Replace scrypt with libsodium's abstractions
This commit is contained in:
Vishnu Mohandas
parent
b06190fbf2
commit
fed7cda7f4
7 changed files with 111 additions and 95 deletions
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@ -21,11 +21,8 @@ class Configuration {
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static const hasOptedForE2EKey = "has_opted_for_e2e_encryption";
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static const foldersToBackUpKey = "folders_to_back_up";
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static const keyKey = "key";
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static const keyEncryptedKey = "encrypted_key";
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static const keyKekSalt = "kek_salt";
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static const keyKekHash = "kek_hash";
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static const keyKekHashSalt = "kek_hash_salt";
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static const keyEncryptedKeyIV = "encrypted_key_iv";
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static const encryptedKeyKey = "encrypted_key";
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static const keyAttributesKey = "key_attributes";
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SharedPreferences _preferences;
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FlutterSecureStorage _secureStorage;
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@ -46,38 +43,45 @@ class Configuration {
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}
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Future<KeyAttributes> generateAndSaveKey(String passphrase) async {
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final key = CryptoUtil.getSecureRandomBytes(length: 32);
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final kekSalt = CryptoUtil.getSecureRandomBytes(length: 32);
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final kek = CryptoUtil.scrypt(utf8.encode(passphrase), kekSalt);
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final kekHashSalt = CryptoUtil.getSecureRandomBytes(length: 32);
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final kekHash = CryptoUtil.scrypt(kek, kekHashSalt);
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// Create a master key
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final key = CryptoUtil.generateMasterKey();
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// Derive a key from the passphrase that will be used to encrypt and
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// decrypt the master key
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final kekSalt = CryptoUtil.getSaltToDeriveKey();
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final kek = CryptoUtil.deriveKey(utf8.encode(passphrase), kekSalt);
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// Encrypt the key with this derived key
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final encryptedKeyData = await CryptoUtil.encrypt(key, key: kek);
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// Hash the passphrase so that its correctness can be compared later
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final passphraseHash = await CryptoUtil.hash(utf8.encode(passphrase));
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final attributes = KeyAttributes(
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Sodium.bin2base64(kekSalt),
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Sodium.bin2base64(kekHash),
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Sodium.bin2base64(kekHashSalt),
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encryptedKeyData.encryptedData.base64,
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encryptedKeyData.nonce.base64);
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passphraseHash: passphraseHash,
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kekSalt: Sodium.bin2base64(kekSalt),
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encryptedKey: encryptedKeyData.encryptedData.base64,
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keyDecryptionNonce: encryptedKeyData.nonce.base64,
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);
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await setKey(Sodium.bin2base64(key));
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await setEncryptedKey(encryptedKeyData.encryptedData.base64);
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await setKeyAttributes(attributes);
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return attributes;
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}
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Future<void> decryptAndSaveKey(
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String passphrase, KeyAttributes attributes) async {
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final kek = CryptoUtil.scrypt(
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utf8.encode(passphrase), base64.decode(attributes.kekSalt));
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final calculatedKekHash =
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CryptoUtil.scrypt(kek, base64.decode(attributes.kekHashSalt));
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final passphraseBytes = utf8.encode(passphrase);
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bool correctPassphrase =
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Sodium.bin2base64(calculatedKekHash) == attributes.kekHash;
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CryptoUtil.verifyHash(passphraseBytes, attributes.passphraseHash);
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if (!correctPassphrase) {
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throw Exception("Incorrect passphrase");
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}
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final kek = CryptoUtil.deriveKey(
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passphraseBytes, Sodium.base642bin(attributes.kekSalt));
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final key = await CryptoUtil.decrypt(
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Sodium.base642bin(attributes.encryptedKey),
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kek,
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Sodium.base642bin(attributes.encryptedKeyIV));
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Sodium.base642bin(attributes.keyDecryptionNonce));
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await setKey(Sodium.bin2base64(key));
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}
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@ -142,31 +146,22 @@ class Configuration {
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Future<void> setKeyAttributes(KeyAttributes attributes) async {
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await _preferences.setString(
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keyKekSalt, attributes == null ? null : attributes.kekSalt);
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await _preferences.setString(
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keyKekHash, attributes == null ? null : attributes.kekHash);
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await _preferences.setString(
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keyKekHashSalt, attributes == null ? null : attributes.kekHashSalt);
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await _preferences.setString(
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keyEncryptedKey, attributes == null ? null : attributes.encryptedKey);
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await _preferences.setString(keyEncryptedKeyIV,
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attributes == null ? null : attributes.encryptedKeyIV);
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keyAttributesKey, attributes == null ? null : attributes.toJson());
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}
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KeyAttributes getKeyAttributes() {
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if (_preferences.getString(keyEncryptedKey) == null) {
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if (_preferences.getString(keyAttributesKey) == null) {
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return null;
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}
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return KeyAttributes(
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_preferences.getString(keyKekSalt),
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_preferences.getString(keyKekHash),
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_preferences.getString(keyKekHashSalt),
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_preferences.getString(keyEncryptedKey),
