001: package org.bouncycastle.crypto.engines;
002:
003: import org.bouncycastle.crypto.BlockCipher;
004: import org.bouncycastle.crypto.CipherParameters;
005: import org.bouncycastle.crypto.DataLengthException;
006: import org.bouncycastle.crypto.params.KeyParameter;
007:
008: /**
009: * a class that provides a basic SKIPJACK engine.
010: */
011: public class SkipjackEngine implements BlockCipher {
012: static final int BLOCK_SIZE = 8;
013:
014: static short ftable[] = { 0xa3, 0xd7, 0x09, 0x83, 0xf8, 0x48, 0xf6,
015: 0xf4, 0xb3, 0x21, 0x15, 0x78, 0x99, 0xb1, 0xaf, 0xf9, 0xe7,
016: 0x2d, 0x4d, 0x8a, 0xce, 0x4c, 0xca, 0x2e, 0x52, 0x95, 0xd9,
017: 0x1e, 0x4e, 0x38, 0x44, 0x28, 0x0a, 0xdf, 0x02, 0xa0, 0x17,
018: 0xf1, 0x60, 0x68, 0x12, 0xb7, 0x7a, 0xc3, 0xe9, 0xfa, 0x3d,
019: 0x53, 0x96, 0x84, 0x6b, 0xba, 0xf2, 0x63, 0x9a, 0x19, 0x7c,
020: 0xae, 0xe5, 0xf5, 0xf7, 0x16, 0x6a, 0xa2, 0x39, 0xb6, 0x7b,
021: 0x0f, 0xc1, 0x93, 0x81, 0x1b, 0xee, 0xb4, 0x1a, 0xea, 0xd0,
022: 0x91, 0x2f, 0xb8, 0x55, 0xb9, 0xda, 0x85, 0x3f, 0x41, 0xbf,
023: 0xe0, 0x5a, 0x58, 0x80, 0x5f, 0x66, 0x0b, 0xd8, 0x90, 0x35,
024: 0xd5, 0xc0, 0xa7, 0x33, 0x06, 0x65, 0x69, 0x45, 0x00, 0x94,
025: 0x56, 0x6d, 0x98, 0x9b, 0x76, 0x97, 0xfc, 0xb2, 0xc2, 0xb0,
026: 0xfe, 0xdb, 0x20, 0xe1, 0xeb, 0xd6, 0xe4, 0xdd, 0x47, 0x4a,
027: 0x1d, 0x42, 0xed, 0x9e, 0x6e, 0x49, 0x3c, 0xcd, 0x43, 0x27,
028: 0xd2, 0x07, 0xd4, 0xde, 0xc7, 0x67, 0x18, 0x89, 0xcb, 0x30,
029: 0x1f, 0x8d, 0xc6, 0x8f, 0xaa, 0xc8, 0x74, 0xdc, 0xc9, 0x5d,
030: 0x5c, 0x31, 0xa4, 0x70, 0x88, 0x61, 0x2c, 0x9f, 0x0d, 0x2b,
031: 0x87, 0x50, 0x82, 0x54, 0x64, 0x26, 0x7d, 0x03, 0x40, 0x34,
032: 0x4b, 0x1c, 0x73, 0xd1, 0xc4, 0xfd, 0x3b, 0xcc, 0xfb, 0x7f,
033: 0xab, 0xe6, 0x3e, 0x5b, 0xa5, 0xad, 0x04, 0x23, 0x9c, 0x14,
034: 0x51, 0x22, 0xf0, 0x29, 0x79, 0x71, 0x7e, 0xff, 0x8c, 0x0e,
035: 0xe2, 0x0c, 0xef, 0xbc, 0x72, 0x75, 0x6f, 0x37, 0xa1, 0xec,
036: 0xd3, 0x8e, 0x62, 0x8b, 0x86, 0x10, 0xe8, 0x08, 0x77, 0x11,
037: 0xbe, 0x92, 0x4f, 0x24, 0xc5, 0x32, 0x36, 0x9d, 0xcf, 0xf3,
038: 0xa6, 0xbb, 0xac, 0x5e, 0x6c, 0xa9, 0x13, 0x57, 0x25, 0xb5,
039: 0xe3, 0xbd, 0xa8, 0x3a, 0x01, 0x05, 0x59, 0x2a, 0x46 };
040:
041: private int[] key0, key1, key2, key3;
042: private boolean encrypting;
043:
044: /**
045: * initialise a SKIPJACK cipher.
046: *
047: * @param encrypting whether or not we are for encryption.
048: * @param params the parameters required to set up the cipher.
049: * @exception IllegalArgumentException if the params argument is
050: * inappropriate.
051: */
052: public void init(boolean encrypting, CipherParameters params) {
053: if (!(params instanceof KeyParameter)) {
054: throw new IllegalArgumentException(
055: "invalid parameter passed to SKIPJACK init - "
056: + params.getClass().getName());
057: }
058:
059: byte[] keyBytes = ((KeyParameter) params).getKey();
060:
061: this .encrypting = encrypting;
062: this .key0 = new int[32];
063: this .key1 = new int[32];
064: this .key2 = new int[32];
065: this .key3 = new int[32];
066:
067: //
068: // expand the key to 128 bytes in 4 parts (saving us a modulo, multiply
069: // and an addition).
