An implementation of RSA and ElGamal PKCs using Java ...

- "Sociálne náklady"- "Kultúra/mentalita"- "nenachádzam žiadne zodpovedajúcepracovné sily "O nahradení pracovníkov z vlasti inýmipracovníkmi z nových členských štátov EÚby ste uvažovali v prípade …Spolupracujete so subdodavateľmi znových členských štátov EÚ?Myslíte si, že rozšírenie EÚ v roku 2004prinieslo Vášmu podniku nové možnostialebo ohrozenia?Zamestnávate pracovníkov z novýchčlenských štátov EÚ?Vývoj počtu zamestnancov…'- zo Slovenska (N=437)- z Česka (n=437)- z Maďarska (n=437)- z iných „nových“ štátov EÚ (N=437)- z krajín bývalej Juhoslávie resp. zTurecka (N=437)- z iných štátov (N=437)FAMO II - Podnikový dotazník - Rakúska/Viedeň (N=1501)hovorí pre 16%hovorí proti 6%ani/ani 71%Neviem / žiadna odpoved 7%hovorí pre 10%hovorí proti 18%ani/ani 65%Neviem / žiadna odpoved 7%hovorí pre 18%hovorí proti 8%ani/ani 67%Neviem / žiadna odpoved 7%učni 1%pomocné sily / zaučení a nevyučení pracovníci 3%kvalifikovaní/é pracovníci/čky 6%zamestnanci bez maturity 2%zamestnanci s maturitou 2%zamestnaní absolventi/tky vysokej školy 1%nenahradia sa 88%Áno 19%Nie 79%Neviem / žiadna odpoved 2%nové možnosti 41%ohrozenia 15%ani/ani 42%neviem 3%Áno 29%Nie 70%Neviem / žiadna odpoved 1%Počet sa zvýšil 5%Počet zostal rovnaký 38%Počet sa znížil 4%nezamestnávam žiadnych 51%neviem 3%Počet sa zvýšil 3%Počet zostal rovnaký 32%Počet sa znížil 3%nezamestnávam žiadnych 59%neviem 4%Počet sa zvýšil 2%Počet zostal rovnaký 41%Počet sa znížil 4%nezamestnávam žiadnych 50%neviem 4%Počet sa zvýšil 6%Počet zostal rovnaký 53%Počet sa znížil 4%nezamestnávam žiadnych 35%neviem 3%Počet sa zvýšil 6%Počet zostal rovnaký 50%Počet sa znížil 6%nezamestnávam žiadnych 34%neviem 4%Počet sa zvýšil 4%Počet zostal rovnaký 47%Počet sa znížil 4%nezamestnávam žiadnych 42%neviem 4%9

}for (int i=0; i < nBlks; i++)for (int j=0; j < blkSz; j++)ba[i][j] = msg[i*blkSz + j];return ba;//put a series of encoded blocks back into a single array of byytes.//The BigInt might be smaller than the block size, so fill the array//from the rear of each block.protected static byte[] unblock(byte[][] ba, int blkSz) {byte[] ub = new byte [ba.length * blkSz];for (int i=0; i= 0) {ub[i*blkSz+j] = ba[i][k];k--; j--;}}return ub;}public static void display(byte[] b) {String digits = "0123456789abcdef";for (int i=0; i>> 4));System.out.print(digits.charAt(b[i] & 0x0f));}System.out.println(" - "+ b.length + " bytes");}//Strip off the extra byte containing the sign bit (always 0 here)//returned by toByteArray() (ref D Bishop p123)protected static byte[] getBytes(BigInteger bg) {byte[] bts = bg.toByteArray();if (bg.bitLength()%8 != 0)return bts;else {byte[] sbts = new byte[bg.bitLength()/8];System.arraycopy(bts, 1, sbts, 0, sbts.length);return sbts;}}public abstract byte[] transform(byte[] msg);} //end class MyTransformer---------------------------------------------------------import java.math.BigInteger;public class MyRSAEncrypter extends MyTransformer {private BigInteger e, n;public MyRSAEncrypter(BigInteger e, BigInteger n) {this.e = e; this.n = n;System.out.println("Encryption key:");System.out.println("n = " + n.toString(16));System.out.println("e = " + e.toString(16));}11

public byte[] transform(byte[] msg) {long startTm = System.currentTimeMillis();int blkSz = (n.bitLength() - 1)/8;byte[][] ba = block(pad(msg, blkSz), blkSz);BigInteger msgBlkInt;System.err.println("" + ba.length + " blocks");for (int i=0; i

