# Crypto Signature 🔏
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## Lightweight TypeScript Signatures library
This documentation provides an overview of the Digital Signature module and demonstrates how to use its methods for creating and verifying digital signatures.
### Table of Contents
- [Getting started](#getting-started)
- [Usage](#usage)
- [Creating a Digital Signature](#creating-a-digital-signature)
- [Verifying a Digital Signature](#verifying-a-digital-signature)
- [Supported Algorithms](#supported-algorithms)
- [Error Handling](#error-handling)
- [Development](#development)
- [ESLint](#eslint)
- [Jest](#jest)
- [Contributing](#contributing)
- [Security](#security)
- [Credits](#made-with-)
### Overview
The module supports multiple algorithms for signing and verifying data, including HMAC, RSA, RSASSA-PSS, DSA, EcDSA and EdDSA. It provides a synchronous interface for cryptographic operations using Node.js's crypto module and custom utility classes.
---
### Getting started
Run the following command to start using `crypto-signature` in your projects:
```bash
npm i @alessiofrittoli/crypto-signature
```
or using `pnpm`
```bash
pnpm i @alessiofrittoli/crypto-signature
```
---
#### Usage
##### Importing the Module
```ts
import { Signature } from "@alessiofrittoli/crypto-signature";
import type { Sign } from "@alessiofrittoli/crypto-signature";
// or
import type { Sign } from "@alessiofrittoli/crypto-signature/types";
```
---
#### Creating a Digital Signature
The `Signature.sign()` method generates a signature for a given data input using a specified algorithm and private key.
##### Parameters
| Parameter | Type | Default | Description |
| ----------- | ------------------------- | ------- | ----------------------------------------------------------------------------------------------- |
| `data` | `CoerceToUint8ArrayInput` | - | The data to be signed. |
| `key` | `Sign.PrivateKey` | - | The private key used for signing. This can be a symmetric key, PEM private key or a key object. |
| `algorithm` | `Sign.AlgorithmJwkName` | `HS256` | The JWK algorithm name. |
##### Returns
Type: `Buffer`
The generated signature Node.js Buffer.
##### Example
```ts
const data = "This is the data to sign";
const key = crypto.createSecretKey(Buffer.from("your-secret-key"));
const algorithm = "HS256";
try {
const signature = Signature.sign(data, key, algorithm);
console.log("Generated Signature:", signature.toString("hex"));
} catch (error) {
console.error("Error generating signature:", error);
}
```
#### Verifying a Digital Signature
The `Signature.isValid()` method verifies the integrity and authenticity of a digital signature.
##### Parameters
| Parameter | Type | Default | Description |
| ----------- | ------------------------- | ------- | -------------------------------------------------------------------------------------------------- |
| `signature` | `CoerceToUint8ArrayInput` | - | The signature to verify. |
| `data` | `CoerceToUint8ArrayInput` | - | The original data that was signed. |
| `key` | `Sign.PublicKey` | - | The public key used for verification. This can be a symmetric key, PEM public key or a key object. |
| `algorithm` | `Sign.AlgorithmJwkName` | `HS256` | The JWK algorithm name. |
##### Returns
Type: `true`
Returns `true` if the signature is valid. Throws an exception otherwise.
