IOTA Signing Scheme
IOTA Signing Scheme
Install using npm:
``
npm install @iota/signing
or using yarn:
`
yarn add @iota/signing
* signing
* .key(subseedTrits, numberOfFragments)
* .validateSignatures(expectedAddress, signatureFragments, bundle)
- errors.ILLEGAL\_SUBSEED\_INDEX : Make sure that the index argument is a number greater than 0.
| Param | Type | Description |
| --- | --- | --- |
| seed | Int8Array | A 243-trit seed to use to derive the subseed |
| index | number | The private key index to use to derive the subseed |
This method derives a subseed from a seed and a private key index.
You can use the subseed to derive private keys and their addresses.
Note: If the given seed is less then 243 trits, 0 trits are appended to it until it is 243 trits long.
To convert a seed from trytes to trits, use the trytesToTrits() method.
To derive a private key from the subseed, use the key() method.
Returns: Int8Array - subseed - A subseed in trits
Example
`js`
const seed = 'MYSUPERSECRETSEED...';
const subseed = Sign.subseed(Converter.trytesToTrits(seed), 0);
- errors.ILLEGAL\_SUBSEED\_LENGTH : Make sure that the subseedTrits argument contains 243 trits.numberOfFragments
- errors.ILLEGAL\_NUMBER\_OF\_FRAGMENTS : Make sure that the argument is a valid security level (between 1 and 3).
| Param | Type | Description |
| --- | --- | --- |
| subseedTrits | Int8Array | A subseed in trits |
| numberOfFragments | number | The security level that you want the private key to have |
This method derives a private key from a subseed.
You can use the private key to derive an address and to sign bundles that withdraw from that address.
To generate a subseed, use the subseed() method.
Returns: Int8Array - privateKey - A private key in trits.
Example
`js
const seed = 'MYSUPERSECRETSEED...';
const subseed = Signing.subseed(Converter.trytesToTrits(seed), 0);
const privateKey = Signing.key(subseed, 2);
`
- errors.ILLEGAL\_KEY\_LENGTH : Make sure that the key argument contains 2,187, 4,374, or 6,561 trits.
| Param | Type | Description |
| --- | --- | --- |
| key | Int8Array | Private key in trits |
This method derives key digests from a private key.
You can use the key digests to generate an address.
To generate a private key, use the key() method.
Returns: Int8Array - digests - Key digests in trits
Example
`js
const seed = 'MYSUPERSECRETSEED...';
const subseed = Signing.subseed(Converter.trytesToTrits(seed), 0);
const privateKey = Signing.key(subseed, 2);
const digests = Signing.digests(privateKey);
`
- errors.ILLEGAL\_DIGESTS\_LENGTH : Make sure that the digests argument contains a multiple of 243 trits.
| Param | Type | Description |
| --- | --- | --- |
| digests | Int8Array | Key digests in trits |
This method derives a 243-trit address from the given key digests.
To generate a private key, use the key() method.
Returns: Int8Array - address - Address in trits
Example
`js
const seed = 'MYSUPERSECRETSEED...';
const subseed = Signing.subseed(Converter.trytesToTrits(seed), 0);
const privateKey = Signing.key(subseed, 2);
const digests = Signing.digests(privateKey);
const address = Signing.address(digests);
`
- errors.ILLEGAL\_BUNDLE\_HASH\_LENGTH : Make sure that the bundle argument contains a 243-trit bundle hash.
| Param | Type | Description |
| --- | --- | --- |
| expectedAddress | Int8Array | Input address in trits |
| signatureFragments | Array.<Int8Array> | Signature fragments in trits |
| bundle | Int8Array | Bundle hash in trits |
This method validates a signature by doing the following:
- Normalizing the bundle hash
- Deriving the key digests of the address, using the normalized bundle hash and the signature
-.Deriving an address from the key digests
- Comparing the derived address to the expectedAddress argument to find out if they match
If the addresses match, the signature is valid.
For more information about signatures see the documentation portal.
To convert trytes such as bundle hashes and addresses to trits, use the trytesToTrits() method.
Returns: boolean - valid - Whether the signatures are valid.
Example
`js`
let valid = Signing.validateSignatures(expectedAddress, signatureFragments, bundle);
- errors.ILLEGAL\_BUNDLE\_HASH\_LENGTH : Make sure that the bundle argument contains a 243-trit bundle hash.
| Param | Type | Description |
| --- | --- | --- |
| bundle | Int8Array | Bundle hash in trits |
This method normalizes the given bundle hash to make sure that only around half of the private key is revealed when the bundle hash is signed.
For more information about signatures see the documentation portal.
To find out more about why the bundle hash is normalized, see this answer on StackExchange.
To convert a bundle hash from trytes to trits, use the trytesToTrits() method.
Returns: Int8Array - Normalized bundle hash in trits
Example
`js``
let normalizedBundleHash = Signing.normalizedBundle(bundle);