| 89 | # endif |
| 90 | |
| 91 | static int crypthead(const char* passwd, /* password string */ |
| 92 | unsigned char* buf, /* where to write header */ |
| 93 | int bufSize, |
| 94 | unsigned long* pkeys, |
| 95 | const z_crc_t* pcrc_32_tab, |
| 96 | unsigned long crcForCrypting) |
| 97 | { |
| 98 | int n; /* index in random header */ |
| 99 | int t; /* temporary */ |
| 100 | int c; /* random byte */ |
| 101 | unsigned char header[RAND_HEAD_LEN - 2]; /* random header */ |
| 102 | static unsigned calls = 0; /* ensure different random header each time */ |
| 103 | |
| 104 | if (bufSize < RAND_HEAD_LEN) |
| 105 | return 0; |
| 106 | |
| 107 | /* First generate RAND_HEAD_LEN-2 random bytes. We encrypt the |
| 108 | * output of rand() to get less predictability, since rand() is |
| 109 | * often poorly implemented. |
| 110 | */ |
| 111 | if (++calls == 1) |
| 112 | { |
| 113 | srand((unsigned)(time(NULL) ^ ZCR_SEED2)); |
| 114 | } |
| 115 | init_keys(passwd, pkeys, pcrc_32_tab); |
| 116 | for (n = 0; n < RAND_HEAD_LEN - 2; n++) |
| 117 | { |
| 118 | c = (rand() >> 7) & 0xff; |
| 119 | header[n] = (unsigned char)zencode(pkeys, pcrc_32_tab, c, t); |
| 120 | } |
| 121 | /* Encrypt random header (last two bytes is high word of crc) */ |
| 122 | init_keys(passwd, pkeys, pcrc_32_tab); |
| 123 | for (n = 0; n < RAND_HEAD_LEN - 2; n++) |
| 124 | { |
| 125 | buf[n] = (unsigned char)zencode(pkeys, pcrc_32_tab, header[n], t); |
| 126 | } |
| 127 | buf[n++] = (unsigned char)zencode(pkeys, pcrc_32_tab, (int)(crcForCrypting >> 16) & 0xff, t); |
| 128 | buf[n++] = (unsigned char)zencode(pkeys, pcrc_32_tab, (int)(crcForCrypting >> 24) & 0xff, t); |
| 129 | return n; |
| 130 | } |
| 131 | |
| 132 | #endif |