# Technical **URL:** https://community.blockcerts.org/c/technical/7.md?page=2 [Latest](https://community.blockcerts.org/latest.md) · [Categories](https://community.blockcerts.org/categories.md) **Page:** 3 --- ## [Verify ethereum certificate (ropsten)](https://community.blockcerts.org/t/verify-ethereum-certificate-ropsten/1065)
**Author:** [@jdelprado](https://community.blockcerts.org/u/jdelprado)\ **Replies:** 6\ **Last updated:** [June 30, 2021, 1:55pm UTC](https://community.blockcerts.org/t/verify-ethereum-certificate-ropsten/1065 "2021-06-30T13:55:03Z")
Hello, I have a problem verifying a certificate generated with cert-issuer. I’m trying to verify it with its online verifier, but it gives me an error. \[Captura%20de%20pantalla%20de%202018-05-25%2000-17-55\] In the co… --- ## [Storing Keys of Multiple Issuers](https://community.blockcerts.org/t/storing-keys-of-multiple-issuers/2215)
**Author:** [@amritnagra](https://community.blockcerts.org/u/amritnagra)\ **Replies:** 1\ **Last updated:** [June 27, 2021, 6:18pm UTC](https://community.blockcerts.org/t/storing-keys-of-multiple-issuers/2215 "2021-06-27T18:18:49Z")
Hi, I’m (newbie) trying to support a solution which would securely store the private and public key pairs of multiple issuers. Imagine a multi- tenant solution supporting multiple issuers that would allow multiple univer… --- ## [\[RESOLVED\] "Transaction occurred at time when issuing address was not considered valid."](https://community.blockcerts.org/t/resolved-transaction-occurred-at-time-when-issuing-address-was-not-considered-valid/1592)
**Author:** [@ppfish45](https://community.blockcerts.org/u/ppfish45)\ **Replies:** 6\ **Last updated:** [June 8, 2020, 6:11am UTC](https://community.blockcerts.org/t/resolved-transaction-occurred-at-time-when-issuing-address-was-not-considered-valid/1592 "2020-06-08T06:11:51Z")
Hi everyone, Recently I am trying to deploy my first blockcert from the scratch. And here is roughly what I have done: Generated a wallet address (as well as the private key) on the bitcoin testate Created an issu… --- ## [Issueing and holding ethereum based certificate Needs clear documentation](https://community.blockcerts.org/t/issueing-and-holding-ethereum-based-certificate-needs-clear-documentation/2878)
**Author:** [@testemailid9101](https://community.blockcerts.org/u/testemailid9101)\ **Replies:** 5\ **Last updated:** [June 10, 2021, 11:56am UTC](https://community.blockcerts.org/t/issueing-and-holding-ethereum-based-certificate-needs-clear-documentation/2878 "2021-06-10T11:56:07Z")
Hi there, Can the existing repository is working with verifying and holding ethereum based certificate? --- ## [Blockcerts verifier requires api key?](https://community.blockcerts.org/t/blockcerts-verifier-requires-api-key/2882)
**Author:** [@testemailid9101](https://community.blockcerts.org/u/testemailid9101)\ **Replies:** 2\ **Last updated:** [June 7, 2021, 11:58am UTC](https://community.blockcerts.org/t/blockcerts-verifier-requires-api-key/2882 "2021-06-07T11:58:07Z")
Does block certs verifiier GitHub - blockchain-certificates/blockcerts-verifier: A Blockcerts verifier and viewer requires api key? when i run it to verify transaction it returns transaction for the first time but for s… --- ## [Public key required in cert issuer](https://community.blockcerts.org/t/public-key-required-in-cert-issuer/2884)
**Author:** [@testemailid9101](https://community.blockcerts.org/u/testemailid9101)\ **Replies:** 0\ **Last updated:** [June 7, 2021, 11:31am UTC](https://community.blockcerts.org/t/public-key-required-in-cert-issuer/2884 "2021-06-07T11:31:45Z")
Is the public key required for the recipient to get the certificate issued? can we use just the email id or some unique id (say college id/student id) only to issue certificate? Please point towards or suggest how that c… --- ## [Revocation List](https://community.blockcerts.org/t/revocation-list/2877)
