/**
* Encode an ASN.1 BIT STRING.
*
* @param value the value to be encoded
* @param nbits the number of bits in the bit string
* @param buf the buffer with space to the left of current position where the value will be
* encoded
* @return the length of the encoded data
*/
public static int encodeBitString(BitSet value, int nbits, ByteBuffer buf) {
if (value == null || nbits < value.length()) {
throw new IllegalArgumentException();
}
int pos = buf.position();
int contentLength = (int) Math.ceil(nbits / 8.0d);
for (int i = contentLength; i > 0; i--) {
byte octet = 0;
for (int j = (i - 1) * 8; j < i * 8; j++) {
if (value.get(j)) {
octet |= BIT_STRING_MASK[j % 8];
}
}
pos--;
buf.put(pos, octet);
}
// Write out padding byte (primitive encoding)
pos--;
buf.put(pos, (byte) 0);
contentLength++;
buf.position(buf.position() - contentLength);
int headerLength =
DerUtils.encodeIdAndLength(
DerId.TagClass.UNIVERSAL,
DerId.EncodingType.PRIMITIVE,
ASN1_BIT_STRING_TAG_NUM,
contentLength,
buf);
return headerLength + contentLength;
}
/**
* Encode an ASN.1 SEQUENCE.
*
* @param contentLength the length of the SEQUENCE
* @param buf the buffer with space to the left of current position where the value will be
* encoded
* @return the length of the encoded data
*/
public static int encodeSequence(int contentLength, ByteBuffer buf) {
int headerLength =
DerUtils.encodeIdAndLength(
DerId.TagClass.UNIVERSAL,
DerId.EncodingType.CONSTRUCTED,
ASN1_SEQUENCE_TAG_NUM,
contentLength,
buf);
return headerLength + contentLength;
}
/**
* Encode an ASN.1 IA5String.
*
* @param value the value to be encoded
* @param buf the buffer with space to the left of current position where the value will be
* encoded
* @return the length of the encoded data
*/
public static int encodeIA5String(String value, ByteBuffer buf) {
int pos = buf.position();
byte[] data = (value == null) ? new byte[0] : value.getBytes();
for (int i = data.length - 1; i >= 0; i--) {
pos--;
buf.put(pos, data[i]);
}
buf.position(buf.position() - data.length);
int headerLength =
DerUtils.encodeIdAndLength(
DerId.TagClass.UNIVERSAL,
DerId.EncodingType.PRIMITIVE,
ASN1_IA5STRING_TAG_NUM,
data.length,
buf);
return headerLength + data.length;
}
/**
* Encode an ASN.1 OCTET STRING.
*
* @param octets the octets
* @param buf the buffer with space to the left of current position where the value will be
* encoded
* @return the length of the encoded data
*/
public static int encodeOctetString(short[] octets, ByteBuffer buf) {
if (octets == null) {
octets = new short[0];
}
int pos = buf.position();
for (int i = octets.length - 1; i >= 0; i--) {
pos--;
buf.put(pos, (byte) octets[i]);
}
buf.position(buf.position() - octets.length);
int headerLength =
DerUtils.encodeIdAndLength(
DerId.TagClass.UNIVERSAL,
DerId.EncodingType.PRIMITIVE,
ASN1_OCTET_STRING_TAG_NUM,
octets.length,
buf);
return headerLength + octets.length;
}
/**
* Encode an ASN.1 INTEGER.
*
* @param value the value to be encoded
* @param buf the buffer with space to the left of current position where the value will be
* encoded
* @return the length of the encoded data
*/
public static int encodeInteger(int value, ByteBuffer buf) {
int pos = buf.position();
int contentLength = 0;
do {
pos--;
buf.put(pos, (byte) (value & 0xff));
value >>>= 8;
contentLength++;
} while (value != 0);
buf.position(buf.position() - contentLength);
int headerLen =
DerUtils.encodeIdAndLength(
DerId.TagClass.UNIVERSAL,
DerId.EncodingType.PRIMITIVE,
ASN1_INTEGER_TAG_NUM,
contentLength,
buf);
return headerLen + contentLength;
}
/**
* Encode an ASN.1 GeneralizedTime.
*
* @param date the date value
* @param buf the buffer with space to the left of current position where the value will be
* encoded
* @return the length of the encoded data
*/
public static int encodeGeneralizedTime(Date date, ByteBuffer buf) {
if (date == null) {
throw new IllegalArgumentException();
}
int pos = buf.position();
SimpleDateFormat format = new SimpleDateFormat(GENERALIZED_TIME_FORMAT);
format.setTimeZone(TimeZone.getTimeZone("GMT")); // always use UTC
String value = format.format(date);
byte[] data = value.getBytes();
for (int i = data.length - 1; i >= 0; i--) {
pos--;
buf.put(pos, data[i]);
}
buf.position(buf.position() - data.length);
int headerLength =
DerUtils.encodeIdAndLength(
DerId.TagClass.UNIVERSAL,
DerId.EncodingType.PRIMITIVE,
ASN1_GENERALIZED_TIME_TAG_NUM,
data.length,
buf);
return headerLength + data.length;
}
