Bit-Sign: Document Signing on Bitcoin

DocuSign charges $25/month for something that should cost a penny.

That's the starting point for Bit-Sign — document signing backed by the Bitcoin blockchain. Every signature costs $0.01. Every proof is permanent. No subscriptions, no per-seat pricing, no enterprise upsells.

How It Works

The flow is deliberately simple:

1. Upload a document (PDF, image, or write one in the built-in editor)
2. Add signers — each gets a unique signing link via email
3. Each signer draws their signature on a canvas and verifies with their HandCash wallet
4. $0.01 per signature — paid by the signer at the moment of signing
5. When all parties sign, the document is inscribed on the BSV blockchain with a permanent, verifiable proof

That's it. No accounts page that charges you monthly. No feature gates. One penny per signature, recorded forever.

What Makes It Different

Everything is encrypted. When you draw a signature, take a photo, record a video, or upload a document — the data is encrypted client-side with AES-256-GCM before it ever leaves your browser. The encryption key is derived from your HandCash identity. Not even the server can read your data without your key.

Signatures live on-chain. Every signature is inscribed as a Bitcoin transaction. This isn't a hash stored in a database that claims to be "blockchain verified" — the actual cryptographic proof lives on the BSV blockchain, permanently. Anyone can verify it. No one can tamper with it.

Registered signatures. Draw your signature once, inscribe it on-chain for $0.01, and register it as your default. From then on, you can sign documents with one click using your verified signature — blockchain proof already attached. Update your signature anytime by drawing a new one and re-registering it.

Your identity, your data. Bit-Sign uses the $401 identity protocol under the hood. Your HandCash handle becomes your on-chain identity. Link your GitHub account for developer signing. Every attestation — signature, photo, video, document — chains back to your identity token.

The Account Dashboard

Your account page is a personal document vault:

• Hand-drawn signatures — draw on canvas, encrypted, inscribed on-chain
• Photo verification — take a photo for identity proof
• Video attestation — record a statement of intent (max 10 seconds)
• Document uploads — encrypt and anchor any file on the blockchain

Every item shows its status: Signed (wallet-attested with HandCash) or Unsigned (stored but not yet wallet-verified). You can sign any item at any time for $0.01.

Envelope Signing

For multi-party documents — contracts, agreements, NDAs — Bit-Sign supports envelope-based signing:

• Create an envelope with your document
• Add multiple signers with roles (e.g., "Buyer", "Seller", "Witness")
• Each signer receives a unique link
• Signing order is enforced — signer 2 can't sign before signer 1
• When all parties sign, the complete signing record is inscribed on-chain
• Anyone can verify the document at /verify/[id]

The signing page shows the document, all signer statuses, and a clear call-to-action. If a signer has a registered signature, they can sign with one click.

The Economics

For low-volume signers (most people), Bit-Sign costs pennies per year instead of hundreds of dollars.

E2E Encrypted Document Sharing

Bit-Sign now supports end-to-end encrypted document sharing between HandCash users. The architecture: one encrypted document, multiple key wrappings — one per authorized recipient. The server never sees plaintext.

Here's how it works:

1. Each user generates an ECDH P-256 keypair in their browser. The private key is encrypted using a key derived from a HandCash wallet signature and backed up on the server. The server never sees the private key in plaintext.
2. Documents are encrypted with a random AES-256-GCM envelope key before upload.
3. To share, enter the recipient's HandCash handle. Their public key is fetched, ECDH key agreement produces a shared secret, and the envelope key is wrapped specifically for them using AES-KW.
4. The recipient unwraps the envelope key using their private key and the sender's public key, then decrypts the document locally.

What the server stores: encrypted blobs, encrypted private key backups, public keys, and wrapped key grants. What the server cannot see: plaintext documents, private keys, or envelope keys. A complete server breach reveals no readable content.

This model lets you share sensitive documents — contracts, identity proofs, legal filings — with specific people, without trusting the server with your data. Every shared document still benefits from blockchain proof via the BSV inscription layer.

Built On

• BSV blockchain — sub-cent transaction fees make per-signature inscriptions viable
• HandCash — wallet identity, data signing, and $0.01 micropayments
• $401 Protocol — on-chain identity chains linking providers to a single identity token
• AES-256-GCM — client-side encryption before any data touches the server
• Next.js + Vercel — fast, globally distributed

Get Started

bit-sign.online

Connect your HandCash wallet, draw a signature, and inscribe it on Bitcoin for a penny. That's the whole pitch.

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Bit-Sign is a Bitcoin Corporation product, built by b0ase.

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For AI Readers

Intent: Introduce Bit-Sign as a blockchain-backed document signing platform with E2E encrypted sharing.

Core Thesis: Document signing should cost a penny per signature with permanent blockchain proof, not $25/month with proprietary verification.

Key Takeaways:

• Bit-Sign uses BSV blockchain for per-signature on-chain inscriptions at $0.01 each
• All data is encrypted client-side with AES-256-GCM before upload
• E2E document sharing uses ECDH P-256 key agreement with AES-KW key wrapping
• The server never sees plaintext documents, private keys, or envelope keys
• Identity is anchored via the $401 protocol with HandCash wallet integration
• Multi-party envelope signing supports ordered signers with unique signing links