Abstract: Computer-implemented methods, devices and computer programs are provided for integrity-preserving document processing. At a first layer, a first hash is generated over at least one first data object of a document and associated given random data. The first hash value is set as a leaf to an existing sparse hash tree (SHT). An updated root of the updated SHT is calculated. At a second layer, a current block is generated including a second hash value over at least the existing root of the existing SHT and at least one digital signature of the existing root of the existing SHT, at least one digital signature of at least the updated root of the updated SHT and the updated root of the updated SHT. A third hash value over current block is generated and, at a third layer, registered with a timestamp service or a blockchain.

Abstract: Computer-implemented methods, devices and computer programs are provided for integrity-preserving document processing. At a first layer, a first hash is generated over at least one first data object of a document and associated given random data. The first hash value is set as a leaf to an existing sparse hash tree (SHT). An updated root of the updated SHT is calculated. At a second layer, a current block is generated including a second hash value over at least the existing root of the existing SHT and at least one digital signature of the existing root of the existing SHT, at least one digital signature of at least the updated root of the updated SHT and the updated root of the updated SHT. A third hash value over current block is generated and, at a third layer, registered with a timestamp service or a blockchain.