##### Example
```ts
const signature = Buffer.from("signature-in-hex", "hex");
const data = "This is the data to verify";
const key = crypto.createSecretKey(Buffer.from("your-secret-key"));
const algorithm = "HS256";
try {
const isValid = Signature.isValid(signature, data, key, algorithm);
console.log("Signature is valid:", isValid);
} catch (error) {
console.error("Error verifying signature:", error);
}
```
#### Supported Algorithms
The module supports the following algorithms:
| Type | JWK name | Description |
| ------------ | -------- | ------------------------------------------------------------------ |
| `HMAC` | | |
| | `HS1` | Signature generated/verified with `HMAC` key and `SHA-1`. |
| | `HS256` | Signature generated/verified with `HMAC` key and `SHA-256`. |
| | `HS384` | Signature generated/verified with `HMAC` key and `SHA-384`. |
| | `HS512` | Signature generated/verified with `HMAC` key and `SHA-512`. |
| `DSA` | | |
| | `DS1` | Signature generated/verified with `DSA` keys and `SHA-1`. |
| | `DS256` | Signature generated/verified with `DSA` keys and `SHA-256`. |
| | `DS384` | Signature generated/verified with `DSA` keys and `SHA-384`. |
| | `DS512` | Signature generated/verified with `DSA` keys and `SHA-512`. |
| `EcDSA` | | |
| | `ES256` | Signature generated/verified with `EC` keys and `SHA-256`. |
| | `ES384` | Signature generated/verified with `EC` keys and `SHA-384`. |
| | `ES512` | Signature generated/verified with `EC` keys and `SHA-512`. |
| `EdDSA` | | |
| | `EdDSA` | Signature generated/verified with `ed448` keys. |
| | `EdDSA` | Signature generated/verified with `ed25519` keys. |
| `RSA` | | |
| | `RS1` | Signature generated/verified with `RSA` keys and `SHA-1`. |
| | `RS256` | Signature generated/verified with `RSA` keys and `SHA-256`. |
| | `RS384` | Signature generated/verified with `RSA` keys and `SHA-384`. |
| | `RS512` | Signature generated/verified with `RSA` keys and `SHA-512`. |
| `RSASSA-PSS` | | |
| | `PS256` | Signature generated/verified with `RSASSA-PSS` keys and `SHA-256`. |
| | `PS384` | Signature generated/verified with `RSASSA-PSS` keys and `SHA-384`. |
| | `PS512` | Signature generated/verified with `RSASSA-PSS` keys and `SHA-512`. |
---
### Error handling
This module throws a new `Exception` when an error occures providing an error code that will help in error handling.
The `ErrorCode` enumerator can be used to handle different errors with ease.
`ErrorCode` enum
| Constant | Description |
| --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `UNKNOWN` | Thrown when: |
| | - `Signature.sign()` encounters an unexpected error while creating a signature (mostly due to unsupported routine). The original thrown error is being reported in the `Exception.cause` property. |
| | - `Signature.isValid()` encounters an unexpected error while verifying a signature (mostly due to unsupported routine). The original thrown error is being reported in the `Exception.cause` property. |
| `EMPTY_VALUE` | Thrown when: |
| | `Signature.sign()` has no `data` to sign. |
| | `Signature.isValid()` has no `data` to verify. |
| `INVALID_SIGN` | Thrown when `Signature.isValid()` encounter an invalid signature (altered data, altered signature, wrong PublicKey). |
| `NO_SIGN` | Thrown when `Signature.isValid()` has no `signature` to verify. |
| `NO_PRIVATEKEY` | Thrown when `Signature.sign()` has no Private Key to sign with. |
| `NO_PUBLICKEY` | Thrown when `Signature.isValid()` has no Public Key to verify the signature with. |
---
Example usage
```ts
import { Exception } from "@alessiofrittoli/exception";
import { Signature } from "@alessiofrittoli/crypto-signature";
import { ErrorCode } from "@alessiofrittoli/crypto-signature/error";
try {
Signature.isValid("invalid signature", "Data", "myscretkey");
} catch (error) {
console.log(error);
// safe type guard the `error` variable.
if (Exception.isException(error)) {
// ... do somethign with `error.code`
if (error.code === ErrorCode.INVALID_SIGN) {
// ...
}
}
}
```
---
This documentation covers the essential functionality of the module, allowing users to securely sign and verify data using various cryptographic algorithms.
---
### Development
#### Install depenendencies
```bash
npm install
```
or using `pnpm`
```bash
pnpm i
```
#### Build the source code
Run the following command to test and build code for distribution.
```bash
pnpm build
```
#### [ESLint](https://www.npmjs.com/package/eslint)
warnings / errors check.
```bash
pnpm lint
```
#### [Jest](https://npmjs.com/package/jest)
Run all the defined test suites by running the following:
```bash
# Run tests and watch file changes.
pnpm test:watch
# Run tests in a CI environment.
pnpm test:ci
```
- See [`package.json`](./package.json) file scripts for more info.
Run tests with coverage.
An HTTP server is then started to serve coverage files from `./coverage` folder.
⚠️ You may see a blank page the first time you run this command. Simply refresh the browser to see the updates.
```bash
test:coverage:serve
```
---
### Contributing
Contributions are truly welcome!
Please refer to the [Contributing Doc](./CONTRIBUTING.md) for more information on how to start contributing to this project.
Help keep this project up to date with [GitHub Sponsor][sponsor-url].
[![GitHub Sponsor][sponsor-badge]][sponsor-url]
---
### Security
If you believe you have found a security vulnerability, we encourage you to **_responsibly disclose this and NOT open a public issue_**. We will investigate all legitimate reports. Email `security@alessiofrittoli.it` to disclose any security vulnerabilities.
### Made with ☕
