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doc: document crypto RNG behaviour across snapshot/checkpoint restore #67342

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doc: document crypto RNG behaviour across snapshot/checkpoint restore #67342

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16 changes: 15 additions & 1 deletion doc/api/crypto.md
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Expand Up @@ -6181,6 +6181,17 @@ changes:
Generates cryptographically strong pseudorandom data. The `size` argument
is a number indicating the number of bytes to generate.

> [!NOTE]
> The random data is drawn from OpenSSL's DRBG inside the process. After a
> snapshot or checkpoint restore (for example a VM restore, Firecracker
> snapshot, or CRIU checkpoint), the DRBG continues from the saved state until
> its next scheduled reseed, and output may repeat across the two continuations
> of a restored process. Applications resumed from a saved image should reseed
> (or draw fresh randomness via their own restore signal) before relying on
> further output from `crypto.randomBytes()`, `crypto.randomInt()`,
> `crypto.randomFill()`, `crypto.randomUUID()`, and
> `crypto.getRandomValues()`. See #66880 for measurements.

If a `callback` function is provided, the bytes are generated asynchronously
and the `callback` function is invoked with two arguments: `err` and `buf`.
If an error occurs, `err` will be an `Error` object; otherwise it is `null`. The
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* Returns: {string}

Generates a random [RFC 4122][] version 4 UUID. The UUID is generated using a
cryptographic pseudorandom number generator.
cryptographic pseudorandom number generator. Because of the entropy cache,
after a snapshot or checkpoint restore up to 128 UUIDs may repeat across the
restored process's continuations unless `disableEntropyCache: true` is used or
fresh randomness is drawn after the restore.

### `crypto.randomUUIDv7([options])`

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