*/import java.math.BigInteger;import java.security.SecureRandom;import java.util.*;public class GeneratorFactory {private int minBits, crtty;private SecureRandom srng;private BigInteger p, g;private static final BigIntegerZERO = BigInteger.ZERO, ONE = BigInteger.ONE,TWO = ONE.add(ONE), THREE = TWO.add(ONE);//Constructorspublic GeneratorFactory (int bits) { this(bits, 300); }public GeneratorFactory (int bits, int crtty) {this(bits, crtty, new SecureRandom());}public GeneratorFactory (int bits, int crtty, SecureRandom sr) {if (bits < 512)System.err.println("WARNING: Safe primes should be >= 512 bits long");this.minBits = bits;this.crtty = crtty;this.srng = sr;}System.out.printf("Making a safe prime of at least %d bits...\n", bits);long startTm = System.currentTimeMillis(), endTm;makeSafePrimeAndGenerator();endTm = System.currentTimeMillis();System.err.printf("Generating p, g took %d ms\n", endTm - startTm);System.out.printf("p = %x (%d bits)\n", p, p.bitLength());System.out.printf("g = %x (%d bits)\n", g, g.bitLength());/* Method to make a safe prime (stored in this.p)* and a generator (this.g) mod p. Uses method suggested by D Bishop:* (1) Find a safe prime p = 2rt + 1 where r is smallish (~10^9), t prime;* (2) Obtain the prime factorization of p-1 (quickish in view of (1));* (3) Repeatedly make a random g, 1 < g < p until* for each prime factor f of p-1, g^((p-1)/f) is incogruent to 1 mod p.*/public void makeSafePrimeAndGenerator() {BigInteger r = BigInteger.valueOf(0x7fffffff),t = new BigInteger(minBits, crtty, srng);//(1) make prime pdo {r = r.add(ONE);p = TWO.multiply(r).multiply(t).add(ONE);} while (!p.isProbablePrime(crtty));//(2) obtain prime factorization of p-1 = 2rtHashSet factors = new HashSet();factors.add(t); factors.add(TWO);if (r.isProbablePrime(crtty))factors.add(r);elsefactors.addAll(primeFact(r));//We have set of prime factors of p-1.//Now (3) look for a generator mod p. Repeatedly make13

a random g, 1 < g < p, until for each prime factor f of p-1,// g^((p-1)/f) is incogruent to 1 mod p.BigInteger pMinusOne = p.subtract(ONE), z, lnr;boolean isGen;do {isGen = true;g = new BigInteger(p.bitLength()-1, srng); //random, < pfor (BigInteger f: factors) { //check cond on g for each fz = pMinusOne.divide(f);lnr = g.modPow(z, p);if (lnr.equals(ONE)) {isGen = false;break;}}} while (!isGen);// Now g is a generator mod p} // end of makeSafePrimeAndGenerator() methodpublic static HashSet primeFact(BigInteger n) {BigInteger nn = new BigInteger(n.toByteArray()); //clone nHashSet factors = new HashSet();BigInteger dvsr = TWO,dvsrSq = dvsr.multiply(dvsr);while (dvsrSq.compareTo(nn)

