1 // Copyright 2021 Code Intelligence GmbH
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 //      http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 package com.code_intelligence.jazzer.instrumentor
16 
17 import java.security.MessageDigest
18 import java.security.SecureRandom
19 
20 // This RNG is resistant to collisions (even under XOR) but fully deterministic.
21 internal class DeterministicRandom(vararg contexts: String) {
<lambda>null22     private val random = SecureRandom.getInstance("SHA1PRNG").apply {
23         val contextHash = MessageDigest.getInstance("SHA-256").run {
24             for (context in contexts) {
25                 update(context.toByteArray())
26             }
27             digest()
28         }
29         setSeed(contextHash)
30     }
31 
nextIntnull32     fun nextInt(bound: Int) = random.nextInt(bound)
33 
34     fun nextInt() = random.nextInt()
35 }
36