crypto: make monotonic counter optional

Author: araujogui

lib/internal/crypto/random.js

@@ -447,28 +447,50 @@ function writeTimestampAndCounterV7(buf, offset) {
   buf[offset + 7] = v7Counter & 0xff;
 }
 
-function getBufferedUUIDv7() {
+function getBufferedUUIDv7(monotonic) {
   uuidDataV7 ??= secureBuffer(16 * kBatchSize);
   if (uuidDataV7 === undefined)
     throw new ERR_OPERATION_FAILED('Out of memory');
 
   if (uuidBatchV7 === 0) randomFillSync(uuidDataV7);
   uuidBatchV7 = (uuidBatchV7 + 1) % kBatchSize;
   const offset = uuidBatchV7 * 16;
-  const seed = ((uuidDataV7[offset + 6] & 0x0f) << 8) | uuidDataV7[offset + 7];
-  advanceV7(seed);
-  writeTimestampAndCounterV7(uuidDataV7, offset);
+  if (monotonic) {
+    const seed = ((uuidDataV7[offset + 6] & 0x0f) << 8) | uuidDataV7[offset + 7];
+    advanceV7(seed);
+    writeTimestampAndCounterV7(uuidDataV7, offset);
+  } else {
+    const now = DateNow();
+    const msb = now / (2 ** 32);
+    uuidDataV7[offset] = msb >>> 8;
+    uuidDataV7[offset + 1] = msb;
+    uuidDataV7[offset + 2] = now >>> 24;
+    uuidDataV7[offset + 3] = now >>> 16;
+    uuidDataV7[offset + 4] = now >>> 8;
+    uuidDataV7[offset + 5] = now;
+  }
   return serializeUUID(uuidDataV7, 0x70, 0x80, offset);
 }
 
-function getUnbufferedUUIDv7() {
+function getUnbufferedUUIDv7(monotonic) {
   uuidNotBuffered ??= secureBuffer(16);
   if (uuidNotBuffered === undefined)
     throw new ERR_OPERATION_FAILED('Out of memory');
   randomFillSync(uuidNotBuffered, 6);
-  const seed = ((uuidNotBuffered[6] & 0x0f) << 8) | uuidNotBuffered[7];
-  advanceV7(seed);
-  writeTimestampAndCounterV7(uuidNotBuffered, 0);
+  if (monotonic) {
+    const seed = ((uuidNotBuffered[6] & 0x0f) << 8) | uuidNotBuffered[7];
+    advanceV7(seed);
+    writeTimestampAndCounterV7(uuidNotBuffered, 0);
+  } else {
+    const now = DateNow();
+    const msb = now / (2 ** 32);
+    uuidNotBuffered[0] = msb >>> 8;
+    uuidNotBuffered[1] = msb;
+    uuidNotBuffered[2] = now >>> 24;
+    uuidNotBuffered[3] = now >>> 16;
+    uuidNotBuffered[4] = now >>> 8;
+    uuidNotBuffered[5] = now;
+  }
   return serializeUUID(uuidNotBuffered, 0x70, 0x80);
 }
 
@@ -477,11 +499,14 @@ function randomUUIDv7(options) {
     validateObject(options, 'options');
   const {
     disableEntropyCache = false,
+    monotonic = true,
   } = options || kEmptyObject;
 
   validateBoolean(disableEntropyCache, 'options.disableEntropyCache');
+  validateBoolean(monotonic, 'options.monotonic');
 
-  return disableEntropyCache ? getUnbufferedUUIDv7() : getBufferedUUIDv7();
+  return disableEntropyCache ?
+    getUnbufferedUUIDv7(monotonic) : getBufferedUUIDv7(monotonic);
 }
 
 function createRandomPrimeJob(type, size, options) {

test/parallel/test-crypto-randomuuidv7.js

@@ -105,13 +105,22 @@ const {
   assert.match(randomUUIDv7({ disableEntropyCache: true }), uuidv7Regex);
   assert.match(randomUUIDv7({ disableEntropyCache: true }), uuidv7Regex);
 
+  // monotonic: false — rand_a is random; UUIDs must still be valid but are not
+  // guaranteed to be strictly ordered within the same millisecond.
+  assert.match(randomUUIDv7({ monotonic: false }), uuidv7Regex);
+  assert.match(randomUUIDv7({ monotonic: false, disableEntropyCache: true }), uuidv7Regex);
+
   assert.throws(() => randomUUIDv7(1), {
     code: 'ERR_INVALID_ARG_TYPE',
   });
 
   assert.throws(() => randomUUIDv7({ disableEntropyCache: '' }), {
     code: 'ERR_INVALID_ARG_TYPE',
   });
+
+  assert.throws(() => randomUUIDv7({ monotonic: 1 }), {
+    code: 'ERR_INVALID_ARG_TYPE',
+  });
 }
 
 {