如何为Amazon S3对象预签名URL，并使其在一周后过期？

如何解决如何为Amazon S3对象预签名URL，并使其在一周后过期？

根据guide，我已经指定了IAM用户凭证（访问密钥和秘密访问密钥），并使用如下所示的AWS Signature版本4生成了预签名的URL：

import random


def snakeEyes():
    # Simulate dice
    # Variables to store integers
    diceCount = 0
    diceSum = 0
    while(diceSum != 2):
        dice1 = random.randint(1,6)
        dice2 = random.randint(1,6)
        diceSum = dice1 + dice2
        diceCount = diceCount + 1

        # if both 1's - snake eyes
        if diceSum == 2:
            combo_name = "snake eyes"
        # if both 6's - Boxcars
        elif diceSum == 12:
            combo_name = "Boxcars"
        # if 7 --> natural
        elif diceSum == 7:
            combo_name = "natural"
        # if sum % 2 == 0 -- we got an even
        # if dice values are same -- "hard"
        # else - easy
        # turn the sum number into text number
        elif diceSum % 2 == 0:
            if dice1 == dice2:
                combo_name = "hard " + str(diceSum)
            else:
                combo_name = "easy " + str(diceSum)
        # else - have an odd number
        # figure out which odd name we are using
        else:
            if diceSum == 3:
                combo_name = "ace deuce"
            elif diceSum == 5:
                combo_name = "fever five"
            elif diceSum == 9:
                combo_name = "nina"
            elif diceSum == 11:
                combo_name = "yo-leven"

        # Print line with dice values and names
        print("Dice1: " + str(dice1) + "  Dice 2: " + str(dice2) + "   " + combo_name)

    print("The dice rolled " + str(diceCount) + " times before it got snake eyes.")


snakeEyes()

但是，该网址在6小时后仍然过期。我的代码有什么错误吗？或者我使用的证书不属于IAM用户吗？如何检查凭证类型（IAM用户或AWS IAM实例配置文件）？我只是遵循the steps来获取我的访问密钥和秘密访问密钥