如何获取Amazon S3 HTTP请求的签名？

Question

我正在跟踪此示例https://docs.aws.amazon.com/AmazonS3/latest/dev/ObjectsinRequesterPaysBuckets.html，在该示例中可以看到这样的GET请求：

GET / [destinationObject] HTTP/1.1
Host: [BucketName].s3.amazonaws.com
x-amz-request-payer : requester
Date: Wed, 01 Mar 2009 12:00:00 GMT
Authorization: AWS [Signature]

此外，如果我们遵循此https://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html#RESTAuthenticationConstructingCanonicalizedAmzHeaders，则可以看到这样的GET请求：

GET /photos/puppy.jpg HTTP/1.1
Host: johnsmith.s3.amazonaws.com
Date: Tue, 27 Mar 2007 19:36:42 +0000

Authorization: AWS AKIAIOSFODNN7EXAMPLE:
bWq2s1WEIj+Ydj0vQ697zp+IXMU=

如果AKIAIOSFODNN7EXAMPLE是AWSAccessKeyId，那么如何生成bWq2s1WEIj+Ydj0vQ697zp+IXMU=？