Abstract: An example operation may include one or more of connecting, by a clock node, to a blockchain network comprised of a plurality of nodes, retrieving, by the clock node, a timestamp (Ts) of the clock node, acquiring, by the clock node, a time window (Tw) based on the Ts, reading, by the clock node, a current window (Cw) from a world state, determining, by the clock node, a gap as a difference between the Tw and the Cw, calculating, by the clock node, a clock fix value based on the gap, and adjusting a clock by a subtraction of the clock fix value from the Ts.

Abstract: An example operation may include one or more of connecting, by a pharmacy node, to a blockchain network configured to store patients' data on a blockchain ledger, receiving, by the pharmacy node, a request from a patient node for a prescription refill, the request contains a secret key of a patient, extracting, by the pharmacy node, the secret key from the request to verify a patient's identity, and executing, by the pharmacy node, a smart contract to: (a) decrypt a prescription data located on the ledger by an application of the secret key, (b) retrieve patient's allergy records from the ledger to check the allergy records against the prescription data, (c) determine a number of remaining refills from the prescription data, (d) check validity of the prescription data based on an expiration date, and commit a prescription refill transaction to the blockchain based on a successful execution of (b)-(d).

Abstract: An example operation may include one or more of receiving, by a validation node, a copy request from a user node over a blockchain network, the request contains a copy token, invoking, by the validation node, a smart contract associated with the copy token to verify the copy token, in response to a verification, generating, by the validation node, media copy keys for generation of a Blu-ray copy, and recording, by the validation node, the copy token on a ledger of the blockchain network to indicate that the copy token is spent.

Abstract: An example operation may include one or more of receiving, by a pharmacy node, a request from a patient node for a prescription refill, the request contains a secret key of a patient, extracting, by the pharmacy node, the secret key from the request to verify a patient's identity, and executing, by the pharmacy node, a smart contract to: (a) decrypt a prescription data located on the ledger by an application of the secret key; (b) retrieve patient's allergy records from the ledger to check the allergy records against the prescription data; (c) determine a number of remaining refills from the prescription data; (d) check validity of the prescription data based on an expiration date; and commit a prescription refill transaction to the blockchain based on a successful execution of (b)-(d).

Abstract: An example operation may include one or more of acquiring, by a provision server, system policy data from a system policy engine, receiving, by the provision server, jurisdiction policy parameters from a jurisdiction policy engine, selecting, by the provision server, a smart contract from a smart contract repository based on the system policy data and the jurisdiction policy parameters, mapping, by the provision server, the smart contract to a node, and provisioning the node to a blockchain network.

Abstract: Encryption key block generation with barrier descriptors is provided. In some embodiments, a descriptor is read. The descriptor includes a list of revoked devices and a list of boundaries between devices. A plurality of subset differences is generated. The plurality of subset-differences covers a plurality of devices. None of the plurality of devices appears in the list of revoked devices. None of the plurality of subset differences spans any of the boundaries. Encrypted information is generated based on the subset differences.

Abstract: An example operation may include one or more of receiving a request for performing a post-commit validation of a chain of blocks on a distributed ledger, the chain of blocks being encrypted using an encryption key, requesting cooperation from one or more auditor nodes associated with the distributed ledger, each auditor node comprising a partial secret of a decryption key corresponding to the encryption key, and, in response to receiving partial secrets from a minimum threshold of auditor nodes, recovering the decryption key based on the received partial secrets, decrypting the chain of blocks based on the recovered decryption key, and validating content included within the chain of blocks.

Abstract: An example operation may include one or more of connecting, by an attester node, to a blockchain network A configured to store hashes of blocks A, coupling, by the attester node, the blockchain network A with a blockchain network B configured to store hashes of blocks B, receiving, by the attester node, a request from the blockchain network A to send a hash of a block A produced at a time t1 (AHash_1) to the blockchain network B, confirming, by the attester node, that the blockchain network A has stored a hash of a block B produced at a time t0 (BHash_0), sending, by the attester node, the AHash_1 to the blockchain network B to be stored, receiving, by the attester node, a hash of the block B produced at the time t1 (BHash_1) from the blockchain network B, confirming, by the attester node, that the blockchain network B has stored a hash of a block A produced at the time t0 (AHash_0), and providing, by the attester node, the BHash_1 to the blockchain network A to be stored, wherein the t0 is less than the t1.

Abstract: An example operation may include one or more of connecting, by an attester node, to a source blockchain network configured to store hashes of source blocks, collaboratively coupling, by the attester node, the source blockchain network with a target blockchain network configured to store hashes of target blocks, receiving, by the attester node, a request from the source blockchain network to store the hash of the source block on the target blockchain network, confirming, by the attester node, that the source network has a previously stored hash of the target block, in response to the confirmation that the source blockchain network has a previously stored hash of the target block, allowing, by the attester node, to store the hash of the source block on the target blockchain network, and continuing, by the attester node, a collaboration between the source blockchain network and the target blockchain network.

Abstract: An example operation may include one or more of receiving a request to certify a digital record, retrieving a first hashed data value of the digital record from a data block included among a first hash-linked chain of blocks on a first blockchain, retrieving a second hashed data value of the digital record from a second data block included among a second hash-linked chain of blocks on a second blockchain which is different from the first blockchain, determining whether the digital record is valid based on a cross-validation of the first hashed data value and the second hashed data value, and storing the determination of the validity of the digital record in a data block among a third hash-linked chain of blocks.