070: //
071: for (int i = 0; i < 32; i++) {
072: key0[i] = keyBytes[(i * 4) % 10] & 0xff;
073: key1[i] = keyBytes[(i * 4 + 1) % 10] & 0xff;
074: key2[i] = keyBytes[(i * 4 + 2) % 10] & 0xff;
075: key3[i] = keyBytes[(i * 4 + 3) % 10] & 0xff;
076: }
077: }
078:
079: public String getAlgorithmName() {
080: return "SKIPJACK";
081: }
082:
083: public int getBlockSize() {
084: return BLOCK_SIZE;
085: }
086:
087: public int processBlock(byte[] in, int inOff, byte[] out, int outOff) {
088: if (key1 == null) {
089: throw new IllegalStateException(
090: "SKIPJACK engine not initialised");
091: }
092:
093: if ((inOff + BLOCK_SIZE) > in.length) {
094: throw new DataLengthException("input buffer too short");
095: }
096:
097: if ((outOff + BLOCK_SIZE) > out.length) {
098: throw new DataLengthException("output buffer too short");
099: }
100:
101: if (encrypting) {
102: encryptBlock(in, inOff, out, outOff);
103: } else {
104: decryptBlock(in, inOff, out, outOff);
105: }
106:
107: return BLOCK_SIZE;
108: }
109:
110: public void reset() {
111: }
112:
113: /**
114: * The G permutation
115: */
116: private int g(int k, int w) {
117: int g1, g2, g3, g4, g5, g6;
118:
119: g1 = (w >> 8) & 0xff;
120: g2 = w & 0xff;
121:
122: g3 = ftable[g2 ^ key0[k]] ^ g1;
123: g4 = ftable[g3 ^ key1[k]] ^ g2;
124: g5 = ftable[g4 ^ key2[k]] ^ g3;
125: g6 = ftable[g5 ^ key3[k]] ^ g4;
126:
127: return ((g5 << 8) + g6);
128: }
129:
130: public int encryptBlock(byte[] in, int inOff, byte[] out, int outOff) {
131: int w1 = (in[inOff + 0] << 8) + (in[inOff + 1] & 0xff);
132: int w2 = (in[inOff + 2] << 8) + (in[inOff + 3] & 0xff);
133: int w3 = (in[inOff + 4] << 8) + (in[inOff + 5] & 0xff);
134: int w4 = (in[inOff + 6] << 8) + (in[inOff + 7] & 0xff);
135:
136: int k = 0;
137:
138: for (int t = 0; t < 2; t++) {
139: for (int i = 0; i < 8; i++) {
140: int tmp = w4;
141: w4 = w3;
142: w3 = w2;
143: w2 = g(k, w1);
144: w1 = w2 ^ tmp ^ (k + 1);
145: k++;
146: }
147:
148: for (int i = 0; i < 8; i++) {
149: int tmp = w4;
150: w4 = w3;
151: w3 = w1 ^ w2 ^ (k + 1);
152: w2 = g(k, w1);
153: w1 = tmp;
154: k++;
155: }
156: }
157:
158: out[outOff + 0] = (byte) ((w1 >> 8));
159: out[outOff + 1] = (byte) (w1);
160: out[outOff + 2] = (byte) ((w2 >> 8));
161: out[outOff + 3] = (byte) (w2);
162: out[outOff + 4] = (byte) ((w3 >> 8));
163: out[outOff + 5] = (byte) (w3);
164: out[outOff + 6] = (byte) ((w4 >> 8));
165: out[outOff + 7] = (byte) (w4);
166:
167: return BLOCK_SIZE;
168: }
169:
170: /**
171: * the inverse of the G permutation.
172: */
173: private int h(int k, int w) {
174: int h1, h2, h3, h4, h5, h6;
175:
176: h1 = w & 0xff;
177: h2 = (w >> 8) & 0xff;
178:
179: h3 = ftable[h2 ^ key3[k]] ^ h1;
180: h4 = ftable[h3 ^ key2[k]] ^ h2;
181: h5 = ftable[h4 ^ key1[k]] ^ h3;
182: h6 = ftable[h5 ^ key0[k]] ^ h4;
183:
184: return ((h6 << 8) + h5);
185: }
186:
187: public int decryptBlock(byte[] in, int inOff, byte[] out, int outOff) {
188: int w2 = (in[inOff + 0] << 8) + (in[inOff + 1] & 0xff);
189: int w1 = (in[inOff + 2] << 8) + (in[inOff + 3] & 0xff);
190: int w4 = (in[inOff + 4] << 8) + (in[inOff + 5] & 0xff);
191: int w3 = (in[inOff + 6] << 8) + (in[inOff + 7] & 0xff);
192:
193: int k = 31;
194:
195: for (int t = 0; t < 2; t++) {
196: for (int i = 0; i < 8; i++) {
197: int tmp = w4;
198: w4 = w3;
199: w3 = w2;
200: w2 = h(k, w1);
201: w1 = w2 ^ tmp ^ (k + 1);
202: k--;
203: }
204:
205: for (int i = 0; i < 8; i++) {
206: int tmp = w4;
207: w4 = w3;
208: w3 = w1 ^ w2 ^ (k + 1);
209: w2 = h(k, w1);
210: w1 = tmp;
211: k--;
212: }
213: }
214:
215: out[outOff + 0] = (byte) ((w2 >> 8));
216: out[outOff + 1] = (byte) (w2);
217: out[outOff + 2] = (byte) ((w1 >> 8));
218: out[outOff + 3] = (byte) (w1);
219: out[outOff + 4] = (byte) ((w4 >> 8));
220: out[outOff + 5] = (byte) (w4);
221: out[outOff + 6] = (byte) ((w3 >> 8));
222: out[outOff + 7] = (byte) (w3);
223:
224: return BLOCK_SIZE;
225: }
226: }
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