**Author:** [@ampatt97](https://community.blockcerts.org/u/ampatt97)\ **Replies:** 0\ **Last updated:** [June 3, 2021, 12:12am UTC](https://community.blockcerts.org/t/revocation-list/2877 "2021-06-03T00:12:56Z")
Struggling to revoke certificates properly. I have an object in the revokedAssertions array at my revocation url with the id set to the assertion url. Is this the correct approach. Thanks Edit: Solved, I guess my bro… --- ## [iOS wallet not importing v2 ethereum-ropsten certs](https://community.blockcerts.org/t/ios-wallet-not-importing-v2-ethereum-ropsten-certs/1351)
**Author:** [@mlisle](https://community.blockcerts.org/u/mlisle)\ **Replies:** 6\ **Last updated:** [September 11, 2018, 9:09pm UTC](https://community.blockcerts.org/t/ios-wallet-not-importing-v2-ethereum-ropsten-certs/1351 "2018-09-11T21:09:35Z")
We’ve issued v2 certs on ethereum-ropsten that import fine into multiple Android wallets and verify on the universal verifier at blockcerts.org/ but they won’t import into the iOS wallet (we’ve tried multiple iPhones). I… --- ## [No module named 'ethereum' for cert-issuer Python](https://community.blockcerts.org/t/no-module-named-ethereum-for-cert-issuer-python/2349)
**Author:** [@arycloud](https://community.blockcerts.org/u/arycloud)\ **Replies:** 2\ **Last updated:** [February 18, 2020, 3:09pm UTC](https://community.blockcerts.org/t/no-module-named-ethereum-for-cert-issuer-python/2349 "2020-02-18T15:09:56Z")
I’m just getting started with Blockcert-python and trying to run it on my local system. Here are the steps I did: Clone the cert-issuer GitHub repo Create a virtual environment for Python 3.5.4 on Mac OS Run python se… --- ## [For s in signed\_hextx.split('80a0'): AttributeError: 'dict' object has no attribute 'split'](https://community.blockcerts.org/t/for-s-in-signed-hextx-split-80a0-attributeerror-dict-object-has-no-attribute-split/1838)
**Author:** [@johnwick](https://community.blockcerts.org/u/johnwick)\ **Replies:** 9\ **Last updated:** [May 28, 2021, 11:15am UTC](https://community.blockcerts.org/t/for-s-in-signed-hextx-split-80a0-attributeerror-dict-object-has-no-attribute-split/1838 "2021-05-28T11:15:07Z")
Hi, I am currently working on my college project where I am using blockcerts on ethereum\_ropsten network. After all the configuration, when I try to issue the cerificate it throws AttributeError: ‘dict’ object has no att… --- ## [Add issuer in the mobile app](https://community.blockcerts.org/t/add-issuer-in-the-mobile-app/1075)
**Author:** [@jdelprado](https://community.blockcerts.org/u/jdelprado)\ **Replies:** 2\ **Last updated:** [May 28, 2021, 10:12am UTC](https://community.blockcerts.org/t/add-issuer-in-the-mobile-app/1075 "2021-05-28T10:12:51Z")
Hello, I am trying to add a new issuer in the mobile application and I do not know what to add in the field “Add your one-time code”. \[foto1\] I have read several previous posts but it is not clear to me. I’m working … --- ## [\[ethereum\_ropsten\] Verification Error: MissingSchema: Invalid URL 'None': No schema supplied](https://community.blockcerts.org/t/ethereum-ropsten-verification-error-missingschema-invalid-url-none-no-schema-supplied/2755)
