Writing more then 65kb results in corrupted data

[ulfgebhardt]

Bugreport

Writing more then 65kb results in corrupted data

reading the corrupt data results in Unexpected token [...] in JSON at position 65536

Data written

Data read

The Code

Writing 30k Integers into the buffer

More Context

The Error

The Version

"react-native-keychain": "^3.0.0-rc.3"

react-native-keychain@^3.0.0-rc.3:
  version "3.0.0"
  resolved "https://registry.yarnpkg.com/react-native-keychain/-/react-native-keychain-3.0.0.tgz#29da1dfa43c2581f76bf9420914fd38a1558cf18"
  integrity sha512-0incABt1+aXsZvG34mDV57KKanSB+iMHmxvWv+N6lgpNLaSoqrCxazjbZdeqD4qJ7Z+Etp5CLf/4v1aI+sNLBw==

The Device

A real Android 6.0 Device using react-native debug mode(maybe this causes trouble?)

The Current Solution

Split up the data into buckets, have another key which indexes the buckets.

This reduces speed, since there are more read/write Operations.

Assume:

• Bucketsize b
• Datapoints n

Results in ceil(n/b) + 1 read/write operations

• Blue = IndexService
• Green = BucketServiceName
• Red = BucketService
• Grey = Result/Input
• Bucketsize = 1

Note: since its not easy to determine the size of an Object in byte, you have to select a size for the buckets which you consider save not to surpass 65kb.

The Current Solution's Code

Sorry for that mess, cleanup is not yet done - ping me here for a followup ;-)

static readKeychain = async () => {
    console.log('readKeychain');
    const keyindex = await Keychain.getGenericPassword(VotesLocal.KEYCHAIN_INDEX_SERVICE);
    if (!keyindex) {
      return null;
    }
    let indexchain = JSON.parse(keyindex.password);
    console.log(`readKeychain: ${JSON.stringify(indexchain)}`);
    indexchain.d = [];
    await Promise.all(
      indexchain.i.map(async serviceId => {
        const service = VotesLocal.KEYCHAIN_VOTES_SERVICE + serviceId;
        const setData = await Keychain.getGenericPassword(service);
        console.log(`readKeychain: ${JSON.stringify(service)}`);
        console.log(`readKeychain: ${JSON.stringify(setData)}`);
        if (setData) {
          indexchain.d.push(...JSON.parse(setData.password));
        }
      }),
    );
    delete indexchain.i;
    console.log(`readKeychain: ${JSON.stringify(indexchain)}`);
    return indexchain;
  };

  static writeKeychain = async data => {
    console.log('writeKeychain');
    console.log(`writeKeychain: ${JSON.stringify(data)}`);
    let index = [];
    // Split Data into packages to avoid error on 65k
    while (data.d.length > 0) {
      const set = data.d.splice(0, VotesLocal.KEYCHAIN_MAXSIZE);
      const setServiceId = index.length;
      const setService = VotesLocal.KEYCHAIN_VOTES_SERVICE + setServiceId;
      console.log(`writeKeychain: ${JSON.stringify(setService)}`);
      console.log(`writeKeychain: ${JSON.stringify(set)}`);
      await Keychain.setGenericPassword(
        VotesLocal.KEYCHAIN_VOTES_KEY,
        JSON.stringify(set),
        setService,
      );
      index.push(setServiceId);
    }

    delete data.d;
    data.i = index;
    console.log(`writeKeychain: ${JSON.stringify(data)}`);
    // console.log(JSON.stringify(data));
    /*const dummy = [];
    for (var i = 0; i < 30000; i++) {
      dummy.push(i);
    }
    data.dummy = dummy;
    console.log(data);
    console.log(JSON.stringify(data));*/

    return await Keychain.setGenericPassword(
      VotesLocal.KEYCHAIN_INDEX_KEY,
      JSON.stringify(data),
      VotesLocal.KEYCHAIN_INDEX_SERVICE,
    );
  };

Furthermore

Since the corruption in the data seem to be random bytes (changing values), I consider it likely that this is a bufferoverflow?!

And yes - this library is made to contain credentials not data - I know that we abuse its scope ;-)

(Possibly) Related

https://github.com/oblador/react-native-keychain/issues/120 https://github.com/oblador/react-native-keychain/issues/174 https://github.com/oblador/react-native-keychain/issues/208

[vonovak]

Thanks for reporting. Specifying the platform and adding a repro would be nice. I will not have time to look into this though. Thanks.

[ulfgebhardt]

@vonovak Done - consider testing it out - its a simple while loop you have to put into your Write-KeyChain-Code

Edit: https://github.com/demokratie-live/democracy-client/blob/3d2aee279d4ad617240bb6cb5a23e7a8f0ee54e2/src/services/VotesLocal.js#L93

[suvro24]

is it fixed in the latest version?

[sebk]

I still have the same problem and also with the latest library versions the problem still exists.

Has somebody else an idea howto solve it instead splitting the reading and writing?

I guess it is also the same as https://github.com/oblador/react-native-keychain/issues/208 (?)

[blankey1337]

Just ran into this on Android 7.

[quicksilverr]

Hey Guys,

I just across the same issue, even in the version 7.0.0. I'm using RSA as the crypto option for android, without which a biometric prompt isn't displayed. But I'm getting string size error. Thanks @ulfgebhardt for the solution to such a complex problem.

I was wondering, can we compress our string token and then pass it as a token to setGenericPassword and then decompress that token when it is returned from getGenericPassword? Is that possible and advisable?