Cryptography Tutorials - Herong's Tutorial Examples - Version 5.21, by Dr. Herong Yang

DES Key Schedule (Round Keys Generation) Algorithm

This section describes DES (Data Encryption Standard) algorithm - A 16-round Feistel cipher with block size of 64 bits.

Key schedule algorithm:

Input:
    K: 64-bit key
    PC1: Permuted choice 1
    PC2: Permuted choice 2
    r1, r2, ..., r16: left shifts (rotations)

Output:
    k1, k2, ..., k16: 16 48-bit round keys
    
Algorithm:
    K' = PC1(K), applying permuted choice 1 and returning 56 bits
    (C0, D0) = K', dividing K' into two 28-bit parts
    (C1, D1) = (r1(C0), r1(D0)), shifting to the left
    k1 = PC2(C1,D1), applying permuted choice 2 and returning 48 bits
    (C2, D2) = (r2(C1), r2(D1)), shifting to the left
    k2 = PC2(C2,D2), applying permuted choice 2 and returning 48 bits
    ......
    k16 = PC2(C16,D16)

DES key schedule supporting tables:

Permuted Choice 1 - PC1:

57   49    41   33    25    17    9
 1   58    50   42    34    26   18
10    2    59   51    43    35   27
19   11     3   60    52    44   36
63   55    47   39    31    23   15
 7   62    54   46    38    30   22
14    6    61   53    45    37   29
21   13     5   28    20    12    4

Permuted Choice 2 - PC2:

14    17   11    24     1    5
 3    28   15     6    21   10
23    19   12     4    26    8
16     7   27    20    13    2
41    52   31    37    47   55
30    40   51    45    33   48
44    49   39    56    34   53
46    42   50    36    29   32

Left shifts (number of bits to rotate) - r1, r2, ..., r16:

 r1  r2  r3  r4  r5  r6  r7  r8  r9 r10 r11 r12 r13 r14 r15 r16 
  1   1   2   2   2   2   2   2   1   2   2   2   2   2   2   1

Table of Contents

 About This Book

 Cryptography Terminology

 Cryptography Basic Concepts

Introduction to DES Algorithm

 What Is Block Cipher?

 DES (Data Encryption Standard) Cipher Algorithm

DES Key Schedule (Round Keys Generation) Algorithm

 DES Decryption 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

 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

 Printable Copy - PDF Version

DES Key Schedule (Round Keys Generation) Algorithm - Updated in 2014, by Dr. Herong Yang