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_preferences.getString(keyEncryptedKeyIV));
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return KeyAttributes.fromJson(_preferences.getString(keyAttributesKey));
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}
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Future<void> setEncryptedKey(String encryptedKey) async {
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await _preferences.setString(encryptedKeyKey, encryptedKey);
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}
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String getEncryptedKey() {
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return _preferences.getString(keyEncryptedKey);
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return _preferences.getString(encryptedKeyKey);
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}
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Future<void> setKey(String key) async {
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8
lib/models/derived_key_result.dart
Normal file
8
lib/models/derived_key_result.dart
Normal file
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@ -0,0 +1,8 @@
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import 'dart:typed_data';
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class DerivedKeyResult {
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final Uint8List key;
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final Uint8List salt;
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DerivedKeyResult(this.key, this.salt);
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}
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@ -1,43 +1,38 @@
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import 'dart:convert';
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class KeyAttributes {
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final String passphraseHash;
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final String kekSalt;
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final String kekHash;
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final String kekHashSalt;
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final String encryptedKey;
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final String encryptedKeyIV;
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final String keyDecryptionNonce;
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KeyAttributes(
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KeyAttributes({
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this.passphraseHash,
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this.kekSalt,
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this.kekHash,
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this.kekHashSalt,
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this.encryptedKey,
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this.encryptedKeyIV,
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);
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this.keyDecryptionNonce,
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});
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KeyAttributes copyWith({
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String passphraseHash,
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String kekSalt,
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String kekHash,
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String kekHashSalt,
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String encryptedKey,
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String encryptedKeyIV,
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String keyDecryptionNonce,
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}) {
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return KeyAttributes(
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kekSalt ?? this.kekSalt,
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kekHash ?? this.kekHash,
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kekHashSalt ?? this.kekHashSalt,
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encryptedKey ?? this.encryptedKey,
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encryptedKeyIV ?? this.encryptedKeyIV,
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passphraseHash: passphraseHash ?? this.passphraseHash,
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kekSalt: kekSalt ?? this.kekSalt,
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encryptedKey: encryptedKey ?? this.encryptedKey,
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keyDecryptionNonce: keyDecryptionNonce ?? this.keyDecryptionNonce,
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);
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}
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Map<String, dynamic> toMap() {
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return {
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'passphraseHash': passphraseHash,
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'kekSalt': kekSalt,
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'kekHash': kekHash,
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'kekHashSalt': kekHashSalt,
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'encryptedKey': encryptedKey,
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'encryptedKeyIV': encryptedKeyIV,
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'keyDecryptionNonce': keyDecryptionNonce,
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};
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}
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@ -45,11 +40,10 @@ class KeyAttributes {
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if (map == null) return null;
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return KeyAttributes(
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map['kekSalt'],
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map['kekHash'],
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map['kekHashSalt'],
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map['encryptedKey'],
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map['encryptedKeyIV'],
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passphraseHash: map['passphraseHash'],
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kekSalt: map['kekSalt'],
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encryptedKey: map['encryptedKey'],
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keyDecryptionNonce: map['keyDecryptionNonce'],
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);
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}
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@ -60,6 +54,25 @@ class KeyAttributes {
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@override
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String toString() {
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return 'KeyAttributes(kekSalt: $kekSalt, kekHash: $kekHash, kekHashSalt: $kekHashSalt, encryptedKey: $encryptedKey, encryptedKeyIV: $encryptedKeyIV)';
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return 'KeyAttributes(passphraseHash: $passphraseHash, kekSalt: $kekSalt, encryptedKey: $encryptedKey, keyDecryptionNonce: $keyDecryptionNonce)';
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}
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@override
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bool operator ==(Object o) {
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if (identical(this, o)) return true;
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return o is KeyAttributes &&
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o.passphraseHash == passphraseHash &&
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o.kekSalt == kekSalt &&
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o.encryptedKey == encryptedKey &&
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o.keyDecryptionNonce == keyDecryptionNonce;
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}
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@override
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int get hashCode {
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return passphraseHash.hashCode ^
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kekSalt.hashCode ^
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encryptedKey.hashCode ^
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keyDecryptionNonce.hashCode;
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}
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}
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@ -294,18 +294,17 @@ class DebugWidget extends StatelessWidget {
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Text("Encrypted Key", style: TextStyle(fontWeight: FontWeight.bold)),
