Я основал свой код на этом ресурсе здесь: https://docs.aws.amazon.com/general/latest/gr/sigv4-signed-request-examples.html#sig-v4-examples-get-auth-header
Я не могу использовать boto3 напрямую, поскольку мой код фактически размещен в Google App Engine. Boto3 не может работать на GAE / python2.7
Я получаю SignatureDoesNotMatch ошибку.
Некоторые заметки:
Моя цель - передать предварительно назначенный URL-адрес s3 клиенту веб-интерфейса для использования.
Я не добавил request_parameters к request_url в конце, потому что он пуст
Я не использовал authorization_header, потому что я хочу создать предопределенный URL для размещения объекта клиентом javascript внешнего интерфейса.
Мой код указан ниже. Моему изменению предшествует # ME комментарий
def _generate_presigned_url(s3_bucket, object_name,
access_key, secret_key):
# ************* REQUEST VALUES *************
method = 'PUT'
service = 's3'
host = s3_bucket + '.s3.amazonaws.com'
region = 'us-west-2'
endpoint = 'https://' + host + '/' + object_name
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, 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
# 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 = '/' + object_name
# 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.
# ME: Not modifing the headers
# canonical_headers = 'host:' + host + '\n' + 'x-amz-date:' + amzdate + '\n'
canonical_headers = 'host:' + host + '\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.
# ME: Not modifing the headers
# signed_headers = 'host;x-amz-date'
signed_headers = 'host'
# 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
# ME: payload is unknown at this point. The presigned_url will be returned to a javascript client for upload
# canonical_request = method + '\n' + canonical_uri + '\n' + canonical_querystring + '\n' + canonical_headers + '\n' + signed_headers + '\n' + payload_hash
canonical_request = method + '\n' + canonical_uri + '\n' + canonical_querystring + '\n' + canonical_headers + '\n' + signed_headers
# ************* 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
enter code here
authorization_header = algorithm + ' ' + \
'Credential=' + access_key + '/' + credential_scope + \
', ' + 'SignedHeaders=' + signed_headers + \
', ' + 'Signature=' + signature
# ME: Use a list of tuple so I can apply urlencode later
authorization =[
('X-Amz-Algorithm', algorithm),
('X-Amz-Expires', '86400'),
('X-Amz-Credential', access_key + '/' + credential_scope),
('X-Amz-SignedHeaders', signed_headers),
('X-Amz-Date', amzdate),
('X-Amz-Signature', signature),
]
authorization_query = urlencode(authorization)
# 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.
# ME: not using headers because I want a presigned url
# headers = {'x-amz-date': amzdate, 'Authorization': authorization_header}
# ************* SEND THE REQUEST *************
request_url = endpoint + '?' + authorization_query
return request_url
Я прикрепил скриншот ответа об ошибке от s3. Я запутал некоторые значения на скриншоте. Но, надеюсь, это поможет выявить проблему.
