# US 7,073,056 B2 · Apparatus and method for demonstrating and confirming the status of digital certificates and other data

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- Number: US 7,073,056 B2
- Document ID: US7073056B2
- Status: Granted
- Kind: B2
- Application number: 10/106,869
- Filed: 2002-03-25
- Published: 2002-12-12
- Granted: 2006-07-04
- Earliest claimed: 1996-05-14
- Assignees: Tumbleweed Communications Corp.
- Inventors: Paul Carl Kocher
- Web page: https://patentgrep.com/patent/US7073056B2

## CPC

- H04L 9/3236: {using cryptographic hash functions}
- H04L 9/3247: {involving digital signatures}
- H04L 9/3268: {using certificate validation, registration, distribution or revocation, e.g. certificate revocation list [CRL]}
- H04L 9/50: {using hash chains, e.g. blockchains or hash trees}
- H04L 2209/30: Compression, e.g. Merkle-Damgard construction
- H04L 2209/56: Financial cryptography, e.g. electronic payment or e-cash
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Methods and apparatuses for providing cryptographic assurance based on ranges as to whether a particular data item is on a list.

## Claims

### Claim 1

A computer-based method of generating an interval hash tree, for use in an electronic communications protocol for generating a cryptographically assured confirmation that a candidate data item does not belong to a plurality of data items, without including all of said data items in said confirmation, comprising the steps of:
(a) storing in a memory device, a plurality of data items;
(b) deriving a plurality of leaf nodes from said data items;
(c) generating an interval hash tree by associating, said leaf nodes with a plurality of intermediate nodes and at least one root node; and
(d) digitally signing said at least one root node.