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The AWS SDK for Java with support for OSGi. The AWS SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).

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/****************************************************************************
 * Amazon Modifications: Copyright 2014 Amazon.com, Inc. or its affiliates. 
 * All Rights Reserved.
 *****************************************************************************
 * Copyright (c) 1998-2010 AOL Inc. 
 * 
 * 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.
 *
 ****************************************************************************/
// http://oauth.googlecode.com/svn/code/branches/jmeter/jmeter/src/main/java/org/apache/jmeter/protocol/oauth/sampler/PrivateKeyReader.java

// http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf
// http://en.wikipedia.org/wiki/Distinguished_Encoding_Rules#DER_encoding
package com.amazonaws.auth;

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.
     */
    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
     */
    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.
     */
    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);
    }
}