AES Key Schedule Example

An example of the AES key schedule is provided to illustrate how 11 round keys get calculate from a given 128-bit cipher key.

As an example, let's try to follow the algorithm of the KeyExpansion() procedure, and expand a real cipher key to 11 round keys. This example was presented in the FIPS publication, "Announcing the ADVANCED ENCRYPTION STANDARD (AES)" in 2001.

Here is the given cipher key in hexadecimal format:
   K = 0x2b7e1516, 0x28aed2a6, 0xabf71588, 0x09cf4f3c

Performing w[0..3] = K:
   w[0] = 0x2b7e1516
   w[1] = 0x28aed2a6
   w[2] = 0xabf71588
   w[3] = 0x09cf4f3c

   temp = w[3]:         0x09cf4f3c

for i = 4: 
   RotWord(temp):       0xcf4f3c09
   SubWord(temp):       0x8a84eb01
   temp XOR 0x01000000: 0x8b84eb01
   temp XOR w[0]:       0xa0fafe17
   w[4] = 0xa0fafe17
   
for i = 5: 
   temp XOR w[1]:       0x88542cb1
   w[5] = 0x88542cb1
   
for i = 6: 
   temp XOR w[2]:       0x23a33939
   w[6] = 0x23a33939

for i = 7: 
   temp XOR w[3]:       0x2a6c7605
   w[7] = 0x2a6c7605
   
for i = 8: 
   RotWord(temp):       0x6c76052a
   SubWord(temp):       0x50386be5
   temp XOR 0x02000000: 0x52386be5
   temp XOR w[4]:       0xf2c295f2
   w[8] = 0xf2c295f2

for i = 9: 
   temp XOR w[5]:       0x7a96b943
   w[9] = 0x7a96b943
   
for i = 10: 
   temp XOR w[6]:       0x5935807a
   w[10] = 0x5935807a

for i = 11: 
   temp XOR w[7]:       0x7359f67f
   w[11] = 0x7359f67f

for i = 12: 
   RotWord(temp):       0x59f67f73
   SubWord(temp):       0xcb42d28f
   temp XOR 0x04000000: 0xcf42d28f
   temp XOR w[8]:       0x3d80477d
   w[12] = 0x3d80477d

for i = 13: 
   temp XOR w[9]:       0x4716fe3e
   w[13] = 0x4716fe3e
   
for i = 14: 
   temp XOR w[10]:      0x1e237e44
   w[14] = 0x1e237e44

for i = 15: 
   temp XOR w[11]:      0x6d7a883b
   w[15] = 0x6d7a883b

for i = 16: 
   RotWord(temp):       0x7a883b6d
   SubWord(temp):       0xdac4e23c
   temp XOR 0x08000000: 0xd2c4e23c
   temp XOR w[12]:      0xef44a541
   w[16] = 0xef44a541
      
for i = 17: 
   temp XOR w[13]:      0xa8525b7f
   w[17] = 0xa8525b7f
   
for i = 18: 
   temp XOR w[14]:      0xb671253b
   w[18] = 0xb671253b
   
for i = 19: 
   temp XOR w[15]:      0xdb0bad00
   w[19] = 0xdb0bad00

for i = 20: 
   RotWord(temp):       0x0bad00db
   SubWord(temp):       0x2b9563b9
   temp XOR 0x10000000: 0x3b9563b9
   temp XOR w[16]:      0xd4d1c6f8
   w[20] = 0xd4d1c6f8
   
for i = 21: 
   temp XOR w[17]:      0x7c839d87
   w[21] = 0x7c839d87

for i = 22: 
   temp XOR w[18]:      0xcaf2b8bc
   w[22] = 0xcaf2b8bc

for i = 23: 
   temp XOR w[19]:      0x11f915bc
   w[23] = 0x11f915bc

for i = 24: 
   RotWord(temp):       0xf915bc11
   SubWord(temp):       0x99596582
   temp XOR 0x20000000: 0xb9596582
   temp XOR w[20]:      0x6d88a37a
   w[24] = 0x6d88a37a