Abstract: One example method of operation may include receiving a request, from an entity, for one or more tokens based on one or more attributes, encrypting and masking the one or more attributes, adding the encrypted and masked one or more attributes to the one or more tokens, and transmitting the one or more tokens to the entity.

Abstract: An example operation may include one or more of connecting, by a clock node, to a blockchain network comprised of a plurality of nodes, retrieving, by the clock node, a timestamp (Ts) of the clock node, acquiring, by the clock node, a time window (Tw) based on the Ts, reading, by the clock node, a current window (Cw) from a world state, determining, by the clock node, a gap as a difference between the Tw and the Cw, calculating, by the clock node, a clock fix value based on the gap, and adjusting a clock by a subtraction of the clock fix value from the

Abstract: An example operation may include one or more of identifying a blockchain transaction, storing the blockchain transaction in a blockchain, assigning the blockchain transaction a transaction number and a block number, hashing a portion of blockchain transaction data associated with the blockchain transaction, and updating a blockchain index based on the hashed portion of the blockchain transaction.

Abstract: An example operation may include one or more of connecting, by a recipient node, to a blockchain network configured to store links to digital assets of an owner, selecting, by the recipient node, an asset from a ledger of the owner, executing, by the recipient node, a smart contract to determine a time frame of the asset use, executing, by the recipient node, a smart contract to download the asset to the recipient node, checking, by the recipient node, if the asset is downloaded successfully, and in response to the successful download of the asset, executing, by the recipient node, a smart contract to log an asset transfer transaction onto the blockchain.

Abstract: An example operation may include one or more of connecting, by an attester node, to a blockchain network A configured to store hashes of blocks A, coupling, by the attester node, the blockchain network A with a blockchain network B configured to store hashes of blocks B, receiving, by the attester node, a request from the blockchain network A to send a hash of a block A produced at a time t1 (AHash_1) to the blockchain network B, confirming, by the attester node, that the blockchain network A has stored a hash of a block B produced at a time t0 (BHash_0), sending, by the attester node, the AHash_1 to the blockchain network B to be stored, receiving, by the attester node, a hash of the block B produced at the time t1 (BHash_1) from the blockchain network B, confirming, by the attester node, that the blockchain network B has stored a hash of a block A produced at the time t0 (AHash_0), and providing, by the attester node, the BHash_1 to the blockchain network A to be stored, wherein the t0 is less than the t1.

Abstract: An example operation may include one or more of connecting, by an attester node, to a source blockchain network configured to store hashes of source blocks, collaboratively coupling, by the attester node, the source blockchain network with a target blockchain network configured to store hashes of target blocks, receiving, by the attester node, a request from the source blockchain network to store the hash of the source block on the target blockchain network, confirming, by the attester node, that the source network has a previously stored hash of the target block, in response to the confirmation that the source blockchain network has a previously stored hash of the target block, allowing, by the attester node, to store the hash of the source block on the target blockchain network, and continuing, by the attester node, a collaboration between the source blockchain network and the target blockchain network.

Abstract: An example operation may include one or more of identifying a blockchain transaction, storing the blockchain transaction in a blockchain, assigning the blockchain transaction a transaction number and a block number, hashing a portion of blockchain transaction data associated with the blockchain transaction, and updating a blockchain index based on the hashed portion of the blockchain transaction.

Abstract: An example operation may include one or more of identifying a group of blockchain member devices attempting to establish a trusted group communication channel, assigning each of the blockchain member devices public/private key pairs, publishing the public keys of the blockchain member devices in a list, identifying a request from a first blockchain member device requesting a private key, associated with a second blockchain member device, be applied to a predetermined nonce value, responsive to identifying a response to the request, verifying, via a public key assigned to the first blockchain member device, that the second blockchain member device is a trusted member of the group of blockchain member devices, and responsive to verifying the second blockchain member device is a trusted member of the group of blockchain member devices, permitting communication between the first blockchain member device and the second blockchain member device on the trusted group communication channel.

Abstract: Encryption key block generation with barrier descriptors is provided. In some embodiments, a descriptor is read. The descriptor includes a list of revoked devices and a list of boundaries between devices. A plurality of subset differences is generated. The plurality of subset-differences covers a plurality of devices. None of the plurality of devices appears in the list of revoked devices. None of the plurality of subset differences spans any of the boundaries. Encrypted information is generated based on the subset differences.

Abstract: An encryption scheme is provided in which subset-difference lists are generated by blacklisting subsets corresponding to compromised devices and splitting subset difference lists corresponding to the blacklisted subsets into multiple subset difference lists. In some embodiments, a subset-difference tree is generated. The subset-difference tree includes a plurality of subsets. The subset-difference tree covers a plurality of nodes. Each of the plurality of subsets has an apex node among the plurality of nodes. At least one blacklisted node of the plurality of nodes is determined. A first subset among the plurality of subsets is identified that covers the at least one blacklisted node. A plurality of substitute subsets is determined. Each of the plurality of substitute subsets overlaps the first subset and does not cover the at least one blacklisted node. The plurality of substitute subsets are substituted for the first subset.