| // Copyright 2018 The Go Authors. All rights reserved. | |
| // Use of this source code is governed by a BSD-style | |
| // license that can be found in the LICENSE file. | |
| // Package randutil contains internal randomness utilities for various | |
| // crypto packages. | |
| package randutil | |
| import ( | |
| "io" | |
| "math/rand/v2" | |
| ) | |
| // MaybeReadByte reads a single byte from r with 50% probability. This is used | |
| // to ensure that callers do not depend on non-guaranteed behaviour, e.g. | |
| // assuming that rsa.GenerateKey is deterministic w.r.t. a given random stream. | |
| // | |
| // This does not affect tests that pass a stream of fixed bytes as the random | |
| // source (e.g. a zeroReader). | |
| func MaybeReadByte(r io.Reader) { | |
| if rand.Uint64()&1 == 1 { | |
| return | |
| } | |
| var buf [1]byte | |
| r.Read(buf[:]) | |
| } | |