refactor: migrate WASignalGroup to TypeScript and remove deprecated files (#1320)

* refactor: migrate WASignalGroup to TypeScript and remove deprecated files

* chore: remove WASignalGroup JavaScript files from package.json

* refactor: update SenderKeyStore and SenderKeyStateStructure interfaces to export and add deserialize method. Fix types

* chore: lint issue

* refactor: improve constructor type checking and getSeed method in SenderChainKey

* refactor: update key handling to use Buffer for improved consistency

* signal: consistent naming and dir structure + add some missing types

* fix: lint issues

---------

Co-authored-by: Rajeh Taher <rajeh@reforward.dev>

src/Signal/Group/sender-key-message.ts

@@ -0,0 +1,96 @@
+import { calculateSignature, verifySignature } from 'libsignal/src/curve'
+import { proto } from '../../../WAProto'
+import { CiphertextMessage } from './ciphertext-message'
+
+interface SenderKeyMessageStructure {
+	id: number
+	iteration: number
+	ciphertext: string | Buffer
+}
+
+export class SenderKeyMessage extends CiphertextMessage {
+	private readonly SIGNATURE_LENGTH = 64
+	private readonly messageVersion: number
+	private readonly keyId: number
+	private readonly iteration: number
+	private readonly ciphertext: Uint8Array
+	private readonly signature: Uint8Array
+	private readonly serialized: Uint8Array
+
+	constructor(
+		keyId?: number | null,
+		iteration?: number | null,
+		ciphertext?: Uint8Array | null,
+		signatureKey?: Uint8Array | null,
+		serialized?: Uint8Array | null
+	) {
+		super()
+
+		if (serialized) {
+			const version = serialized[0]
+			const message = serialized.slice(1, serialized.length - this.SIGNATURE_LENGTH)
+			const signature = serialized.slice(-1 * this.SIGNATURE_LENGTH)
+			const senderKeyMessage = proto.SenderKeyMessage.decode(message).toJSON() as SenderKeyMessageStructure
+
+			this.serialized = serialized
+			this.messageVersion = (version & 0xff) >> 4
+			this.keyId = senderKeyMessage.id
+			this.iteration = senderKeyMessage.iteration
+			this.ciphertext =
+				typeof senderKeyMessage.ciphertext === 'string'
+					? Buffer.from(senderKeyMessage.ciphertext, 'base64')
+					: senderKeyMessage.ciphertext
+			this.signature = signature
+		} else {
+			const version = (((this.CURRENT_VERSION << 4) | this.CURRENT_VERSION) & 0xff) % 256
+			const ciphertextBuffer = Buffer.from(ciphertext!)
+			const message = proto.SenderKeyMessage.encode(
+				proto.SenderKeyMessage.create({
+					id: keyId!,
+					iteration: iteration!,
+					ciphertext: ciphertextBuffer
+				})
+			).finish()
+
+			const signature = this.getSignature(signatureKey!, Buffer.concat([Buffer.from([version]), message]))
+
+			this.serialized = Buffer.concat([Buffer.from([version]), message, Buffer.from(signature)])
+			this.messageVersion = this.CURRENT_VERSION
+			this.keyId = keyId!
+			this.iteration = iteration!
+			this.ciphertext = ciphertextBuffer
+			this.signature = signature
+		}
+	}
+
+	public getKeyId(): number {
+		return this.keyId
+	}
+
+	public getIteration(): number {
+		return this.iteration
+	}
+
+	public getCipherText(): Uint8Array {
+		return this.ciphertext
+	}
+
+	public verifySignature(signatureKey: Uint8Array): void {
+		const part1 = this.serialized.slice(0, this.serialized.length - this.SIGNATURE_LENGTH)
+		const part2 = this.serialized.slice(-1 * this.SIGNATURE_LENGTH)
+		const res = verifySignature(signatureKey, part1, part2)
+		if (!res) throw new Error('Invalid signature!')
+	}
+
+	private getSignature(signatureKey: Uint8Array, serialized: Uint8Array): Uint8Array {
+		return Buffer.from(calculateSignature(signatureKey, serialized))
+	}
+
+	public serialize(): Uint8Array {
+		return this.serialized
+	}
+
+	public getType(): number {
+		return 4
+	}
+}