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Woleet.io

Sign Data

👍

Too busy to read the documentation?

You will find here very simple curl and shell code samples demonstrating the basic usage of the Woleet API.

Signing a file using the Woleet API is equivalent to creating a timestamped proof of signature of this file.

To do so, you first need to compute the SHA256 hash of your file.

Let's do it using a simple shell command using openssl to do the computation:

$ cat <your file> | openssl dgst -sha256 |  cut -d " " -f 2

e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

Now you have the SHA256 hash of your file, you can sign the hash to generate a signature compatible with the bitcoin signature scheme (ECDSA).

The easiest way to generate the signature is to use Woleet.ID Server: this application allows you to manage the identities of your users and seals, as well as their associated signature keys. It provides an API allowing to sign any hash or message using these keys.

Once installed and configured, you need to:

  • take note of the URL of the signature API
  • generate an API token that you will use to authenticate
    This is out of scope of this procedure, so please see the related documentation for details.

📘

What else can I use?

There is plenty of tools you can use to generate bitcoin compatible/ECDSA signatures.

curl --oauth2-bearer <WIDS API token> https://<WIDS signature API URL>/sign?hashToSign=e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

{
  "pubKey":"17wD8dR42yPvMqngaVhftypFxfYNpvPj42",
  "signedHash":"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
  "signature":"ID5Vd2re4VtcPxhZ+TKDOOd3wBuwpRW6VoxdQElamqH/VACfxy6QKTHyio4CNg3IkKtL7WfLyLywR9vVuE4muRE=",
  "identityURL":<WIDS identity URL>
}

Now you have the signature and its associated public key, you can create a signature anchor.

An anchor is like a proof creation request: it asks the platform to create the proof, and allows you to retrieve the proof a few hours later.

Let's use a simple curl command to do a POST request:

curl --request POST \
  -u <email>:<password> \
  --url https://api.woleet.io/v1/anchor \
  --header 'accept: application/json' \
  --header 'content-type: application/json' \
  --data '{"name":"My anchor","signedHash":"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855","signature":"ID5Vd2re4VtcPxhZ+TKDOOd3wBuwpRW6VoxdQElamqH/VACfxy6QKTHyio4CNg3IkKtL7WfLyLywR9vVuE4muRE=","pubKey":"17wD8dR42yPvMqngaVhftypFxfYNpvPj42","identityURL":<WIDS identity URL>}'

{
  "id":"331674c8-0563-45f4-b363-e6cebc0625bb",
  "created":1591631377577,
  "lastModified":1591631377577,
  "name":"My anchor",
  "hash":"b9736a6b96420fc2c0e09aa297a0012470600fc1c6de9a1f0500aa7d64f0bdd0",`"signedHash":"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
  "pubKey":"17wD8dR42yPvMqngaVhftypFxfYNpvPj42",
  "signature":"ID5Vd2re4VtcPxhZ+TKDOOd3wBuwpRW6VoxdQElamqH/VACfxy6QKTHyio4CNg3IkKtL7WfLyLywR9vVuE4muRE=",
  "identityURL":<WIDS identity URL>,
  "status":"WAIT"
}

You anchor is created!

Its identifier is present in the JSON object returned in the body of the response.

Note the its status is WAIT, meaning that the proof is waiting to be anchored. The Woleet platform batches proof creation requests, so you will have to wait a mean time of 3 hours to get your proof of existence.

You can probe your anchor status at any time with a simple GET request (or if you have a backend server, use our callback mechanism to get informed in realtime):

curl --request GET \
  -u <email>:<password>
  --url https://api.woleet.io/v1/anchor/331674c8-0563-45f4-b363-e6cebc0625bb \
  --header 'accept: application/json'
  
{
  "id":"331674c8-0563-45f4-b363-e6cebc0625bb",
  "created":1591631377577,
  "lastModified":1591631377577,
  "name":"My anchor",
  "hash":"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
  "status":"CONFIRMED"
}

When the status is SENT (sent to the bitcoin blockchain) or CONFIRMED (confirmed 6 times by the bitcoin blockchain) you can (and should!) retrieve your proof:

curl --request GET \
  --url https://api.woleet.io/v1/receipt/331674c8-0563-45f4-b363-e6cebc0625bb \
  --header 'accept: application/json'
  
{
  "targetHash":"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
  "merkleRoot":"ec4a21d9b4f4c60e34700012bfe0b3dacd46d928e9ff7cb12bbc1e8dc567093b",
  "proof":[{"left":"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"},
  {"right":"164ea6ef8984a1be9a9064e40f58e1e99f82aa9ecff29bd1a07bee74965f7a49"},
  {"left":"19d54943a3ae4172fef2856f953d1eb988e7b512c9b9d06c53e225ae94c231c0"},
  {"right":"06f5f7540b35461cd1b9366a9e765c9165bd99c6679cb49d2c67bfae851c54cf"},
  {"left":"a3ce3262b6c61042fd7097c19b3af3acc72ceb63dcf53ef2017f184ec4740c78"},
  {"right":"4a15851b48ffdafe0212c7e489b1859cee3d7a53dde40393711ec957020f7b02"}],
  "anchors":[{"sourceId":"096e1f0f2406210db9b1ba0a1d08615ed8e4bebbdf444c541a21a028ed6829eb",
 "type":"BTCOpReturn"}],
  "type":"ChainpointSHA256v2",
  "@context":"https://w3id.org/chainpoint/v2"
}

You get your proof of existence. Keep it along the proven file: you need both to verify the proof.

You are all set!

📘

What about Java, Javascript, Node, Python and PHP code samples?

For other programming languages, you can generate sample code using our actionable API Reference just below.