xref: /optee_os/core/lib/libtomcrypt/src/ciphers/xtea.c (revision 5a913ee74d3c71af2a2860ce8a4e7aeab2916f9b) 
1 // SPDX-License-Identifier: BSD-2-Clause
2 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
3  *
4  * LibTomCrypt is a library that provides various cryptographic
5  * algorithms in a highly modular and flexible manner.
6  *
7  * The library is free for all purposes without any express
8  * guarantee it works.
9  */
10 
11 /**
12   @file xtea.c
13   Implementation of LTC_XTEA, Tom St Denis
14 */
15 #include "tomcrypt_private.h"
16 
17 #ifdef LTC_XTEA
18 
19 const struct ltc_cipher_descriptor xtea_desc =
20 {
21     "xtea",
22     1,
23     16, 16, 8, 32,
24     &xtea_setup,
25     &xtea_ecb_encrypt,
26     &xtea_ecb_decrypt,
27     &xtea_test,
28     &xtea_done,
29     &xtea_keysize,
30     NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
31 };
32 
33 int xtea_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
34 {
35    ulong32 x, sum, K[4];
36 
37    LTC_ARGCHK(key != NULL);
38    LTC_ARGCHK(skey != NULL);
39 
40    /* check arguments */
41    if (keylen != 16) {
42       return CRYPT_INVALID_KEYSIZE;
43    }
44 
45    if (num_rounds != 0 && num_rounds != 32) {
46       return CRYPT_INVALID_ROUNDS;
47    }
48 
49    /* load key */
50    LOAD32H(K[0], key+0);
51    LOAD32H(K[1], key+4);
52    LOAD32H(K[2], key+8);
53    LOAD32H(K[3], key+12);
54 
55    for (x = sum = 0; x < 32; x++) {
56        skey->xtea.A[x] = (sum + K[sum&3]) & 0xFFFFFFFFUL;
57        sum = (sum + 0x9E3779B9UL) & 0xFFFFFFFFUL;
58        skey->xtea.B[x] = (sum + K[(sum>>11)&3]) & 0xFFFFFFFFUL;
59    }
60 
61 #ifdef LTC_CLEAN_STACK
62    zeromem(&K, sizeof(K));
63 #endif
64 
65    return CRYPT_OK;
66 }
67 
68 /**
69   Encrypts a block of text with LTC_XTEA
70   @param pt The input plaintext (8 bytes)
71   @param ct The output ciphertext (8 bytes)
72   @param skey The key as scheduled
73   @return CRYPT_OK if successful
74 */
75 int xtea_ecb_encrypt(const unsigned char *pt, unsigned char *ct, const symmetric_key *skey)
76 {
77    ulong32 y, z;
78    int r;
79 
80    LTC_ARGCHK(pt   != NULL);
81    LTC_ARGCHK(ct   != NULL);
82    LTC_ARGCHK(skey != NULL);
83 
84    LOAD32H(y, &pt[0]);
85    LOAD32H(z, &pt[4]);
86    for (r = 0; r < 32; r += 4) {
87        y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r])) & 0xFFFFFFFFUL;
88        z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r])) & 0xFFFFFFFFUL;
89 
90        y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+1])) & 0xFFFFFFFFUL;
91        z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+1])) & 0xFFFFFFFFUL;
92 
93        y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+2])) & 0xFFFFFFFFUL;
94        z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+2])) & 0xFFFFFFFFUL;
95 
96        y = (y + ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r+3])) & 0xFFFFFFFFUL;
97        z = (z + ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r+3])) & 0xFFFFFFFFUL;
98    }
99    STORE32H(y, &ct[0]);
100    STORE32H(z, &ct[4]);
101    return CRYPT_OK;
102 }
103 
104 /**
105   Decrypts a block of text with LTC_XTEA
106   @param ct The input ciphertext (8 bytes)
107   @param pt The output plaintext (8 bytes)
108   @param skey The key as scheduled
109   @return CRYPT_OK if successful
110 */
111 int xtea_ecb_decrypt(const unsigned char *ct, unsigned char *pt, const symmetric_key *skey)
112 {
113    ulong32 y, z;
114    int r;
115 
116    LTC_ARGCHK(pt   != NULL);
117    LTC_ARGCHK(ct   != NULL);
118    LTC_ARGCHK(skey != NULL);
119 
120    LOAD32H(y, &ct[0]);
121    LOAD32H(z, &ct[4]);
122    for (r = 31; r >= 0; r -= 4) {
123        z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r])) & 0xFFFFFFFFUL;
124        y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r])) & 0xFFFFFFFFUL;
125 
126        z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-1])) & 0xFFFFFFFFUL;
127        y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-1])) & 0xFFFFFFFFUL;
128 
129        z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-2])) & 0xFFFFFFFFUL;
130        y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-2])) & 0xFFFFFFFFUL;
131 
132        z = (z - ((((y<<4)^(y>>5)) + y) ^ skey->xtea.B[r-3])) & 0xFFFFFFFFUL;
133        y = (y - ((((z<<4)^(z>>5)) + z) ^ skey->xtea.A[r-3])) & 0xFFFFFFFFUL;
134    }
135    STORE32H(y, &pt[0]);
136    STORE32H(z, &pt[4]);
137    return CRYPT_OK;
138 }
139 
140 /**
141   Performs a self-test of the LTC_XTEA block cipher
142   @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled
143 */
144 int xtea_test(void)
145 {
146  #ifndef LTC_TEST
147     return CRYPT_NOP;
148  #else
149     static const struct {
150         unsigned char key[16], pt[8], ct[8];
151     } tests[] = {
