# Possible bug with AWS Signature auth

**URL:** <https://community.postman.com/t/possible-bug-with-aws-signature-auth/2743>\
**Category:** Help Hub\
**Created:** [September 20, 2018, 6:11pm UTC](https://community.postman.com/t/possible-bug-with-aws-signature-auth/2743 "2018-09-20T18:11:35Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![chryosolo](https://sea2.discourse-cdn.com/getpostman/user_avatar/community.postman.com/chryosolo/32/941_2.png) [@chryosolo](https://community.postman.com/u/chryosolo)\
**Post date:** [September 20, 2018, 6:11pm UTC](https://community.postman.com/t/possible-bug-with-aws-signature-auth/2743/1 "2018-09-20T18:11:35Z")

</div>

We are just getting started with Postman, and have run into an issue with AWS Signature authorization. If I understand the problem correctly, there may be a bug in how the host header is added into the canonical string which is then used to calculate the signature.

If we make a POST to `https://aws-api-gateway-url:443/path`, we get the following response:

```auto
{
    "message": "The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details. ..."
}

```

However, if we make a post to `https://aws-api-gateway-url/path` (no port), we get a valid response.

Next observation comes from comparing the `host` header (under the Headers tab, there is a calculated header `host: aws-api-gateway-url:443` – includes port) to the suggested header in the error message returned (`...The Canonical String for this request should have been ... host:aws-api-gateway-url ...` – no port).

Is it possible that Postman is including the port in the generated host header when AWS is not, and thus this breaks the signature, at least for the default https port?