}//Warning: a large prime factor will take a long time to find!HashSet factors = primeFact(pMinusOne);boolean isGen = true;for (BigInteger f: factors) { //check cond on g for each fz = pMinusOne.divide(f);if (g.modPow(z, p).equals(ONE)) {isGen = false;System.err.println("g is not a generator mod p.");break;}}return isGen;}//Test driverpublic static void main(String[] args) {int bitLen = 512;if (args.length > 0) {try {bitLen = Integer.parseInt(args[0]);} catch(NumberFormatException ex) {bitLen = 512;}}GeneratorFactory fact = new GeneratorFactory(bitLen);BigInteger p = fact.getP(), g = fact.getG();System.out.println("p probable prime: "+ (p.isProbablePrime(300)?"yes":"no"));if (g.compareTo(p) < 0)System.out.println("g < p");elseSystem.out.println("p divides g: " + (g.mod(p).equals(ZERO)?"yes":"no"));}/* Note on generator test:* If p is prime and not a factor of g then |g|_p is in general a divisor of* p-1 (see eg Bishop prop 37 or Apostol thm 10.1). So if g is NOT* a generator mod p then |g|_p is a PROPER divisor of p-1.* In that case, if F is the set of all prime factors of p-1 then some* (p-1)/f, f in F, will be a multiple of |g|_p and hence fail the test (3).*/---------------------------------------------------------import java.math.BigInteger;public class GenTest {public static void main(String[] args) {boolean isGen = GeneratorFactory.isGenerator(new BigInteger(args[0], 16), new BigInteger(args[1], 16), 300);System.err.println(args[1] + (isGen?" is ":" is not ")+ "a generator mod "+ args[0]);}}---------------------------------------------------------import java.math.BigInteger;import java.security.SecureRandom;import java.io.*;public class MyElGamal {private BigInteger p, g, a, r, pMinus2;15

private SecureRandom srng;private static final int CRTTY = 300;private static final String configPath = "MyElGamalConfig.txt";private static final BigIntegerZERO = BigInteger.ZERO, ONE = BigInteger.ONE,TWO = ONE.add(ONE), THREE = TWO.add(ONE);//Two constructors -//Option 1: generate a random system using specified key size; save config:public MyElGamal(int kSz) { //Random system with at least (kSz) bits in psrng = new SecureRandom();GeneratorFactory fact = new GeneratorFactory(kSz, CRTTY, srng);p = fact.getP(); pMinus2 = p.subtract(TWO);g = fact.getG();//a should be a random integer in range 1 < a < p-1BigInteger pmt = p.subtract(THREE);a = (new BigInteger(p.bitLength(), srng)).mod(pmt).add(TWO);r = g.modPow(a, p);saveConfig();}//Option 2 (default) -- construct a system from saved values:public MyElGamal() {srng = new SecureRandom();try {BufferedReader in = new BufferedReader(new FileReader(configPath));p = new BigInteger(in.readLine(), 16);g = new BigInteger(in.readLine(), 16);a = new BigInteger(in.readLine(), 16);in.close();} catch (NumberFormatException ex) {System.err.println("Invalid data in config file - " + ex);System.exit(1);} catch (EOFException ex) {System.err.println("Unexpected end of config file");System.exit(1);} catch (IOException ex) {System.err.println("Trouble reading config file");System.exit(1);} catch (NullPointerException ex) {System.err.println("Trouble reading string from config file - " +ex);System.exit(1);}if (!p.isProbablePrime(CRTTY)) {System.err.println(p.toString(16) + " is not prime. Terminating.");System.exit(1);}if (g.mod(p).equals(ZERO)) {System.err.println(p.toString(16) + " divides " + g.toString(16) +". Terminating.");System.exit(1);}//That g is truely a generator mod p will take inordinately long to//check if p-1 has a large prime factor.//Notwithstading this, we have a system if we have go to here.pMinus2 = p.subtract(TWO);r = g.modPow(a, p);}public String toString() {String dspStg = "p = " + p.toString(16);16

