⚙ Pearl PSBT

2 · Inspect — read every byte before you sign

Paste any PSBT (this desk's or another wallet's). The inspector parses the BIP-174 maps, decodes each input's witness UTXO, internal key, tap leaves and partial signatures, and flags anything suspicious — before a key ever touches it.

3 · Sign — one input, one key, verified before it sticks

Sign a single input. The desk computes the exact BIP-341 sighash, signs with BIP-340 Schnorr, then re-verifies the signature before writing it into the PSBT. The private key lives in memory only for the signing call and is wiped immediately after.

4 · Combine — merge co-signer PSBTs

Two signers, two PSBTs, one transaction. Combining requires byte-identical unsigned transactions and refuses conflicting signatures — the merge is order-independent and idempotent.

5 · Finalize — verify everything, emit the transaction

Finalizing re-verifies every signature against its own BIP-341 sighash, assembles the witnesses ([sig] for keypath, [sig, script, control block] for scriptpath), and serializes the complete transaction. Nothing is broadcast — broadcasting is your node's job.

6 · Methodology & honest limits

What this desk does

• Create — builds a BIP-174 PSBT: global unsigned tx, per-input witness UTXOs, Taproot internal keys, and single-leaf tap scripts with their control blocks. Amounts are exact BigInt grains (1 PRL = 10⁸).
• Inspect — parses every BIP-174 map, decodes witness UTXOs, checks each leaf's control block against its internal key, and names every partial signature's sighash type. Read it before you sign it.
• Sign — computes the exact BIP-341 sighash (all 7 sighash types), signs BIP-340 Schnorr, and re-verifies before mutating the PSBT. Keypath accepts the internal key (desk applies the TapTweak) or an already-tweaked key; scriptpath requires the key to appear as a 32-byte push in a declared leaf.
• Combine — merges PSBT maps key-wise; requires byte-identical unsigned transactions; rejects conflicting signatures and duplicate keys.
• Finalize — re-verifies every signature against its own sighash, strips partial-sig metadata per BIP-174, and emits the witness transaction.
• Address rules — BIP-350 bech32m, HRP prl, witness version 1, 32-byte program, canonical re-encode — same rules as the audited Names desk.

Crypto lineage

• No new cryptography. Every primitive is vendored from the audited sign/src/crypto.js core (pearlpurse lineage): SHA-256, tagged hashes, the TapTweak (tapTweak / tweakPrivKeypath), BIP-340 Schnorr, and bech32m.
• The PSBT sighash construction is differentially pinned against the audited keypathSigDigestEx — byte-identical digests for SIGHASH_DEFAULT and SIGHASH_SINGLE|ANYONECANPAY across inputs. The test suite re-runs that pinning.
• PSBT serialization, the BIP-341 message layout, script assembly and witness building are new code in src/psbt-core.js — covered by 39 tests (158 assertions), including malformed-PSBT rejections, 1-bit tamper tests, and combine conflict rejection.