discarding bits from their valid first received set of secret symbols, i.e. their respective encryption key. On the other hand, the second endpoint device, Carol in their example, discards bits from the fourth symbol string, i.e. the intermediate key.
and wherein the discarding, by each of the endpoint devices, of bits from the respective encryption key or intermediate key comprises discarding bits that are in the determined set of positions (Par. [0130]-[0134]).
Regarding Claim 48:
Childe teaches the following limitation:
wherein determining the set of positions comprises performing a non-exclusive combination of the determined set of bits of the encryption key received by the first endpoint device that were validly received with the determined set of bits of the encryption key received by the second endpoint device that were validly received (Par. [0130]-[0134]). In Childe, the basis flag sets represent bit strings where each bit represents where a bit in that particular position was validly received or not. Childe then teaches the two endpoint devices combining these strings to determine which positions in both bit strings both bits were validly received. For example, given bit string 1100 and bit string 0101, the combination of these bit strings must reflect that in both positions of the above bit strings, the bit reads as valid. Given the convention that 0 represents a valid bit and 1 represents an invalid bit, this corresponds to a non-exclusive logical OR operation, i.e. in the example above, the resulting bit string is 1101 (only in the third position do both strings have a valid bit of 0).
Regarding Claim 49:
Childe teaches the following limitation:
wherein the non-exclusive combination is a logical OR operation (Par. [0130]-[0134]). This combination was previously shown to be a non-exclusive logical OR combination.
Regarding Claim 50:
Childe teaches the following limitation:
wherein a bit is determined as being validly received if it was received in the same basis as the basis in which it was transmitted by the intermediary device (Par. [0050], Par. [0113], Par. [0118], Par. [0123]). Childe was previously shown to teach this aspect regarding basis state flags.
Regarding Claim 51:
Childe teaches the following limitations:
wherein each quantum communication channel is a lossy channel (Par. [0115]-[0116], Par. [0120]-[0121]). Childe accounts for the quantum channels being lossy.
and the method further comprises: sending, from each of the endpoint devices, a respective indication of which bits of the respective encryption key were successfully transmitted over the corresponding quantum communication channel (Par. [0010]-[0011], Par. [0114]-[0117], Par. [0120]-[0122]). Childe teaches the intermediate device receiving positions of successfully received bits.
and before sending the respective set of transmitting bases from the intermediary device to each of the endpoint devices, modifying the respective encryption key by discarding bits corresponding to those bits that were not successfully transmitted over the quantum communication channel, such that all further operations by the intermediary device based on the respective encryption key are based on the modified respective encryption key (Par. [0010]-[0011], Par. [0114]-[0117], Par. [0120]-[0122]). Childe teaches the intermediate device and endpoint device discarding bits which were unsuccessfully received due to the channel being lossy.
Regarding Claim 52:
Childe teaches the following limitations:
A computer-implemented method for generating a group key for a group of endpoint devices in a communication system, the method being performable by an endpoint device in the group, said endpoint device being communicatively linked to an intermediary device by a quantum communication channel and a classical communication channel, the method comprising (Fig. 1, Par. [0007], Par. [0068], Par. [0108]).
receiving, from the intermediary device, over the quantum communication channel, an encryption key, said encryption key being defined by a string of bits (Par. [0007], Par. [0101], Par. [0110], Par. [0119], Par. [0125]).
wherein each bit of the encryption key is transmitted in a randomly selected basis state such that there is a corresponding set of transmitting bases indicative of the basis in which each bit of the encryption key was sent to the endpoint device (Par. [0008], Par. [0110]-[0112], Par. [0119]).
and wherein each bit of the encryption key is received in a randomly selected bases state such that there is a corresponding set of receiving bases indicative of the basis in which each bit of the encryption key was received by the endpoint device (Par. [0021], Par. [0113], Par. [0119]).
receiving, from the intermediary device, over the classical communication channel, the set of transmitting bases corresponding to the encryption key (Par. [0008], Par. [0118], Par. [0123]).
determining a set of bits of the encryption key that were validly received based on a combination of the set of transmitting bases and the set of receiving bases (Par. [0030], Par. [0113], Par. [0123]).
(taught by Ko below)
(taught by Ko below)
(taught by Ko below)
wherein each iteration of the distributing comprises: agreeing, with respectively further endpoint devices in the group of endpoint devices that are not in possession of the group key, a respective pairwise encryption key (Par. [0008], Par. [0019], Par. [0130]-[0134]).
wherein the agreeing of the pairwise encryption key is based on: the respective sets of transmitting bases corresponding to each of the endpoint device in possession of the group key and the endpoint device not in possession of the group key (Par. [0008], Par. [0019], Par. [0130]-[0134]).
the respective sets of receiving bases corresponding to each of the endpoint device in possession of the group key and the endpoint device not in possession of the group key (Par. [0008], Par. [0019], Par. [0130]-[0134]).
and the respective encryption keys received by each of the endpoint device in possession of the group key and the endpoint device not in possession of the group key (Par. [0008], Par. [0019], Par. [0130]-[0134]).
