| 0a886a1d |
1 | //----------------------------------------------------------------------------- |
| 2 | // This code is licensed to you under the terms of the GNU GPL, version 2 or, |
| 3 | // at your option, any later version. See the LICENSE.txt file for the text of |
| 4 | // the license. |
| 5 | //----------------------------------------------------------------------------- |
| 6 | // Generic TEA crypto code. |
| 7 | // ref: http://143.53.36.235:8080/source.htm#ansi |
| 8 | //----------------------------------------------------------------------------- |
| 9 | #include "tea.h" |
| 10 | #define ROUNDS 32 |
| 11 | #define DELTA 0x9E3779B9 |
| 12 | #define SUM 0xC6EF3720 |
| 13 | #define SWAPENDIAN(x)\ |
| 14 | (x = (x >> 8 & 0xff00ff) | (x & 0xff00ff) << 8, x = x >> 16 | x << 16) |
| 15 | |
| 16 | void tea_encrypt(uint8_t *v, uint8_t *key) { |
| 17 | |
| 18 | uint32_t a=0,b=0,c=0,d=0,y=0,z=0; |
| 19 | uint32_t sum = 0; |
| 20 | uint8_t n = ROUNDS; |
| 21 | |
| 22 | //key |
| 23 | a = bytes_to_num(key, 4); |
| 24 | b = bytes_to_num(key+4, 4); |
| 25 | c = bytes_to_num(key+8, 4); |
| 26 | d = bytes_to_num(key+12, 4); |
| 27 | |
| 28 | //input |
| 29 | y = bytes_to_num(v, 4); |
| 30 | z = bytes_to_num(v+4, 4); |
| 31 | |
| 32 | // SWAPENDIAN(a); |
| 33 | // SWAPENDIAN(b); |
| 34 | // SWAPENDIAN(c); |
| 35 | // SWAPENDIAN(d); |
| 36 | // SWAPENDIAN(y); |
| 37 | // SWAPENDIAN(z); |
| 38 | |
| 39 | while ( n-- > 0 ) { |
| 40 | sum += DELTA; |
| 41 | y += ((z << 4) + a) ^ (z + sum) ^ ((z >> 5) + b); |
| 42 | z += ((y << 4) + c) ^ (y + sum) ^ ((y >> 5) + d); |
| 43 | } |
| 44 | |
| 45 | // SWAPENDIAN(y); |
| 46 | // SWAPENDIAN(z); |
| 47 | |
| 48 | num_to_bytes(y, 4, v); |
| 49 | num_to_bytes(z, 4, v+4); |
| 50 | } |
| 51 | |
| 52 | void tea_decrypt(uint8_t *v, uint8_t *key) { |
| 53 | |
| 54 | uint32_t a=0,b=0,c=0,d=0,y=0,z=0; |
| 55 | uint32_t sum = SUM; |
| 56 | uint8_t n = ROUNDS; |
| 57 | |
| 58 | //key |
| 59 | a = bytes_to_num(key, 4); |
| 60 | b = bytes_to_num(key+4, 4); |
| 61 | c = bytes_to_num(key+8, 4); |
| 62 | d = bytes_to_num(key+12, 4); |
| 63 | |
| 64 | //input |
| 65 | y = bytes_to_num(v, 4); |
| 66 | z = bytes_to_num(v+4, 4); |
| 67 | |
| 68 | // SWAPENDIAN(a); |
| 69 | // SWAPENDIAN(b); |
| 70 | // SWAPENDIAN(c); |
| 71 | // SWAPENDIAN(d); |
| 72 | // SWAPENDIAN(y); |
| 73 | // SWAPENDIAN(z); |
| 74 | |
| 75 | /* sum = delta<<5, in general sum = delta * n */ |
| 76 | while ( n-- > 0 ) { |
| 77 | z -= ((y << 4) + c) ^ (y + sum) ^ ((y >> 5) + d); |
| 78 | y -= ((z << 4) + a) ^ (z + sum) ^ ((z >> 5) + b); |
| 79 | sum -= DELTA; |
| 80 | } |
| 81 | |
| 82 | // SWAPENDIAN(y); |
| 83 | // SWAPENDIAN(z); |
| 84 | num_to_bytes(y, 4, v); |
| 85 | num_to_bytes(z, 4, v+4); |
| 86 | } |
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