Signature Version 4 完整签名过程的示例(Python) - Amazon 一般参考
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Signature Version 4 完整签名过程的示例(Python)

本节展示用 Python 编写的示例程序,这些程序阐释如何在Amazon中使用 Signature Version 4。我们特意将这些示例程序编写得很简单(仅使用极少 Python 特定功能),便于您更轻松地了解签署Amazon请求的完整过程。

注意

如果您使用的是 Amazon SDK 之一(包括 SDK for C++、SDK for Go、SDK for Java、Amazon SDK for JavaScript、Amazon SDK for .NET、SDK for PHP、SDK for Python (Boto3) 或 SDK for Ruby),您不必手动执行派生签名密钥和将身份验证信息添加到请求的步骤。这些软件开发工具包将为您执行这些工作。仅当您直接发出 HTTP 或 HTTPS 请求时,才需要您手动签署请求。

要使用这些示例程序,您需要:

  • 计算机上安装有 Python 2.x,您可以从 Python 站点获取。这些程序已使用 Python 2.7 和 3.6 测试过。

  • Python 请求,示例脚本使用此库发出 Web 请求。一种方便的 Python 程序包安装方法是使用 pip,它可从 Python 程序包索引站点获取程序包。然后,您可以在命令行上运行 requests 来安装 pip install requests

  • 环境变量中名为 AWS_ACCESS_KEY_IDAWS_SECRET_ACCESS_KEY 的访问密钥(访问密钥 ID 和私有访问密钥)。或者,您也可以在凭证文件中保存这些值,然后从这些文件中读取。作为最佳实践,我们建议您不要在代码中嵌入凭证。有关更多信息,请参阅亚马逊云科技一般参考中的管理Amazon访问密钥的最佳实践

以下示例使用 UTF-8 对规范请求和待签字符串进行编码,而签名版本 4 不需要您使用特定字符编码。不过,一些 Amazon 服务可能需要特定编码。有关更多信息,请参阅该服务的文档。

结合使用 GET 和 Authorization 标头 (Python)

以下示例说明了如何在不使用 SDK for Python (Boto3) 的情况下,使用 Amazon EC2 查询 API 发出请求。该请求发出 GET 请求,并使用 Authorization 标头将身份验证信息发送到Amazon。

# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. # SPDX-License-Identifier: Apache-2.0 """ Important The AWS SDKs sign API requests for you using the access key that you specify when you configure the SDK. When you use an SDK, you don’t need to learn how to sign API requests. We recommend that you use the AWS SDKs to send API requests, instead of writing your own code. The following example is a reference to help you get started if you have a need to write your own code to send and sign requests. The example is for reference only and is not maintained as functional code. """ # AWS Version 4 signing example # EC2 API (DescribeRegions) # See: http://docs.aws.amazon.com/general/latest/gr/sigv4_signing.html # This version makes a GET request and passes the signature # in the Authorization header. import sys, os, base64, datetime, hashlib, hmac import requests # pip install requests # ************* REQUEST VALUES ************* method = 'GET' service = 'ec2' host = 'ec2.amazonaws.com' region = 'us-east-1' endpoint = 'https://ec2.amazonaws.com' request_parameters = 'Action=DescribeRegions&Version=2013-10-15' # Key derivation functions. See: # http://docs.aws.amazon.com/general/latest/gr/signature-v4-examples.html#signature-v4-examples-python def sign(key, msg): return hmac.new(key, msg.encode('utf-8'), hashlib.sha256).digest() def getSignatureKey(key, dateStamp, regionName, serviceName): kDate = sign(('AWS4' + key).encode('utf-8'), dateStamp) kRegion = sign(kDate, regionName) kService = sign(kRegion, serviceName) kSigning = sign(kService, 'aws4_request') return kSigning # Read AWS access key from env. variables or configuration file. Best practice is NOT # to embed credentials in code. access_key = os.environ.get('AWS_ACCESS_KEY_ID') secret_key = os.environ.get('AWS_SECRET_ACCESS_KEY') if access_key is None or secret_key is None: print('No access key is available.') sys.exit() # Create a date for headers and the credential string t = datetime.datetime.utcnow() amzdate = t.strftime('%Y%m%dT%H%M%SZ') datestamp = t.strftime('%Y%m%d') # Date w/o time, used in credential scope # ************* TASK 1: CREATE A CANONICAL REQUEST ************* # http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html # Step 1 is to define the verb (GET, POST, etc.)--already done. # Step 2: Create canonical URI--the part of the URI from domain to query # string (use '/' if no path) canonical_uri = '/' # Step 3: Create the canonical query string. In this example (a GET request), # request parameters are in the query string. Query string values must # be URL-encoded (space=%20). The parameters must be sorted by name. # For this example, the query string is pre-formatted in the request_parameters variable. canonical_querystring = request_parameters # Step 4: Create the canonical headers and signed headers. Header names # must be trimmed and lowercase, and sorted in code point order from # low to high. Note that there is a trailing \n. canonical_headers = 'host:' + host + '\n' + 'x-amz-date:' + amzdate + '\n' # Step 5: Create the list of signed headers. This lists the headers # in the canonical_headers list, delimited with ";" and in alpha order. # Note: The request can include any headers; canonical_headers and # signed_headers lists those that you want to be included in the # hash of the request. "Host" and "x-amz-date" are always required. signed_headers = 'host;x-amz-date' # Step 6: Create payload hash (hash of the request body content). For GET # requests, the payload is an empty string (""). payload_hash = hashlib.sha256(('').encode('utf-8')).hexdigest() # Step 7: Combine elements to create canonical request canonical_request = method + '\n' + canonical_uri + '\n' + canonical_querystring + '\n' + canonical_headers + '\n' + signed_headers + '\n' + payload_hash # ************* TASK 2: CREATE THE STRING TO SIGN************* # Match the algorithm to the hashing algorithm you use, either SHA-1 or # SHA-256 (recommended) algorithm = 'AWS4-HMAC-SHA256' credential_scope = datestamp + '/' + region + '/' + service + '/' + 'aws4_request' string_to_sign = algorithm + '\n' + amzdate + '\n' + credential_scope + '\n' + hashlib.sha256(canonical_request.encode('utf-8')).hexdigest() # ************* TASK 3: CALCULATE THE SIGNATURE ************* # Create the signing key using the function defined above. signing_key = getSignatureKey(secret_key, datestamp, region, service) # Sign the string_to_sign using the signing_key signature = hmac.new(signing_key, (string_to_sign).encode('utf-8'), hashlib.sha256).hexdigest() # ************* TASK 4: ADD SIGNING INFORMATION TO THE REQUEST ************* # The signing information can be either in a query string value or in # a header named Authorization. This code shows how to use a header. # Create authorization header and add to request headers authorization_header = algorithm + ' ' + 'Credential=' + access_key + '/' + credential_scope + ', ' + 'SignedHeaders=' + signed_headers + ', ' + 'Signature=' + signature # The request can include any headers, but MUST include "host", "x-amz-date", # and (for this scenario) "Authorization". "host" and "x-amz-date" must # be included in the canonical_headers and signed_headers, as noted # earlier. Order here is not significant. # Python note: The 'host' header is added automatically by the Python 'requests' library. headers = {'x-amz-date':amzdate, 'Authorization':authorization_header} # ************* SEND THE REQUEST ************* request_url = endpoint + '?' + canonical_querystring print('\nBEGIN REQUEST++++++++++++++++++++++++++++++++++++') print('Request URL = ' + request_url) r = requests.get(request_url, headers=headers) print('\nRESPONSE++++++++++++++++++++++++++++++++++++') print('Response code: %d\n' % r.status_code) print(r.text)

使用 POST(Python)

以下示例说明了如何在不使用 SDK for Python (Boto3) 的情况下,使用 Amazon DynamoDB 查询 API 发出请求。该请求发出 POST 请求并在请求正文中将值传递给Amazon。身份验证信息是通过 Authorization 请求标头传递的。

# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. # SPDX-License-Identifier: Apache-2.0 """ Important The AWS SDKs sign API requests for you using the access key that you specify when you configure the SDK. When you use an SDK, you don’t need to learn how to sign API requests. We recommend that you use the AWS SDKs to send API requests, instead of writing your own code. The following example is a reference to help you get started if you have a need to write your own code to send and sign requests. The example is for reference only and is not maintained as functional code. """ # AWS Version 4 signing example # DynamoDB API (CreateTable) # See: http://docs.aws.amazon.com/general/latest/gr/sigv4_signing.html # This version makes a POST request and passes request parameters # in the body (payload) of the request. Auth information is passed in # an Authorization header. import sys, os, base64, datetime, hashlib, hmac import requests # pip install requests # ************* REQUEST VALUES ************* method = 'POST' service = 'dynamodb' host = 'dynamodb.us-west-2.amazonaws.com' region = 'us-west-2' endpoint = 'https://dynamodb.us-west-2.amazonaws.com/' # POST requests use a content type header. For DynamoDB, # the content is JSON. content_type = 'application/x-amz-json-1.0' # DynamoDB requires an x-amz-target header that has this format: # DynamoDB_<API version>.<operationName> amz_target = 'DynamoDB_20120810.CreateTable' # Request parameters for CreateTable--passed in a JSON block. request_parameters = '{' request_parameters += '"KeySchema": [{"KeyType": "HASH","AttributeName": "Id"}],' request_parameters += '"TableName": "TestTable","AttributeDefinitions": [{"AttributeName": "Id","AttributeType": "S"}],' request_parameters += '"ProvisionedThroughput": {"WriteCapacityUnits": 5,"ReadCapacityUnits": 5}' request_parameters += '}' # Key derivation functions. See: # http://docs.aws.amazon.com/general/latest/gr/signature-v4-examples.html#signature-v4-examples-python def sign(key, msg): return hmac.new(key, msg.encode("utf-8"), hashlib.sha256).digest() def getSignatureKey(key, date_stamp, regionName, serviceName): kDate = sign(('AWS4' + key).encode('utf-8'), date_stamp) kRegion = sign(kDate, regionName) kService = sign(kRegion, serviceName) kSigning = sign(kService, 'aws4_request') return kSigning # Read AWS access key from env. variables or configuration file. Best practice is NOT # to embed credentials in code. access_key = os.environ.get('AWS_ACCESS_KEY_ID') secret_key = os.environ.get('AWS_SECRET_ACCESS_KEY') if access_key is None or secret_key is None: print('No access key is available.') sys.exit() # Create a date for headers and the credential string t = datetime.datetime.utcnow() amz_date = t.strftime('%Y%m%dT%H%M%SZ') date_stamp = t.strftime('%Y%m%d') # Date w/o time, used in credential scope # ************* TASK 1: CREATE A CANONICAL REQUEST ************* # http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html # Step 1 is to define the verb (GET, POST, etc.)