com.google.crypto.tink.util.SecretBigInteger Maven / Gradle / Ivy
// Copyright 2022 Google LLC
//
// 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.
//
////////////////////////////////////////////////////////////////////////////////
package com.google.crypto.tink.util;
import com.google.crypto.tink.SecretKeyAccess;
import com.google.errorprone.annotations.Immutable;
import java.math.BigInteger;
import java.security.MessageDigest;
/** A class storing a secret BigInteger, protecting the value via {@link SecretKeyAccess}. */
@Immutable
public final class SecretBigInteger {
private final BigInteger value;
private SecretBigInteger(BigInteger value) {
this.value = value;
}
/**
* Creates a new SecretBigInteger with the content given in {@code value}.
*
* The parameter {@code access} must be non-null.
*/
public static SecretBigInteger fromBigInteger(BigInteger value, SecretKeyAccess access) {
if (access == null) {
throw new NullPointerException("SecretKeyAccess required");
}
// Since BigInteger is immutable, there is no need to make a copy.
return new SecretBigInteger(value);
}
/**
* Returns the value wrapped by this object.
*
*
The parameter {@code access} must be non-null.
*/
public BigInteger getBigInteger(SecretKeyAccess access) {
if (access == null) {
throw new NullPointerException("SecretKeyAccess required");
}
return value;
}
/**
* Returns true if {@code other} has the same secret value.
*
*
Note that the time may depend on the length of the byte-encoding of the BigIntegers.
*/
public boolean equalsSecretBigInteger(SecretBigInteger other) {
// BigInteger.toByteArray always return the minimal encoding, so it is not possible that two
// BigInteger of the same values return different encodings.
byte[] myArray = value.toByteArray();
byte[] otherArray = other.value.toByteArray();
return MessageDigest.isEqual(myArray, otherArray);
}
}