152        {
153          { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
154            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
155          { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
156          { 0xde, 0xe9, 0xd4, 0xd8, 0xf7, 0x13, 0x1e, 0xd9 }
157        }, {
158          { 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x02,
159            0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x04 },
160          { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
161          { 0xa5, 0x97, 0xab, 0x41, 0x76, 0x01, 0x4d, 0x72 }
162        }, {
163          { 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x04,
164            0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 0x06 },
165          { 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x02 },
166          { 0xb1, 0xfd, 0x5d, 0xa9, 0xcc, 0x6d, 0xc9, 0xdc }
167        }, {
168          { 0x78, 0x69, 0x5a, 0x4b, 0x3c, 0x2d, 0x1e, 0x0f,
169            0xf0, 0xe1, 0xd2, 0xc3, 0xb4, 0xa5, 0x96, 0x87 },
170          { 0xf0, 0xe1, 0xd2, 0xc3, 0xb4, 0xa5, 0x96, 0x87 },
171          { 0x70, 0x4b, 0x31, 0x34, 0x47, 0x44, 0xdf, 0xab }
172        }, {
173          { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
174            0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
175          { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
176          { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 }
177        }, {
178          { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
179            0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
180          { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
181          { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 }
182        }, {
183          { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
184            0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
185          { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
186          { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
187        }, {
188          { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
189            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
190          { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
191          { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 }
192        }, {
193          { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
194            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
195          { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
196          { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d }
197        }, {
198          { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
199            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
200          { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 },
201          { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
202        }
203     };
204    unsigned char tmp[2][8];
205    symmetric_key skey;
206    int i, err, y;
207    for (i = 0; i < (int)(sizeof(tests)/sizeof(tests[0])); i++) {
208        zeromem(&skey, sizeof(skey));
209        if ((err = xtea_setup(tests[i].key, 16, 0, &skey)) != CRYPT_OK)  {
210           return err;
211        }
212        xtea_ecb_encrypt(tests[i].pt, tmp[0], &skey);
213        xtea_ecb_decrypt(tmp[0], tmp[1], &skey);
214 
215        if (compare_testvector(tmp[0], 8, tests[i].ct, 8, "XTEA Encrypt", i) != 0 ||
216              compare_testvector(tmp[1], 8, tests[i].pt, 8, "XTEA Decrypt", i) != 0) {
217           return CRYPT_FAIL_TESTVECTOR;
218        }
219 
220       /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
221       for (y = 0; y < 8; y++) tmp[0][y] = 0;
222       for (y = 0; y < 1000; y++) xtea_ecb_encrypt(tmp[0], tmp[0], &skey);
223       for (y = 0; y < 1000; y++) xtea_ecb_decrypt(tmp[0], tmp[0], &skey);
224       for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
225    } /* for */
226 
227    return CRYPT_OK;
228  #endif
229 }
230 
231 /** Terminate the context
232    @param skey    The scheduled key
233 */
234 void xtea_done(symmetric_key *skey)
235 {
236   LTC_UNUSED_PARAM(skey);
237 }
238 
239 /**
240   Gets suitable key size
241   @param keysize [in/out] The length of the recommended key (in bytes).  This function will store the suitable size back in this variable.
242   @return CRYPT_OK if the input key size is acceptable.
243 */
244 int xtea_keysize(int *keysize)
245 {
246    LTC_ARGCHK(keysize != NULL);
247    if (*keysize < 16) {
248       return CRYPT_INVALID_KEYSIZE;
249    }
250    *keysize = 16;
251    return CRYPT_OK;
252 }
253 
254 
255 #endif
256 
257 
258 
259 
260 /* ref:         $Format:%D$ */
261 /* git commit:  $Format:%H$ */
262 /* commit time: $Format:%ai$ */
263