As presented in Droidcon Tel Aviv 2017: http://il.droidcon.com

1. Droid On Chain
An android journey into the ethereum blockchain
berry@kik.comBerry Ventura Lev kin.kik.com

2. Kin
Kin Foundation kin.kik.com
A decentralized ecosystem of digital
services for daily life

3. Working
together

4. Agenda
•Intro to Blockchain
•Kin in Kik
•Kin SDK how to
•Kin SDK challenges

5. Intro to Blockchain

6. locks of transactions

7. P2P
network
locks of transactions

8. P2P
network
Decentralized Consensus
locks of transactions

9. Ethereum in a nutshell
• A multipurpose blockchain
• Currency: Ether
• Smart Contracts
• Gas
• DApp - Decentralized App

10. DApp Examples
• KIN Wallet
• Insurance
• Music / Art
• Travel Booking
• Voting
And many many more...

11. DApp Examples
• KIN Wallet
• Insurance
• Music / Art
• Travel Booking
• Voting
And many many more...

12. Ethereum Challenges
• Scalability

13. Ethereum Challenges
• Scalability
• Confirmation time
• Gas fees in ether
• Difficult for users to adopt

14. Kin in Kik

15. Kin in Kik
● Selected Kik Power Users
● Created a wallet
● Awarded them with Kin

16. Kin in Kik
● View Balance
● Spend Experience
○ Stickers
● Earn Experiences
○ Polls
○ Upload stickers

17. Kin in Kik
● Advanced
● View public address
● Export account

18. Kin Android SDK
Overview

19. Kin Android SDK
1. Create an account
2. Access account
3. Get Account balance
4. Transfer kin to address
5. Get Account Pending balance
6. Export account details
It’s open source on
github.com/kinfoundation/kin-sdk-core-android

20. Exploring Libraries
Javascript
• web3.js (github.com/ethereum/web3.js)
Android
• geth (github.com/ethereum/go-ethereum)
• web3j (github.com/web3j/web3j)

21. Kin Android SDK
1. Create an account
2. Access account
3. Get Account balance
4. Transfer kin to address
5. Get Account Pending balance
6. Export account details
It’s open source on
github.com/kinfoundation/kin-sdk-core-android

22. KinClient
ServiceProvider infuraProvider =
new ServiceProvider(“https://ropsten.infura.io/TOKEN”,
ServiceProvider.NETWORK_ID_ROPSTEN));
KinClient kinClient = new KinClient(context, infuraProvider);
// Infura Registration: https://infura.io/register.html

23. 1. Create an account
KinAccount account;
try {
if (!kinClient.hasAccount()) {
account = kinClient.createAccount("aPassphrase");
}
} catch (CreateAccountException e) {
e.printStackTrace();
}

24. 2. Access account
KinAccount account;
if (kinClient.hasAccount()) {
account = kinClient.getAccount();
}
String address = kinAccount.getPublicAddress();

25. 3. Kin Balance
Request<Balance> balanceRequest = account.getBalance();
balanceRequest.run(new ResultCallback<Balance>() {
@Override
public void onResult(Balance result) {
Log.d("example", "The balance is: " + result.value(2));
}
@Override
public void onError(Exception e) {
// Most likely OperationFailedException - check exception message
}
});

26. 4. Transfer Kin
transactionRequest = account.sendTransaction(toAddress, passphrase,
new BigDecimal("100"));
transactionRequest.run(new ResultCallback<TransactionId>() {
@Override
public void onResult(TransactionId result) {
Log.d("example", "The transaction id: " + result.toString());
}
@Override
public void onError(Exception e) {
// could be OperationFailedException, PassphraseException
}
});

27. 5. Pending Balance
Request<Balance> balanceRequest = account.getPendingBalance();
balanceRequest.run(new ResultCallback<Balance>() {
@Override
public void onResult(Balance result) {
Log.d("example", "The pending balance is: " + result.value(2));
}
@Override
public void onError(Exception e) {
// Most likely OperationFailedException - check exception message
}
});

28. 6. Export account
try {
String json = kinAccount.exportKeystore(“originalPass”, “newpass”);
} catch (PassphraseException e) {
e.printStackTrace();
}

