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[mob] LowerMem & increase ops limit for key derivation

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This commit is contained in:
Neeraj Gupta
2025-01-18 16:08:56 +05:30
parent b6d267e0cd
commit 73af752f52
1 changed files with 23 additions and 17 deletions
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40
mobile/lib/utils/crypto_util.dart
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@@ -18,6 +18,8 @@ const int loginSubKeyLen = 32;
const int loginSubKeyId = 1;
const String loginSubKeyContext = "loginctx";
const int _keyDerivcationStregth = 1073741824 * 4;
Uint8List cryptoSecretboxEasy(Map<String, dynamic> args) {
return Sodium.cryptoSecretboxEasy(args["source"], args["nonce"], args["key"]);
}
@@ -392,24 +394,28 @@ class CryptoUtil {
Uint8List salt,
) async {
final logger = Logger("pwhash");
int memLimit = Sodium.cryptoPwhashMemlimitSensitive;
int opsLimit = Sodium.cryptoPwhashOpslimitSensitive;
if (await isLowSpecDevice()) {
logger.info("low spec device detected");
// When sensitive memLimit (1 GB) is used, on low spec device the OS might
// kill the app with OOM. To avoid that, start with 256 MB and
// corresponding ops limit (16).
// This ensures that the product of these two variables
// (the area under the graph that determines the amount of work required)
// stays the same
// SODIUM_CRYPTO_PWHASH_MEMLIMIT_SENSITIVE: 1073741824
// SODIUM_CRYPTO_PWHASH_MEMLIMIT_MODERATE: 268435456
// SODIUM_CRYPTO_PWHASH_OPSLIMIT_SENSITIVE: 4
memLimit = Sodium.cryptoPwhashMemlimitModerate;
final factor = Sodium.cryptoPwhashMemlimitSensitive ~/
Sodium.cryptoPwhashMemlimitModerate; // = 4
opsLimit = opsLimit * factor; // = 16
final int desiredStrength = Sodium.cryptoPwhashMemlimitSensitive *
Sodium.cryptoPwhashOpslimitSensitive;
// When sensitive memLimit (1 GB) is used, on low spec device the OS might
// kill the app with OOM. To avoid that, start with 256 MB and
// corresponding ops limit (16).
// This ensures that the product of these two variables
// (the area under the graph that determines the amount of work required)
// stays the same
// SODIUM_CRYPTO_PWHASH_MEMLIMIT_SENSITIVE: 1073741824
// SODIUM_CRYPTO_PWHASH_MEMLIMIT_MODERATE: 268435456
// SODIUM_CRYPTO_PWHASH_OPSLIMIT_SENSITIVE: 4
int memLimit = Sodium.cryptoPwhashMemlimitModerate;
final factor = Sodium.cryptoPwhashMemlimitSensitive ~/
Sodium.cryptoPwhashMemlimitModerate; // = 4
int opsLimit = Sodium.cryptoPwhashOpslimitSensitive * factor; // = 16
if (memLimit * opsLimit != desiredStrength ||
desiredStrength != _keyDerivcationStregth) {
throw UnsupportedError(
"unexpcted values for memLimit $memLimit and opsLimit: $opsLimit or desiredStrength: $desiredStrength",
);
}
Uint8List key;
while (memLimit >= Sodium.cryptoPwhashMemlimitMin &&
opsLimit <= Sodium.cryptoPwhashOpslimitMax) {