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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8.
package org.bouncycastle.asn1;
import java.io.IOException;
import java.util.Enumeration;
import java.util.NoSuchElementException;
/**
* ASN.1 OctetStrings, with indefinite length rules, and constructed form support.
*
* The Basic Encoding Rules (BER) format allows encoding using so called "constructed form",
* which DER and CER formats forbid allowing only "primitive form".
*
* This class always produces the constructed form with underlying segments
* in an indefinite length array. If the input wasn't the same, then this output
* is not faithful reproduction.
*
*
* See {@link ASN1OctetString} for X.690 encoding rules of OCTET-STRING objects.
*
*/
public class BEROctetString
extends ASN1OctetString
{
private static final int DEFAULT_SEGMENT_LIMIT = 1000;
private final int segmentLimit;
private final ASN1OctetString[] elements;
/**
* Convert a vector of octet strings into a single byte string
*/
static byte[] flattenOctetStrings(ASN1OctetString[] octetStrings)
{
int count = octetStrings.length;
switch (count)
{
case 0:
return EMPTY_OCTETS;
case 1:
return octetStrings[0].string;
default:
{
int totalOctets = 0;
for (int i = 0; i < count; ++i)
{
totalOctets += octetStrings[i].string.length;
}
byte[] string = new byte[totalOctets];
for (int i = 0, pos = 0; i < count; ++i)
{
byte[] octets = octetStrings[i].string;
System.arraycopy(octets, 0, string, pos, octets.length);
pos += octets.length;
}
// assert pos == totalOctets;
return string;
}
}
}
/**
* Create an OCTET-STRING object from a byte[]
* @param string the octets making up the octet string.
*/
public BEROctetString(byte[] string)
{
this(string, DEFAULT_SEGMENT_LIMIT);
}
/**
* Multiple {@link ASN1OctetString} data blocks are input,
* the result is constructed form.
*
* @param elements an array of OCTET STRING to construct the BER OCTET STRING from.
*/
public BEROctetString(ASN1OctetString[] elements)
{
this(elements, DEFAULT_SEGMENT_LIMIT);
}
/**
* Create an OCTET-STRING object from a byte[]
* @param string the octets making up the octet string.
* @param segmentLimit the number of octets stored in each DER encoded component OCTET STRING.
*/
public BEROctetString(byte[] string, int segmentLimit)
{
this(string, new ASN1OctetString[] { new DEROctetString(string) }, segmentLimit);
}
/**
* Multiple {@link ASN1OctetString} data blocks are input,
* the result is constructed form.
*
* @param elements an array of OCTET STRING to construct the BER OCTET STRING from.
* @param segmentLimit the number of octets stored in each DER encoded component OCTET STRING.
*/
public BEROctetString(ASN1OctetString[] elements, int segmentLimit)
{
this(flattenOctetStrings(elements), elements, segmentLimit);
}
private BEROctetString(byte[] string, ASN1OctetString[] elements, int segmentLimit)
{
super(string);
this.elements = elements;
this.segmentLimit = segmentLimit;
}
/**
* Return the OCTET STRINGs that make up this string.
*
* @return an Enumeration of the component OCTET STRINGs.
*
* @deprecated Will be removed.
*/
public Enumeration getObjects()
{
if (elements == null)
{
return new Enumeration()
{
int pos = 0;
public boolean hasMoreElements()
{
return pos < string.length;
}
public Object nextElement()
{
if (pos < string.length)
{
int length = Math.min(string.length - pos, segmentLimit);
byte[] segment = new byte[length];
System.arraycopy(string, pos, segment, 0, length);
pos += length;
return new DEROctetString(segment);
}
throw new NoSuchElementException();
}
};
}
return new Enumeration()
{
int counter = 0;
public boolean hasMoreElements()
{
return counter < elements.length;
}
public Object nextElement()
{
if (counter < elements.length)
{
return elements[counter++];
}
throw new NoSuchElementException();
}
};
}
boolean encodeConstructed()
{
return null != elements || string.length > segmentLimit;
}
int encodedLength(boolean withTag)
throws IOException
{
if (!encodeConstructed())
{
return DEROctetString.encodedLength(withTag, string.length);
}
int totalLength = withTag ? 4 : 3;
if (null != elements)
{
for (int i = 0; i < elements.length; ++i)
{
totalLength += elements[i].encodedLength(true);
}
}
else
{
int fullSegments = string.length / segmentLimit;
totalLength += fullSegments * DEROctetString.encodedLength(true, segmentLimit);
int lastSegmentLength = string.length - (fullSegments * segmentLimit);
if (lastSegmentLength > 0)
{
totalLength += DEROctetString.encodedLength(true, lastSegmentLength);
}
}
return totalLength;
}
void encode(ASN1OutputStream out, boolean withTag) throws IOException
{
if (!encodeConstructed())
{
DEROctetString.encode(out, withTag, string, 0, string.length);
return;
}
out.writeIdentifier(withTag, BERTags.CONSTRUCTED | BERTags.OCTET_STRING);
out.write(0x80);
if (null != elements)
{
out.writePrimitives(elements);
}
else
{
int pos = 0;
while (pos < string.length)
{
int segmentLength = Math.min(string.length - pos, segmentLimit);
DEROctetString.encode(out, true, string, pos, segmentLength);
pos += segmentLength;
}
}
out.write(0x00);
out.write(0x00);
}
}