**Author:** [@nitinb](https://community.blockcerts.org/u/nitinb)\ **Replies:** 1\ **Last updated:** [March 12, 2021, 2:35pm UTC](https://community.blockcerts.org/t/ethereum-ropsten-verification-error-missingschema-invalid-url-none-no-schema-supplied/2755 "2021-03-12T14:35:20Z")
I am able to issue a certificate in Etherium ropsten network . I can view the certificate using flask app cert-viewer . but when I tried to verify the certificate by clicking the verify button ,It doesn’t verify. There… --- ## ["Security analysis of a blockchain-based protocol for the certification of academic credentials"](https://community.blockcerts.org/t/security-analysis-of-a-blockchain-based-protocol-for-the-certification-of-academic-credentials/2762)
**Author:** [@jakes](https://community.blockcerts.org/u/jakes)\ **Replies:** 0\ **Last updated:** [March 6, 2021, 8:41pm UTC](https://community.blockcerts.org/t/security-analysis-of-a-blockchain-based-protocol-for-the-certification-of-academic-credentials/2762 "2021-03-06T20:41:00Z")
We have analyzed a blockchain-based protocol for the certification of academic credentials named Blockcerts, which aims at certifying digital certificates compliant with the Open Badges standard through a public bloc… --- ## [Can we verify a pdf/image file directly using blockcerts](https://community.blockcerts.org/t/can-we-verify-a-pdf-image-file-directly-using-blockcerts/2748)
**Author:** [@nitinb](https://community.blockcerts.org/u/nitinb)\ **Replies:** 3\ **Last updated:** [February 25, 2021, 7:02am UTC](https://community.blockcerts.org/t/can-we-verify-a-pdf-image-file-directly-using-blockcerts/2748 "2021-02-25T07:02:47Z")
Hi Guys, Past few days I am trying my hand on Blockcerts. Its awesome. Really liked trying it out. I have just one query . Can we verify a PDF file directly? The file may contain some Images, graphs ,Text. The idea i… --- ## [Use cert\_issuer instead of cert tools to create certificate?](https://community.blockcerts.org/t/use-cert-issuer-instead-of-cert-tools-to-create-certificate/2725)
**Author:** [@nitinb](https://community.blockcerts.org/u/nitinb)\ **Replies:** 1\ **Last updated:** [February 24, 2021, 2:18pm UTC](https://community.blockcerts.org/t/use-cert-issuer-instead-of-cert-tools-to-create-certificate/2725 "2021-02-24T14:18:03Z")
As I understood Cert\_tools repo is used to create a blockcert certificate. & cert issuer can issue certificate ,ie put them in blockchain network. But I have a querry- Can we use cert\_issuer to both create and issue … --- ## [Fix iso format for v3 in cert-tool](https://community.blockcerts.org/t/fix-iso-format-for-v3-in-cert-tool/2753)
**Author:** [@yosuke](https://community.blockcerts.org/u/yosuke)\ **Replies:** 1\ **Last updated:** [February 24, 2021, 2:10pm UTC](https://community.blockcerts.org/t/fix-iso-format-for-v3-in-cert-tool/2753 "2021-02-24T14:10:34Z")
I just found the problem of iso\_format between cert\_tool and cert\_issuer in V3. When I tried to issue the template that I created with cert\_tool, I got the format error because the value of “issueOn” did not match the m… --- ## [Android Wallet - Credential is in an outaded format](https://community.blockcerts.org/t/android-wallet-credential-is-in-an-outaded-format/2747)
**Author:** [@nSync](https://community.blockcerts.org/u/nSync)\ **Replies:** 0\ **Last updated:** [February 9, 2021, 4:40pm UTC](https://community.blockcerts.org/t/android-wallet-credential-is-in-an-outaded-format/2747 "2021-02-09T16:40:22Z")
Hi! I’m currently working on Blockcertes for my thesis and I have created my own certificate with cert-tools and cert-issuer in the bitcoin testnet but, when I try to view my certificate with the app “Blockcerts”, for a… --- ## [Open Badges implementation without Blockcerts](https://community.blockcerts.org/t/open-badges-implementation-without-blockcerts/2742)
