[ethereum] sign transactions

[florianlenz]

Feature / Issue

Geth has an interface for singing transactions - we should change the key manager to implement it. Right now we send the the transaction parameters to pangea were they are signed. We should change it so that we send the transaction params pangea BUT sign them in panthalassa which will be the main difference.

Acceptance criteria

• tests
• key manager implement ethereum signing interface

Related to

• [key_manager] stop exposing private keys #30

[borjantrajanoski]

Is there any spec describing how the transaction parameters are currently send to Pangea?
From what I've been able to figure out, it looks like it's using the protobuffs located at panthalassa/api/pb

Is our goal to correctly fill the hash field below directly from Panthalassa or do we need to modify protobuffers?

message Response {

    message SendEthereumTransaction {
        uint32 nonce = 1;
        // must be base 10!
        string gasPrice = 2;
        // must be base 10!
        string gasLimit = 3;
        string to = 4;
        // must be base 10!
        string value = 5;
        string data = 6;
        string v = 7;
        string r = 8;
        string s = 9;
        uint32 chainID = 10;
        string from = 11;
        string hash = 12; <== Should this field store the correctly signed transaction? 
    }
    SendEthereumTransaction sendEthereumTransaction = 6;
}

[florianlenz]

@kevowevo this should be done at the 29th