Getting the below error when trying to decrypt an encrypted string sent from my server. Printing description of error: ▿ Optional<Unmanaged<CFErrorRef>> ▿ some : Unmanaged<CFErrorRef> - _value : Error Domain=NSOSStatusErrorDomain Code=-50 "<SecKeyRef algorithm id: 1, key type: RSAPrivateKey, version: 4, 2048 bits (block size: 256), addr: 0x600000cb16c0>: sign - input buffer bad size (344 bytes)" UserInfo={numberOfErrorsDeep=0, NSDescription=<SecKeyRef algorithm id: 1, key type: RSAPrivateKey, version: 4, 2048 bits (block size: 256), addr: 0x600000cb16c0>: sign - input buffer bad size (344 bytes)} I generated the RSA 2048 public private key pairs using private func getRsaKeyPair()->(String,SecKey)?{ let publicKeyAttr: [NSObject: Any] = [ kSecAttrIsPermanent: true, kSecAttrApplicationTag: "com.appname.one.rsa.public".data(using: String.Encoding.utf8)!, kSecClass: kSecClassKey, kSecReturnData: kCFBooleanTrue as Any] let privateKeyAttr: [NSObject: Any] = [ kSecAttrIsPermanent:true, kSecAttrApplicationTag:"com.appname.one.rsa.private".data(using: String.Encoding.utf8)!, kSecClass: kSecClassKey, kSecReturnData: kCFBooleanTrue as Any] var keyPairAttr = [NSObject: Any]() keyPairAttr[kSecAttrKeyType] = kSecAttrKeyTypeRSA keyPairAttr[kSecAttrKeySizeInBits] = 2048 keyPairAttr[kSecPublicKeyAttrs] = publicKeyAttr keyPairAttr[kSecPrivateKeyAttrs] = privateKeyAttr var error: Unmanaged<CFError>? = nil let privateKey = SecKeyCreateRandomKey(keyPairAttr as CFDictionary, &error) if let privateKey { var resultPublicKey: AnyObject? let statusPublicKey = SecItemCopyMatching(publicKeyAttr as CFDictionary, &resultPublicKey) if statusPublicKey == noErr { if let publicKey = resultPublicKey as? Data { return(publicKey.base64EncodedString(), privateKey) } } } return nil } i then sent the public key to my node js server which then returned me a string encrypted with the said public key. I decrypt it as follows guard let key = data.encStr?.data(using: .utf8) else{ return } print("encStr Size: \(key.count) bytes") var error: Unmanaged<CFError>? = nil if let plaintext = SecKeyCreateDecryptedData(privateKey, .rsaEncryptionPKCS1 , key as CFData, &error) as? Data{ print("HURRAY:\(plaintext)") if let plainTextStr = String(data: plaintext, encoding: .utf8){ print(plainTextStr) } }else{ print(error.debugDescription) } But i get the above mentioned error when decrypting using my private key.