md5( timestamp + App Key ) = md5( 1453014943466UtOCzqb67d3sN12Kts4URwy8 )= d5bcbb897e19b2f6633c716dfdfaf9be + -H "X-LC-Sign: d5bcbb897e19b2f6633c716dfdfaf9be,1453014943466" \ 1. 使用Master Key 来计算 sign: + md5( timestamp + Master Key )= md5( 1453014943466DyJegPlemooo...