What Is DER (Distinguished Encoding Rules) Encoding?

This section describes the DER (Distinguished Encoding Rules) - A binary format of encoding a data value of any data types including nested data structures.

What Is DER? DER (Distinguished Encoding Rules) is one of ASN.1 encoding rules defined in ITU-T X.690, 2002, specification. ASN.1 encoding rules can be used to encode any data object into a binary file.

The basic encoding rule of DER is that a data value of all data types shall be encoded as four components in the following order:

Of course, complex data types are supported to create data values of nested structures like this example:

{
 name {givenName "John",initial "P",familyName "Smith"},
 title "Director",
 number 51,
 dateOfHire "19710917",
 nameOfSpouse {givenName "Mary",initial "T",familyName "Smith"},
 children 
  {
   {
    name {givenName "Ralph",initial "T",familyName "Smith"},
    dateOfBirth "19571111"
   },
   {
    name {givenName "Susan",initial "B",familyName "Jones"},
    dateOfBirth "19590717"
   }
  }
 }

As you can see from this example, DER is flexible enough to encode almost any data object.

The full specification of DER is in ITU-T X.690 - Information technology - ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER) .

DER is used as the most popular encoding format to store X.509 certificates in files. Those certificate DER files are binary files, which can not be viewed with text editors. But they can be processed by application without any problems.

DER encoded certificate files are supported by almost all applications. "OpenSSL" and "keytool" support DER encoded certificate files with no problem. See other sections below for examples of certificate files saved in DER encoding.

Last update: 2013.

Table of Contents

 About This Book

 Cryptography Terminology

 Cryptography Basic Concepts

 Introduction to AES (Advanced Encryption Standard)

 Introduction to DES Algorithm

 DES Algorithm - Illustrated with Java Programs

 DES Algorithm Java Implementation

 DES Algorithm - Java Implementation in JDK JCE

 DES Encryption Operation Modes

 DES in Stream Cipher Modes

 PHP Implementation of DES - mcrypt

 Blowfish - 8-Byte Block Cipher

 Secret Key Generation and Management

 Cipher - Secret Key Encryption and Decryption

 Introduction of RSA Algorithm

 RSA Implementation using java.math.BigInteger Class

 Introduction of DSA (Digital Signature Algorithm)

 Java Default Implementation of DSA

 Private key and Public Key Pair Generation

 PKCS#8/X.509 Private/Public Encoding Standards

 Cipher - Public Key Encryption and Decryption

 MD5 Mesasge Digest Algorithm

 SHA1 Mesasge Digest Algorithm

 OpenSSL Introduction and Installation

 OpenSSL Generating and Managing RSA Keys

 OpenSSL Managing Certificates

 OpenSSL Generating and Signing CSR

 OpenSSL Validating Certificate Path

 "keytool" and "keystore" from JDK

 "OpenSSL" Signing CSR Generated by "keytool"

 Migrating Keys from "keystore" to "OpenSSL" Key Files

Certificate X.509 Standard and DER/PEM Formats

 X.509 Certificate Standard

What Is DER (Distinguished Encoding Rules) Encoding?

 What Is PEM (Privacy Enhanced Mail) Encoding?

 Certificate in PEM Format

 "keytool" Exporting Certificates in DER and PEM

 "OpenSSL" Viewing Certificates in DER and PEM

 "OpenSSL" Generating Certificates in DER and PEM

 "keytool" Viewing Certificates in DER and PEM

 "keytool" Importing Certificates in DER and PEM

 Migrating Keys from "OpenSSL" Key Files to "keystore"

 Using Certificates in IE (Internet Explorer)

 Using Certificates in Firefox

 Using Certificates in Google Chrome

 Outdated Tutorials

 References

 PDF Printing Version