void des_3cbc_encrypt(des_cblock *input,des_cblock *output,long length,
des_key_schedule sk1,des_key_schedule sk2,
des_cblock *ivec1,des_cblock *ivec2,int enc);
void des_3cbc_encrypt(des_cblock *input,des_cblock *output,long length,
des_key_schedule sk1,des_key_schedule sk2,
des_cblock *ivec1,des_cblock *ivec2,int enc);