29. {
"address": "c136e3ca8510e126ed1785f8456c4918beb903",
"crypto": {
"cipher": "aes-128-ctr",
"ciphertext":"63f85debdbc0d5b9467fc1cebd2d99038e40c3b03ca67c",
"cipherparams": { "iv": "fd8cfc14c2f19eef580448d352424a37" },
"kdf": "scrypt",
"kdfparams": {
"dklen": 32, "n": 4096, "p": 6, "r": 8,
"salt":"8cb2df621289db5882f385303f2dff71b26e1c1604b33b0f294206f7b"
},
"mac":"cb0b2621ae6c7de219224b827a5a3d1f3ccc0fee8d10f01106b8c8eda68"
},
"id": "884cc847-ae42-4491-815e-15768d6b8270",
"version": 3
}
Account Keystore JSON// this is a manually modified file to fit the screen. address & crypto don’t match

30. Hackathon!

31. •

32. Kin SDK
Challenges

33. Kin Balance
Request<Balance> balanceRequest = account.getBalance();
balanceRequest.run(new ResultCallback<Balance>() {
@Override
public void onResult(Balance result) {
Log.d("example", "The balance is: " + result.value(2));
}
@Override
public void onError(Exception e) {
// Most likely OperationFailedException - check exception message
}
});

34. Kin Contract
Address contractAddress =
Geth.newAddressFromHex(“0xEB203DEa15fC49d0872C7614910C”);
BoundContract boundContract =
Geth.bindContract(contractAddress, KIN_CONTRACT_ABI,
ethereumClient);

35. [{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"c
onstant":false,"inputs":[{"name":"_newOwnerCandidate","type":"address"}],"name":"requestOwnershipTransfer","outputs":[],"payable":false,"
stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint
256"}],"name":"approve","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true
,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":f
alse,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transferFrom","ou
tputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"decimal
s","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","typ
e":"address"},{"name":"_value","type":"uint256"}],"name":"issueTokens","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"fun
ction"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"
}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"acceptOwnership","outputs":[],"payable":fals
e,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payabl
e":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":
false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"
name":"transfer","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs
":[],"name":"newOwnerCandidate","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constan
t":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining"
,"type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type
":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"},{
"anonymous":false,"inputs":[{"indexed":true,"name":"owner","type":"address"},{"indexed":true,"name":"spender","type":"address"},{"indexed":f
alse,"name":"value","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_by","type":"add
ress"},{"indexed":true,"name":"_to","type":"address"}],"name":"OwnershipRequested","type":"event"},{"anonymous":false,"inputs":[{"indexed":t
rue,"name":"_from","type":"address"},{"indexed":true,"name":"_to","type":"address"}],"name":"OwnershipTransferred","type":"event"}]
Kin Smart Contract ABI// this IS the real kin contract abi

36. Dive in - getBalance
Interface accountAddress = Geth.newInterface();
accountAddress.setAddress(account.getAddress());
Interfaces inputParams = Geth.newInterfaces(1);
inputParams.set(0, accountAddress);
Interface balanceResult = Geth.newInterface();
balanceInterface.setDefaultBigInt();
Interfaces results = Geth.newInterfaces(1);
results.set(0, balanceResult);
CallOpts callOpts = Geth.newCallOpts();
callOpts.setContext(gethContext);
boundContract.call(callOpts, results, "balanceOf", inputParams);

37. Pending Balance
• Challenge: Event log filtering on geth mobile library missing
• Solution: Added... but still didn’t work!

38. Pending Balance
• Challenge: Event log filtering on geth mobile library missing
• Solution: Added... but still didn’t work!
• Challenge: Bug in geth node implementation
• Solution: Build our own parity node implementation cluster

39. Pending Balance
• Challenge: Event log filtering on geth mobile library missing
• Solution: Added... but still didn’t work!
• Challenge: Bug in geth node implementation
• Solution: Build our own parity node implementation cluster
• Challenge: Inconsistent Balance
• Solution: Enable cookies, so that same node is reused

40. Pending Balance
• Challenge: Event log filtering on geth mobile library missing
• Solution: Added... but still didn’t work!
• Challenge: Bug in geth node implementation
• Solution: Build our own parity node implementation cluster
• Challenge: Inconsistent Balance
• Solution: Enable cookies, so that same node is reused
• Challenge: Still inconsistent balance with sticker shop
• Solution: Using a single node, with a backup node ready if needed

41. To be continued...
• Our journey is a bumpy one, but this is just the beginning
• We are taking part in the greater effort of bringing blockchain to
maturity and to mass adoption
• Watch out our progress on our community channels
Medium Contributors Reddit Telegram
• Start playing with our SDK on testnet - see sample app
• Remember that Kin Reward Engine is on its way !

42. Thank You!
berry@kik.comBerry Ventura Lev kin.kik.com