Updated 2019-11-18

# Node Keys

Each node has a node key pair consisting of a node private key and node public key.

## Node Private Key

If a key file does not exist in the data directory and the --node-private-key-file option is not specified when Besu is started, a node private key is generated and written to the key file. If Besu is stopped and restarted without deleting the key file, the same private key is used when Besu is restarted.

If a key file exists in the data directory when Besu is started, the node is started with the private key in the key file.

Info

The private key is not encrypted.

## Node Public Key

The node public key is displayed in the log after starting Besu. Use the public-key subcommand to export the public key to a file.

The node public key is also referred to as the node ID. The node ID forms part of the enode URL for a node.

## Enode URL

Nodes are identified by their enode URL. For example, the --bootnodes option and perm_addNodesToWhitelist method specify nodes by the enode URL.

The enode URL is enode://<id>@<host:port> where:

• <id> is the node public key excluding the initial 0x.
• <host:port> is the host and port the bootnode is listening on for P2P peer discovery. Specified by the --p2p-host and --p2p-port options (default host is 127.0.0.1 and port is 30303).

Example

If the --p2p-host or --p2p-port options are not specified and the node public key is 0xc35c3ec90a8a51fd5703594c6303382f3ae6b2ecb9589bab2c04b3794f2bc3fc2631dabb0c08af795787a6c004d8f532230ae6e9925cbbefb0b28b79295d615f

The enode URL is: enode://c35c3ec90a8a51fd5703594c6303382f3ae6b2ecb9589bab2c04b3794f2bc3fc2[email protected]127.0.0.1:30303

The enode is displayed when starting a Besu node and can be obtained using the net_enode JSON-RPC API method.

If UPnP is enabled, the enode advertised to other nodes during discovery is the external IP address and port.

## Specifying a Custom Node Private Key File

Use the --node-private-key-file option to specify a custom key file in any location.

If the key file exists, the node is started with the private key in the custom key file. If the custom key file does not exist, a node private key is generated and written to the custom key file.

For example, the following command either reads the node private key from the privatekeyfile or writes the generated private key to the privatekeyfile:

Example

besu --node-private-key-file="/Users/username/privatekeyfile"