for i = 25: 
   temp XOR w[21]:      0x110b3efd
   w[25] = 0x110b3efd

for i = 26: 
   temp XOR w[22]:      0xdbf98641
   w[26] = 0xdbf98641

for i = 27: 
   temp XOR w[23]:      0xca0093fd
   w[27] = 0xca0093fd

for i = 28: 
   RotWord(temp):       0x0093fdca
   SubWord(temp):       0x63dc5474
   temp XOR 0x40000000: 0x23dc5474
   temp XOR w[24]:      0x4e54f70e
   w[28] = 0x4e54f70e

for i = 29: 
   temp XOR w[25]:      0x5f5fc9f3
   w[25] = 0x5f5fc9f3

for i = 30: 
   temp XOR w[26]:      0x84a64fb2
   w[26] = 0x84a64fb2

for i = 31: 
   temp XOR w[27]:      0x4ea6dc4f
   w[31] = 0x4ea6dc4f

for i = 32: 
   RotWord(temp):       0xa6dc4f4e
   SubWord(temp):       0x2486842f
   temp XOR 0x80000000: 0xa486842f
   temp XOR w[28]:      0xead27321
   w[32] = 0xv

for i = 33: 
   temp XOR w[29]:      0xb58dbad2
   w[33] = 0xb58dbad2

for i = 34: 
   temp XOR w[30]:      0x312bf560
   w[34] = 0x312bf560

for i = 35: 
   temp XOR w[31]:      0x7f8d292f
   w[35] = 0x7f8d292f

for i = 36: 
   RotWord(temp):       0x8d292f7f
   SubWord(temp):       0x5da515d2
   temp XOR 0x1b000000: 0x46a515d2
   temp XOR w[32]:      0xac7766f3
   w[36] = 0xac7766f3

for i = 37: 
   temp XOR w[33]:      0x19fadc21
   w[33] = 0x19fadc21

for i = 38: 
   temp XOR w[34]:      0x28d12941
   w[38] = 0x28d12941

for i = 39: 
   temp XOR w[35]:      0x575c006e
   w[39] = 0x575c006e

for i = 40: 
   RotWord(temp):       0x5c006e57
   SubWord(temp):       0x4a639f5b
   temp XOR 0x36000000: 0x7c639f5b
   temp XOR w[36]:      0xd014f9a8
   w[40] = 0xd014f9a8

for i = 41: 
   temp XOR w[37]:      0xc9ee2589
   w[41] = 0xc9ee2589

for i = 42: 
   temp XOR w[38]:      0xe13f0cc8
   w[42] = 0xe13f0cc8

for i = 43: 
   temp XOR w[39]:      0xb6630ca6
   w[43] = 0xb6630ca6

Building 11 round keys from w[]
   k[ 0] = 0x2b7e1516, 0x28aed2a6, 0xabf71588, 0x09cf4f3c
   k[ 1] = 0xa0fafe17, 0x88542cb1, 0x23a33939, 0x2a6c7605
   k[ 2] = 0xf2c295f2, 0x7a96b943, 0x5935807a, 0x7359f67f
   k[ 3] = 0x3d80477d, 0x4716fe3e, 0x1e237e44, 0x6d7a883b
   k[ 4] = 0xef44a541, 0xa8525b7f, 0xb671253b, 0xdb0bad00
   k[ 5] = 0xd4d1c6f8, 0x7c839d87, 0xcaf2b8bc, 0x11f915bc
   k[ 6] = 0x6d88a37a, 0x110b3efd, 0xdbf98641, 0xca0093fd
   k[ 7] = 0x4e54f70e, 0x5f5fc9f3, 0x84a64fb2, 0x4ea6dc4f
   k[ 8] = 0xead27321, 0xb58dbad2, 0x312bf560, 0x7f8d292f
   k[ 9] = 0xac7766f3, 0x19fadc21, 0x28d12941, 0x575c006e
   k[10] = 0xd014f9a8, 0xc9ee2589, 0xe13f0cc8, 0xb6630ca6

Last update: 2015.

Table of Contents

 About This Book

 Cryptography Terminology

 Cryptography Basic Concepts

Introduction to AES (Advanced Encryption Standard)

 What Is AES (Advanced Encryption Standard)?

 AES, or Rijndael, Encryption Algorithm

 AES Key Schedule Algorithm

AES Key Schedule Example

 AES MixColumns() Procedure Algorithm

 Example Vector of AES Encryption

 AES Standard Decryption Algorithm

 AES Equivalent Decryption Algorithm

 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

 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