DES Key Schedule (Round Keys Generation) Algorithm

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∟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 AES (Advanced Encryption Standard)

►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

Using Certificates in Google Chrome

Using Certificates in Firefox

Archived Tutorials

References

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