# DCRM SDK

## **DCRM SDK BETA**

Note : dcrm-sdk is considered beta software. We make no warranties or guarantees of its security or stability.\*

Github repo: <https://github.com/fsn-dev/dcrm-sdk>

## Introduction

DCRM SDK is a distributed key generation and distributed signature module that forms the cornerstone of decentralized value exchange. This technology was developed for over a year, with the feedback of 4 leading cryptographers: Rosario Gennaro, Steven Goldfeder, Pascal Paillier, Louis Goubin.

When used in context of blockchain, this module can serve as a non-custodial solution, a keyless wallet, a component to an interoperable solution, and more. Please read the [Wiki](https://github.com/fsn-dev/dcrm-sdk/wiki) for more information.

This SDK allows you to connect to DCRM's network directly in either:

1. a 2+1 configuration where you form a private group with 2 fusion nodes and your own node.
2. a local configuration where you can set any ownership of nodes in your group.

This library contains 2 functions:

1. Distributed key generation which returns the public key (dcrm\_genPubkey)
2. Distributed signing of transactions (dcrm\_sign)

## Prerequisites

1. Linux terminal
2. Golang ^1.12

## Setting Up

### Clone The Repository

To get started, launch your terminal and download the latest version of the SDK.

```
mkdir -p $GOPATH/src/github.com/fsn-dev

cd $GOPATH/src/github.com/fsn-dev

git clone https://github.com/fsn-dev/dcrm-sdk.git
```

### Build

Next compile the code. Make sure you are in /dcrm-sdk directory.

```
cd dcrm-sdk && make
```

### config file

cmd/conf.toml (bin/cmd/conf.toml)

### Run

Open access to the APIs by running the compiled code.

```
./bin/cmd/gdcrm
```

The `gdcrm` will provide two RPC APIs:

1. `dcrm_genPubkey`
2. `dcrm_sign`

The default RPC port is port 5559.

Note:

1. If you want to call RPC API, please wait at least 2 minutes after running the node.
2. If you want to call RPC API quickly more than once,please wait longer.

## JSON RPC API

**dcrm\_genPubkey**

This API return a public key which distributed generated by the P2P network's nodes.

**Parameters**

None

**Return**

`error` - Error info.

`pubkey` - DCRM public key generated by the P2P network's nodes.

**Example**

```
// Request

curl -X POST -H "Content-Type":application/json --data '{"jsonrpc":"2.0","method":"dcrm_genPubkey","params":[],"id":67}' http://127.0.0.1:5559

// Result

{
"pubkey":"049ac626ee0f0f79a49d6ed37f14ff2ad4e4f45fddf6e5293bcaa6a607e5392b49dde27a8f0602e23bc5fa0b847bd28d46e2f2d1d0d8cf59514785e4276b28de9d"
}
```

**dcrm\_sign**

This API return a signature which distributed signed by the P2P network's nodes.

**Parameters**

1. `DATA`,pubkey - the pubkey from `dcrm_genPubkey` returned.
2. `String`,HexNumber - the message hash to be signed. The format is 32-bit hexadecimal string appended with prifex "0x".\
   &#x20;For example: 0x19b6236d2e7eb3e925d0c6e8850502c1f04822eb9aa67cb92e5004f7017e5e41.

**Return**

`error` - Error info.

`rsv` - The signature string which distributed signed by the P2P network's nodes.

**Example**

```
// Request

curl -X POST -H "Content-Type":application/json --data '{"jsonrpc":"2.0","method":"dcrm_sign","params":["049ac626ee0f0f79a49d6ed37f14ff2ad4e4f45fddf6e5293bcaa6a607e5392b49dde27a8f0602e23bc5fa0b847bd28d46e2f2d1d0d8cf59514785e4276b28de9d","0x19b6236d2e7eb3e925d0c6e8850502c1f04822eb9aa67cb92e5004f7017e5e41"],"id":67}' http://127.0.0.1:5559

// Result

{
"rsv":"FFBB398B95ED2ED308B0FE87BC254FFC2C9957742EA05C18A1411C672B74FBDF6FBD6F4915799F2B4186192581D4506039ADEB79C8EB954E779901FDB9575C8301"
}
```

## Run Local

The SDK can also be configured to run locally, where the user can control ownership of all nodes in the P2P network.

#### Run bootnode

```
./bin/cmd/bootnode --genkey ./bootnode.key

./bin/cmd/bootnode --nodekey ./bootnode.key --addr :5550 --group 0 --nodes 3
```

will print bootnode which use for run node with args --bootnodes bootnode key such as enode://16ab118525ec559dde2640b513676b8df7368aac3a80cc5c9d9e8b9c71781c09103fe3e8b5dd17bf245f0c71b891ec4848b142852763ab2146a1e288df15da40\@127.0.0.1:5550

The default bootnode parameters are:

1. addr: 5550
2. group: 0 (group mode)
3. nodes: 3 (group's nodes number)

**Run nodes (3 nodes at least)**

The Default setup parameters are:

1. nodekey: node.key
2. rpcport: 5559
3. port: 5551
4. bootnodes: "enode://16ab118525ec559dde2640b513676b8df7368aac3a80cc5c9d9e8b9c71781c09103fe3e8b5dd17bf245f0c71b891ec4848b142852763ab2146a1e288df15da40\@127.0.0.1:5550"

Note: If you want to reboot a node, please wait 1 minute after closing node before restarting the node.

Setup the node's key:

```
./bin/cmd/gdcrm
./bin/cmd/gdcrm --genkey node1.key

./bin/cmd/gdcrm --genkey node2.key

./bin/cmd/gdcrm --genkey node3.key
```

Start three nodes with custom parameters:

```
./bin/cmd/gdcrm --rpcport 9011 --bootnodes "enode://16ab118525ec559dde2640b513676b8df7368aac3a80cc5c9d9e8b9c71781c09103fe3e8b5dd17bf245f0c71b891ec4848b142852763ab2146a1e288df15da40@127.0.0.1:5550" --port 12341 --nodekey "node1.key"

./bin/cmd/gdcrm --rpcport 9012 --bootnodes "enode://16ab118525ec559dde2640b513676b8df7368aac3a80cc5c9d9e8b9c71781c09103fe3e8b5dd17bf245f0c71b891ec4848b142852763ab2146a1e288df15da40@127.0.0.1:5550" --port 12342 --nodekey "node2.key"

./bin/cmd/gdcrm --rpcport 9013 --bootnodes "enode://16ab118525ec559dde2640b513676b8df7368aac3a80cc5c9d9e8b9c71781c09103fe3e8b5dd17bf245f0c71b891ec4848b142852763ab2146a1e288df15da40@127.0.0.1:5550" --port 12343 --nodekey "node3.key"

```

After bootnode and three nodes started, use curl connect to the node's rpc port, test `dcrm_genPubkey` and `dcrm_sign` APIs.