(taught by Ko below)
Ko teaches the following limitations:
optionally, determining a group key, KO (Par. [0018], Par. [0031], Par. [0168]).
and either: if not in possession of the group key: agreeing with a further endpoint device in the group of endpoint devices in possession of the group key, a pairwise encryption key, and receiving from the further endpoint device, an encrypted copy of the group key, encrypted with the pairwise encryption key (Par. [0018], Par. [0031], Par. [0169]-[0177]). Previously, it was shown that Ko taught iteratively distributing the encrypted group key, and this means receiving the group key for those who do not initially generate the group key.
or: if in possession of the group key: iteratively distributing the group key (Par. [0018], Par. [0031], Par. [0169]-[0177]).
encrypting a copy of the group key with the respective pairwise encryption key, and sending, to the respective further endpoint device, the respective encrypted copy of the group key (Par. [0018], Par. [0031], Par. [0169]-[0177]).
Childe teaches a quantum key distribution for agreeing on a pairwise encryption key, but does not teach distributing a group key. Ko however teaches that a group key can be iteratively distributed along nodes by encrypting a group key for each pair of endpoint devices. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to combine the quantum key distribution system (QKD) of Childe with the group key distribution of Ko in order to gain the predictable result of the group key being iteratively distributed by means of pairwise encryption keys between nodes. One of ordinary skill in the art would have recognized that the QKD system of Childe ultimately amounts to two endpoint devices agreeing upon a shared encryption key for further communication between the two devices. On the other hand, Ko teaches a group key distribution system in which endpoint devices transmit and receive a group key in a pairwise manner. Therefore, one of ordinary skill in the art would have recognized that the QKD system of Childe is compatible with Ko, as the shared encryption key can be used to implement the secure communication of the group key in Ko, and gain the predictable result of the group key being iteratively distributed through negotiated pairwise encryption keys as in Childe.
Regarding Claim 53:
Childe teaches the following limitation:
wherein determining the set of bits of the encryption key that were validly received comprises: combining the set of transmitting bases and the set of receiving bases by performing an XOR operation between the set of transmitting bases and the set of receiving bases (Par. [0050], Par. [0113], Par. [0118], Par. [0123]).
Regarding Claim 54:
Childe teaches the following limitations:
wherein agreeing between the endpoint device and the respective further endpoint device, a pairwise encryption key comprises: exchanging, with the further endpoint device, over a communication channel communicatively linking the endpoint device with the further endpoint device, the determined set of bits of the encryption key that were validly received by the endpoint device and a further set of bits of the further encryption key that were determined by the further endpoint device as being validly received by the further endpoint device from the intermediary device (Par. [0008], Par. [0019], Par. [0130]-[0134]). Childe was previously shown to teach the first/second endpoint devices determining a common set of valid bits.
and if the endpoint device is not in possession of the group key: receiving, from the intermediary device, pairwise key information based on: information associated with a further encryption key sent from the intermediary device to the further endpoint device, and information associated with the encryption key received from the intermediary device (Par. [0017]-[0018], Par. [0124]-[0127]). Childe was previously shown to teach the second endpoint device receiving pairwise key information, i.e. third secret symbol string which was a combination of the first/second symbol strings.
determining an intermediate key based on the pairwise key information and the received encryption key (Par. [0124]-[0127]). Childe was previously shown to teach the second endpoint device generating a fourth secret symbol string.
and discarding bits from the intermediate key that are in positions within the intermediate key corresponding to the positions, within one or both of the encryption key and the further encryption key, of the bits that were not validly received by either or both of the endpoint device and the further endpoint device, to obtain a copy of the pairwise encryption key (Par. [0008], Par. [0019], Par. [0130]-[0134]). Childe was previously shown to teach the second endpoint device discard bits to create their copy of the encryption key.
or if the endpoint device is in possession of the group key: discarding bits from the received encryption key that are in positions within the encryption key corresponding to the positions, within one or both of the encryption key and the further encryption key, of the bits that were not validly received by either or both of the endpoint device and the further endpoint device, to obtain a copy of the pairwise encryption key (Par. [0008], Par. [0019], Par. [0130]-[0134]). Childe was previously shown to teach the first endpoint device discarding bits to create their copy of the encryption key.
Regarding Claim 55:
Childe teaches the following limitation:
wherein the pairwise key information comprises a combination of information indicative of the encryption key sent to the endpoint device by the intermediary device and information indicative of the further encryption key sent to the further endpoint device by the intermediary device (Par. [0017]-[0018], Par. [0124]-[0127]).
Regarding Claim 56:
Childe teaches the following limitation:
wherein the combination of information indicative of the encryption key sent to the endpoint device by the intermediary device and information indicative of the further encryption key sent to the further endpoint device by the intermediary device comprises a bit string obtainable by performing an XOR operation between the encryption key sent to the endpoint device and the further encryption key sent to the further endpoint device (Par. [0017]-[0018], Par. [0124]-[0127]).
Regarding Claim 57:
Childe teaches the following limitation:
wherein determining the intermediate key comprises combining the received encryption key with the pairwise key information (Par. [0124]-[0127]).
