key3
clen = key3(key, ctext_ex);
static DES_cblock key3 = {0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0, 0x12, 0x34};
DES_set_key_unchecked(&key3, &sch3);
u_char key3[16];
memset(key3, 0xaa, sizeof(key3));
hmac_test(key3, sizeof(key3), data3, sizeof(data3), dig3, sizeof(dig3));