net.oauth.signature.pem.Asn1Object Maven / Gradle / Ivy
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/****************************************************************************
* Copyright (c) 1998-2009 AOL 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 net.oauth.signature.pem;
import java.io.IOException;
import java.math.BigInteger;
/**
* An ASN.1 TLV. The object is not parsed. It can
* only handle integers and strings.
*
* @author zhang
*
*/
class Asn1Object {
protected final int type;
protected final int length;
protected final byte[] value;
protected final int tag;
/**
* Construct a ASN.1 TLV. The TLV could be either a
* constructed or primitive entity.
*
* The first byte in DER encoding is made of following fields,
*
*-------------------------------------------------
*|Bit 8|Bit 7|Bit 6|Bit 5|Bit 4|Bit 3|Bit 2|Bit 1|
*-------------------------------------------------
*| Class | CF | + Type |
*-------------------------------------------------
*
*
* - Class: Universal, Application, Context or Private
*
- CF: Constructed flag. If 1, the field is constructed.
*
- Type: This is actually called tag in ASN.1. It
* indicates data type (Integer, String) or a construct
* (sequence, choice, set).
*
*
* @param tag Tag or Identifier
* @param length Length of the field
* @param value Encoded octet string for the field.
*/
public Asn1Object(int tag, int length, byte[] value) {
this.tag = tag;
this.type = tag & 0x1F;
this.length = length;
this.value = value;
}
public int getType() {
return type;
}
public int getLength() {
return length;
}
public byte[] getValue() {
return value;
}
public boolean isConstructed() {
return (tag & DerParser.CONSTRUCTED) == DerParser.CONSTRUCTED;
}
/**
* For constructed field, return a parser for its content.
*
* @return A parser for the construct.
* @throws IOException
*/
public DerParser getParser() throws IOException {
if (!isConstructed())
throw new IOException("Invalid DER: can't parse primitive entity"); //$NON-NLS-1$
return new DerParser(value);
}
/**
* Get the value as integer
*
* @return BigInteger
* @throws IOException
*/
public BigInteger getInteger() throws IOException {
if (type != DerParser.INTEGER)
throw new IOException("Invalid DER: object is not integer"); //$NON-NLS-1$
return new BigInteger(value);
}
/**
* Get value as string. Most strings are treated
* as Latin-1.
*
* @return Java string
* @throws IOException
*/
public String getString() throws IOException {
String encoding;
switch (type) {
// Not all are Latin-1 but it's the closest thing
case DerParser.NUMERIC_STRING:
case DerParser.PRINTABLE_STRING:
case DerParser.VIDEOTEX_STRING:
case DerParser.IA5_STRING:
case DerParser.GRAPHIC_STRING:
case DerParser.ISO646_STRING:
case DerParser.GENERAL_STRING:
encoding = "ISO-8859-1"; //$NON-NLS-1$
break;
case DerParser.BMP_STRING:
encoding = "UTF-16BE"; //$NON-NLS-1$
break;
case DerParser.UTF8_STRING:
encoding = "UTF-8"; //$NON-NLS-1$
break;
case DerParser.UNIVERSAL_STRING:
throw new IOException("Invalid DER: can't handle UCS-4 string"); //$NON-NLS-1$
default:
throw new IOException("Invalid DER: object is not a string"); //$NON-NLS-1$
}
return new String(value, encoding);
}
}