diff --git a/lib/crypto/Crypto.js b/lib/crypto/Crypto.js
index 6fd612e..1cefdac 100644
--- a/lib/crypto/Crypto.js
+++ b/lib/crypto/Crypto.js
@@ -72,7 +72,7 @@ module.exports = class Crypto {
 		const mod = new BigNumber(key.n());
 		const buffer = modPow(base, power, mod).toBEBuffer();
 
-		if (buffer.byteLength !== 257 && buffer[0] === 0x00)
+		if (buffer.byteLength === 257 && buffer[0] === 0x00)
 			return buffer.slice(1).toString('base64');
 
 		return buffer.toString('base64');