Add EthSigner for signing byte strings and structured data (EIP712)

- for EIP712 encoding used library https://github.com/komputing/KEthereum/tree/master/erc712

ethereumkit/build.gradle

@@ -75,6 +75,10 @@ dependencies {
     implementation 'androidx.room:room-rxjava2:2.2.5'
     kapt 'androidx.room:room-compiler:2.2.5'
 
+    //Eip712
+    def kethereum_version = "0.83.6"
+    implementation "com.github.komputing.kethereum:erc712:$kethereum_version"
+
     // Test helpers
     testImplementation 'junit:junit:4.13'
     testImplementation 'org.mockito:mockito-core:3.3.3'

ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/core/EthereumKit.kt

@@ -12,6 +12,8 @@ import io.horizontalsystems.ethereumkit.api.models.AccountState
 import io.horizontalsystems.ethereumkit.api.models.EthereumKitState
 import io.horizontalsystems.ethereumkit.api.storage.ApiStorage
 import io.horizontalsystems.ethereumkit.crypto.CryptoUtils
+import io.horizontalsystems.ethereumkit.crypto.EIP712Encoder
+import io.horizontalsystems.ethereumkit.crypto.EthSigner
 import io.horizontalsystems.ethereumkit.crypto.InternalBouncyCastleProvider
 import io.horizontalsystems.ethereumkit.models.*
 import io.horizontalsystems.ethereumkit.network.*
@@ -43,6 +45,7 @@ class EthereumKit(
         val walletId: String,
         val etherscanService: EtherscanService,
         private val decorationManager: DecorationManager,
+        private val ethSigner: EthSigner,
         private val state: EthereumKitState = EthereumKitState()
 ) : IBlockchainListener {
 
@@ -194,6 +197,14 @@ class EthereumKit(
         return transactionBuilder.encode(rawTransaction, signature)
     }
 
+    fun signByteArray(message: ByteArray): ByteArray {
+        return ethSigner.signByteArray(message)
+    }
+
+    fun signTypedData(rawJsonMessage: String): ByteArray {
+        return ethSigner.signTypedData(rawJsonMessage)
+    }
+
     fun getLogs(address: Address?, topics: List<ByteArray?>, fromBlock: Long, toBlock: Long, pullTimestamps: Boolean): Single<List<TransactionLog>> {
         return blockchain.getLogs(address, topics, fromBlock, toBlock, pullTimestamps)
     }
@@ -390,8 +401,9 @@ class EthereumKit(
 
             val transactionManager = TransactionManager(address, transactionSyncManager, transactionStorage)
             val decorationManager = DecorationManager(address)
+            val ethSigner = EthSigner(privateKey, CryptoUtils, EIP712Encoder())
 
-            val ethereumKit = EthereumKit(blockchain, transactionManager, transactionSyncManager, transactionBuilder, transactionSigner, connectionManager, address, networkType, walletId, etherscanService, decorationManager)
+            val ethereumKit = EthereumKit(blockchain, transactionManager, transactionSyncManager, transactionBuilder, transactionSigner, connectionManager, address, networkType, walletId, etherscanService, decorationManager, ethSigner)
 
             blockchain.listener = ethereumKit
             transactionSyncManager.set(ethereumKit)

ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/crypto/EIP712Encoder.kt

@@ -0,0 +1,55 @@
+package io.horizontalsystems.ethereumkit.crypto
+
+import com.google.gson.Gson
+import pm.gnosis.eip712.EIP712JsonAdapter
+import pm.gnosis.eip712.EIP712JsonParser
+import pm.gnosis.eip712.typedDataHash
+import java.io.BufferedReader
+import java.io.InputStream
+import java.io.InputStreamReader
+
+class EIP712Encoder {
+
+    private val eip712JsonAdapter = EIP712GsonAdapter()
+
+    fun encodeTypedDataHash(rawJsonMessage: String): ByteArray {
+        val domainWithMessage = EIP712JsonParser(eip712JsonAdapter).parseMessage(rawJsonMessage)
+        return typedDataHash(domainWithMessage.message, domainWithMessage.domain)
+    }
+
+    private class EIP712GsonAdapter : EIP712JsonAdapter {
+        private val gson = Gson()
+
+        override fun parse(inputStream: InputStream): EIP712JsonAdapter.Result {
+            val typedData = gson.fromJson(BufferedReader(InputStreamReader(inputStream)), TypedData::class.java)
+            return parse(typedData)
+        }
+
+        override fun parse(typedDataJson: String): EIP712JsonAdapter.Result {
+            val typedData = gson.fromJson(typedDataJson, TypedData::class.java)
+            return parse(typedData)
+        }
+
+        private fun parse(typedData: TypedData): EIP712JsonAdapter.Result {
+            return EIP712JsonAdapter.Result(
+                    primaryType = typedData.primaryType,
+                    domain = typedData.domain,
+                    message = typedData.message,
+                    types = typedData.types.mapValues { (_, types) -> types.map { EIP712JsonAdapter.Parameter(it.name, it.type) } }
+            )
+        }
+
+        data class TypedData(
+                val types: Map<String, List<TypeParam>>,
+                val primaryType: String,
+                val domain: Map<String, Any>,
+                val message: Map<String, Any>
+        )
+
+        data class TypeParam(
+                val name: String,
+                val type: String
+        )
+    }
+
+}

ethereumkit/src/main/java/io/horizontalsystems/ethereumkit/crypto/EthSigner.kt

@@ -0,0 +1,24 @@
+package io.horizontalsystems.ethereumkit.crypto
+
+import java.math.BigInteger
+
+class EthSigner(
+        private val privateKey: BigInteger,
+        private val cryptoUtils: CryptoUtils,
+        private val eip712Encoder: EIP712Encoder
+) {
+
+    fun signByteArray(message: ByteArray): ByteArray {
+        val prefix = "\u0019Ethereum Signed Message:\n" + message.size
+        val hashedMessage = cryptoUtils.sha3(prefix.toByteArray() + message)
+        return sign(hashedMessage)
+    }
+
+    fun signTypedData(rawJsonMessage: String): ByteArray {
+        val encodedMessage = eip712Encoder.encodeTypedDataHash(rawJsonMessage)
+        return sign(encodedMessage)
+    }
+
+    private fun sign(message: ByteArray): ByteArray = cryptoUtils.ellipticSign(message, privateKey)
+
+}