Cartouche.Signer is a GenServer which can sign messages. This module takes an
mfa (mod, func, args triple) which defines how to actually sign messages.
For instance, Cartouche.Signer.Curvy will sign with a public key, or
Cartouche.Signer.CloudKMS will sign using a GCP Cloud KMS key. In either
case, the caller should start the GenServer, and then call:
Cartouche.Signer.sign(MySigner, "message"). This should return back a
properly signed message.
Note: we also enforce that a given signer process knows its public key, such that we can verify signatures recovery bits. That is, since CloudKMS and other signing tools don't return a recovery bit, necessary for Ethereum, we test all 4 possible bits to make sure a signature recovers to the correct signer address, but we need to know what that address should be to accomplish this task.
Additionally, chain_id is used to return EIP-155 compliant signatures.
Summary
Functions
Gets the address for this signer.
Gets the chain id for this signer.
Returns a specification to start this module under a supervisor.
Signs a message using this signing key.
Directly sign a message, not using a signer process.
Starts a new Cartouche.Signer process.
Functions
@spec address(GenServer.name()) :: Cartouche.address()
Gets the address for this signer.
Examples
iex> signer_proc = Cartouche.Test.Signer.start_signer()
iex> Cartouche.Signer.address(signer_proc) |> Cartouche.Hex.to_address()
"0x63Cc7c25e0cdb121aBb0fE477a6b9901889F99A7"@spec chain_id(GenServer.name()) :: integer()
Gets the chain id for this signer.
Examples
iex> signer_proc = Cartouche.Test.Signer.start_signer()
iex> Cartouche.Signer.chain_id(signer_proc)
5Returns a specification to start this module under a supervisor.
See Supervisor.
@spec sign(String.t(), GenServer.name(), Keyword.t()) :: {:ok, binary()} | {:error, String.t()}
Signs a message using this signing key.
Examples
iex> signer_proc = Cartouche.Test.Signer.start_signer()
iex> {:ok, sig} = Cartouche.Signer.sign("test", signer_proc)
iex> Cartouche.Recover.recover_eth("test", sig)
...> |> Cartouche.Hex.to_address()
"0x63Cc7c25e0cdb121aBb0fE477a6b9901889F99A7"
iex> signer_proc = Cartouche.Test.Signer.start_signer()
iex> {:ok, <<_r::256, _s::256, v::binary>>} = Cartouche.Signer.sign("test", signer_proc, chain_id: 0x05f5e0ff)
iex> :binary.decode_unsigned(v)
0x05f5e0ff * 2 + 35 + 1@spec sign_direct(String.t(), binary(), {module(), atom(), [any()]}, integer()) :: {:ok, binary()} | {:error, String.t()}
Directly sign a message, not using a signer process.
This is mostly used internally, but can be used safely externally as well.
@spec start_link(mfa: {module(), atom(), [any()]}, name: GenServer.name()) :: GenServer.on_start()
Starts a new Cartouche.Signer process.