--already done. # Step 2: Create canonical URI--the part of the URI from domain to query # string (use '/' if no path) canonical_uri = '/' ## Step 3: Create the canonical query string. In this example, request # parameters are passed in the body of the request and the query string # is blank. canonical_querystring = '' # Step 4: Create the canonical headers. Header names must be trimmed # and lowercase, and sorted in code point order from low to high. # Note that there is a trailing \n. canonical_headers = 'content-type:' + content_type + '\n' + 'host:' + host + '\n' + 'x-amz-date:' + amz_date + '\n' + 'x-amz-target:' + amz_target + '\n' # Step 5: Create the list of signed headers. This lists the headers # in the canonical_headers list, delimited with ";" and in alpha order. # Note: The request can include any headers; canonical_headers and # signed_headers include those that you want to be included in the # hash of the request. "Host" and "x-amz-date" are always required. # For DynamoDB, content-type and x-amz-target are also required. signed_headers = 'content-type;host;x-amz-date;x-amz-target' # Step 6: Create payload hash. In this example, the payload (body of # the request) contains the request parameters. payload_hash = hashlib.sha256(request_parameters.encode('utf-8')).hexdigest() # Step 7: Combine elements to create canonical request canonical_request = method + '\n' + canonical_uri + '\n' + canonical_querystring + '\n' + canonical_headers + '\n' + signed_headers + '\n' + payload_hash # ************* TASK 2: CREATE THE STRING TO SIGN************* # Match the algorithm to the hashing algorithm you use, either SHA-1 or # SHA-256 (recommended) algorithm = 'AWS4-HMAC-SHA256' credential_scope = date_stamp + '/' + region + '/' + service + '/' + 'aws4_request' string_to_sign = algorithm + '\n' + amz_date + '\n' + credential_scope + '\n' + hashlib.sha256(canonical_request.encode('utf-8')).hexdigest() # ************* TASK 3: CALCULATE THE SIGNATURE ************* # Create the signing key using the function defined above. signing_key = getSignatureKey(secret_key, date_stamp, region, service) # Sign the string_to_sign using the signing_key signature = hmac.new(signing_key, (string_to_sign).encode('utf-8'), hashlib.sha256).hexdigest() # ************* TASK 4: ADD SIGNING INFORMATION TO THE REQUEST ************* # Put the signature information in a header named Authorization. authorization_header = algorithm + ' ' + 'Credential=' + access_key + '/' + credential_scope + ', ' + 'SignedHeaders=' + signed_headers + ', ' + 'Signature=' + signature # For DynamoDB, the request can include any headers, but MUST include "host", "x-amz-date", # "x-amz-target", "content-type", and "Authorization". Except for the authorization # header, the headers must be included in the canonical_headers and signed_headers values, as # noted earlier. Order here is not significant. # # Python note: The 'host' header is added automatically by the Python 'requests' library. headers = {'Content-Type':content_type, 'X-Amz-Date':amz_date, 'X-Amz-Target':amz_target, 'Authorization':authorization_header} # ************* SEND THE REQUEST ************* print('\nBEGIN REQUEST++++++++++++++++++++++++++++++++++++') print('Request URL = ' + endpoint) r = requests.post(endpoint, data=request_parameters, headers=headers) print('\nRESPONSE++++++++++++++++++++++++++++++++++++') print('Response code: %d\n' % r.status_code) print(r.text)

