Cryptography Tutorials - Herong's Tutorial Examples - v5.42, by Herong Yang
DES (Data Encryption Standard) Cipher Algorithm
This section describes DES (Data Encryption Standard) algorithm - A 16-round Feistel cipher with block size of 64 bits.
DES Cipher - A 16-round Feistel cipher with block size of 64 bits. DES stands for Data Encryption Standard.
DES was developed by IBM in 1974 in response to a federal government public invitation for data encryption algorithms. In 977, DES was published as a federal standard, FIPS PUB 46.
DES algorithm:
Input: T: 64 bits of clear text k1, k2, ..., k16: 16 round keys IP: Initial permutation FP: Final permutation f(): Round function Output: C: 64 bits of cipher text Algorithm: T' = IP(T), applying initial permutation (L0, R0) = T', dividing T' into two 32-bit parts (L1, R1) = (R0, L0 ^ f(R0, k1)) (L2, R2) = (R1, L1 ^ f(R1, k2)) ...... C' = (R16, L16), swapping the two parts C = FP(C'), applying final permutation
where ^ is the XOR operation.
The round function f(R,k) is defined as:
Input: R: 32-bit input data k: 48-bit round key E: Expansion permutation P: Round permutation s(): S boxes function Output R' = f(R,k): 32-bit output data Algorithm X = E(R), applying expansion permutation and returning 48-bit data X' = X ^ k, XOR with the round key X" = s(X'), applying S boxes function and returning 32-bit data R' = P(X"), applying the round permutation
The S boxes function s(X) is defined as:
Input: X: 48-bit input data S1, S2, ..., S8: 8 S boxes - 4 x 16 tables Output: X' = s(X): 32-bit output data Algorithm: (X1, X2, ..., X8) = X, dividing X into 8 6-bit parts X' = (S1(X1), S2(X2), ..., S8(X8)) where Si(Xi) is the value at row r and column c of S box i with r = 2*b1 + b6 c = 8*b2 + 4*b3 + 2*b3 + b4 b1, b2, b3, b4, b5, b6 are the 6 bits of the Xi
DES cipher algorithm supporting tables:
Initial Permutation - IP:
58 50 42 34 26 18 10 2 60 52 44 36 28 20 12 4 62 54 46 38 30 22 14 6 64 56 48 40 32 24 16 8 57 49 41 33 25 17 9 1 59 51 43 35 27 19 11 3 61 53 45 37 29 21 13 5 63 55 47 39 31 23 15 7
Final Permutation - FP:
40 8 48 16 56 24 64 32 39 7 47 15 55 23 63 31 38 6 46 14 54 22 62 30 37 5 45 13 53 21 61 29 36 4 44 12 52 20 60 28 35 3 43 11 51 19 59 27 34 2 42 10 50 18 58 26 33 1 41 9 49 17 57 25
Expansion permutation - E:
32 1 2 3 4 5 4 5 6 7 8 9 8 9 10 11 12 13 12 13 14 15 16 17 16 17 18 19 20 21 20 21 22 23 24 25 24 25 26 27 28 29 28 29 30 31 32 1
Round permutation - P:
16 7 20 21 29 12 28 17 1 15 23 26 5 18 31 10 2 8 24 14 32 27 3 9 19 13 30 6 22 11 4 25
S boxes - S1, S2, ..., S8:
S1 14 4 13 1 2 15 11 8 3 10 6 12 5 9 0 7 0 15 7 4 14 2 13 1 10 6 12 11 9 5 3 8 4 1 14 8 13 6 2 11 15 12 9 7 3 10 5 0 15 12 8 2 4 9 1 7 5 11 3 14 10 0 6 13 S2 15 1 8 14 6 11 3 4 9 7 2 13 12 0 5 10 3 13 4 7 15 2 8 14 12 0 1 10 6 9 11 5 0 14 7 11 10 4 13 1 5 8 12 6 9 3 2 15 13 8 10 1 3 15 4 2 11 6 7 12 0 5 14 9 S3 10 0 9 14 6 3 15 5 1 13 12 7 11 4 2 8 13 7 0 9 3 4 6 10 2 8 5 14 12 11 15 1 13 6 4 9 8 15 3 0 11 1 2 12 5 10 14 7 1 10 13 0 6 9 8 7 4 15 14 3 11 5 2 12 S4 7 13 14 3 0 6 9 10 1 2 8 5 11 12 4 15 13 8 11 5 6 15 0 3 4 7 2 12 1 10 14 9 10 6 9 0 12 11 7 13 15 1 3 14 5 2 8 4 3 15 0 6 10 1 13 8 9 4 5 11 12 7 2 14 S5 2 12 4 1 7 10 11 6 8 5 3 15 13 0 14 9 14 11 2 12 4 7 13 1 5 0 15 10 3 9 8 6 4 2 1 11 10 13 7 8 15 9 12 5 6 3 0 14 11 8 12 7 1 14 2 13 6 15 0 9 10 4 5 3 S6 12 1 10 15 9 2 6 8 0 13 3 4 14 7 5 11 10 15 4 2 7 12 9 5 6 1 13 14 0 11 3 8 9 14 15 5 2 8 12 3 7 0 4 10 1 13 11 6 4 3 2 12 9 5 15 10 11 14 1 7 6 0 8 13 S7 4 11 2 14 15 0 8 13 3 12 9 7 5 10 6 1 13 0 11 7 4 9 1 10 14 3 5 12 2 15 8 6 1 4 11 13 12 3 7 14 10 15 6 8 0 5 9 2 6 11 13 8 1 4 10 7 9 5 0 15 14 2 3 12 S8 13 2 8 4 6 15 11 1 10 9 3 14 5 0 12 7 1 15 13 8 10 3 7 4 12 5 6 11 0 14 9 2 7 11 4 1 9 12 14 2 0 6 10 13 15 3 5 8 2 1 14 7 4 10 8 13 15 12 9 0 3 5 6 11
Table of Contents
Introduction to AES (Advanced Encryption Standard)
►Introduction to DES Algorithm
►DES (Data Encryption Standard) Cipher Algorithm
DES Key Schedule (Round Keys Generation) Algorithm
DES Algorithm - Illustrated with Java Programs
DES Algorithm Java Implementation
DES Algorithm - Java Implementation in JDK JCE
DES Encryption Operation Modes
PHP Implementation of DES - mcrypt
Blowfish - 8-Byte Block Cipher
Secret Key Generation and Management
Cipher - Secret Key Encryption and Decryption
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
OpenSSL Introduction and Installation
OpenSSL Generating and Managing RSA Keys
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"