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SecureEq.scala
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SecureEq.scala
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/*
* Copyright 2021 Typelevel
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Copyright (c) 2000-2021 The Legion of the Bouncy Castle Inc. (https://www.bouncycastle.org)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software
* and associated documentation files (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or substantial
* portions of the Software.
*/
package bobcats
import cats.kernel.Eq
import scodec.bits.ByteVector
trait SecureEq[A] extends Eq[A] {
/**
* A constant time equals comparison - does not terminate early if test will fail. For best
* results always pass the expected value as the first parameter.
*/
override def eqv(expected: A, supplied: A): Boolean
}
object SecureEq extends SecureEqCompanionPlatform {
def apply[A](implicit eq: SecureEq[A]): eq.type = eq
private[bobcats] final class ByteVectorSecureEq extends SecureEq[ByteVector] {
override def eqv(expected: ByteVector, supplied: ByteVector): Boolean =
(expected eq supplied) || {
val expectedLen = expected.size
val suppliedLen = supplied.size
val len = Math.min(expectedLen, suppliedLen)
var nonEqual = expected.length ^ supplied.length;
var i = 0L
while (i != len) {
nonEqual |= (expected(i) ^ supplied(i))
i += 1
}
i = len
while (i < suppliedLen) {
nonEqual |= (supplied(i) ^ ~supplied(i))
i += 1
}
nonEqual == 0
}
}
}