1 // Copyright 2022 Google LLC 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 //////////////////////////////////////////////////////////////////////////////// 16 17 package com.google.crypto.tink.signature; 18 19 import com.google.crypto.tink.Key; 20 import com.google.crypto.tink.PrivateKey; 21 import com.google.crypto.tink.annotations.Alpha; 22 import com.google.crypto.tink.util.Bytes; 23 import com.google.errorprone.annotations.Immutable; 24 import javax.annotation.Nullable; 25 26 /** 27 * A {@link SignaturePrivateKey} represents a digital signature primitive, which consists of a sign 28 * and a verify function. 29 * 30 * <p>The verify function is only available indirectly, with {@link #getPublicKey}. 31 */ 32 @Immutable 33 @Alpha 34 public abstract class SignaturePrivateKey extends Key implements PrivateKey { 35 /** 36 * Returns the {@link SignaturePublicKey}, which contains the verify function of the digital 37 * signature primitive. 38 */ 39 @Override getPublicKey()40 public abstract SignaturePublicKey getPublicKey(); 41 42 /** 43 * Returns a {@link Bytes} instance which is prefixed to every signature. 44 * 45 * <p>Returns the same as {@code getPublicKey().getOutputPrefix()}. 46 */ getOutputPrefix()47 public final Bytes getOutputPrefix() { 48 return getPublicKey().getOutputPrefix(); 49 } 50 51 @Override 52 @Nullable getIdRequirementOrNull()53 public Integer getIdRequirementOrNull() { 54 return getPublicKey().getIdRequirementOrNull(); 55 } 56 57 /** 58 * Returns the parameters of this key. 59 * 60 * <p>Returns the same as {@code getPublicKey().getParameters()}. 61 */ 62 @Override getParameters()63 public SignatureParameters getParameters() { 64 return getPublicKey().getParameters(); 65 } 66 } 67