Document verification with distributed calendar infrastructure

• US 9,122,846 B2
• Filed: 04/30/2014
• Issued: 09/01/2015
• Est. Priority Date: 12/22/2003
• Status: Active Grant

• Current Assignee: Guardtime SA
• Original Assignee: Guardtime IP Holdings Limited
• Inventors: Buldas, Ahto, Saarepera, Mrt
• Primary Examiner(s): Paliwal, Yogesh
• Application Number:
  US14/265,478
• Publication Number:
  US 20140282863A1
• Time in Patent Office: 489 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 21/30 Authentication, i.e. establishing the identity or authorisation of security principals
• CPC Class Codes: G06F 21/64 Protecting data integrity, e.g. using checksums, certificates or signatures
• CPC Class Codes: G06F 21/645 using a third party
• CPC Class Codes: H04L 63/0823 using certificates cryptographic mechanisms or cryptographic arrangements for entity authentication involving certificates H04L9/3263
• CPC Class Codes: H04L 63/0876 based on the identity of the terminal or configuration, e.g. MAC address, hardware or software configuration or device fingerprint
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3265 using certificate chains, trees or paths; Hierarchical trust model
• CPC Class Codes: H04L 9/50 using hash chains, e.g. blockchains or hash trees

Abstract

Transformations of digital records are used as lowest level inputs to a tree data structure having a root in a core system and having nodes computed as digital combinations of child node values. Signature vectors are associated with the digital records and have parameters that enable recomputation upward through the tree data structure to either a current calendar value or onward to a composite calendar value that is a function of calendar values in a calendar, which comprises a set of computed calendar values, such that the calendar values have a time correspondence. Recomputation yields the same value only if a candidate digital record is an exact version of the original digital record included in the original computation of the value, indicating authentication of the candidate digital record. The authentication process as such is independent of any trust authority that issues cryptographic keys.

Claims

1. A method for enabling authentication of digital records, comprising:

receiving, at a core system on a core processing level, from each of at least one highest non-core processing system at a respective highest non-core processing level, a current highest-level combined output value that is formed as digital combinations of successively lower-level combined output values computed in lower non-core processing levels as node values of a tree data structure having lowest level inputs formed as digital transformations, computed in user-level systems, of digital input records;

computing, for a current calendar period, a current calendar value as a digital combination of the current highest-level combined output values;

returning to at least the highest non-core processing level from the core system the current calendar value, whereupon recomputation parameters are distributed downward to the user-level systems for association with respective ones of the digital input records such that an arbitrary subsequent test digital record is considered authenticated relative to the corresponding digital input record if, applying the corresponding digital transformation to the test digital record and, using the recomputation parameters to recomputed the node values upward through the tree data structure and core, the same current calendar value is attained as when it was originally computed with the corresponding digital input record forming the lowest level input;

compiling and maintaining a calendar, said calendar comprising a set of the current calendar value and of previous calendar values computed in previous calendar periods from the beginning of an initial calendar time, such that there is a correspondence between calendar values in the calendar and physical time;

periodically computing a composite calendar value as a function of at least a subset of the set of the calendar values in the calendar including the current calendar value; and

distributing downward to at least one non-core processing level recomputation parameters of the composite calendar value in addition to the recomputation parameters of the current calendar value, whereupon the arbitrary subsequent test digital record is considered trust-independently authenticated relative to the corresponding digital input record if, applying the corresponding digital transformation to the test digital record and, using the recomputation parameters of the current calendar value and the composite calendar value to recomputed the node values upward through the tree data structure and core, the same composite calendar value is attained as when it was originally computed

in which;

the recomputation parameters are keyless and therefore independent of any trust authority parameters, including cryptographic keys.

2. A method as in claim 1, further comprising computing the composite calendar value as the root value of a non-linking, non-chaining, Merkle tree structure having the current calendar values as leaf nodes.

3. A method as in claim 1, in which the digital combinations are cryptographic hashes.

4. A method as in claim 1, in which the tree data structure is a hash tree data structure.

5. A method as in claim 1, in which the recomputation parameters include, for each digital input record, the sibling node values in a directed path in the tree data structure from the digital transformations of the digital input record up to the current calendar value.

6. A method as in claim 1, in which the recomputation parameters include, for each digital input record, the sibling node values in a directed path in the tree data structure from the digital transformations of the digital input record up to the composite calendar value.