**Author:** [@Takuma](https://community.blockcerts.org/u/Takuma)\ **Replies:** 1\ **Last updated:** [February 8, 2021, 11:03am UTC](https://community.blockcerts.org/t/open-badges-implementation-without-blockcerts/2742 "2021-02-08T11:03:58Z")
Hi, everyone. I have a quesion on Open Badges. Are there any way to implement Open Badges without Blockcerts? If so, I wonder how can I ensure security? I mean how to prevent forgeries and / or falsifications? I rea… --- ## [How to get issuer\_public\_key to put in conf.in in cert\_tools](https://community.blockcerts.org/t/how-to-get-issuer-public-key-to-put-in-conf-in-in-cert-tools/2724)
**Author:** [@nitinb](https://community.blockcerts.org/u/nitinb)\ **Replies:** 0\ **Last updated:** [January 29, 2021, 11:31am UTC](https://community.blockcerts.org/t/how-to-get-issuer-public-key-to-put-in-conf-in-in-cert-tools/2724 "2021-01-29T11:31:06Z")
Hi I am fairly new to blockcerts and trying to replicate it. I am using cert\_tools to create a custom certificate. I have few doubts doubts - How can I get the issuer\_public\_key to mention in conf.ini in the cert\_… --- ## [Cert Verifier with external explorer APIs](https://community.blockcerts.org/t/cert-verifier-with-external-explorer-apis/2711)
**Author:** [@danishfastian](https://community.blockcerts.org/u/danishfastian)\ **Replies:** 1\ **Last updated:** [January 24, 2021, 10:24am UTC](https://community.blockcerts.org/t/cert-verifier-with-external-explorer-apis/2711 "2021-01-24T10:24:24Z")
Has anyone tried Cert Verifier JS with options to pass Explorer API implementation as an argument. I can see the documentation however when I tried to pass implementation it gives an error. Below is the code. and error I… --- ## [Blockcerts-verifier: Styling Whitelist](https://community.blockcerts.org/t/blockcerts-verifier-styling-whitelist/2622)
**Author:** [@ampatt97](https://community.blockcerts.org/u/ampatt97)\ **Replies:** 3\ **Last updated:** [January 20, 2021, 2:34pm UTC](https://community.blockcerts.org/t/blockcerts-verifier-styling-whitelist/2622 "2021-01-20T14:34:10Z")
I’ve managed to use inline styling to get a decent display html up and running. As we scale, building html for certs with incline styles is going to be quite time consuming. Does adding styles to the whitelist open avail… --- ## [Problems with LinkedIn Sharing(FIXED)](https://community.blockcerts.org/t/problems-with-linkedin-sharing-fixed/2708)
**Author:** [@ampatt97](https://community.blockcerts.org/u/ampatt97)\ **Replies:** 0\ **Last updated:** [January 15, 2021, 6:50pm UTC](https://community.blockcerts.org/t/problems-with-linkedin-sharing-fixed/2708 "2021-01-15T18:50:30Z")
Running into issues with the linkedIn share button on the blockcerts-verifier npm package and curious if anyone else has experienced something like this. Here is a screenshot of the page i see on linked in when I try to … --- ## [Cert-schema 2.x.x missing from pypi.org](https://community.blockcerts.org/t/cert-schema-2-x-x-missing-from-pypi-org/2685)
**Author:** [@Marius](https://community.blockcerts.org/u/Marius)\ **Replies:** 1\ **Last updated:** [December 8, 2020, 1:12am UTC](https://community.blockcerts.org/t/cert-schema-2-x-x-missing-from-pypi-org/2685 "2020-12-08T01:12:18Z")
Hello, I noticed recently that cert-schema 2.x.x is pissing from pypi.org repository. The only versions available are two 3.0.0.x pre-releases. Does anybody know if this has been done on purpose and what the direction… --- ## [Issue certificate on testnet](https://community.blockcerts.org/t/issue-certificate-on-testnet/2671)
