node-sovrin-did

node.js module to generate DID and Ed25519 keys to use with Sovrin

Install

$ npm i sovrin-did

Example

var sovrinDID = require("sovrin-did");

var d = sovrinDID.gen();

console.log(d);

output:

{ did: 'S7evWWTSbaXELyE9w53sFr',
  verifyKey: 'EgvhZsLKSsqsbNBfJ2wfR9FFWo9YqkpxpfXeT4ifR1Cq',
  encryptionPublicKey: '5UAXeov4Gi7ioSTLDoMPtdvqX6RRmJcQAWagVgdaxUej',
  secret:
   { seed: '36a572a7e43956784b517c57b26720a8ef838d114c0619f1d8c7801c37fa4f6a',
     signKey: '4gKLe7Qq2WX249NBfymQySZbAzXboq2emMig6wBR82Bj',
     encryptionPrivateKey: '7H25Jfb2ND51hhaomL5FPhhqQvBGujd1jJeSjZZ8HQzR'} }

API

gen()

Generates a new did, verification key, signing key, and also gives you the seed used to generate them. It also includes the public and private key used for encryption.

{
    did: "<base58 did>",
    verifyKey: "<base58 publicKey>",
    publicKey: "<base58 publicKey>",

    secret: {
        seed: "<hex encoded 32-byte seed>",
        signKey: "<base58 secretKey>",
        privateKey: "<base58 privateKey>"
    }
}

fromSeed(seed)

Same as .gen() except you supply the seed. The seed should be a 32-byte Uint8Array (i.e. Buffer).

Example:

var seed = Buffer.from("36a572a7e43956784b517c57b26720a8ef838d114c0619f1d8c7801c37fa4f6a", "hex");

var d = sovrinDID.fromSeed(seed);

console.log(d);

The output is the same as the .gen() example.

signMessage(message, signKey, verifyKey)

Signs a message with the given signKey and verifyKey.

• The message should be a string.
• Both the signKey and verifyKey should be the signKey and verifyKey given from the gen() or fromSeed(seed) methods

Returns a signed message as a Uint8Array (i.e. Buffer).

Example:

  var sovrin = sovrinDID.gen();
 
  var signKey = sovrin.secret.signKey;
  var verifyKey = sovrin.verifyKey;
  var message = "Hello World!!";
 
  var signedMessage = sovrinDID.signMessage(message, signKey, verifyKey);

verifySignedMessage(signedMessage, verifyKey)

Verifies that the given message has been signed by the possessor of the given verifyKey.

• The signedMessage should be what is returned from signMessage(message, signKey, verifyKey)
• The verifyKey should be the verifyKey given from the gen() or fromSeed(seed) methods

Returns the original message if the message was signed by the owner of the verifyKey false otherwise.

Example:

  var sovrin = sovrinDID.gen();
  var sovrin2 = sovrinDID.gen();
 
  var signKey = sovrin.secret.signKey;
  var verifyKey = sovrin.verifyKey;
  var verifyKey2 = sovrin2.verifyKey;
 
  var message = "Hello World!!";
 
  var signedMessage = sovrinDID.signMessage(message, signKey, verifyKey);
 
  console.log(sovrinDID.verifySignedMessage(signedMessage, verifyKey));
  console.log(sovrinDID.verifySignedMessage(signedMessage, verifyKey2));

Output:

  Hello World!!
  false

getKeyPairFromSignKey(signKey)

Returns a key pair that is valid to use for encrypting.

• The signKey should be the signKey given from the object given from gen() or fromSeed()

Example:

var sovrin = sovrinDID.gen();
var signKey = sovrin.secret.signKey;

var keyPair = sovrinDID.getKeyPairFromSignKey(signKey);
console.log(keyPair);

Output:

{
   publicKey: ...   // Uint8Array with 32-byte public key
   secretKey: ...   // Uint8Array with 32-byte secret key
}

getNonce()

Returns a random nonce as a Uint8Array that can be used for encrypting.

Example:

var nonce = sovrinDID.getNonce();

getSharedSecret(theirVerifyKey, mySigningKey)

Computes a sharedSecret to be used for encryption.

