Source code for hvac.aws_utils

import hmac
from datetime import datetime
from hashlib import sha256
import requests

[docs]class SigV4Auth:
[docs] def __init__(self, access_key, secret_key, session_token=None, region="us-east-1"): self.access_key = access_key self.secret_key = secret_key self.session_token = session_token self.region = region
[docs] def add_auth(self, request): timestamp = datetime.utcnow().strftime("%Y%m%dT%H%M%SZ") request.headers["X-Amz-Date"] = timestamp if self.session_token: request.headers["X-Amz-Security-Token"] = self.session_token # canonical_headers = "".join( f"{k.lower()}:{request.headers[k]}\n" for k in sorted(request.headers) ) signed_headers = ";".join(k.lower() for k in sorted(request.headers)) payload_hash = sha256(request.body.encode("utf-8")).hexdigest() canonical_request = "\n".join( [request.method, "/", "", canonical_headers, signed_headers, payload_hash] ) # algorithm = "AWS4-HMAC-SHA256" credential_scope = "/".join( [timestamp[0:8], self.region, "sts", "aws4_request"] ) canonical_request_hash = sha256(canonical_request.encode("utf-8")).hexdigest() string_to_sign = "\n".join( [algorithm, timestamp, credential_scope, canonical_request_hash] ) # key = f"AWS4{self.secret_key}".encode() key =, timestamp[0:8].encode("utf-8"), sha256).digest() key =, self.region.encode("utf-8"), sha256).digest() key =, b"sts", sha256).digest() key =, b"aws4_request", sha256).digest() signature =, string_to_sign.encode("utf-8"), sha256).hexdigest() # authorization = "{} Credential={}/{}, SignedHeaders={}, Signature={}".format( algorithm, self.access_key, credential_scope, signed_headers, signature ) request.headers["Authorization"] = authorization
[docs]def generate_sigv4_auth_request(header_value=None): """Helper function to prepare a AWS API request to subsequently generate a "AWS Signature Version 4" header. :param header_value: Vault allows you to require an additional header, X-Vault-AWS-IAM-Server-ID, to be present to mitigate against different types of replay attacks. Depending on the configuration of the AWS auth backend, providing a argument to this optional parameter may be required. :type header_value: str :return: A PreparedRequest instance, optionally containing the provided header value under a 'X-Vault-AWS-IAM-Server-ID' header name pointed to AWS's simple token service with action "GetCallerIdentity" :rtype: requests.PreparedRequest """ request = requests.Request( method="POST", url="", headers={ "Content-Type": "application/x-www-form-urlencoded; charset=utf-8", "Host": "", }, data="Action=GetCallerIdentity&Version=2011-06-15", ) if header_value: request.headers["X-Vault-AWS-IAM-Server-ID"] = header_value prepared_request = request.prepare() return prepared_request