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1
19
20 package com.maverick.crypto.publickey;
21
22 import java.io.IOException  ;
23
24 import java.math.BigInteger ;
25 import com.maverick.crypto.security.SecureRandom;
26
27 public final class Rsa {
28
29 private static BigInteger ONE = BigInteger.valueOf(1);
30
31 public static BigInteger doPrivateCrt(BigInteger input,
32 BigInteger privateExponent,
33 BigInteger primeP, BigInteger primeQ,
34 BigInteger crtCoefficient) {
35 return doPrivateCrt(input,
36 primeP, primeQ,
37 getPrimeExponent(privateExponent, primeP),
38 getPrimeExponent(privateExponent, primeQ),
39 crtCoefficient);
40 }
41
42 public static BigInteger doPrivateCrt(BigInteger input,
43 BigInteger p, BigInteger q,
44 BigInteger dP,
45 BigInteger dQ,
46 BigInteger qInv) {
47 if (!qInv.equals(q.modInverse(p))) {
48 BigInteger t = p;
49 p = q;
50 q = t;
51 t = dP;
52 dP = dQ;
53 dQ = t;
54 }
55
56 BigInteger s_1 = input.modPow(dP, p);
57 BigInteger s_2 = input.modPow(dQ, q);
58 BigInteger h = qInv.multiply(s_1.subtract(s_2)).mod(p);
59 return s_2.add(h.multiply(q));
60
61 }
62
63 public static BigInteger getPrimeExponent(BigInteger privateExponent,
64 BigInteger prime) {
65 BigInteger pe = prime.subtract(ONE);
66 return privateExponent.mod(pe);
67 }
68
69 public static BigInteger padPKCS1(BigInteger input, int type,
70 int padLen) throws
71 IllegalStateException {
72 BigInteger result;
73 BigInteger rndInt;
74 int inByteLen = (input.bitLength() + 7) / 8;
75
76 if (inByteLen > padLen - 11) {
77 throw new IllegalStateException ("PKCS1 failed to pad input! "
78 + "input=" + String.valueOf(inByteLen)
79 + " padding=" + String.valueOf(padLen));
80 }
81
82 byte[] padBytes = new byte[ (padLen - inByteLen - 3) + 1];
83 padBytes[0] = 0;
84
85 for (int i = 1; i < (padLen - inByteLen - 3 + 1); i++) {
86 if (type == 0x01) {
87 padBytes[i] = (byte) 0xff;
88 }
89 else {
90 byte[] b = new byte[1];
91 do {
92 SecureRandom.getInstance().nextBytes(b);
93 }
94 while (b[0] == 0);
95 padBytes[i] = b[0];
96 }
97 }
98
99 rndInt = new BigInteger (1, padBytes);
100 rndInt = rndInt.shiftLeft( (inByteLen + 1) * 8);
101 result = BigInteger.valueOf(type);
102 result = result.shiftLeft( (padLen - 2) * 8);
103 result = result.or(rndInt);
104 result = result.or(input);
105
106 return result;
107 }
108
109 public static BigInteger removePKCS1(BigInteger input, int type) throws
110 IllegalStateException {
111 byte[] strip = input.toByteArray();
112 byte[] val;
113 int i;
114
115 if (strip[0] != type) {
116 throw new IllegalStateException ("PKCS1 padding type " +
117 type + " is not valid");
118 }
119
120 for (i = 1; i < strip.length; i++) {
121 if (strip[i] == 0) {
122 break;
123 }
124 if (type == 0x01 && strip[i] != (byte) 0xff) {
125 throw new IllegalStateException ("Corrupt data found in expected PKSC1 padding");
126 }
127 }
128
129 if (i == strip.length) {
130 throw new IllegalStateException ("Corrupt data found in expected PKSC1 padding");
131 }
132
133 val = new byte[strip.length - i];
134 System.arraycopy(strip, i, val, 0, val.length);
135 return new BigInteger (1, val);
136 }
137
138 public static RsaPrivateCrtKey generateKey(int bits, SecureRandom secRand) {
139 return generateKey(bits, BigInteger.valueOf(0x10001L), secRand);
140 }
141
142 public static RsaPrivateCrtKey generateKey(int bits, BigInteger e,
143 SecureRandom secRand) {
144 BigInteger p = null;
145 BigInteger q = null;
146 BigInteger t = null;
147 BigInteger phi = null;
148 BigInteger d = null;
149 BigInteger u = null;
150 BigInteger n = null;
151 boolean finished = false;
152 BigInteger ONE = BigInteger.valueOf(1);
153
154 int pbits = (bits + 1) / 2;
155 int qbits = bits - pbits;
156
157 while (!finished) {
158 p = new BigInteger (pbits, 80, secRand);
159 q = new BigInteger (qbits, 80, secRand);
160
161 if (p.compareTo(q) == 0) {
162 continue;
163 }
164 else if (p.compareTo(q) < 0) {
165 t = q;
166 q = p;
167 p = t;
168 }
169
170 if (!p.isProbablePrime(25))
171 continue;
172
173 if(!q.isProbablePrime(25))
174 continue;
175
176 t = p.gcd(q);
177 if (t.compareTo(ONE) != 0) {
178 continue;
179 }
180
181 n = p.multiply(q);
182
183 if (n.bitLength() != bits) {
184 continue;
185 }
186
187 phi = p.subtract(ONE).multiply(q.subtract(ONE));
188 d = e.modInverse(phi);
189 u = q.modInverse(p);
190
191 finished = true;
192 }
193
194 return new RsaPrivateCrtKey(n, e, d, p, q,
195 Rsa.getPrimeExponent(d, p),
196 Rsa.getPrimeExponent(d, q),
197 u);
198
199
200 }
201
202 public static BigInteger doPublic(BigInteger input, BigInteger modulus,
203 BigInteger publicExponent) {
204 return input.modPow(publicExponent, modulus);
205 }
206
207 public static BigInteger doPrivate(BigInteger input, BigInteger modulus,
208 BigInteger privateExponent) {
209 return doPublic(input, modulus, privateExponent);
210 }
211
212 }
213 |
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