DerElement Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/ssl/pem/PemPrivateKeyParser.java lines 349–442

	static final class DerElement {

		private final ValueType valueType;

		private final long tagType;

		private final ByteBuffer contents;

		private DerElement(ByteBuffer bytes) {
			byte b = bytes.get();
			this.valueType = ((b & 0x20) == 0) ? ValueType.PRIMITIVE : ValueType.ENCODED;
			this.tagType = decodeTagType(b, bytes);
			int length = decodeLength(bytes);
			bytes.limit(bytes.position() + length);
			this.contents = bytes.slice();
			bytes.limit(bytes.capacity());
			bytes.position(bytes.position() + length);
		}

		private long decodeTagType(byte b, ByteBuffer bytes) {
			long tagType = (b & 0x1F);
			if (tagType != 0x1F) {
				return tagType;
			}
			tagType = 0;
			b = bytes.get();
			while ((b & 0x80) != 0) {
				tagType <<= 7;
				tagType = tagType | (b & 0x7F);
				b = bytes.get();
			}
			return tagType;
		}

		private int decodeLength(ByteBuffer bytes) {
			byte b = bytes.get();
			if ((b & 0x80) == 0) {
				return b & 0x7F;
			}
			int numberOfLengthBytes = (b & 0x7F);
			Assert.state(numberOfLengthBytes != 0, "Infinite length encoding is not supported");
			Assert.state(numberOfLengthBytes != 0x7F, "Reserved length encoding is not supported");
			Assert.state(numberOfLengthBytes <= 4, "Length overflow");
			int length = 0;
			for (int i = 0; i < numberOfLengthBytes; i++) {
				length <<= 8;
				length |= (bytes.get() & 0xFF);
			}
			return length;
		}

		boolean isType(ValueType valueType) {
			return this.valueType == valueType;
		}

		boolean isType(ValueType valueType, TagType tagType) {
			return this.valueType == valueType && this.tagType == tagType.getNumber();
		}

		ByteBuffer getContents() {
			return this.contents;
		}

		static @Nullable DerElement of(byte[] bytes) {
			return of(ByteBuffer.wrap(bytes));
		}

		static @Nullable DerElement of(ByteBuffer bytes) {
			return (bytes.remaining() > 0) ? new DerElement(bytes) : null;
		}

		enum ValueType {

			PRIMITIVE, ENCODED

		}

		enum TagType {

			INTEGER(0x02), OCTET_STRING(0x04), OBJECT_IDENTIFIER(0x06), SEQUENCE(0x10);

			private final int number;

			TagType(int number) {
				this.number = number;
			}

			int getNumber() {
				return this.number;
			}

		}

	}