/*
* 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 com.android.apksig.internal.asn1.ber;
import com.android.apksig.internal.asn1.Asn1Type;
import com.android.apksig.internal.asn1.Asn1TagClass;
/**
* ASN.1 Basic Encoding Rules (BER) constants and helper methods. See {@code X.690}.
*/
public abstract class BerEncoding {
private BerEncoding() {}
/**
* Constructed vs primitive flag in the first identifier byte.
*/
public static final int ID_FLAG_CONSTRUCTED_ENCODING = 1 << 5;
/**
* Tag class: UNIVERSAL
*/
public static final int TAG_CLASS_UNIVERSAL = 0;
/**
* Tag class: APPLICATION
*/
public static final int TAG_CLASS_APPLICATION = 1;
/**
* Tag class: CONTEXT SPECIFIC
*/
public static final int TAG_CLASS_CONTEXT_SPECIFIC = 2;
/**
* Tag class: PRIVATE
*/
public static final int TAG_CLASS_PRIVATE = 3;
/**
* Tag number: BOOLEAN
*/
public static final int TAG_NUMBER_BOOLEAN = 0x1;
/**
* Tag number: INTEGER
*/
public static final int TAG_NUMBER_INTEGER = 0x2;
/**
* Tag number: BIT STRING
*/
public static final int TAG_NUMBER_BIT_STRING = 0x3;
/**
* Tag number: OCTET STRING
*/
public static final int TAG_NUMBER_OCTET_STRING = 0x4;
/**
* Tag number: NULL
*/
public static final int TAG_NUMBER_NULL = 0x05;
/**
* Tag number: OBJECT IDENTIFIER
*/
public static final int TAG_NUMBER_OBJECT_IDENTIFIER = 0x6;
/**
* Tag number: SEQUENCE
*/
public static final int TAG_NUMBER_SEQUENCE = 0x10;
/**
* Tag number: SET
*/
public static final int TAG_NUMBER_SET = 0x11;
/**
* Tag number: UTC_TIME
*/
public final static int TAG_NUMBER_UTC_TIME = 0x17;
/**
* Tag number: GENERALIZED_TIME
*/
public final static int TAG_NUMBER_GENERALIZED_TIME = 0x18;
public static int getTagNumber(Asn1Type dataType) {
switch (dataType) {
case INTEGER:
return TAG_NUMBER_INTEGER;
case OBJECT_IDENTIFIER:
return TAG_NUMBER_OBJECT_IDENTIFIER;
case OCTET_STRING:
return TAG_NUMBER_OCTET_STRING;
case BIT_STRING:
return TAG_NUMBER_BIT_STRING;
case SET_OF:
return TAG_NUMBER_SET;
case SEQUENCE:
case SEQUENCE_OF:
return TAG_NUMBER_SEQUENCE;
case UTC_TIME:
return TAG_NUMBER_UTC_TIME;
case GENERALIZED_TIME:
return TAG_NUMBER_GENERALIZED_TIME;
case BOOLEAN:
return TAG_NUMBER_BOOLEAN;
default:
throw new IllegalArgumentException("Unsupported data type: " + dataType);
}
}
public static int getTagClass(Asn1TagClass tagClass) {
switch (tagClass) {
case APPLICATION:
return TAG_CLASS_APPLICATION;
case CONTEXT_SPECIFIC:
return TAG_CLASS_CONTEXT_SPECIFIC;
case PRIVATE:
return TAG_CLASS_PRIVATE;
case UNIVERSAL:
return TAG_CLASS_UNIVERSAL;
default:
throw new IllegalArgumentException("Unsupported tag class: " + tagClass);
}
}
public static String tagClassToString(int typeClass) {
switch (typeClass) {
case TAG_CLASS_APPLICATION:
return "APPLICATION";
case TAG_CLASS_CONTEXT_SPECIFIC:
return "";
case TAG_CLASS_PRIVATE:
return "PRIVATE";
case TAG_CLASS_UNIVERSAL:
return "UNIVERSAL";
default:
throw new IllegalArgumentException("Unsupported type class: " + typeClass);
}
}
public static String tagClassAndNumberToString(int tagClass, int tagNumber) {
String classString = tagClassToString(tagClass);
String numberString = tagNumberToString(tagNumber);
return classString.isEmpty() ? numberString : classString + " " + numberString;
}
public static String tagNumberToString(int tagNumber) {
switch (tagNumber) {
case TAG_NUMBER_INTEGER:
return "INTEGER";
case TAG_NUMBER_OCTET_STRING:
return "OCTET STRING";
case TAG_NUMBER_BIT_STRING:
return "BIT STRING";
case TAG_NUMBER_NULL:
return "NULL";
case TAG_NUMBER_OBJECT_IDENTIFIER:
return "OBJECT IDENTIFIER";
case TAG_NUMBER_SEQUENCE:
return "SEQUENCE";
case TAG_NUMBER_SET:
return "SET";
case TAG_NUMBER_BOOLEAN:
return "BOOLEAN";
case TAG_NUMBER_GENERALIZED_TIME:
return "GENERALIZED TIME";
case TAG_NUMBER_UTC_TIME:
return "UTC TIME";
default:
return "0x" + Integer.toHexString(tagNumber);
}
}
/**
* Returns {@code true} if the provided first identifier byte indicates that the data value uses
* constructed encoding for its contents, or {@code false} if the data value uses primitive
* encoding for its contents.
*/
public static boolean isConstructed(byte firstIdentifierByte) {
return (firstIdentifierByte & ID_FLAG_CONSTRUCTED_ENCODING) != 0;
}
/**
* Returns the tag class encoded in the provided first identifier byte. See {@code TAG_CLASS}
* constants.
*/
public static int getTagClass(byte firstIdentifierByte) {
return (firstIdentifierByte & 0xff) >> 6;
}
public static byte setTagClass(byte firstIdentifierByte, int tagClass) {
return (byte) ((firstIdentifierByte & 0x3f) | (tagClass << 6));
}
/**
* Returns the tag number encoded in the provided first identifier byte. See {@code TAG_NUMBER}
* constants.
*/
public static int getTagNumber(byte firstIdentifierByte) {
return firstIdentifierByte & 0x1f;
}
public static byte setTagNumber(byte firstIdentifierByte, int tagNumber) {
return (byte) ((firstIdentifierByte & ~0x1f) | tagNumber);
}
}
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