# KeeeX Key handling library



This library provide a Keys class allowing easy generation, exportation,
importation and usage of cryptographic keys for the purpose of digital
signature.

Currently only support the "Bitcoin" type of keys, which exposes their public key as a Bitcoin address.

## Quick how-to

The `@keeex/js-keys` library uses the `@keeex/crypto` library to generate
cryptographically secure random keys.

### Initialize crypto provider

To make sure the correct cryptographic is imported before using this library. See the package
`@keeex/crypto` for more details about provider.

```JavaScript
import "@keeex/crypto-provider-node";
```

### Manipulating keys

To generate a new key:

```JavaScript
import {
  generateKey,
  KeyType,
} from "@keeex/js-keys/lib/keys";

generateKey(KeyType.bitcoin).then(key => console.log(key));
```

To export a key as JSON:

```JavaScript
const key = /* get your key object */
key.exportKey(false, {type: "json"}).then(
  exportedData => console.log(Buffer.from(exportedData).toString())
);
```

`exportedData` is an ArrayBuffer. In the case of a JSON export the ArrayBuffer
will contain text data.
The first argument of `exportKey()` is "publicOnly", to only export public data.

To import a key from a previous JSON export:

```JavaScript
import {
  importKey,
  KeyType,
} from "@keeex/js-keys/lib/keys";

importKey(KeyType.bitcoin, {type:"json", value: keyData})
  .then(key => console.log(key));
```

To export a key protected by a password:

```JavaScript
const key = /* get your key object */
key.exportKey(
    false,
    {
      type: "json",
      password: "somepass",
    }
  )
).then(secureKey => ...);
```

To import a key protected by a password:

```JavaScript
import {
  importKey,
  KeyType,
} from "@keeex/js-keys/lib/keys";

importKey(KeyType.bitcoin, {
  type: "json",
  password: "somepass",
  value: previouslySealedKey,
});
```

### Signature/verification

To sign:

```JavaScript
key.sign(data).then(signature => ...);
```

Both data and signature are ArrayBuffer

To verify:

```JavaScript
key.verify(data, signature).then(signOk => ...);
```

Both data and signature are ArrayBuffer; signOk is a boolean.

In the case of bitcoin-message signature, it is possible to convert the signature to a string.

### Data encryption/decryption

It is possible to encrypt data only knowing the recipient's public key.

There are many functions and methods to tweak the process, but the main usage is:

```JavaScript
import {Bundle} from "@keeex/js-keys/lib/bundle";
import "@keeex/crypto-provider-node";
import {generateKey, KeyType} from "@keeex/js-keys/lib/keys";
import assert from "assert";

const main = async(): Promise<void> => {
  // Recipients only need publicKey part
  const recipientKey1 = await generateKey(KeyType.bitcoin);
  const recipientKey2 = await generateKey(KeyType.bitcoin);

  // The data and metadata to encrypt
  const inputData = new Uint8Array([1, 2, 3, 4]).buffer;
  const inputMetadata = new Uint8Array([5, 6, 7, 8]).buffer;

  const bigBundle = await Bundle.createBundle(
    [
      recipientKey1,
      recipientKey2,
    ],
    {
      metadata: inputMetadata,
      data: inputData,
    },
  );
  const encryptedMetadataBundle = await bigBundle.saveBundle(["metadata"]);
  const encryptedDataBundle = await bigBundle.saveBundle(["data"]);

  // Decrypt data
  // For this, the recipient key must have the private part
  const readBundleMetadata = await Bundle.loadBundle(encryptedMetadataBundle);
  const readBundleData = await Bundle.loadBundle(encryptedDataBundle);
  const decryptedMetadata = await readBundleMetadata.getData(
    recipientKey1,
    "metadata",
  );
  const decryptedData = await readBundleData.getData(recipientKey1, "data");
  assert.deepStrictEqual(decryptedMetadata, inputMetadata);
  assert.deepStrictEqual(decryptedData, inputData);
  console.log("Ok");
};
main().catch(e => console.error(e));
```