com.google.crypto.tink.mac.HmacParameters 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.mac;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.Immutable;
import java.security.GeneralSecurityException;
import java.security.InvalidAlgorithmParameterException;
import java.util.Objects;
import javax.annotation.Nullable;
/** Describes the parameters of an {@link HmacKey}. */
public final class HmacParameters extends MacParameters {
/**
* Describes details of the mac computation.
*
* The standard HMAC key is used for variant "NO_PREFIX". Other variants slightly change how
* the mac is computed, or add a prefix to every computation depending on the key id.
*/
@Immutable
public static final class Variant {
public static final Variant TINK = new Variant("TINK");
public static final Variant CRUNCHY = new Variant("CRUNCHY");
public static final Variant LEGACY = new Variant("LEGACY");
public static final Variant NO_PREFIX = new Variant("NO_PREFIX");
private final String name;
private Variant(String name) {
this.name = name;
}
@Override
public String toString() {
return name;
}
}
/** The Hash algorithm used. */
@Immutable
public static final class HashType {
public static final HashType SHA1 = new HashType("SHA1");
public static final HashType SHA224 = new HashType("SHA224");
public static final HashType SHA256 = new HashType("SHA256");
public static final HashType SHA384 = new HashType("SHA384");
public static final HashType SHA512 = new HashType("SHA512");
private final String name;
private HashType(String name) {
this.name = name;
}
@Override
public String toString() {
return name;
}
}
/** Builds a new HmacParameters instance. */
public static final class Builder {
@Nullable private Integer keySizeBytes = null;
@Nullable private Integer tagSizeBytes = null;
private HashType hashType = null;
private Variant variant = Variant.NO_PREFIX;
private Builder() {}
@CanIgnoreReturnValue
public Builder setKeySizeBytes(int keySizeBytes) throws GeneralSecurityException {
this.keySizeBytes = keySizeBytes;
return this;
}
@CanIgnoreReturnValue
public Builder setTagSizeBytes(int tagSizeBytes) throws GeneralSecurityException {
this.tagSizeBytes = tagSizeBytes;
return this;
}
@CanIgnoreReturnValue
public Builder setVariant(Variant variant) {
this.variant = variant;
return this;
}
@CanIgnoreReturnValue
public Builder setHashType(HashType hashType) {
this.hashType = hashType;
return this;
}
private static void validateTagSizeBytes(int tagSizeBytes, HashType hashType)
throws GeneralSecurityException {
if (tagSizeBytes < 10) {
throw new GeneralSecurityException(
String.format("Invalid tag size in bytes %d; must be at least 10 bytes", tagSizeBytes));
}
if (hashType == HashType.SHA1) {
if (tagSizeBytes > 20) {
throw new GeneralSecurityException(
String.format(
"Invalid tag size in bytes %d; can be at most 20 bytes for SHA1", tagSizeBytes));
}
return;
}
if (hashType == HashType.SHA224) {
if (tagSizeBytes > 28) {
throw new GeneralSecurityException(
String.format(
"Invalid tag size in bytes %d; can be at most 28 bytes for SHA224",
tagSizeBytes));
}
return;
}
if (hashType == HashType.SHA256) {
if (tagSizeBytes > 32) {
throw new GeneralSecurityException(
String.format(
"Invalid tag size in bytes %d; can be at most 32 bytes for SHA256",
tagSizeBytes));
}
return;
}
if (hashType == HashType.SHA384) {
if (tagSizeBytes > 48) {
throw new GeneralSecurityException(
String.format(
"Invalid tag size in bytes %d; can be at most 48 bytes for SHA384",
tagSizeBytes));
}
return;
}
if (hashType == HashType.SHA512) {
if (tagSizeBytes > 64) {
throw new GeneralSecurityException(
String.format(
"Invalid tag size in bytes %d; can be at most 64 bytes for SHA512",
tagSizeBytes));
}
return;
}
throw new GeneralSecurityException("unknown hash type; must be SHA256, SHA384 or SHA512");
}
public HmacParameters build() throws GeneralSecurityException {
if (keySizeBytes == null) {
throw new GeneralSecurityException("key size is not set");
}
if (tagSizeBytes == null) {
throw new GeneralSecurityException("tag size is not set");
}
if (hashType == null) {
throw new GeneralSecurityException("hash type is not set");
}
if (variant == null) {
throw new GeneralSecurityException("variant is not set");
}
if (keySizeBytes < 16) {
throw new InvalidAlgorithmParameterException(
String.format("Invalid key size in bytes %d; must be at least 16 bytes", keySizeBytes));
}
validateTagSizeBytes(tagSizeBytes, hashType);
return new HmacParameters(keySizeBytes, tagSizeBytes, variant, hashType);
}
}
private final int keySizeBytes;
private final int tagSizeBytes;
private final Variant variant;
private final HashType hashType;
private HmacParameters(int keySizeBytes, int tagSizeBytes, Variant variant, HashType hashType) {
this.keySizeBytes = keySizeBytes;
this.tagSizeBytes = tagSizeBytes;
this.variant = variant;
this.hashType = hashType;
}
public static Builder builder() {
return new Builder();
}
public int getKeySizeBytes() {
return keySizeBytes;
}
/**
* Returns the size of the tag which is computed cryptographically from the message.
*
*
This may differ from the total size of the tag, as for some keys, Tink prefixes the tag with
* a key dependent output prefix.
*/
public int getCryptographicTagSizeBytes() {
return tagSizeBytes;
}
/**
* Returns the size of the security relevant tag plus the size of the prefix with which this key
* prefixes every tag.
*/
public int getTotalTagSizeBytes() {
if (variant == Variant.NO_PREFIX) {
return getCryptographicTagSizeBytes();
}
if (variant == Variant.TINK) {
return getCryptographicTagSizeBytes() + 5;
}
if (variant == Variant.CRUNCHY) {
return getCryptographicTagSizeBytes() + 5;
}
if (variant == Variant.LEGACY) {
return getCryptographicTagSizeBytes() + 5;
}
throw new IllegalStateException("Unknown variant");
}
/** Returns a variant object. */
public Variant getVariant() {
return variant;
}
/** Returns a hash type object. */
public HashType getHashType() {
return hashType;
}
@Override
public boolean equals(Object o) {
if (!(o instanceof HmacParameters)) {
return false;
}
HmacParameters that = (HmacParameters) o;
return that.getKeySizeBytes() == getKeySizeBytes()
&& that.getTotalTagSizeBytes() == getTotalTagSizeBytes()
&& that.getVariant() == getVariant()
&& that.getHashType() == getHashType();
}
@Override
public int hashCode() {
return Objects.hash(HmacParameters.class, keySizeBytes, tagSizeBytes, variant, hashType);
}
@Override
public boolean hasIdRequirement() {
return variant != Variant.NO_PREFIX;
}
@Override
public String toString() {
return "HMAC Parameters (variant: "
+ variant
+ ", hashType: "
+ hashType
+ ", "
+ tagSizeBytes
+ "-byte tags, and "
+ keySizeBytes
+ "-byte key)";
}
}