在查询字符串中结合使用 GET 和身份验证信息 (Python)

以下示例说明了如何在不使用 SDK for Python (Boto3) 的情况下,使用 IAM 查询 API 发出请求。该请求发出 GET 请求,并使用查询字符串传递参数和签名信息。

# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. # SPDX-License-Identifier: Apache-2.0 """ Important The AWS SDKs sign API requests for you using the access key that you specify when you configure the SDK. When you use an SDK, you don’t need to learn how to sign API requests. We recommend that you use the AWS SDKs to send API requests, instead of writing your own code. The following example is a reference to help you get started if you have a need to write your own code to send and sign requests. The example is for reference only and is not maintained as functional code. """ # AWS Version 4 signing example # IAM API (CreateUser) # See: http://docs.aws.amazon.com/general/latest/gr/sigv4_signing.html # This version makes a GET request and passes request parameters # and authorization information in the query string import sys, os, datetime, hashlib, hmac, urllib.parse import requests # pip install requests # ************* REQUEST VALUES ************* method = 'GET' service = 'iam' host = 'iam.amazonaws.com' region = 'us-east-1' endpoint = 'https://iam.amazonaws.com' # Key derivation functions. See: # http://docs.aws.amazon.com/general/latest/gr/signature-v4-examples.html#signature-v4-examples-python def sign(key, msg): return hmac.new(key, msg.encode('utf-8'), hashlib.sha256).digest() def getSignatureKey(key, dateStamp, regionName, serviceName): kDate = sign(('AWS4' + key).encode('utf-8'), dateStamp) kRegion = sign(kDate, regionName) kService = sign(kRegion, serviceName) kSigning = sign(kService, 'aws4_request') return kSigning # Read AWS access key from env. variables or configuration file. Best practice is NOT # to embed credentials in code. access_key = os.environ.get('AWS_ACCESS_KEY_ID') secret_key = os.environ.get('AWS_SECRET_ACCESS_KEY') if access_key is None or secret_key is None: print('No access key is available.') sys.exit() # Create a date for headers and the credential string t = datetime.datetime.utcnow() amz_date = t.strftime('%Y%m%dT%H%M%SZ') # Format date as YYYYMMDD'T'HHMMSS'Z' datestamp = t.strftime('%Y%m%d') # Date w/o time, used in credential scope # ************* TASK 1: CREATE A CANONICAL REQUEST ************* # http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html # Because almost all information is being passed in the query string, # the order of these steps is slightly different than examples that # use an authorization header. # Step 1: Define the verb (GET, POST, etc.)--already done. # Step 2: Create canonical URI--the part of the URI from domain to query # string (use '/' if no path) canonical_uri = '/' # Step 3: Create the canonical headers and signed headers. Header names # must be trimmed and lowercase, and sorted in code point order from # low to high. Note trailing \n in canonical_headers. # signed_headers is the list of headers that are being included # as part of the signing process. For requests that use query strings, # only "host" is included in the signed headers. canonical_headers = 'host:' + host + '\n' signed_headers = 'host' # Match the algorithm to the hashing algorithm you use, either SHA-1 or # SHA-256 (recommended) algorithm = 'AWS4-HMAC-SHA256' credential_scope = datestamp + '/' + region + '/' + service + '/' + 'aws4_request' # Step 4: Create the canonical query string. In this example, request # parameters are in the query string. Query string values must # be URL-encoded (space=%20). The parameters must be sorted by name. canonical_querystring = 'Action=CreateUser&UserName=NewUser&Version=2010-05-08' canonical_querystring += '&X-Amz-Algorithm=AWS4-HMAC-SHA256' canonical_querystring += '&X-Amz-Credential=' + urllib.parse.quote_plus(access_key + '/' + credential_scope) canonical_querystring += '&X-Amz-Date=' + amz_date canonical_querystring += '&X-Amz-Expires=30' canonical_querystring += '&X-Amz-SignedHeaders=' + signed_headers # Step 5: Create payload hash. For GET requests, the payload is an # empty string (""). payload_hash = hashlib.sha256(('').encode('utf-8')).hexdigest() # Step 6: Combine elements to create canonical request canonical_request = method + '\n' + canonical_uri + '\n' + canonical_querystring + '\n' + canonical_headers + '\n' + signed_headers + '\n' + payload_hash # ************* TASK 2: CREATE THE STRING TO SIGN************* string_to_sign = algorithm + '\n' + amz_date + '\n' + credential_scope + '\n' + hashlib.sha256(canonical_request.encode('utf-8')).hexdigest() # ************* TASK 3: CALCULATE THE SIGNATURE ************* # Create the signing key signing_key = getSignatureKey(secret_key, datestamp, region, service) # Sign the string_to_sign using the signing_key signature = hmac.new(signing_key, (string_to_sign).encode("utf-8"), hashlib.sha256).hexdigest() # ************* TASK 4: ADD SIGNING INFORMATION TO THE REQUEST ************* # The auth information can be either in a query string # value or in a header named Authorization. This code shows how to put # everything into a query string. canonical_querystring += '&X-Amz-Signature=' + signature # ************* SEND THE REQUEST ************* # The 'host' header is added automatically by the Python 'request' lib. But it # must exist as a header in the request. request_url = endpoint + "?" + canonical_querystring print('\nBEGIN REQUEST++++++++++++++++++++++++++++++++++++') print('Request URL = ' + request_url) r = requests.get(request_url) print('\nRESPONSE++++++++++++++++++++++++++++++++++++') print('Response code: %d\n' % r.status_code) print(r.text)