Systems and methods to timestamp and authenticate digital documents using a secure ledger are described. Some implementations can include computer-implemented method to timestamp and authenticate electronic documents. The method can include receiving, by a timestamp and authentication server and from a user device, a unique hash value that is generated at the user device based on a source document and a device identifier of the user device, and verifying, by the timestamp and authentication server, the device identifier. The method can also include, upon verifying the device identifier, inserting, by the timestamp and authentication server, the hash value and the device identifier into a secure ledger, and upon successful insertion into the secure ledger, transmitting, from the timestamp and authentication server to the user device, a success status message including a location in the secure ledger where the hash value was inserted.

Systems and methods of providing immutable records, and immutable ordering of records, in a computing system are disclosed. The computing system can be a member of a blockchain network of a plurality of blockchains. Each block can include a cryptographic digest (or hash) conforming to a minimum degree of difficulty, a nonce by which the cryptographic digest was generated in conformation with the degree of difficulty, and a list of cryptographic digests of most recent blocks of participating neighbor blockchains. Blocks may be passed between blockchains of the plurality of blockchains, which enables each member of the blockchain network to verify an immutable record of data transactions free of the mutual trust requirement of a typical blockchain environment. In conjunction with the generation of each block, an event record may be entered into an event log of the computing system wherein the block was generated. The event record, which may contain actionable instructions, requests, etc., may be transmitted to computing systems of participating neighbor blockchains, where actionable items may be acted upon. Further, the event logs of each computing system may be exchanged, compared, and adjusted to reflect the earliest appearance of each block of each participating neighbor blockchain.

Systems, devices, media, and methods are presented for retrieving authentication credentials and decryption keys to access remotely stored user-generated content. The systems and methods receive a first authentication credential and access a second authentication credential based on receiving the first authentication credential. The system and methods generate an authentication token and an encryption token. Based on the authentication token, the system and methods access a set of encrypted content and an encrypted content key. The systems and methods decrypt the encrypted content key using the encryption token and decrypt the set of encrypted content using the decrypted content key. At least a portion of the content is presented at the user device.

A verification platform may include a data connection to receive a stream of industrial asset data, including a subset of the industrial asset data, from industrial asset sensors. The verification platform may store the subset of industrial asset data into a data store, the subset of industrial asset data being marked as invalid, and record a hash value associated with a compressed representation of the subset of industrial asset data combined with metadata in a secure, distributed ledger (e.g., associated with blockchain technology). The verification platform may then receive a transaction identifier from the secure, distributed ledger and mark the subset of industrial asset data in the data store as being valid after using the transaction identifier to verify that the recorded hash value matches a hash value of an independently created version of the compressed representation of the subset of industrial asset data combined with metadata.

It is provided a method for controlling access to a physical space using a co-sign delegation. The method is performed in a lock device and comprises the steps of: receiving an access request from an electronic key; obtaining a plurality of delegations, wherein each delegation is a delegation from a delegator to a delegatee, the plurality of delegations collectively forming a chain of delegations; determining that a delegation is a co-sign delegation, indicating that all further delegations need to be cryptographically signed by both the delegator of the respective delegation and by an access controller; and granting access to the physical space when the chain of delegations start in an owner of the lock device and ends in the electronic key; and when all delegations in the chain of delegations after the co-sign delegation are cryptographically signed by both the delegator of the respective delegation and by the access controller.

Disclosed herein are methods, systems, and apparatus for processing blockchain-based guarantee information. One of the methods includes receiving a first cyphertext of a first digital document specifying a guarantee from a first computing device associated with at least a first guarantor and one or more zero-knowledge proofs (ZKPs) related to one or more values associated with the guarantee, and the first digital document specifies one or more predetermined conditions of executing the guarantee; verifying that the one or more ZKPs are correct; storing the first cyphertext to a blockchain based on performing a consensus algorithm; receiving a first message from a second computing device associated with a beneficiary or a representative of the beneficiary.

An example operation may include one or more of identifying a plurality of instances of a blockchain storage request that have been independently submitted by a plurality of clients, respectively, verifying whether execution content of the plurality of instances of the blockchain storage request match, and in response to verifying the match, storing the blockchain storage request within a block among a hash-linked chain of blocks.

A method for optimizing blockchain storage size through use of relative values includes: receiving, by a blockchain node in a blockchain network that manages a blockchain, a plurality of blockchain data values, each including unspent transaction outputs, at least one destination address, and, for each destination address, an original currency amount; identifying a base value; modifying the original currency amount included in each blockchain data value to be a relative currency amount based on a difference between the identified base value and the original currency amount; generating a new block, the new block including a block header and the modified plurality of blockchain data values; and transmitting the generated new block to a plurality of additional nodes in the blockchain network.

An example operation may include one or more of capturing a current version of sensitive data by a data processor node, hashing, by the data processor node, the current version of the sensitive data, storing, by the data processor node, a hash of the current version of the sensitive data on a first blockchain, encrypting, by the data processor node, the current version of the sensitive data using a secret key, and storing the encrypted current version of the sensitive data on a second blockchain.

Embodiments described herein provide for system and methods to enable the secure streaming of real-time location data between electronic devices. One embodiment provides for a non-transitory machine-readable medium storing instructions to perform operations comprising creating record to specify a location streaming relationship between a first device registered with a first user account and a second device registered with a second online account, the record including a secret key. The record is stored to an online datastore and shared between the first user account and the second online account. The location data stream can be encrypted using the secret key stored in the record.