Regarding Claim 58:
Childe teaches the following limitation:
wherein combining the received encryption key with the pairwise key information comprises performing an XOR operation between the received encryption key and the pairwise key information (Par. [0124]-[0127]).
Regarding Claim 59:
Childe teaches the following limitations:
A computer-readable medium comprising instructions that, when executed by one or more computers, cause the one or more computers to carry out a method of generating a group key for a group of endpoint devices in a communication system, the method being performable by an endpoint device in the group, said endpoint device being communicatively linked to an intermediary device by a quantum communication channel and a classical communication channel, the method comprising (Fig. 1, Par. [0007], Par. [0068], Par. [0084], Par. [0108], Par. [0298]).
receiving, from the intermediary device, over the quantum communication channel, an encryption key, said encryption key being defined by a string of bits (Par. [0007], Par. [0101], Par. [0110], Par. [0119], Par. [0125]).
wherein each bit of the encryption key is transmitted in a randomly selected basis state such that there is a corresponding set of transmitting bases indicative of the basis in which each bit of the encryption key was sent to the endpoint device (Par. [0008], Par. [0110]-[0112], Par. [0119]).
and wherein each bit of the encryption key is received in a randomly selected bases state such that there is a corresponding set of receiving bases indicative of the basis in which each bit of the encryption key was received by the endpoint device (Par. [0021], Par. [0113], Par. [0119]).
receiving, from the intermediary device, over the classical communication channel, the set of transmitting bases corresponding to the encryption key (Par. [0008], Par. [0118], Par. [0123]).
determining a set of bits of the encryption key that were validly received based on a combination of the set of transmitting bases and the set of receiving bases (Par. [0030], Par. [0113], Par. [0123]).
(taught by Ko below)
(taught by Ko below)
(taught by Ko below)
wherein each iteration of the distributing comprises: agreeing, with respectively further endpoint devices in the group of endpoint devices that are not in possession of the group key, a respective pairwise encryption key (Par. [0008], Par. [0019], Par. [0130]-[0134]).
wherein the agreeing of the pairwise encryption key is based on: the respective sets of transmitting bases corresponding to each of the endpoint device in possession of the group key and the endpoint device not in possession of the group key (Par. [0008], Par. [0019], Par. [0130]-[0134]).
the respective sets of receiving bases corresponding to each of the endpoint device in possession of the group key and the endpoint device not in possession of the group key (Par. [0008], Par. [0019], Par. [0130]-[0134]).
and the respective encryption keys received by each of the endpoint device in possession of the group key and the endpoint device not in possession of the group key (Par. [0008], Par. [0019], Par. [0130]-[0134]).
(taught by Ko below)
Ko teaches the following limitations:
optionally, determining a group key, KO (Par. [0018], Par. [0031], Par. [0168]).
and either: if not in possession of the group key: agreeing with a further endpoint device in the group of endpoint devices in possession of the group key, a pairwise encryption key, and receiving from the further endpoint device, an encrypted copy of the group key, encrypted with the pairwise encryption key (Par. [0018], Par. [0031], Par. [0169]-[0177]).
or: if in possession of the group key: iteratively distributing the group key (Par. [0018], Par. [0031], Par. [0169]-[0177]).
encrypting a copy of the group key with the respective pairwise encryption key, and sending, to the respective further endpoint device, the respective encrypted copy of the group key (Par. [0018], Par. [0031], Par. [0169]-[0177]).
Childe teaches a quantum key distribution for agreeing on a pairwise encryption key, but does not teach distributing a group key. Ko however teaches that a group key can be iteratively distributed along nodes by encrypting a group key for each pair of endpoint devices. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to combine the quantum key distribution system (QKD) of Childe with the group key distribution of Ko in order to gain the predictable result of the group key being iteratively distributed by means of pairwise encryption keys between nodes. One of ordinary skill in the art would have recognized that the QKD system of Childe ultimately amounts to two endpoint devices agreeing upon a shared encryption key for further communication between the two devices. On the other hand, Ko teaches a group key distribution system in which endpoint devices transmit and receive a group key in a pairwise manner. Therefore, one of ordinary skill in the art would have recognized that the QKD system of Childe is compatible with Ko, as the shared encryption key can be used to implement the secure communication of the group key in Ko, and gain the predictable result of the group key being iteratively distributed through negotiated pairwise encryption keys as in Childe.
Related Art
The following prior art made of record and cited on PTO-892, but not relied upon, is considered pertinent to applicant’s disclosure:
Lesovik et al. (U.S. Pub. No. 2022/0271928 A1) – Includes methods regarding quantum key distribution
Cho (U.S. Pub. No. 2015/0226609 A1) – Includes methods regarding quantum key distribution
Cho et al. (U.S. Pub. No. 2023/0018829 A1) – Includes methods regarding relaying an encryption key
Walenta et al. (U.S. Pub. No. 2020/0351086 A1) – Includes methods regarding quantum key distribution
Conclusion
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/E.V.V./Examiner, Art Unit 2431 /LYNN D FEILD/Supervisory Patent Examiner, Art Unit 2431