1 package org.bouncycastle.crypto.engines;
2 
3 import org.bouncycastle.crypto.BlockCipher;
4 import org.bouncycastle.crypto.CipherParameters;
5 import org.bouncycastle.crypto.DataLengthException;
6 import org.bouncycastle.crypto.OutputLengthException;
7 import org.bouncycastle.crypto.params.KeyParameter;
8 import org.bouncycastle.util.Pack;
9 
10 /**
11  * SM4 Block Cipher - SM4 is a 128 bit block cipher with a 128 bit key.
12  * <p>
13  *     The implementation here is based on the document <a href="http://eprint.iacr.org/2008/329.pdf">http://eprint.iacr.org/2008/329.pdf</a>
14  *     by Whitfield Diffie and George Ledin, which is a translation of Prof. LU Shu-wang's original standard.
15  * </p>
16  */
17 public class SM4Engine
18     implements BlockCipher
19 {
20     private static final int BLOCK_SIZE = 16;
21 
22     private final static byte[] Sbox =
23     {
24         (byte)0xd6, (byte)0x90, (byte)0xe9, (byte)0xfe, (byte)0xcc, (byte)0xe1, (byte)0x3d, (byte)0xb7, (byte)0x16, (byte)0xb6, (byte)0x14, (byte)0xc2, (byte)0x28, (byte)0xfb, (byte)0x2c, (byte)0x05,
25         (byte)0x2b, (byte)0x67, (byte)0x9a, (byte)0x76, (byte)0x2a, (byte)0xbe, (byte)0x04, (byte)0xc3, (byte)0xaa, (byte)0x44, (byte)0x13, (byte)0x26, (byte)0x49, (byte)0x86, (byte)0x06, (byte)0x99,
26         (byte)0x9c, (byte)0x42, (byte)0x50, (byte)0xf4, (byte)0x91, (byte)0xef, (byte)0x98, (byte)0x7a, (byte)0x33, (byte)0x54, (byte)0x0b, (byte)0x43, (byte)0xed, (byte)0xcf, (byte)0xac, (byte)0x62,
27         (byte)0xe4, (byte)0xb3, (byte)0x1c, (byte)0xa9, (byte)0xc9, (byte)0x08, (byte)0xe8, (byte)0x95, (byte)0x80, (byte)0xdf, (byte)0x94, (byte)0xfa, (byte)0x75, (byte)0x8f, (byte)0x3f, (byte)0xa6,
28         (byte)0x47, (byte)0x07, (byte)0xa7, (byte)0xfc, (byte)0xf3, (byte)0x73, (byte)0x17, (byte)0xba, (byte)0x83, (byte)0x59, (byte)0x3c, (byte)0x19, (byte)0xe6, (byte)0x85, (byte)0x4f, (byte)0xa8,
29         (byte)0x68, (byte)0x6b, (byte)0x81, (byte)0xb2, (byte)0x71, (byte)0x64, (byte)0xda, (byte)0x8b, (byte)0xf8, (byte)0xeb, (byte)0x0f, (byte)0x4b, (byte)0x70, (byte)0x56, (byte)0x9d, (byte)0x35,
30         (byte)0x1e, (byte)0x24, (byte)0x0e, (byte)0x5e, (byte)0x63, (byte)0x58, (byte)0xd1, (byte)0xa2, (byte)0x25, (byte)0x22, (byte)0x7c, (byte)0x3b, (byte)0x01, (byte)0x21, (byte)0x78, (byte)0x87,
31         (byte)0xd4, (byte)0x00, (byte)0x46, (byte)0x57, (byte)0x9f, (byte)0xd3, (byte)0x27, (byte)0x52, (byte)0x4c, (byte)0x36, (byte)0x02, (byte)0xe7, (byte)0xa0, (byte)0xc4, (byte)0xc8, (byte)0x9e,
32         (byte)0xea, (byte)0xbf, (byte)0x8a, (byte)0xd2, (byte)0x40, (byte)0xc7, (byte)0x38, (byte)0xb5, (byte)0xa3, (byte)0xf7, (byte)0xf2, (byte)0xce, (byte)0xf9, (byte)0x61, (byte)0x15, (byte)0xa1,
33         (byte)0xe0, (byte)0xae, (byte)0x5d, (byte)0xa4, (byte)0x9b, (byte)0x34, (byte)0x1a, (byte)0x55, (byte)0xad, (byte)0x93, (byte)0x32, (byte)0x30, (byte)0xf5, (byte)0x8c, (byte)0xb1, (byte)0xe3,
34         (byte)0x1d, (byte)0xf6, (byte)0xe2, (byte)0x2e, (byte)0x82, (byte)0x66, (byte)0xca, (byte)0x60, (byte)0xc0, (byte)0x29, (byte)0x23, (byte)0xab, (byte)0x0d, (byte)0x53, (byte)0x4e, (byte)0x6f,
35         (byte)0xd5, (byte)0xdb, (byte)0x37, (byte)0x45, (byte)0xde, (byte)0xfd, (byte)0x8e, (byte)0x2f, (byte)0x03, (byte)0xff, (byte)0x6a, (byte)0x72, (byte)0x6d, (byte)0x6c, (byte)0x5b, (byte)0x51,
36         (byte)0x8d, (byte)0x1b, (byte)0xaf, (byte)0x92, (byte)0xbb, (byte)0xdd, (byte)0xbc, (byte)0x7f, (byte)0x11, (byte)0xd9, (byte)0x5c, (byte)0x41, (byte)0x1f, (byte)0x10, (byte)0x5a, (byte)0xd8,
