How Anchors Help Ensure Authenticity on the Blockchain

As a distributed ledger technology, the Blockchain maintains copies of its entire ledger on nodes across the network. As more and more companies and software developers start using the Blockchain there is a tendency to want to put more data on the ledger. With public Blockchains like the Traceability Blockchain, this is especially problematic because all data in every block is hashed as part of the proof of work algorithm.

What is an Anchor?

An anchor is a digital fingerprint of external data that is included in a Blockchain transaction to prove the external data is authentic. A key element of cryptography are one-way functions also called hash functions. A one way function, like SHA-256 creates a fingerprint of the source data returning a unique string. If even a single byte of the source data changes, the fingerprint will change. Since the cryptographic functions publicly available they can be used to match a source document to the fingerprint stored on the Blockchain when it is necessary to validate the data.

Verifying Authenticity of Data

One of the most valuable features of the Blockchain is Immutability. Data stored on the Blockchain cannot be changed once it has been added to a block and it is not possible to go back in time to add forged data to a previous block. In addition to being a search engine for tracing the history of products in the supply chain, the Traceability Blockchain also provides a mechanism for verifying external data related to each product as it moves through the supply chain.

Consider tracing a product through a supply chain as it moves from location to location and is transformed into other products along the way. At each step in the chain of custody, the holder of the product is responsible for it. Each member of the supply chain maintains records, documents, and information about their processes that may be need to be provided in the case of a product recall. These documents are far too large to be stored on the Blockchain. Anchoring allows the documents to be combined into a secure object using encryption and protected by the Blockchain.

What an Anchor Looks Like

The fingerprint of the data is only one part of the anchor that is stored on the Blockchain. In addition, the Blockchain needs to know how to find the find the data if it is needed. This is done by linking to another asset stored on the Blockchain, called an anchor index, that contains pointers to locations where the data is located. The anchor index is maintained like other non-monetary assets on the Blockchain so that it can be updated using subsequent transactions if the location of the anchored data is changed.

Anchored Data in the Recall Process

During any recall process it is necessary to provide auditors with data related to the processor’s operation include certifications, licenses, and documents directly to the products being recalled. Anchoring data to the Blockchain proves the documents and other data provide are authentic as of the time the asset was added to the Blockchain.

Anchored data is a key element of effectively using the Blockchain for product traceability and the supply chain. For more information about the Traceability Blockchain and the Traceability Blockchain API, visit

Ed is the Chief Blockchain Architect at Tritanium Labs who developed the Traceability Blockchain, public blockchain for supply chain traceability.

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