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What It Is

Sigbash is a cryptographic authorization and co-signing layer for Bitcoin, not an exchange or a standard wallet. Its core positioning is “zero-knowledge, non-custodial, no lock-in, no leakage”: users or platforms can embed policy-constrained signing capabilities into wallets, exchanges, vaults, or bridge products. Individuals can use the hosted Webapp at sigbash.com, while institutions can integrate via @sigbash/sdk or a single-tenant HTTP service.

Core Capabilities and Security

According to the text, Sigbash is built exclusively around Bitcoin, using Taproot, Schnorr, and MuSig2, while remaining compatible with existing Bitcoin custody stacks such as xpub and PSBT. Its key differentiator is that policy enforcement does not require the server to see transactions or policies in plaintext: users generate zero-knowledge proofs locally in the browser, and the server only verifies that “the policy has been satisfied” before contributing a partial signature. Supported policies include multi-level approvals, vendor whitelists, amount/rate limits, time windows, inheritance paths, and multi-party quorums. Transaction amounts, recipients, and the specific policy clauses triggered are not disclosed to the co-signer. The main text does not disclose details on cold wallets, insurance, third-party audits, or operational security certifications.

Pricing and Target Users

The personal Webapp is listed as free, allowing users to apply for a co-signing key and sign PSBTs through the interface. Commercial or institutional use requires the SDK; integrators start on Signet by default, with Mainnet access enabled after signing a contract. Specific pricing is not public. Target users include wallet providers, exchanges, vault platforms, Bitcoin infrastructure teams, custodians, family offices, trading firms, and high-net-worth individuals.

Pros and Cons

Its strengths are that it is non-custodial, offers strong transaction privacy, supports complex spending policies, and can be white-labeled into proprietary products. It is well suited to teams that already hold Bitcoin and care about approval controls and privacy. The limitations are also clear: it only supports Bitcoin, with no trading pairs, fiat on/off-ramps, derivatives, or leverage. KYC, licensing, insurance, and commercial pricing information are not disclosed. For ordinary users, PSBTs, policy trees, and zero-knowledge proofs create a learning curve.

China Access and Alternatives

The main text does not provide information on mainland China access, payment methods, or local compliance, so china_access can only be assessed as unknown. If the goal is simply to manage Bitcoin, wallets such as Sparrow, Electrum, and BlueWallet are alternatives. For institutional approval workflows, traditional multisig, MPC, or custodial co-signing solutions may also be compared, though these typically involve trade-offs among privacy, custody risk, and policy capabilities.