Why This Matters

The file's SHA-256 hash appears in three independent places:

1. The CashToken commitment — permanently on the Bitcoin Cash blockchain, verified by thousands of nodes worldwide
2. The BCMR metadata on IPFS — decentralized storage, tamper-evident by design (the content determines the address)
3. Computable from the original file — anyone can independently verify the hash

If any single link in this chain is tampered with, the hashes won't match and the tampering is immediately detectable. No one — not even TrustAnchor — can alter the on-chain record.

What is a CashToken?

CashTokens are a native token protocol built directly into Bitcoin Cash (activated May 2023). Unlike tokens on other blockchains that rely on smart contracts, CashTokens are validated by every node on the network as part of the consensus rules.

TrustAnchor mints an immutable NFT — a non-fungible token with capability: none, meaning it can never be modified after creation. The token's commitment field holds up to 40 bytes of arbitrary data, which we use to store the file's SHA-256 hash (32 bytes).

The token category (a unique identifier) is derived from the genesis transaction, making every verification token globally unique and traceable back to its moment of creation.

What is BCMR?

BCMR (Bitcoin Cash Metadata Registry) is an open standard for associating metadata with CashTokens. It works by publishing an OP_RETURN output in the token's authchain — a linked sequence of transactions starting from the token's genesis.

The OP_RETURN contains three pieces of data:

• BCMR — the protocol identifier (4 bytes)
• SHA-256 hash of the metadata JSON (32 bytes) — ensures integrity
• IPFS URI (variable length) — where to find the full metadata document

Any wallet or application can follow the authchain, find the OP_RETURN, fetch the metadata from IPFS, verify its hash matches, and display rich information about the token. No central server required.

What is IPFS?

IPFS (InterPlanetary File System) is a decentralized storage network where files are addressed by their content hash, not by a location. This means:

• If the content changes, the address changes — making tampering detectable
• Files can be served by any node that has a copy — no single point of failure
• Content persists as long as at least one node pins it

TrustAnchor pins both the BCMR metadata and the original document (for public anchors) to IPFS, ensuring they remain available independently of the TrustAnchor website.

Private vs Public Anchors

Public anchors upload the file to IPFS and create a full BCMR metadata record. Anyone can download the original file and independently verify everything.

Private anchors never upload your file. The SHA-256 hash is computed in your browser, and only the hash leaves your device. An immutable CashToken is still minted with the hash in the commitment, proving the document existed at that point in time — but the file itself remains entirely in your possession.

To verify a private anchor later, the original file must be provided. Its hash is computed and compared against the on-chain commitment.

On-Chain Proof

TrustAnchor connects directly to Bitcoin Cash network nodes via the Electrum protocol to fetch raw transaction data and decode it. The On-Chain Proof section on every verification page shows:

• Token Category — the globally unique token identifier
• NFT Capability — always "none (immutable)" for TrustAnchor tokens
• Commitment — the file's SHA-256 hash, with a match indicator
• Block height and confirmations — proving when the token was created

This data is not read from a database — it is fetched and decoded from the actual blockchain in real time. You are seeing the same data that every Bitcoin Cash node on the planet has validated.

What If TrustAnchor Disappears?

Once a document is anchored, the proof exists entirely on public infrastructure. If TrustAnchor ceased to exist tomorrow, your verification would still be intact:

• The CashToken lives on the Bitcoin Cash blockchain, maintained by thousands of independent nodes worldwide
• The BCMR metadata and original document live on IPFS, a decentralized network with no single owner
• The OP_RETURN linking them is on-chain and permanent

Anyone with a Bitcoin Cash node and access to IPFS can independently verify an anchored document without ever contacting TrustAnchor. The blockchain doesn't need our permission, our servers, or our cooperation. That's the point.