Package de.xima.fc.model.encoding

Class DerUtils

java.lang.Object

de.xima.fc.model.encoding.DerUtils

public class DerUtils
extends Object

Since:

8.5.4

Author:

Norman Lorenz

Method Summary

Modifier and Type	Method	Description
static String	decodeDerStringValue(byte[] derBytes)	Decodes a DER-encoded (Distinguished Encoding Rules per ITU-T X.690) ASN.1 string value into a plain Java String.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

decodeDerStringValue

public static String decodeDerStringValue(byte[] derBytes)

Decodes a DER-encoded (Distinguished Encoding Rules per ITU-T X.690) ASN.1 string value into a plain Java String.

This method expects the input byte array to contain a complete TLV (Tag-Length-Value) structure as used in ASN.1 DER encoding:

• Tag (1 byte): ASN.1 type identifier (e.g., 0x16 for IA5String)
• Length (1+ bytes): Short form (0x00–0x7F) or long form (0x80–0xFF)
• Value (n bytes): The actual string content

Charset selection:

• Tag 0x16 (IA5String): US-ASCII
• All other tags: UTF-8

Common use case: Decoding RFC 2253 hex-encoded DN attributes. When Java's X500Principal outputs a DN with email attributes (e.g., 1.2.840.113549.1.9.1=#1623...), the hex part after # represents the DER-encoded value. This method decodes such values.

Parameters:

derBytes - the complete DER-encoded TLV byte array (must not be null or empty)

Returns:

the decoded string value

Throws:

IllegalArgumentException - if:

• derBytes is null or shorter than 2 bytes
• the length field is malformed or inconsistent with the actual payload
• the DER structure violates basic format rules

Since:

8.5.4

See Also:

ITU-T X.690 – DER encoding, RFC 2253 – LDAP DN String Representation, RFC 5280 – X.509 Certificates