Der (NetPhantom® 8.0 Java API Specification)

java.lang.Object
- co.mindus.certs.Der

```
public final class Der
extends Object
```
Minimal DER (Distinguished Encoding Rules) writer, sufficient to construct an X.509 v3 certificate by hand.
Why hand-written: NetPhantom is Java 8 and dependency-free by policy. The JDK has no public API for BUILDING certificates - only for parsing them - and the internal sun.security.x509 classes are absent from the compile-time API of the JDK 17 and JDK 21 cross-compilation passes, so using them would break the three-pass build. Encoding DER directly needs only java.security for the cryptography, and the JDK's own CertificateFactory then parses and verifies the result, which keeps the encoder honest: everything produced here is round-tripped through an independent implementation in the test harness.
Only the universal types an X.509 certificate needs are provided: SEQUENCE, SET, INTEGER, BOOLEAN, OBJECT IDENTIFIER, UTF8String, IA5String, PrintableString, BIT STRING, OCTET STRING, UTCTime, GeneralizedTime and context-specific tagging. All methods are static and thread-safe; instances are the growing byte buffers themselves.
Author:
Christopher Mindus

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`BIT_STRING` Universal tag: BIT STRING.
`static int`	`BOOLEAN` Universal tag: BOOLEAN.
`static int`	`GENERALIZED_TIME` Universal tag: GeneralizedTime.
`static int`	`IA5_STRING` Universal tag: IA5String.
`static int`	`INTEGER` Universal tag: INTEGER.
`static int`	`OCTET_STRING` Universal tag: OCTET STRING.
`static int`	`OID` Universal tag: OBJECT IDENTIFIER.
`static int`	`PRINTABLE_STRING` Universal tag: PrintableString.
`static int`	`SEQUENCE` Universal tag: SEQUENCE (constructed).
`static int`	`SET` Universal tag: SET (constructed).
`static int`	`UTC_TIME` Universal tag: UTCTime.
`static int`	`UTF8_STRING` Universal tag: UTF8String.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static byte[]`	`bitString(byte[] bits)` Encodes a BIT STRING with zero unused bits, which is what signatures and public keys use.
`static byte[]`	`bool(boolean value)` Encodes a BOOLEAN.
`static byte[]`	`constructed(int tag, byte[]... parts)` Encodes a constructed value (SEQUENCE, SET, or an explicit context tag) from parts.
`static byte[]`	`contextExplicit(int n, byte[] inner)` Encodes an EXPLICIT context-specific tag [n], wrapping one inner encoding.
`static byte[]`	`contextImplicit(int n, byte[] content)` Encodes an IMPLICIT context-specific PRIMITIVE tag [n] over raw content bytes.
`static byte[]`	`ia5(String s)` Encodes an IA5String (ASCII).
`static byte[]`	`integer(BigInteger value)` Encodes an INTEGER from a BigInteger.
`static byte[]`	`integer(int value)` Encodes a small non-negative INTEGER.
`static byte[]`	`namedBits(int bitsHighFirst, int bitCount)` Encodes a BIT STRING for X.509 KeyUsage: named bits, DER minimal-length rules applied (trailing zero bits stripped, unused-bit count set accordingly).
`static byte[]`	`octetString(byte[] value)` Encodes an OCTET STRING.
`static byte[]`	`oid(String dotted)` Encodes an OBJECT IDENTIFIER from dotted-decimal text, e.g.
`static byte[]`	`sequence(byte[]... parts)` Encodes a SEQUENCE.
`static byte[]`	`set(byte[]... parts)` Encodes a SET.
`static byte[]`	`tlv(int tag, byte[] value)` Encodes a TLV (tag, length, value) triplet.
`static byte[]`	`utf8(String s)` Encodes a UTF8String.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - BOOLEAN
```
public static final int BOOLEAN
```
    Universal tag: BOOLEAN.
    See Also:
    Constant Field Values
  - INTEGER
```
public static final int INTEGER
```
    Universal tag: INTEGER.
    See Also:
    Constant Field Values
  - BIT_STRING
```
public static final int BIT_STRING
```
    Universal tag: BIT STRING.
    See Also:
    Constant Field Values
  - OCTET_STRING
```
public static final int OCTET_STRING
```
    Universal tag: OCTET STRING.
    See Also:
    Constant Field Values
  - OID
```
public static final int OID
```
    Universal tag: OBJECT IDENTIFIER.
    See Also:
    Constant Field Values
  - UTF8_STRING
```
public static final int UTF8_STRING
```
    Universal tag: UTF8String.
    See Also:
    Constant Field Values
  - PRINTABLE_STRING
```
public static final int PRINTABLE_STRING
```
    Universal tag: PrintableString.
    See Also:
