1 files changed, 133 insertions, 0 deletions
diff --git a/src/remote/activitypub/misc/ld-signature.ts b/src/remote/activitypub/misc/ld-signature.ts
new file mode 100644
index 0000000000..d61b430f7a
--- /dev/null
+++ b/src/remote/activitypub/misc/ld-signature.ts
@@ -0,0 +1,133 @@
+import * as crypto from 'crypto';
+import * as jsonld from 'jsonld';
+import { CONTEXTS } from './contexts';
+import fetch from 'node-fetch';
+import { httpAgent, httpsAgent } from '../../../misc/fetch';
+
+// RsaSignature2017 based from https://github.com/transmute-industries/RsaSignature2017
+
+export class LdSignature {
+	public debug = false;
+	public preLoad = true;
+	public loderTimeout = 10 * 1000;
+
+	constructor() {
+	}
+
+	public async signRsaSignature2017(data: any, privateKey: string, creator: string, domain?: string, created?: Date): Promise<any> {
+		const options = {
+			type: 'RsaSignature2017',
+			creator,
+			domain,
+			nonce: crypto.randomBytes(16).toString('hex'),
+			created: (created || new Date()).toISOString()
+		} as {
+			type: string;
+			creator: string;
+			domain: string;
+			nonce: string;
+			created: string;
+		};
+
+		if (!domain) {
+			delete options.domain;
+		}
+
+		const toBeSigned = await this.createVerifyData(data, options);
+
+		const signer = crypto.createSign('sha256');
+		signer.update(toBeSigned);
+		signer.end();
+
+		const signature = signer.sign(privateKey);
+
+		return {
+			...data,
+			signature: {
+				...options,
+				signatureValue: signature.toString('base64')
+			}
+		};
+	}
+
+	public async verifyRsaSignature2017(data: any, publicKey: string): Promise<boolean> {
+		const toBeSigned = await this.createVerifyData(data, data.signature);
+		const verifier = crypto.createVerify('sha256');
+		verifier.update(toBeSigned);
+		return verifier.verify(publicKey, data.signature.signatureValue, 'base64');
+	}
+
+	public async createVerifyData(data: any, options: any) {
+		const transformedOptions = {
+			...options,
+			'@context': 'https://w3id.org/identity/v1'
+		};
+		delete transformedOptions['type'];
+		delete transformedOptions['id'];
+		delete transformedOptions['signatureValue'];
+		const canonizedOptions = await this.normalize(transformedOptions);
+		const optionsHash = this.sha256(canonizedOptions);
+		const transformedData = { ...data };
+		delete transformedData['signature'];
+		const cannonidedData = await this.normalize(transformedData);
+		const documentHash = this.sha256(cannonidedData);
+		const verifyData = `${optionsHash}${documentHash}`;
+		return verifyData;
+	}
+
+	public async normalize(data: any) {
+		const customLoader = this.getLoader();
+		return await jsonld.normalize(data, {
+			documentLoader: customLoader
+		});
+	}
+
+	private getLoader() {
+		return async (url: string): Promise<any> => {
+			if (!url.match('^https?\:\/\/')) throw `Invalid URL ${url}`;
+
+			if (this.preLoad) {
+				if (url in CONTEXTS) {
+					if (this.debug) console.debug(`HIT: ${url}`);
+					return {
+						contextUrl: null,
+						document: CONTEXTS[url],
+						documentUrl: url
+					};
+				}
+			}
+
+			if (this.debug) console.debug(`MISS: ${url}`);
+			const document = await this.fetchDocument(url);
+			return {
+				contextUrl: null,
+				document: document,
+				documentUrl: url
+			};
+		};
+	}
+
+	private async fetchDocument(url: string) {
+		const json = await fetch(url, {
+			headers: {
+				Accept: 'application/ld+json, application/json',
+			},
+			timeout: this.loderTimeout,
+			agent: u => u.protocol == 'http:' ? httpAgent : httpsAgent,
+		}).then(res => {
+			if (!res.ok) {
+				throw `${res.status} ${res.statusText}`;
+			} else {
+				return res.json();
+			}
+		});
+
+		return json;
+	}
+
+	public sha256(data: string): string {
+		const hash = crypto.createHash('sha256');
+		hash.update(data);
+		return hash.digest('hex');
+	}
+}