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/*
* Copyright (C) 2017 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 android.net;
import android.annotation.StringDef;
import android.os.Parcel;
import android.os.Parcelable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
/**
* IpSecAlgorithm specifies a single algorithm that can be applied to an IpSec Transform. Refer to
* RFC 4301.
*
* @hide
*/
public final class IpSecAlgorithm implements Parcelable {
/**
* AES-CBC Encryption/Ciphering Algorithm.
*
* <p>Valid lengths for this key are {128, 192, 256}.
*/
public static final String CRYPT_AES_CBC = "cbc(aes)";
/**
* MD5 HMAC Authentication/Integrity Algorithm. This algorithm is not recommended for use in new
* applications and is provided for legacy compatibility with 3gpp infrastructure.
*
* <p>Valid truncation lengths are multiples of 8 bits from 96 to (default) 128.
*/
public static final String AUTH_HMAC_MD5 = "hmac(md5)";
/**
* SHA1 HMAC Authentication/Integrity Algorithm. This algorithm is not recommended for use in
* new applications and is provided for legacy compatibility with 3gpp infrastructure.
*
* <p>Valid truncation lengths are multiples of 8 bits from 96 to (default) 160.
*/
public static final String AUTH_HMAC_SHA1 = "hmac(sha1)";
/**
* SHA256 HMAC Authentication/Integrity Algorithm.
*
* <p>Valid truncation lengths are multiples of 8 bits from 96 to (default) 256.
*/
public static final String AUTH_HMAC_SHA256 = "hmac(sha256)";
/**
* SHA384 HMAC Authentication/Integrity Algorithm.
*
* <p>Valid truncation lengths are multiples of 8 bits from 192 to (default) 384.
*/
public static final String AUTH_HMAC_SHA384 = "hmac(sha384)";
/**
* SHA512 HMAC Authentication/Integrity Algorithm
*
* <p>Valid truncation lengths are multiples of 8 bits from 256 to (default) 512.
*/
public static final String AUTH_HMAC_SHA512 = "hmac(sha512)";
/** @hide */
@StringDef({
CRYPT_AES_CBC,
AUTH_HMAC_MD5,
AUTH_HMAC_SHA1,
AUTH_HMAC_SHA256,
AUTH_HMAC_SHA512
})
@Retention(RetentionPolicy.SOURCE)
public @interface AlgorithmName {}
private final String mName;
private final byte[] mKey;
private final int mTruncLenBits;
/**
* Specify a IpSecAlgorithm of one of the supported types including the truncation length of the
* algorithm
*
* @param algorithm type for IpSec.
* @param key non-null Key padded to a multiple of 8 bits.
*/
public IpSecAlgorithm(String algorithm, byte[] key) {
this(algorithm, key, key.length * 8);
}
/**
* Specify a IpSecAlgorithm of one of the supported types including the truncation length of the
* algorithm
*
* @param algoName precise name of the algorithm to be used.
* @param key non-null Key padded to a multiple of 8 bits.
* @param truncLenBits the number of bits of output hash to use; only meaningful for
* Authentication.
*/
public IpSecAlgorithm(@AlgorithmName String algoName, byte[] key, int truncLenBits) {
if (!isTruncationLengthValid(algoName, truncLenBits)) {
throw new IllegalArgumentException("Unknown algorithm or invalid length");
}
mName = algoName;
mKey = key.clone();
mTruncLenBits = Math.min(truncLenBits, key.length * 8);
}
/** Retrieve the algorithm name */
public String getName() {
return mName;
}
/** Retrieve the key for this algorithm */
public byte[] getKey() {
return mKey.clone();
}
/**
* Retrieve the truncation length, in bits, for the key in this algo. By default this will be
* the length in bits of the key.
*/
public int getTruncationLengthBits() {
return mTruncLenBits;
}
/* Parcelable Implementation */
public int describeContents() {
return 0;
}
/** Write to parcel */
public void writeToParcel(Parcel out, int flags) {
out.writeString(mName);
out.writeByteArray(mKey);
out.writeInt(mTruncLenBits);
}
/** Parcelable Creator */
public static final Parcelable.Creator<IpSecAlgorithm> CREATOR =
new Parcelable.Creator<IpSecAlgorithm>() {
public IpSecAlgorithm createFromParcel(Parcel in) {
return new IpSecAlgorithm(in);
}
public IpSecAlgorithm[] newArray(int size) {
return new IpSecAlgorithm[size];
}
};
private IpSecAlgorithm(Parcel in) {
mName = in.readString();
mKey = in.createByteArray();
mTruncLenBits = in.readInt();
}
private static boolean isTruncationLengthValid(String algo, int truncLenBits) {
switch (algo) {
case CRYPT_AES_CBC:
return (truncLenBits == 128 || truncLenBits == 192 || truncLenBits == 256);
case AUTH_HMAC_MD5:
return (truncLenBits >= 96 && truncLenBits <= 128);
case AUTH_HMAC_SHA1:
return (truncLenBits >= 96 && truncLenBits <= 160);
case AUTH_HMAC_SHA256:
return (truncLenBits >= 96 && truncLenBits <= 256);
case AUTH_HMAC_SHA384:
return (truncLenBits >= 192 && truncLenBits <= 384);
case AUTH_HMAC_SHA512:
return (truncLenBits >= 256 && truncLenBits <= 512);
default:
return false;
}
}
};
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