# Calculate hash from full (RAW) request body

**URL:** <https://community.postman.com/t/calculate-hash-from-full-raw-request-body/1320>\
**Category:** Help Hub\
**Tags:** authentication\
**Created:** [March 28, 2018, 7:48am UTC](https://community.postman.com/t/calculate-hash-from-full-raw-request-body/1320 "2018-03-28T07:48:21Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Misiu](https://sea2.discourse-cdn.com/getpostman/user_avatar/community.postman.com/misiu/32/478_2.png) [@Misiu](https://community.postman.com/u/Misiu)\
**Post date:** [March 28, 2018, 7:48am UTC](https://community.postman.com/t/calculate-hash-from-full-raw-request-body/1320/1 "2018-03-28T07:48:21Z")

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Hi,  
I’m quite new to Postman, so sorry if I ask question that was answered before (I didn’t found anything similar).  
I’m trying to implement HMAC authentication schema for my requests.  
As part of hash I need to calculate I need MD5 from body.  
I’ve posted [same question on Stackoverflow](https://stackoverflow.com/questions/49509612/postman-access-full-request-body-to-calculate-hash-in-pre-request-script) but I was asked by @singhsivcan to post that question in Postman community.

When I do GET request everything works fine, but when I form-data with files I can’t calculate MD5 from body, because I don’t have access to it.  
Please take a look at [my github issue](https://github.com/postmanlabs/postman-app-support/issues/4377).

How can this be done right now inside Postman native app? Is this even possible?

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**Author:** ![deepak.pathania](https://avatars.discourse-cdn.com/v4/letter/d/50afbb/32.png) [@deepak.pathania](https://community.postman.com/u/deepak.pathania)\
**Post date:** [May 7, 2018, 9:57am UTC](https://community.postman.com/t/calculate-hash-from-full-raw-request-body/1320/2 "2018-05-07T09:57:32Z")

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As mentioned by @kamalaknn in [this](https://github.com/postmanlabs/postman-app-support/issues/1050#issuecomment-376791029) comment, we do not allow access to the request body with the file contents in the pre-request scripts.

Just wanted to specify here in case other people stumble upon this issue here.

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**Author:** ![Misiu](https://sea2.discourse-cdn.com/getpostman/user_avatar/community.postman.com/misiu/32/478_2.png) [@Misiu](https://community.postman.com/u/Misiu)\
**Post date:** [May 7, 2018, 10:13am UTC](https://community.postman.com/t/calculate-hash-from-full-raw-request-body/1320/3 "2018-05-07T10:13:20Z")

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@deepak.pathania so how can I solve this?  
Any plans to add this as supported (build in) authentication method?

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**Author:** ![deepak.pathania](https://avatars.discourse-cdn.com/v4/letter/d/50afbb/32.png) [@deepak.pathania](https://community.postman.com/u/deepak.pathania)\
**Post date:** [May 7, 2018, 10:16am UTC](https://community.postman.com/t/calculate-hash-from-full-raw-request-body/1320/4 "2018-05-07T10:16:06Z")

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We do have plans to support custom authentication methods, this would most certainly be handled by that. Unfortunately, we do not intend to support this as a built-in authentication method for the reasons explained in the GitHub thread.

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<div class="post-metadata">

**Author:** ![Misiu](https://sea2.discourse-cdn.com/getpostman/user_avatar/community.postman.com/misiu/32/478_2.png) [@Misiu](https://community.postman.com/u/Misiu)\
**Post date:** [January 28, 2019, 3:03pm UTC](https://community.postman.com/t/calculate-hash-from-full-raw-request-body/1320/5 "2019-01-28T15:03:41Z")

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@deepak.pathania any news about custom authentication methods?  
Currently, I have C# app just to test that HMAC authentication and I would like to replace that with Postman.