45 lines
2.3 KiB
JavaScript
45 lines
2.3 KiB
JavaScript
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// Publisher signatures on community extensions.
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//
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// A community extension's updates.json entry carries `publisherSig`: a
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// 65-byte BCH message signature (base64) over
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// sha256("silentmode.extension-v1|<id>|<version>|<tarball-sha256>|<publisher-name>")
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// made with the key that holds the publisher name's NFT. The gateway checks
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// it before storing the entry; Theseus checks it AGAIN against the owner it
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// reads from its own chain index, so a tampered catalog or a compromised
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// relay cannot hand the browser someone else's code under a trusted name.
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//
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// ESM because @bitauth/libauth is ESM-only; main.js loads it with import().
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import { secp256k1, sha256, ripemd160, encodeCashAddress, base64ToBin, utf8ToBin } from "@bitauth/libauth";
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export const EXT_SIG_DOMAIN = "silentmode.extension-v1";
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export function entryMessage({ id, version, sha256: tarballSha256, publisher }) {
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return `${EXT_SIG_DOMAIN}|${id}|${version}|${String(tarballSha256).toLowerCase()}|${publisher}`;
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}
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// Recover the signer of `message` and return it as a CashAddress with the
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// same prefix as `likeAddress` (bitcoincash: / bchtest:). null on any error.
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export function recoverSigner(message, signatureBase64, likeAddress) {
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try {
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const sig = base64ToBin(String(signatureBase64 || "").trim());
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if (!(sig instanceof Uint8Array) || sig.length !== 65) return null;
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const header = sig[0];
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if (header < 27 || header > 34) return null;
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const digest = sha256.hash(utf8ToBin(message));
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const recover = header >= 31 ? secp256k1.recoverPublicKeyCompressed : secp256k1.recoverPublicKeyUncompressed;
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const pub = recover(sig.slice(1), (header - 27) & 3, digest);
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if (typeof pub === "string") return null;
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const prefix = String(likeAddress || "bitcoincash:").split(":")[0] || "bitcoincash";
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const enc = encodeCashAddress({ prefix, type: "p2pkh", payload: ripemd160.hash(sha256.hash(pub)) });
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return typeof enc === "string" ? enc : (enc?.address ?? null);
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} catch { return null; }
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}
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// True when the entry was signed by `ownerAddress` (the publisher name's
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// current NFT holder as the caller's own index reports it).
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export function verifyPublisherEntry(entry, ownerAddress) {
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if (!entry || !ownerAddress || !entry.publisherSig) return false;
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const who = recoverSigner(entryMessage(entry), entry.publisherSig, ownerAddress);
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return !!who && who === ownerAddress;
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}
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