# Where is hash of a certificate on blockchain?

**URL:** <https://community.blockcerts.org/t/where-is-hash-of-a-certificate-on-blockchain/1557>\
**Category:** Community\
**Created:** [December 8, 2018, 2:32am UTC](https://community.blockcerts.org/t/where-is-hash-of-a-certificate-on-blockchain/1557 "2018-12-08T02:32:36Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![ranjanrecker](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@ranjanrecker](https://community.blockcerts.org/u/ranjanrecker)\
**Post date:** [December 8, 2018, 2:32am UTC](https://community.blockcerts.org/t/where-is-hash-of-a-certificate-on-blockchain/1557/1 "2018-12-08T02:32:36Z")

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Hi, This is a very fascinating open source which is solving a real problem. I am bit lost in certificate verification flow.

1. recipient sends his Public key through wallet to Issuer.
2. Issuer uses that key to create the hash of the certificate and reciept
3. Issuer put all these hashes into a merkle and only the merkle hash is getting recorded in the Bitcoin/Ethereum.
4. Issuer saves the certificate at some URL and sends that url to recipient. Does the last part of url contain the public key or some random generated url?
5. Recipient can send the URL to employer/some third party.

This is where I am lost too.

Whoever is verying can see only the Merkle root hash but how does he/she find the hash of the certificate?

Any clarification is much appreciated.

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**Author:** ![ranjanrecker](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@ranjanrecker](https://community.blockcerts.org/u/ranjanrecker)\
**Post date:** [December 8, 2018, 4:33pm UTC](https://community.blockcerts.org/t/where-is-hash-of-a-certificate-on-blockchain/1557/2 "2018-12-08T16:33:42Z")

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As I am digging more,

> **[What we learned from designing an academic certificates system on the blockchain](https://medium.com/mit-media-lab/what-we-learned-from-designing-an-academic-certificates-system-on-the-blockchain-34ba5874f196)**
>
> Over the past year, we have been working on a set of tools to issue, display, and verify digital credentials using the Bitcoin blockchain…

  
as per this post, it seems each recipient gets hash of his/her certificate in op\_return field on recipients public key.  
is this still true?

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**Author:** ![danishfastian](https://avatars.discourse-cdn.com/v4/letter/d/85f322/32.png) [@danishfastian](https://community.blockcerts.org/u/danishfastian)\
**Post date:** [December 9, 2018, 5:10pm UTC](https://community.blockcerts.org/t/where-is-hash-of-a-certificate-on-blockchain/1557/3 "2018-12-09T17:10:45Z")

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There is one blockchain transaction per batch whether it has 1 certificate or 1000. The hash of each certificate is used to build Merkle tree and Merkle root is written on the OP\_RETURN field.

The process is clearly documented below

> **[blockchain-certificates/cert-issuer](https://github.com/blockchain-certificates/cert-issuer)**
>
> Issues Blockcerts using either the Bitcoin or Ethereum blockchain - blockchain-certificates/cert-issuer

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**Author:** ![ranjancrypto](https://avatars.discourse-cdn.com/v4/letter/r/41988e/32.png) [@ranjancrypto](https://community.blockcerts.org/u/ranjancrypto)\
**Post date:** [December 10, 2018, 7:08pm UTC](https://community.blockcerts.org/t/where-is-hash-of-a-certificate-on-blockchain/1557/4 "2018-12-10T19:08:50Z")

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Thanks Danish… let me go through these documents.