fixes

src/exe.js

@@ -83,8 +83,9 @@ function extractFromServiceExe(buffer, version) {
 	size = readBits(buffer.slice(offset));
 	out[3] = { size, offset: offset - size };
 
-	let cipherLength = buffer.length - (out[0].size + out[1].size + out[2].size + out[3].size + verions[version][0]);
-	debug(`cipherLength=${cipherLength}`);
+	let cipherKeyLength = buffer.length - (out[0].size + out[1].size + out[2].size + out[3].size + verions[version][1]);
+	let cipherKey = buffer.subarray(0, cipherKeyLength);
+	debug(`cipherKeyLength=${cipherKeyLength}`);
 
 	// Decrypt blocks
 	let payloads = [];
@@ -96,8 +97,8 @@ function extractFromServiceExe(buffer, version) {
 
 		if (out[i].size) {
 			debug(sprintf("BLOCK %08X %08X", out[i].offset, out[i].size));
-			let payload = buffer.subarray(out[i].offset, out[i].offset + out[i].size);
-			applyXor(payload, buffer.slice(0, cipherLength));
+			let payload = Buffer.from(buffer.subarray(out[i].offset, out[i].offset + out[i].size));
+			applyXor(payload, cipherKey);
 			payloads[i] = payload;
 		}
 	}

src/xbz.js

@@ -71,6 +71,8 @@ export function isXbz(buffer) {
 
 export function parseXbz(buffer) {
 	let xbzFormat = detectXbzFormat(buffer);
+	if (!xbzFormat)
+		return null;
 
 	debug("XBZ version: " + xbzFormat.version);
 	debug("XBZ signed: " + xbzFormat.signed);
@@ -177,18 +179,20 @@ function decodeXbzWriteFrame(version, buffer, offset) {
 		let addr = (buffer.readUInt8(0) << 16) | (buffer.readUInt8(1) << 8) | (buffer.readUInt8(2));
 		let size = buffer.readUInt8(3);
 		let chk = buffer.readUInt8(4 + size);
+		let actualChk = calcChecksum(buffer, 4 + size);
 
-		if (chk != calcChecksum(buffer, 4 + size))
-			throw new Error(`Invalid chk: ${chk}`);
+		if (chk != actualChk)
+			throw new Error(`Invalid chk: ${sprintf("%08X %04X CHK:%02X != %02X", addr, size, chk, actualChk)} at ${buffer.byteOffset}`);
 
 		return [ 4 + 1 + size, { addr, size, offset: offset + 4 } ];
 	} else if (version == 32) {
 		let addr = buffer.readUInt32BE(0);
 		let size = buffer.readUInt16BE(4);
 		let chk = buffer.readUInt8(6 + size);
+		let actualChk = calcChecksum(buffer, 6 + size);
 
-		if (chk != calcChecksum(buffer, 6 + size))
-			throw new Error(`Invalid chk: ${chk}`);
+		if (chk != actualChk)
+			throw new Error(`Invalid chk: ${sprintf("%08X %04X CHK:%02X != %02X", addr, size, chk, actualChk)} at ${buffer.byteOffset}`);
 
 		return [ 6 + 1 + size, { addr, size, offset: offset + 6 } ];
 	}
@@ -236,6 +240,8 @@ function decodeXbzFrame(frameType, version, buffer) {
 
 function calcChecksum(buffer, size) {
 	let chk = 0;
+	if (size > buffer.length)
+		throw new Error(`Truncated file! [${size} > ${buffer.length}]`);
 	for (let i = 0; i < size; i++)
 		chk ^= buffer[i];
 	return chk;