4100身份认证失败，用户身份验证失败

from hashlib import sha1

import httplib, urllib,datetime,base64,hmac,random,time,math

SecretId='AKIDT8G5AsY1D3MChWooNq1rFSw1fyBVCX9D'

SecretKey='pxPgRWDbCy86ZYyqBTDk7WmeRZSmPco0'

keyArr=['limit', 'Nonce','SecretId', 'Action','Timestamp',"offset"]

keyArr.sort()

print(keyArr)

dict={

'Action' : 'DescribeCdnHosts',

'Nonce':random.randint(999999,9999999),

'SecretId' : SecretId,

'Timestamp' : int(time.time()),

'limit' : 10,

'offset' : 0

}

print(dict['Action'])

signSrc=''

for index in keyArr:

print(index)

signSrc=signSrc+"&"+index+'='+str(dict[index])

signSrc=signSrc[1:]

signSrc='POSTcdn.api.qcloud.com/v2/index.php?'+signSrc

print(signSrc)

my_sign = hmac.new(SecretKey,signSrc , sha1).digest()

my_sign = base64.b64encode(my_sign)

print(my_sign)

my_sign=urllib.urlencode({'1':my_sign})

print(my_sign)

sign=my_sign[2:]

print(sign)

dict['Signature']=sign

print(dict)

params = urllib.urlencode(dict)

headers = {"Content-type": "application/x-www-form-urlencoded"}

conn = httplib.HTTPSConnection("cdn.api.qcloud.com")

conn.request("POST", "/v2/index.php", params, headers)

response = conn.getresponse()

print response.status, response.reason

data = response.read()

print data

conn.close()

签名生成和例子里面一模一样，但是改成自己的参数就是身份认证失败啊啊啊啊啊啊