Main question Is it possible for me to unencrypt my

Questions regarding encryption and backups about safenotes HOT 1 CLOSED

KobeW50 commented on June 14, 2024

Questions regarding encryption and backups

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Comments (1)

keshav-space commented on June 14, 2024 1

SafeNotes uses standard AES-256 encryption, and you can decrypt your notes as long as you remember the correct passphrase.

How exactly is the symmetric key derived?

Here is the algorithm for how we generate the Key and IV for encryption using a passphrase and salt.

safenotes/lib/encryption/aes_encryption.dart

Lines 70 to 91 in 3bf776a

 Tuple2<Uint8List, Uint8List> deriveKeyAndIV(String passphrase, Uint8List salt) { 

 var password = createUint8ListFromString(passphrase); 

 Uint8List concatenatedHashes = Uint8List(0); 

 Uint8List currentHash = Uint8List(0); 

 bool enoughBytesForKey = false; 

 Uint8List preHash = Uint8List(0); 

 while (!enoughBytesForKey) { 

 if (currentHash.length > 0) 

 preHash = Uint8List.fromList(currentHash + password + salt); 

 else 

 preHash = Uint8List.fromList(password + salt); 

 currentHash = Uint8List.fromList(sha256.convert(preHash).bytes); 

 concatenatedHashes = Uint8List.fromList(concatenatedHashes + currentHash); 

 if (concatenatedHashes.length >= 48) enoughBytesForKey = true; 

 } 

 var keyBytes = concatenatedHashes.sublist( 

 0, 32); //32 Byte key length => 256 bit key for AES-256 

 var ivBytes = concatenatedHashes.sublist(32, 48); 

 return new Tuple2(keyBytes, ivBytes); 

 }

Also, is the salt used when generating the symmetric key within the .json backup file? If yes, which field contains the salt?

We create a new salt for each text we encrypt, and the salt is appended at the beginning of the encrypted string. Here is the algorithm for decrypting the notes:

safenotes/lib/encryption/aes_encryption.dart

Lines 49 to 68 in 3bf776a

 String decryptAES(String encrypted, String passphrase) { 

 try { 

 Uint8List encryptedBytesWithSalt = base64.decode(encrypted); 

 Uint8List encryptedBytes = 

 encryptedBytesWithSalt.sublist(16, encryptedBytesWithSalt.length); 

 final salt = encryptedBytesWithSalt.sublist(8, 16); 

 var keyndIV = deriveKeyAndIV(passphrase, salt); 

 final key = encrypt.Key(keyndIV.item1); 

 final iv = encrypt.IV(keyndIV.item2); 

 final encrypter = encrypt.Encrypter( 

 encrypt.AES(key, mode: encrypt.AESMode.cbc, padding: "PKCS7")); 

 final decrypted = 

 encrypter.decrypt64(base64.encode(encryptedBytes), iv: iv); 

 return decrypted; 

 } catch (error) { 

 throw error; 

 } 

 }

I am just concerned about relying on a single application with the ability to unencrypt my important notes.

That's the whole point of having it open source. All the encryption algorithms are public and can be cross-verified. Anyone can create a small utility to decrypt the notes using the correct passphrase in any programming language.

You may also want to see this: #119 (comment)

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Questions regarding encryption and backups about safenotes HOT 1 CLOSED

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	Tuple2<Uint8List, Uint8List> deriveKeyAndIV(String passphrase, Uint8List salt) {
	var password = createUint8ListFromString(passphrase);
	Uint8List concatenatedHashes = Uint8List(0);
	Uint8List currentHash = Uint8List(0);
	bool enoughBytesForKey = false;
	Uint8List preHash = Uint8List(0);

	while (!enoughBytesForKey) {
	if (currentHash.length > 0)
	preHash = Uint8List.fromList(currentHash + password + salt);
	else
	preHash = Uint8List.fromList(password + salt);
	currentHash = Uint8List.fromList(sha256.convert(preHash).bytes);
	concatenatedHashes = Uint8List.fromList(concatenatedHashes + currentHash);
	if (concatenatedHashes.length >= 48) enoughBytesForKey = true;
	}

	var keyBytes = concatenatedHashes.sublist(
	0, 32); //32 Byte key length => 256 bit key for AES-256
	var ivBytes = concatenatedHashes.sublist(32, 48);
	return new Tuple2(keyBytes, ivBytes);
	}

	String decryptAES(String encrypted, String passphrase) {
	try {
	Uint8List encryptedBytesWithSalt = base64.decode(encrypted);

	Uint8List encryptedBytes =
	encryptedBytesWithSalt.sublist(16, encryptedBytesWithSalt.length);
	final salt = encryptedBytesWithSalt.sublist(8, 16);
	var keyndIV = deriveKeyAndIV(passphrase, salt);
	final key = encrypt.Key(keyndIV.item1);
	final iv = encrypt.IV(keyndIV.item2);

	final encrypter = encrypt.Encrypter(
	encrypt.AES(key, mode: encrypt.AESMode.cbc, padding: "PKCS7"));
	final decrypted =
	encrypter.decrypt64(base64.encode(encryptedBytes), iv: iv);
	return decrypted;
	} catch (error) {
	throw error;
	}
	}