/**
* Decode an ASN.1 BIT STRING.
*
* @param buf the buffer containing the DER-encoded BIT STRING.
* @return the bits in the BIT STRING
*/
public static BitSet decodeBitString(ByteBuffer buf) {
DerId id = DerId.decode(buf);
if (!id.matches(DerId.TagClass.UNIVERSAL, DerId.EncodingType.PRIMITIVE, ASN1_BIT_STRING_TAG_NUM)
&& !id.matches(
DerId.TagClass.UNIVERSAL, DerId.EncodingType.CONSTRUCTED, ASN1_BIT_STRING_TAG_NUM)) {
throw new IllegalArgumentException("Expected BIT STRING identifier, received " + id);
}
int len = DerUtils.decodeLength(buf);
if (buf.remaining() < len) {
throw new IllegalArgumentException("Insufficient content for BIT STRING");
}
// If primitive encoding, then the initial octet is just used for padding
if (id.getEncodingType() == DerId.EncodingType.PRIMITIVE) {
buf.get();
len--;
}
int nbits = len * 8;
BitSet bits = new BitSet(nbits);
for (int i = 0; i < len; i++) {
short next = (short) (0xff & buf.get());
int bitIndex = (i + 1) * 8 - 1;
while (next != 0) {
if ((next & 1) == 1) {
bits.set(bitIndex);
}
bitIndex--;
next >>>= 1;
}
}
return bits;
}
/**
* Decode an ASN.1 SEQUENCE by reading the identifier and length octets. The remaining data in the
* buffer is the SEQUENCE.
*
* @param buf the DER-encoded SEQUENCE
* @return the length of the SEQUENCE
*/
public static int decodeSequence(ByteBuffer buf) {
DerId id = DerId.decode(buf);
if (!id.matches(
DerId.TagClass.UNIVERSAL, DerId.EncodingType.CONSTRUCTED, ASN1_SEQUENCE_TAG_NUM)) {
throw new IllegalArgumentException("Expected SEQUENCE identifier, received " + id);
}
int len = DerUtils.decodeLength(buf);
if (buf.remaining() < len) {
throw new IllegalArgumentException("Insufficient content for SEQUENCE");
}
return len;
}
/**
* Decode an ASN.1 IA5String.
*
* @param buf the DER-encoded IA5String
* @return the string
*/
public static String decodeIA5String(ByteBuffer buf) {
DerId id = DerId.decode(buf);
if (!id.matches(
DerId.TagClass.UNIVERSAL, DerId.EncodingType.PRIMITIVE, ASN1_IA5STRING_TAG_NUM)) {
throw new IllegalArgumentException("Expected IA5String identifier, received " + id);
}
int len = DerUtils.decodeLength(buf);
if (buf.remaining() < len) {
throw new IllegalArgumentException("Insufficient content for IA5String");
}
byte[] dst = new byte[len];
buf.get(dst);
return new String(dst);
}
/**
* Decode an ASN.1 GeneralizedTime.
*
* @param buf the DER-encoded GeneralizedTime
* @return the data and time
*/
public static Date decodeGeneralizedTime(ByteBuffer buf) {
// GeneralizedTime ::= [UNIVERSAL 24] IMPLICIT VisibleString
DerId id = DerId.decode(buf);
if (!id.matches(
DerId.TagClass.UNIVERSAL, DerId.EncodingType.PRIMITIVE, ASN1_GENERALIZED_TIME_TAG_NUM)) {
throw new IllegalArgumentException("Expected GeneralizedTime identifier, received " + id);
}
int len = DerUtils.decodeLength(buf);
if (buf.remaining() < len) {
throw new IllegalArgumentException("Insufficient content for GeneralizedTime");
}
Date date = null;
byte[] dst = new byte[len];
buf.get(dst);
String iso8601DateString = new String(dst);
Matcher matcher = GENERALIZED_TIME_PATTERN.matcher(iso8601DateString);
if (matcher.matches()) {
Calendar cal = Calendar.getInstance();
cal.clear();
// Process yyyyMMddHHmmss
cal.set(Calendar.YEAR, Integer.parseInt(matcher.group(1)));
cal.set(
Calendar.MONTH, Integer.parseInt(matcher.group(2)) - 1); // Calendar.MONTH is zero based
cal.set(Calendar.DAY_OF_MONTH, Integer.parseInt(matcher.group(3)));
cal.set(Calendar.HOUR_OF_DAY, Integer.parseInt(matcher.group(4)));
cal.set(Calendar.MINUTE, Integer.parseInt(matcher.group(5)));
cal.set(Calendar.SECOND, Integer.parseInt(matcher.group(6)));
// Process fractional seconds, if any
String fracSecStr = matcher.group(7);
if (fracSecStr != null) {
cal.set(Calendar.MILLISECOND, (int) (Float.parseFloat(fracSecStr) * 1000));
}
// Process time zone, if any
String tzStr = matcher.group(8);
if (tzStr != null) {
cal.setTimeZone(TimeZone.getTimeZone("Z".equals(tzStr) ? "GMT" : "GMT" + tzStr));
}
date = cal.getTime();
} else {
throw new IllegalArgumentException("Malformed GeneralizedTime " + iso8601DateString);
}
return date;
}
/**
* Decode an ASN.1 OCTET STRING.
*
* @param buf the DER-encoded OCTET STRING
* @return the octets
*/
public static short[] decodeOctetString(ByteBuffer buf) {
DerId id = DerId.decode(buf);
if (!id.matches(DerId.TagClass.UNIVERSAL, ASN1_OCTET_STRING_TAG_NUM)) {
throw new IllegalArgumentException("Expected OCTET STRING identifier, received " + id);
}
int len = DerUtils.decodeLength(buf);
if (buf.remaining() < len) {
throw new IllegalArgumentException("Insufficient content for OCTET STRING");
}
short[] dst = new short[len];
for (int i = 0; i < len; i++) {
dst[i] = (short) (0xff & buf.get());
}
return dst;
}
/**
* Decode an ASN.1 INTEGER.
*
* @param buf the buffer containing the DER-encoded INTEGER
* @return the value of the INTEGER
*/
public static int decodeInteger(ByteBuffer buf) {
DerId id = DerId.decode(buf);
if (!id.matches(DerId.TagClass.UNIVERSAL, DerId.EncodingType.PRIMITIVE, ASN1_INTEGER_TAG_NUM)) {
throw new IllegalArgumentException("Expected INTEGER identifier, received " + id);
}
int len = DerUtils.decodeLength(buf);
if (buf.remaining() < len) {
throw new IllegalArgumentException("Insufficient content for INTEGER");
}
int value = 0;
for (int i = 0; i < len; i++) {
value = (value << 8) + (0xff & buf.get());
}
return value;
}