}String nl = dspStg.length() > 80? "\n\n": "\n";dspStg += nl + "g = " + g.toString(16);dspStg += nl + "a = " + a.toString(16);dspStg += nl + "r = " + r.toString(16);return dspStg;public void saveConfig() {try {PrintWriter out = new PrintWriter(new FileWriter(configPath));out.println(p.toString(16)); out.println(g.toString(16));out.println(a.toString(16));out.close();} catch (IOException ex) {System.err.println("Could not save the config");}}public BigInteger getP() { return p; }public BigInteger getG() { return g; }public BigInteger getR() { return r; }//A message block is considered a BigInteger.//Returns pair of BigIntegers comprising the ElGamal cipher-"text"public BigInteger[] encrypt(BigInteger m) {BigInteger k = new BigInteger(p.bitLength(), srng);k = k.mod(pMinus2).add(ONE);BigInteger[] cipher = new BigInteger[2];cipher[0] = g.modPow(k, p);cipher[1] = r.modPow(k, p).multiply(m).mod(p);return cipher;}public BigInteger decrypt(BigInteger c0, BigInteger c1) {BigInteger c = c0.modPow(a, p).modInverse(p); //c0^-a mod preturn c.multiply(c1).mod(p);}public MyElGamalEncrypter getEncrypter() {return new MyElGamalEncrypter(p, g, r);}public MyElGamalDecrypter getDecrypter() {return new MyElGamalDecrypter(p, a);}/* Test bed* Run with single integer argument, kSz, to generate a system and save it.* Run with no arguments to initialise a system from a saved config,* generate a random BigInteger < p, encrypt it and decrypt it again.*/public static void main(String[] args) {if (args.length > 0) {new MyElGamal(Integer.parseInt(args[0]));System.err.println("Config saved in " + configPath);} else {MyElGamal sys = new MyElGamal();SecureRandom sr = new SecureRandom();BigInteger p = sys.getP(),msg = (new BigInteger(p.bitLength(), sr)).mod(p);System.out.println("Message = " + msg.toString(16));17

BigInteger[] c = sys.encrypt(msg);System.out.println("Cipher: c0 = " + c[0].toString(16));System.out.println("Cipher: c1 = " + c[1].toString(16));BigInteger d = sys.decrypt(c[0], c[1]);System.out.println("Decrypted = " + d.toString(16));}}} // end MyElGamal class---------------------------------------------------------import java.math.BigInteger;import java.io.*;public class MyElGamalTst {public static void main(String[] args) throws IOException {if (args.length < 2) {System.out.println("Usage: java MyElGamalTst [e|d] ");return;}MyElGamal pkc = new MyElGamal();MyTransformer trfmr;if (args[0].charAt(0) == 'e')trfmr = pkc.getEncrypter();else if (args[0].charAt(0) == 'd')trfmr = pkc.getDecrypter();else {System.out.println(pkc);System.out.println("No encrypt/decrypt option specified");return;}File inFile = new File(args[1]);int inputLength = (int)(inFile.length()/100 + 1)*100;BufferedInputStream inStrm = new BufferedInputStream(new FileInputStream(inFile));BufferedOutputStream outStrm = new BufferedOutputStream(new FileOutputStream(args[1]+".out"));System.err.println("Buffer size = " + inputLength);byte[] buf = new byte[inputLength];int nBytes = inStrm.read(buf);System.out.println("\n" + nBytes + " bytes read");byte[] msg = new byte[nBytes];System.arraycopy(buf, 0, msg, 0, nBytes);byte[] tmsg = trfmr.transform(msg);System.out.println("" + tmsg.length + " bytes produced");outStrm.write(tmsg);inStrm.close();outStrm.close();}}---------------------------------------------------------public class MyTransformersame as RSA’s---------------------------------------------------------18

import java.math.BigInteger;import java.security.SecureRandom;public class MyElGamalEncrypter extends MyTransformer {private BigInteger p, g, r, pMinus2;private SecureRandom srng;private static final BigInteger ONE = BigInteger.ONE, TWO = ONE.add(ONE);//Assume p is prime, g is a gen mod p, r = g^a mod p (a = pvt key)public MyElGamalEncrypter(BigInteger p, BigInteger g, BigInteger r) {srng = new SecureRandom();this.p = p; this.g = g; this.r = r;pMinus2 = p.subtract(TWO);System.out.println("Encryption key:");System.out.println("p = " + p.toString(16));System.out.println("g = " + g.toString(16));System.out.println("r = " + r.toString(16));}public byte[] transform(byte[] msg) {long startTm = System.currentTimeMillis();int blkSz = (p.bitLength() - 1)/8;byte[][] ba = block(pad(msg, blkSz), blkSz);byte[][] ba2 = new byte[2*ba.length][];BigInteger m, c0, c1, k;System.err.println("" + ba.length + " blocks");for (int i=0; i

long startTm = System.currentTimeMillis();int blkSz = (p.bitLength()-1)/8 + 1;byte[][] ba2 = block(msg, blkSz);byte[][] ba = new byte[ba2.length/2][];BigInteger m, c0, c1, c;System.err.println("" + ba.length + " blocks");for (int i=0; i