    Constant Field Values
  - IA5_STRING
```
public static final int IA5_STRING
```
    Universal tag: IA5String.
    See Also:
    Constant Field Values
  - UTC_TIME
```
public static final int UTC_TIME
```
    Universal tag: UTCTime.
    See Also:
    Constant Field Values
  - GENERALIZED_TIME
```
public static final int GENERALIZED_TIME
```
    Universal tag: GeneralizedTime.
    See Also:
    Constant Field Values
  - SEQUENCE
```
public static final int SEQUENCE
```
    Universal tag: SEQUENCE (constructed).
    See Also:
    Constant Field Values
  - SET
```
public static final int SET
```
    Universal tag: SET (constructed).
    See Also:
    Constant Field Values
- Method Detail
  - tlv
```
public static byte[] tlv(int tag,
                         byte[] value)
```
    Encodes a TLV (tag, length, value) triplet.
    Parameters:
    tag - The DER tag byte (including class and constructed bits).
    value - The already-encoded content bytes.
    Returns:
    The complete TLV encoding.
  - constructed
```
public static byte[] constructed(int tag,
                                 byte[]... parts)
```
    Encodes a constructed value (SEQUENCE, SET, or an explicit context tag) from parts.
    Parameters:
    tag - The constructed tag.
    parts - The already-encoded children, concatenated in order.
    Returns:
    The complete encoding.
  - sequence
```
public static byte[] sequence(byte[]... parts)
```
    Encodes a SEQUENCE.
  - set
```
public static byte[] set(byte[]... parts)
```
    Encodes a SET.
  - contextExplicit
```
public static byte[] contextExplicit(int n,
                                     byte[] inner)
```
    Encodes an EXPLICIT context-specific tag [n], wrapping one inner encoding.
    Parameters:
    n - The context tag number, 0-30.
    inner - The complete inner encoding.
    Returns:
    The complete encoding.
  - contextImplicit
```
public static byte[] contextImplicit(int n,
                                     byte[] content)
```
    Encodes an IMPLICIT context-specific PRIMITIVE tag [n] over raw content bytes.
    Parameters:
    n - The context tag number, 0-30.
    content - The raw content (not a TLV).
    Returns:
    The complete encoding.
  - integer
```
public static byte[] integer(BigInteger value)
```
    Encodes an INTEGER from a BigInteger. DER's INTEGER is signed two's complement, which BigInteger.toByteArray() already produces, minimal-length included.
  - integer
```
public static byte[] integer(int value)
```
    Encodes a small non-negative INTEGER.
  - bool
```
public static byte[] bool(boolean value)
```
    Encodes a BOOLEAN. DER requires TRUE to be exactly 0xFF.
  - oid
```
public static byte[] oid(String dotted)
```
    Encodes an OBJECT IDENTIFIER from dotted-decimal text, e.g. "2.5.4.3".
    The first two arcs combine into one byte as 40*first+second; every later arc is base-128 with the continuation bit set on all but the last byte.
    Parameters:
    dotted - The OID in dotted-decimal form.
    Returns:
    The complete encoding.
    Throws:
    IllegalArgumentException - If the text is not a valid OID.
  - utf8
```
public static byte[] utf8(String s)
```
    Encodes a UTF8String.
  - ia5
```
public static byte[] ia5(String s)
```
    Encodes an IA5String (ASCII). Used for dNSName in SubjectAltName.
  - bitString
```
public static byte[] bitString(byte[] bits)
```
    Encodes a BIT STRING with zero unused bits, which is what signatures and public keys use.
  - namedBits
```
public static byte[] namedBits(int bitsHighFirst,
                               int bitCount)
```
    Encodes a BIT STRING for X.509 KeyUsage: named bits, DER minimal-length rules applied (trailing zero bits stripped, unused-bit count set accordingly).
    Parameters:
    bitsHighFirst - Bit 0 = most significant bit of the first byte, per X.680.
    bitCount - How many bits are meaningful.
  - octetString
```
public static byte[] octetString(byte[] value)
```
    Encodes an OCTET STRING.

Class Der

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

BOOLEAN

INTEGER

BIT_STRING

OCTET_STRING

OID

UTF8_STRING

PRINTABLE_STRING

IA5_STRING

UTC_TIME

GENERALIZED_TIME

SEQUENCE

SET

Method Detail

tlv

constructed

sequence

set

contextExplicit

contextImplicit

integer

integer

bool

oid

utf8

ia5

bitString

namedBits

octetString