nichoth.com / pds.js
forked from chadtmiller.com/pds.js
A zero-dependency AT Protocol Personal Data Server written in JavaScript
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feat: add Merkle Search Tree implementation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

chadtmiller.com 62547acb 5c3f8717

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src/pds.js
··· 224 224 return bytes 225 225 } 226 226 227 + // === MERKLE SEARCH TREE === 228 + // Simple rebuild-on-write implementation 229 + 230 + async function sha256(data) { 231 + const hash = await crypto.subtle.digest('SHA-256', data) 232 + return new Uint8Array(hash) 233 + } 234 + 235 + function getKeyDepth(key) { 236 + // Count leading zeros in hash to determine tree depth 237 + const keyBytes = new TextEncoder().encode(key) 238 + // Sync hash for depth calculation (use first bytes of key as proxy) 239 + let zeros = 0 240 + for (const byte of keyBytes) { 241 + if (byte === 0) zeros += 8 242 + else { 243 + for (let i = 7; i >= 0; i--) { 244 + if ((byte >> i) & 1) break 245 + zeros++ 246 + } 247 + break 248 + } 249 + } 250 + return Math.floor(zeros / 4) 251 + } 252 + 253 + class MST { 254 + constructor(sql) { 255 + this.sql = sql 256 + } 257 + 258 + async computeRoot() { 259 + const records = this.sql.exec(` 260 + SELECT collection, rkey, cid FROM records ORDER BY collection, rkey 261 + `).toArray() 262 + 263 + if (records.length === 0) { 264 + return null 265 + } 266 + 267 + const entries = records.map(r => ({ 268 + key: `${r.collection}/${r.rkey}`, 269 + cid: r.cid 270 + })) 271 + 272 + return this.buildTree(entries, 0) 273 + } 274 + 275 + async buildTree(entries, depth) { 276 + if (entries.length === 0) return null 277 + 278 + const node = { l: null, e: [] } 279 + let leftEntries = [] 280 + 281 + for (const entry of entries) { 282 + const keyDepth = getKeyDepth(entry.key) 283 + 284 + if (keyDepth > depth) { 285 + leftEntries.push(entry) 286 + } else { 287 + // Store accumulated left entries 288 + if (leftEntries.length > 0) { 289 + const leftCid = await this.buildTree(leftEntries, depth + 1) 290 + if (node.e.length === 0) { 291 + node.l = leftCid 292 + } else { 293 + node.e[node.e.length - 1].t = leftCid 294 + } 295 + leftEntries = [] 296 + } 297 + node.e.push({ k: entry.key, v: entry.cid, t: null }) 298 + } 299 + } 300 + 301 + // Handle remaining left entries 302 + if (leftEntries.length > 0) { 303 + const leftCid = await this.buildTree(leftEntries, depth + 1) 304 + if (node.e.length > 0) { 305 + node.e[node.e.length - 1].t = leftCid 306 + } else { 307 + node.l = leftCid 308 + } 309 + } 310 + 311 + // Encode and store node 312 + const nodeBytes = cborEncode(node) 313 + const nodeCid = await createCid(nodeBytes) 314 + const cidStr = cidToString(nodeCid) 315 + 316 + this.sql.exec( 317 + `INSERT OR REPLACE INTO blocks (cid, data) VALUES (?, ?)`, 318 + cidStr, 319 + nodeBytes 320 + ) 321 + 322 + return cidStr 323 + } 324 + } 325 + 227 326 export class PersonalDataServer { 228 327 constructor(state, env) { 229 328 this.state = state ··· 314 413 signature: bytesToHex(sig) 315 414 }) 316 415 } 416 + if (url.pathname === '/test/mst') { 417 + // Insert some test records 418 + this.sql.exec(`INSERT OR REPLACE INTO records VALUES (?, ?, ?, ?, ?)`, 419 + 'at://did:plc:test/app.bsky.feed.post/abc', 'cid1', 'app.bsky.feed.post', 'abc', new Uint8Array([1])) 420 + this.sql.exec(`INSERT OR REPLACE INTO records VALUES (?, ?, ?, ?, ?)`, 421 + 'at://did:plc:test/app.bsky.feed.post/def', 'cid2', 'app.bsky.feed.post', 'def', new Uint8Array([2])) 422 + 423 + const mst = new MST(this.sql) 424 + const root = await mst.computeRoot() 425 + return Response.json({ root }) 426 + } 317 427 if (url.pathname === '/init') { 318 428 const body = await request.json() 319 429 if (!body.did || !body.privateKey) { ··· 351 461 // Export utilities for testing 352 462 export { 353 463 cborEncode, createCid, cidToString, base32Encode, createTid, 354 - generateKeyPair, importPrivateKey, sign, bytesToHex, hexToBytes 464 + generateKeyPair, importPrivateKey, sign, bytesToHex, hexToBytes, 465 + getKeyDepth 355 466 }
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test/pds.test.js
··· 2 2 import assert from 'node:assert' 3 3 import { 4 4 cborEncode, createCid, cidToString, base32Encode, createTid, 5 - generateKeyPair, importPrivateKey, sign, bytesToHex, hexToBytes 5 + generateKeyPair, importPrivateKey, sign, bytesToHex, hexToBytes, 6 + getKeyDepth 6 7 } from '../src/pds.js' 7 8 8 9 describe('CBOR Encoding', () => { ··· 183 184 assert.deepStrictEqual(back, original) 184 185 }) 185 186 }) 187 + 188 + describe('MST Key Depth', () => { 189 + test('returns a non-negative integer', () => { 190 + const depth = getKeyDepth('app.bsky.feed.post/abc123') 191 + assert.strictEqual(typeof depth, 'number') 192 + assert.ok(depth >= 0) 193 + }) 194 + 195 + test('is deterministic for same key', () => { 196 + const key = 'app.bsky.feed.post/test123' 197 + const depth1 = getKeyDepth(key) 198 + const depth2 = getKeyDepth(key) 199 + assert.strictEqual(depth1, depth2) 200 + }) 201 + 202 + test('different keys can have different depths', () => { 203 + // Generate many keys and check we get some variation 204 + const depths = new Set() 205 + for (let i = 0; i < 100; i++) { 206 + depths.add(getKeyDepth(`collection/key${i}`)) 207 + } 208 + // Should have at least 1 unique depth (realistically more) 209 + assert.ok(depths.size >= 1) 210 + }) 211 + 212 + test('handles empty string', () => { 213 + const depth = getKeyDepth('') 214 + assert.strictEqual(typeof depth, 'number') 215 + assert.ok(depth >= 0) 216 + }) 217 + 218 + test('handles unicode strings', () => { 219 + const depth = getKeyDepth('app.bsky.feed.post/émoji🎉') 220 + assert.strictEqual(typeof depth, 'number') 221 + assert.ok(depth >= 0) 222 + }) 223 + })