37         (byte)0x0a, (byte)0xc1, (byte)0x31, (byte)0x88, (byte)0xa5, (byte)0xcd, (byte)0x7b, (byte)0xbd, (byte)0x2d, (byte)0x74, (byte)0xd0, (byte)0x12, (byte)0xb8, (byte)0xe5, (byte)0xb4, (byte)0xb0,
38         (byte)0x89, (byte)0x69, (byte)0x97, (byte)0x4a, (byte)0x0c, (byte)0x96, (byte)0x77, (byte)0x7e, (byte)0x65, (byte)0xb9, (byte)0xf1, (byte)0x09, (byte)0xc5, (byte)0x6e, (byte)0xc6, (byte)0x84,
39         (byte)0x18, (byte)0xf0, (byte)0x7d, (byte)0xec, (byte)0x3a, (byte)0xdc, (byte)0x4d, (byte)0x20, (byte)0x79, (byte)0xee, (byte)0x5f, (byte)0x3e, (byte)0xd7, (byte)0xcb, (byte)0x39, (byte)0x48
40     };
41 
42     private final static int[] CK =
43     {
44         0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269,
45         0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9,
46         0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249,
47         0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9,
48         0xc0c7ced5, 0xdce3eaf1, 0xf8ff060d, 0x141b2229,
49         0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299,
50         0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209,
51         0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279
52     };
53 
54     private final static int[] FK =
55     {
56         0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc
57     };
58 
59     private final int[] X = new int[4];
60 
61     private int[] rk;
62 
rotateLeft( int x, int bits)63     private int rotateLeft(
64         int x,
65         int bits)
66     {
67         return (x << bits) | (x >>> -bits);
68     }
69 
70     // non-linear substitution tau.
tau( int A)71     private int tau(
72         int A)
73     {
74         int b0 = Sbox[(A >> 24) & 0xff] & 0xff;
75         int b1 = Sbox[(A >> 16) & 0xff] & 0xff;
76         int b2 = Sbox[(A >> 8) & 0xff] & 0xff;
77         int b3 = Sbox[A & 0xff] & 0xff;
78 
79         return (b0 << 24) | (b1 << 16) | (b2 << 8) | b3;
80     }
81 
L_ap( int B)82     private int L_ap(
83         int B)
84     {
85         return (B ^ (rotateLeft(B, 13)) ^ (rotateLeft(B, 23)));
86     }
87 
T_ap( int Z)88     private int T_ap(
89         int Z)
90     {
91         return L_ap(tau(Z));
92     }
93 
94     // Key expansion
expandKey(boolean forEncryption, byte[] key)95     private int[] expandKey(boolean forEncryption, byte[] key)
96     {
97         int[] rk = new int[32];
98         int[] MK = new int[4];
99 
100         MK[0] = Pack.bigEndianToInt(key, 0);
101         MK[1] = Pack.bigEndianToInt(key, 4);
102         MK[2] = Pack.bigEndianToInt(key, 8);
103         MK[3] = Pack.bigEndianToInt(key, 12);
104 
105         int i;
106         int[] K = new int[4];
107         K[0] = MK[0] ^ FK[0];
108         K[1] = MK[1] ^ FK[1];
109         K[2] = MK[2] ^ FK[2];
110         K[3] = MK[3] ^ FK[3];
111 
112         if (forEncryption)
113         {
114             rk[0] = K[0] ^ T_ap(K[1] ^ K[2] ^ K[3] ^ CK[0]);
115             rk[1] = K[1] ^ T_ap(K[2] ^ K[3] ^ rk[0] ^ CK[1]);
116             rk[2] = K[2] ^ T_ap(K[3] ^ rk[0] ^ rk[1] ^ CK[2]);
117             rk[3] = K[3] ^ T_ap(rk[0] ^ rk[1] ^ rk[2] ^ CK[3]);
118             for (i = 4; i < 32; i++)
119             {
120                 rk[i] = rk[i - 4] ^ T_ap(rk[i - 3] ^ rk[i - 2] ^ rk[i - 1] ^ CK[i]);
121             }
122         }
123         else
124         {
125             rk[31] = K[0] ^ T_ap(K[1] ^ K[2] ^ K[3] ^ CK[0]);
126             rk[30] = K[1] ^ T_ap(K[2] ^ K[3] ^ rk[31] ^ CK[1]);
127             rk[29] = K[2] ^ T_ap(K[3] ^ rk[31] ^ rk[30] ^ CK[2]);
128             rk[28] = K[3] ^ T_ap(rk[31] ^ rk[30] ^ rk[29] ^ CK[3]);
129             for (i = 27; i >= 0; i--)
