Guardtime IP Holdings Limited

Guardtime Sa

Risto Laanoja

Ahto Buldas

Ahto Truu

Jeffrey Pearce

Mart Saarepera

Michael Gault

Martin Ruubel

Jian Tan

Peter Rajnak

David F A Piesse

Exclusive ownership of data units, such as monetary units, is transferred by inputting a request from a transferor, to transfer to a transferee at least a designated one of the data units, said request including an identifier of the transferor, an identifier of the designated data unit, and an identifier of a transferee. The identifier of the transferor is verified and the absence of any other request to transfer the designated data unit is confirmed. A designation of ownership of the designated data unit is then changed from the transferor to the transferee in a ledger, which is comprised of a group of subledgers, each configured as a blockchain.

Verifiable transfer of data using sharded blockchain

A set of secret, indexed keys is generated and used in requests from a signing entity to a signing server for digital signature of messages. The signing server maintains a counter as well as a hash tree that aggregates requests during a round into a root value that is stored in an append-only data structure in a repository. Each signing entity is associated with a leaf of the hash tree. After a signature is formed, the counter for the requesting signing entity is incremented, whereby the secret key that was used cannot be used again.

Blockchain-assisted hash-based data signature system and method

A digital message is signed and, if a request is approved, receives a time stamp. The request is computed as a first function of the message and a current one of a sequence of passwords computed such that each password corresponds to an index unit. Each of the passwords may be computed as a function, such as a hash function, pseudo-random function, or encryption function, of the subsequent password, whereby the sequence terminates with an initial password that forms a public key parameter for the password sequence. At least one hash tree uses at least a subset of the passwords as inputs to a hash tree used to verify the passwords.

System and method for sequential data signatures

A code is added as a marking to a document and encodes an identifier that maps to a copy of the document stored in a database. Database copies of stored documents are preferably digitally signed. Using a device such as a smart phone, a user may extract the document identifier from the marking on a purported authentic version of the document and retrieve a copy of the document from the corresponding location in the database. The user can then visually compare the purported authentic version of the document with the retrieved database copy.

System and method for field-verifiable record authentication

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Risto Laanoja