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/*
* Copyright (C) 2016 The Android Open Source Project
*
* 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.android.apkzlib.sign;
import com.android.annotations.NonNull;
import java.security.NoSuchAlgorithmException;
/**
* Signature algorithm.
*/
public enum SignatureAlgorithm {
/**
* RSA algorithm.
*/
RSA("RSA", 0, "withRSA"),
/**
* ECDSA algorithm.
*/
ECDSA("EC", 18, "withECDSA"),
/**
* DSA algorithm.
*/
DSA("DSA", 0, "withDSA");
/**
* Name of the private key as reported by {@code PrivateKey}.
*/
@NonNull
public final String keyAlgorithm;
/**
* Minimum SDK version that allows this signature.
*/
public final int minSdkVersion;
/**
* Suffix appended to digest algorithm to obtain signature algorithm.
*/
@NonNull
public final String signatureAlgorithmSuffix;
/**
* Creates a new signature algorithm.
*
* @param keyAlgorithm the name as reported by {@code PrivateKey}
* @param minSdkVersion minimum SDK version that allows this signature
* @param signatureAlgorithmSuffix suffix for signature name with used with a digest
*/
SignatureAlgorithm(
@NonNull String keyAlgorithm, int minSdkVersion, @NonNull String signatureAlgorithmSuffix) {
this.keyAlgorithm = keyAlgorithm;
this.minSdkVersion = minSdkVersion;
this.signatureAlgorithmSuffix = signatureAlgorithmSuffix;
}
/**
* Obtains the signature algorithm that corresponds to a private key name applicable to a
* SDK version.
*
* @param keyAlgorithm the named referred in the {@code PrivateKey}
* @param minSdkVersion minimum SDK version to run
* @return the algorithm that has {@link #keyAlgorithm} equal to {@code keyAlgorithm}
* @throws NoSuchAlgorithmException if no algorithm was found for the given private key; an
* algorithm was found but is not applicable to the given SDK version
*/
@NonNull
public static SignatureAlgorithm fromKeyAlgorithm(@NonNull String keyAlgorithm,
int minSdkVersion) throws NoSuchAlgorithmException {
for (SignatureAlgorithm alg : values()) {
if (alg.keyAlgorithm.equalsIgnoreCase(keyAlgorithm)) {
if (alg.minSdkVersion > minSdkVersion) {
throw new NoSuchAlgorithmException("Signatures with " + keyAlgorithm
+ " keys are not supported on minSdkVersion " + minSdkVersion
+ ". They are supported only for minSdkVersion >= "
+ alg.minSdkVersion);
}
return alg;
}
}
throw new NoSuchAlgorithmException("Signing with " + keyAlgorithm
+ " keys is not supported");
}
/**
* Obtains the name of the signature algorithm when used with a digest algorithm.
*
* @param digestAlgorithm the digest algorithm to use
* @return the name of the signature algorithm
*/
@NonNull
public String signatureAlgorithmName(@NonNull DigestAlgorithm digestAlgorithm) {
return digestAlgorithm.messageDigestName.replace("-", "") + signatureAlgorithmSuffix;
}
}
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