130             {
131                 rk[i] = rk[i + 4] ^ T_ap(rk[i + 3] ^ rk[i + 2] ^ rk[i + 1] ^ CK[31 - i]);
132             }
133         }
134 
135         return rk;
136     }
137 
138 
139     // Linear substitution L
L(int B)140     private int L(int B)
141     {
142         int C;
143         C = (B ^ (rotateLeft(B, 2)) ^ (rotateLeft(B, 10)) ^ (rotateLeft(B,
144             18)) ^ (rotateLeft(B, 24)));
145         return C;
146     }
147 
148     // Mixer-substitution T
T(int Z)149     private int T(int Z)
150     {
151         return L(tau(Z));
152     }
153 
154     // The round functions
F0(int[] X, int rk)155     private int F0(int[] X, int rk)
156     {
157         return (X[0] ^ T(X[1] ^ X[2] ^ X[3] ^ rk));
158     }
159 
F1(int[] X, int rk)160     private int F1(int[] X, int rk)
161     {
162         return (X[1] ^ T(X[2] ^ X[3] ^ X[0] ^ rk));
163     }
164 
F2(int[] X, int rk)165     private int F2(int[] X, int rk)
166     {
167         return (X[2] ^ T(X[3] ^ X[0] ^ X[1] ^ rk));
168     }
169 
F3(int[] X, int rk)170     private int F3(int[] X, int rk)
171     {
172         return (X[3] ^ T(X[0] ^ X[1] ^ X[2] ^ rk));
173     }
174 
init(boolean forEncryption, CipherParameters params)175     public void init(boolean forEncryption, CipherParameters params)
176         throws IllegalArgumentException
177     {
178         if (params instanceof KeyParameter)
179         {
180             byte[] key = ((KeyParameter)params).getKey();
181 
182             if (key.length != 16)
183             {
184                 throw new IllegalArgumentException("SM4 requires a 128 bit key");
185             }
186 
187             rk = expandKey(forEncryption, key);
188         }
189         else
190         {
191             throw new IllegalArgumentException("invalid parameter passed to SM4 init - " + params.getClass().getName());
192         }
193     }
194 
getAlgorithmName()195     public String getAlgorithmName()
196     {
197         return "SM4";
198     }
199 
getBlockSize()200     public int getBlockSize()
201     {
202         return BLOCK_SIZE;
203     }
204 
processBlock(byte[] in, int inOff, byte[] out, int outOff)205     public int processBlock(byte[] in, int inOff, byte[] out, int outOff)
206         throws DataLengthException, IllegalStateException
207     {
208         if (rk == null)
209         {
210             throw new IllegalStateException("SM4 not initialised");
211         }
212 
213         if ((inOff + BLOCK_SIZE) > in.length)
214         {
215             throw new DataLengthException("input buffer too short");
216         }
217 
218         if ((outOff + BLOCK_SIZE) > out.length)
219         {
220             throw new OutputLengthException("output buffer too short");
221         }
222 
223         X[0] = Pack.bigEndianToInt(in, inOff);
224         X[1] = Pack.bigEndianToInt(in, inOff + 4);
225         X[2] = Pack.bigEndianToInt(in, inOff + 8);
226         X[3] = Pack.bigEndianToInt(in, inOff + 12);
227 
228         int i;
229 
230         for (i = 0; i < 32; i += 4)
231         {
232             X[0] = F0(X, rk[i]);
233             X[1] = F1(X, rk[i + 1]);
234             X[2] = F2(X, rk[i + 2]);
235             X[3] = F3(X, rk[i + 3]);
236         }
237 
238         Pack.intToBigEndian(X[3], out, outOff);
239         Pack.intToBigEndian(X[2], out, outOff + 4);
240         Pack.intToBigEndian(X[1], out, outOff + 8);
241         Pack.intToBigEndian(X[0], out, outOff + 12);
242 
243         return BLOCK_SIZE;
244     }
245 
reset()246     public void reset()
247     {
248     }
249 }
250