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Chainkit API Quickstart

Last updated: November 14, 2019

Summary:

This quickstart covers the four easy steps to using the Chainkit API: Hash, Authenticate, Register, Verify

Step 1: Generate a Hash

Create a digital fingerprint, a hash value, of your file or data. We have sample code for many programming languages and platforms.

Hash a File

Mac/Linux Example:

cat sample-document.pdf | openssl sha256

Javascript Example:

crypto.createHmac('sha256', fileContents)

Java Example:

hashString(fileContents, "SHA-256");

Output Value

The Hash Value generated for that specific file would be the same on every platform. For example:

ba3f474830169ddaece741cbbfbec13086139d88907104564b765c3935109d64

Step 2: Authenticate to Chainkit API

Submit your username and password to the Chainkit token API. Get an account here if needed. The API returns JSON with multiple values. You will need to extract the accessToken value for use in the Next Step.

Example Request:

curl -s -X POST https://api.chainkit.com/token -H 'Content-Type: application/json' -d '{"userId":"your-username", "password": "your-password"}'

Example Response:

{"data":{"expiresIn":"3600", "accessToken": "eyJraWQiOiJETzRxQWFGb...", "refreshToken": "..."}}

In the response above, you need to copy the full accessToken eyJraWQiOiJETzRxQWFGb... which we have truncated in order to save space.

Step 3: Register Your Hash Value

Submit the hash value you created in Step 1 along with the accessToken which you created in Step 2 to the Chainkit Register API.

If successful, the API will returns an assetId unique to that registration and hash value. Save this assetId, as it will be used in Step 4 to verify the file.

Chainkit allows storage on private and public blockchains. For example, you could choose to store your hash on the public Ethereum blockchain, or a private blockchain including Hyperledger Sawtooth or VMware Blockchain. Private is faster and recommended for testing.

In this example we are storing the hash value on Chainkit's Hyperledger Sawtooth blockchain. Please contact us if you would want to upgrade your account permissions to use other blockchains (Contact Information is at the end of this document.)

Example Request:

Here is the basic syntax of the Register() API.

curl -s -X POST https://api.chainkit.com/register -H 'Content-Type: application/json' -d '{"hash":"your-hash-value", "storage":"pencil"}' -H 'Authorization: Bearer 'your-accessToken-value''

So, following along in this example, substitute your values from the prior steps for "your-hash-value" and "your-accessToken-value". Note: Pay close attention to the single quote marks that must be including at the end of the command.

curl -s -X POST https://api.chainkit.com/register -H 'Content-Type: application/json' -d  '{"hash":"ba3f474830169ddaece741cbbfbec13086139d88907104564b765c3935109d64", "storage":"pencil"}' -H 'Authorization: Bearer 'eyJraWQiOiJETzRxQWFGb...''

Example Response

{"assetId":"1526398776829"}

Save the assetId for later verification.

Step 4: Verify Your Hash Value

To verify that your file has not been tampered with, first create a Fresh Hash, using the same hashing formula from Step 1. Do not reuse the original hash you used at registration, as that defeats the purpose.

Then you will submit the fresh hash, the assetId you got from registration, and your accessToken to the Verify API. It will return true if your new hash matches what was originally submitted to us or false to indicate the hash value does not match and something in your file or data has changed.

Example Request:

Here is the basic syntax of the Verify() API.

curl -s -X GET 'https://api.chainkit.com/verify/your-assetId?hash=your-freshly-generated-hash-value&storage=private' -H 'Authorization: Bearer your-accessToken-value'

So, in this example, you will need to subsitute your values from prior steps for "assetID" and "your-freshly-generated-hash-value" and "your-accessToken-value". Note: Pay close attention to the single quote marks that must be including at the end of the command.

curl -s -X GET 'https://api.chainkit.com/verify/1526398776829?hash=ba3f474830169ddaece741cbbfbec13086139d88907104564b765c3935109d64&storage=pencil' -H 'Authorization: Bearer 'eyJraWQiOiJETzRxQWFGb...''

Example Response

{"verified":true}

This response shows that your fresh hash matches the original stored on the Chainkit API for that assetId.

Note: You can test this verification by altering the original file, hashing the altered version, and submitting that to the verify API with the original assetId. It will return false, since the hash of the altered file does not match what was originally registered with us.

Need help?

Contact us at info@chainkit.com