**Author:** [@satz007](https://community.blockcerts.org/u/satz007)\ **Replies:** 0\ **Last updated:** [November 12, 2020, 11:32pm UTC](https://community.blockcerts.org/t/issue-certificate-on-testnet/2671 "2020-11-12T23:32:48Z")
Hi, I am trying to issue certificate in testnet mode (bitcoin) and I have a local bitcoin node running on testnet mode. I have copied the sample unsigned certificate from examples folder in cert-issuer to /etc/cert-iss… --- ## [Blockcert in Hedera hashgraph](https://community.blockcerts.org/t/blockcert-in-hedera-hashgraph/2668)
**Author:** [@sophie](https://community.blockcerts.org/u/sophie)\ **Replies:** 0\ **Last updated:** [November 11, 2020, 11:22am UTC](https://community.blockcerts.org/t/blockcert-in-hedera-hashgraph/2668 "2020-11-11T11:22:32Z")
When Blockcert going to support Hedera hashgraph. Hashgraph is becoming the next competitor to Ethereum and Bitcoin compared to Speed and fee. --- ## [Implementing shared-styles into displayHTML](https://community.blockcerts.org/t/implementing-shared-styles-into-displayhtml/2650)
**Author:** [@ampatt97](https://community.blockcerts.org/u/ampatt97)\ **Replies:** 1\ **Last updated:** [November 2, 2020, 6:07pm UTC](https://community.blockcerts.org/t/implementing-shared-styles-into-displayhtml/2650 "2020-11-02T18:07:19Z")
Working through trying to get displayHTML working, I used all inline styling to get things working initially. I just noticed some documentation about shared-styles on github. More specifically, it states that the SASS co… --- ## [Which outbound TCP ports are required](https://community.blockcerts.org/t/which-outbound-tcp-ports-are-required/2652)
**Author:** [@elmike.eth](https://community.blockcerts.org/u/elmike.eth)\ **Replies:** 0\ **Last updated:** [October 22, 2020, 6:09pm UTC](https://community.blockcerts.org/t/which-outbound-tcp-ports-are-required/2652 "2020-10-22T18:09:51Z")
Hi everyone. Is there any Blockcerts documentation to verify which outbound TCP ports are required? Or what ports do I need to have open in a productive environment? --- ## [Add Issuer Failed](https://community.blockcerts.org/t/add-issuer-failed/1607)
**Author:** [@sunder](https://community.blockcerts.org/u/sunder)\ **Replies:** 4\ **Last updated:** [October 19, 2020, 1:55pm UTC](https://community.blockcerts.org/t/add-issuer-failed/1607 "2020-10-19T13:55:33Z")
Hello Support team, With reference to @Kim reply (https://community.blockcerts.org/t/importing-certificates-to-the-ios-wallet/283), trying to add issuer (https://www.blockcerts.org/samples/2.0/issuer-testnet.json) in my… --- ## [Cert-issuer Issue](https://community.blockcerts.org/t/cert-issuer-issue/2573)
**Author:** [@Danjetech](https://community.blockcerts.org/u/Danjetech)\ **Replies:** 3\ **Last updated:** [September 7, 2020, 7:06pm UTC](https://community.blockcerts.org/t/cert-issuer-issue/2573 "2020-09-07T19:06:19Z")
bash-4.3# cert-issuer -c /etc/cert-issuer/conf.ini bash: cert-issuer: command not found Everything was working fine, I’m stuck with the above error Your help is much appreciated --- ## [Docker blockcerts with Ethereum](https://community.blockcerts.org/t/docker-blockcerts-with-ethereum/2614)
**Author:** [@flachica](https://community.blockcerts.org/u/flachica)\ **Replies:** 0\ **Last updated:** [September 6, 2020, 10:02am UTC](https://community.blockcerts.org/t/docker-blockcerts-with-ethereum/2614 "2020-09-06T10:02:49Z")
I have seen that the configuration to raise cert-issuer with docker uses bitcoin. Do you know if there is a possibility of having the service in docker but using Ethereum? Regards. [Previous page](https://community.blockcerts.org/c/technical/7.md?page=1) [Next page](https://community.blockcerts.org/c/technical/7.md?page=3)