Cryptography Tutorials - Herong's Tutorial Examples - Version 5.36, by Dr. Herong Yang
RsaKeyValidator.java for RSA Key Validation
This section provides a tutorial example on how to validate RSA keys by encrypting and decrypting some random sample messages.
Before writing the RSA encryption and decryption programs, I want to validate RSA keys generated from by RsaKeyGenerator.java program.
Here is my RSA key validation program:
/* RsaKeyValidator.java #- Copyright (c) 2013, HerongYang.com, All Rights Reserved. */ import java.math.BigInteger; import java.util.Random; import java.io.*; class RsaKeyValidator { private BigInteger n, e, d; public static void main(String[] a) { if (a.length<1) { System.out.println("Usage:"); System.out.println("java RsaKeyValidator input"); return; } String input = a[0]; RsaKeyValidator validator = new RsaKeyValidator(input); validator.test(); validator.test(); validator.test(); } // Reading in RSA public key and private key RsaKeyValidator(String input) { try { BufferedReader in = new BufferedReader(new FileReader(input)); String line = in.readLine(); while (line!=null) { if (line.indexOf("Modulus: ")>=0) { n = new BigInteger(line.substring(9)); } if (line.indexOf("Public key: ")>=0) { e = new BigInteger(line.substring(12)); } if (line.indexOf("Private key: ")>=0) { d = new BigInteger(line.substring(13)); } line = in.readLine(); } } catch (Exception ex) { ex.printStackTrace(); } System.out.println("--- Reading public key and private key ---"); System.out.println("Modulus: "+n); System.out.println("Key size: "+n.bitLength()); System.out.println("Public key: "+e); System.out.println("Private key: "+d); } // Testing encryption and description public void test() { Random rnd = new Random(); int size = rnd.nextInt(n.bitLength()-1); BigInteger text = new BigInteger(size,rnd); BigInteger cipher = text.modPow(e,n); BigInteger decrypted = cipher.modPow(d,n); boolean isPassed = text.equals(decrypted); System.out.println("--- RSA encryption test ---"); System.out.println("Is test passed: "+isPassed); System.out.println("Original text: "+text); System.out.println("Cipher text: "+cipher); System.out.println("Decrypted text: "+decrypted); } }
Some notes on RsaKeyValidator.java:
Testing result is presented in the next tutorial.
Last update: 2013.
Table of Contents
Introduction to AES (Advanced Encryption Standard)
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
Generating Prime Number with BigInteger Class
Performance of Prime Number Generation
RSA Encryption Implementation using BigInteger Class
RsaKeyGenerator.java for RSA Key Generation
RSA Keys Generated by RsaKeyGenerator.java
►RsaKeyValidator.java for RSA Key Validation
64-bit RSA Key Validated by RsaKeyValidator.java
Converting Byte Sequences to Positive Integers
Cleartext Block Size for RSA Encryption
Cleartext Message Padding and Revised Block Size
Ciphertext Block Size for RSA Encryption
RsaKeyEncryption.java for RSA Encryption Operation
RsaKeyDecryption.java for RSA Decryption Operation
Testing RsaKeyEncryption.java with a 16-bit Key
Testing RsaKeyEncryption.java with a 64-bit Key
Testing RsaKeyEncryption.java with a 3072-bit Key
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"
Using Certificates in IE (Internet Explorer)