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Text(keyAttributes.encryptedKey),
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Padding(padding: EdgeInsets.all(12)),
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Text("Encrypted Key IV",
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Text("Key Decryption Nonce",
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style: TextStyle(fontWeight: FontWeight.bold)),
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Text(keyAttributes.encryptedKeyIV),
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Text(keyAttributes.keyDecryptionNonce),
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Padding(padding: EdgeInsets.all(12)),
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Text("KEK Salt", style: TextStyle(fontWeight: FontWeight.bold)),
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Text(keyAttributes.kekSalt),
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Padding(padding: EdgeInsets.all(12)),
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Text("KEK Hash", style: TextStyle(fontWeight: FontWeight.bold)),
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Text(keyAttributes.kekHash),
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Text("Passphrase Hash",
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style: TextStyle(fontWeight: FontWeight.bold)),
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Text(keyAttributes.passphraseHash),
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Padding(padding: EdgeInsets.all(12)),
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Text("KEK Hash Salt", style: TextStyle(fontWeight: FontWeight.bold)),
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Text(keyAttributes.kekHashSalt),
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]),
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),
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actions: [
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@ -8,7 +8,6 @@ import 'package:logging/logging.dart';
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import 'package:photos/models/encrypted_data_attributes.dart';
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import 'package:photos/models/encrypted_file_attributes.dart';
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import 'package:photos/models/encryption_attribute.dart';
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import 'package:steel_crypt/steel_crypt.dart' as steel;
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final int encryptionChunkSize = 4 * 1024 * 1024;
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final int decryptionChunkSize =
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@ -152,8 +151,32 @@ class CryptoUtil {
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return Sodium.randombytesBuf(length);
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}
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static Uint8List scrypt(Uint8List plainText, Uint8List salt) {
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return steel.PassCryptRaw.scrypt()
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.hash(salt: salt, plain: plainText, len: 32);
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static Uint8List generateMasterKey() {
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return Sodium.cryptoKdfKeygen();
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}
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static Uint8List getSaltToDeriveKey() {
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return Sodium.randombytesBuf(Sodium.cryptoPwhashSaltbytes);
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}
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static Uint8List deriveKey(Uint8List passphrase, Uint8List salt) {
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return Sodium.cryptoPwhash(
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Sodium.cryptoSecretboxKeybytes,
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passphrase,
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salt,
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Sodium.cryptoPwhashOpslimitInteractive,
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Sodium.cryptoPwhashMemlimitInteractive,
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Sodium.cryptoPwhashAlgDefault);
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}
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static Future<String> hash(Uint8List passphrase) async {
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return Sodium.cryptoPwhashStr(
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passphrase,
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Sodium.cryptoPwhashOpslimitSensitive,
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Sodium.cryptoPwhashMemlimitSensitive);
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}
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static bool verifyHash(Uint8List passphrase, String hash) {
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return Sodium.cryptoPwhashStrVerify(hash, passphrase) == 0;
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}
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}
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21
pubspec.lock
21
pubspec.lock
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@ -22,13 +22,6 @@ packages:
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url: "https://pub.dartlang.org"
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source: hosted
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version: "1.6.0"
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asn1lib:
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dependency: transitive
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description:
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name: asn1lib
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url: "https://pub.dartlang.org"
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source: hosted
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version: "0.6.5"
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async:
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dependency: transitive
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description:
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@ -443,13 +436,6 @@ packages:
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url: "https://pub.dartlang.org"
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source: hosted
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version: "1.0.2"
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pc_steelcrypt:
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dependency: transitive
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description:
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name: pc_steelcrypt
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url: "https://pub.dartlang.org"
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source: hosted
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version: "1.1.1"
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pedantic:
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dependency: transitive
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description:
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@ -637,13 +623,6 @@ packages:
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url: "https://pub.dartlang.org"
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source: hosted
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version: "1.9.3"
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steel_crypt:
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dependency: "direct main"
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description:
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name: steel_crypt
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url: "https://pub.dartlang.org"
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source: hosted
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version: "2.2.2+1"
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stream_channel:
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dependency: transitive
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description:
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@ -62,7 +62,6 @@ dependencies:
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uni_links: ^0.4.0
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crisp: ^0.1.3
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uuid: 2.2.2
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steel_crypt: ^2.2.2+1
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flutter_sodium: ^0.1.4
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dev_dependencies:
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