• theirVerifyKey should be the publicKey given from the getKeyPairFromSignKey(signKey) method or the publicKey string given from the gen() method.
• mySigningKey should be the secretKey given from the getKeyPairFromSignKey(signKey) method or the privateKey given from the gen() method.

Example:

var sovrin1 = sovrinDID.gen();
var sovrin2 = sovrinDID.gen();

// Using the strings given via the gen() method
var sharedSecret1 = sovrinDID.getSharedSecret(sovrin2.encryptionPublicKey, sovrin1.secret.encryptionPrivateKey);
var sharedSecret2 = sovrinDID.getSharedSecret(sovrin1.encryptionPublicKey, sovrin2.secret.encryptionPrivateKey);

var signKey1 = sovrin1.secret.signKey;
var signKey2 = sovrin2.secret.signKey;

var keyPair1 = sovrinDID.getKeyPairFromSignKey(signKey1);
var keyPair2 = sovrinDID.getKeyPairFromSignKey(signKey2);

// Using the buffer given from the getKeyPairFromSignKey(signKey2) method
var sharedSecret3 = sovrinDID.getSharedSecret(keyPair2.publicKey, keyPair1.secretKey);
var sharedSecret4 = sovrinDID.getSharedSecret(keyPair1.publicKey, keyPair2.secretKey);

// All the secrets generated are equivalent

encryptMessage(message, nonce, sharedSecret)

Encrypts a the given message using a precomputed sharedSecret.

• message should be given as a string
• nonce should be a nonce from the getNonce() method
  • Note: The nonce used for encrypting and decrypting need to be the same
• sharedSecret should be computed using the getSharedSecret(theirVerifyKey, mySigningKey) method

Example:

var sovrin1 = sovrinDID.gen();
var sovrin2 = sovrinDID.gen();

var signKey1 = sovrin1.secret.signKey;
var signKey2 = sovrin2.secret.signKey;

var keyPair1 = sovrinDID.getKeyPairFromSignKey(signKey1);
var keyPair2 = sovrinDID.getKeyPairFromSignKey(signKey2);
var sharedSecret1To2 = sovrinDID.getSharedSecret(keyPair2.publicKey, keyPair1.secretKey);

var message = "Hello World!!";
var nonce = sovrinDID.getNonce();
var encryptedMessage = sovrinDID.encryptMessage(message, nonce, sharedSecret1To2);

decryptMessage(encryptedMessage, nonce, sharedSecret)

Verifies and decrypts a previously encrypted message.

• encryptedMessage should be what is returned from the encryptMessage(message, nonce, sharedSecret) method
• nonce should be a nonce given from the getNonce() method
  • Note: The nonce used for encrypting and decrypting need to be the same
• sharedSecret should be computed using the getSharedSecret(theirVerifyKey, mySigningKey) method

Example:

var signKey1 = "4bMnc36WuLYJqsWTZtiazJJrtkvPwgyWnirn7gKk7ium";
var signKey2 = "516mChDX1BRjwHJc2w838W8cXxy8a6Eb35HKXjPR2fD8";
var signKey3 = "7H25Jfb2ND51hhaomL5FPhhqQvBGujd1jJeSjZZ8HQzR";

var keyPair1 = sovrinDID.getKeyPairFromSignKey(signKey1);
var keyPair2 = sovrinDID.getKeyPairFromSignKey(signKey2);
var keyPair3 = sovrinDID.getKeyPairFromSignKey(signKey3);

var sharedSecret1To2 = sovrinDID.getSharedSecret(keyPair2.publicKey, keyPair1.secretKey);
var sharedSecret2To1 = sovrinDID.getSharedSecret(keyPair1.publicKey, keyPair2.secretKey);
var sharedSecret3To1 = sovrinDID.getSharedSecret(keyPair3.publicKey, keyPair1.secretKey);

var message = "Hello World!!";
var nonce = sovrinDID.getNonce();

var encryptedMessage = sovrinDID.encryptMessage(message, nonce, sharedSecret1To2);
var decryptedMessage = sovrinDID.decryptMessage(encryptedMessage, nonce, sharedSecret2To1);
var attemptedDecryption = sovrinDID.decryptMessage(encryptedMessage, nonce, sharedSecret3To1);

console.log(decryptedMessage);
console.log(attemptedDecryption);

Output:

Hello World!!
false

License

MIT