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bootstrap-process.md

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The Initialization Of Secret Network

Bootstrap Process

Secret Network is set up to perform computation while having encrypted state, input and output. The state is encrypted using private keys generated during the network bootstrapping from a consensus_seed. The bootstrap node was the first full node on the network and generated the shared secrets similar to a universal trusted zero knowledge setup.

The bootstrap node first does a remote attestation to prove they are running a genuine SGX enclave with updated software. After registering the bootstrap node handled the initialization of following variables:

  • Consensus_seed a true random 256 bit seed used as entropy for generating shareable keypairs between the nodes of the network.
  • consensus_seed_exchange_pubkey - consensus_seed_exchange_pubkey an HDKF private key and a matching curve25519 public key for encryption of the random seed and sharing this with other full nodes in the network.
  • consensus_io_exchange_pubkey - consensus_io_exchange_pubkey an HDKF private key and a matching curve25519 public key for encrypting transactions IO in the network. Also referenced as the "Secret Network keypair".
  • consensus_state_ikm An input keyring material (IKM) for HKDF-SHA256 is used to derive encryption keys for contract state.
  • consensus_callback_secret A curve25519 private key is used to create callback signatures when contracts call other contracts

Bootstrap process epilogue

1. Remote attestation

The bootstrap node proves to have a genuine enclave after which it can participate in the network. More information can be found on this page.

2. generate consensus_seed

The bootstrap node is instructed when started to generate a true random 256 bit seed inside the enclave, the consensus_seed.

The consensus_seed is sealed with MRSIGNER to a local file : $HOME/.sgx_secrets/consensus_seed.sealed

// 256 bits
consensus_seed = true_random({ bytes: 32 });

seal({
  key: "MRSIGNER",
  data: consensus_seed,
  to_file: "$HOME/.sgx_secrets/consensus_seed.sealed",
});

2. Generate seed exchange keypair

For the network to start decentralizing the bootstrap node needs to be able to share the consensus_seed. The network can then use the seed to create shared secrets while in the enclave. To securely share the seed the Network uses a DH-key exchange.

Using HKDF-SHA256, hkdf_salt and consensus_seed a private key is derived. From consensus_seed_exchange_privkey calculate consensus_seed_exchange_pubkey

consensus_seed_exchange_privkey = hkdf({
  salt: hkdf_salt,
  ikm: consensus_seed.append(uint8(1)),
}); // 256 bits

consensus_seed_exchange_pubkey = calculate_curve25519_pubkey(
  consensus_seed_exchange_privkey
);

3. Generate IO encryption keypair

Using HKDF-SHA256, hkdf_salt and consensus_seed a private key is derived. - From consensus_io_exchange_privkey calculate consensus_io_exchange_pubkey

consensus_io_exchange_privkey = hkdf({
  salt: hkdf_salt,
  ikm: consensus_seed.append(uint8(2)),
}); // 256 bits

consensus_io_exchange_pubkey = calculate_curve25519_pubkey(
  consensus_io_exchange_privkey
);

4. Generate consensus_state_ikm

Using HKDF-SHA256, hkdf_salt and consensus_seed derive consensus_state_ikm

consensus_state_ikm = hkdf({
  salt: hkdf_salt,
  ikm: consensus_seed.append(uint8(3)),
}); // 256 bits

5. consensus_callback_secret

Using HKDF-SHA256, hkdf_salt and consensus_seed derive consensus_callback_secret

consensus_state_ikm = hkdf({
  salt: hkdf_salt,
  ikm: consensus_seed.append(uint8(4)),
}); // 256 bits

6. add info to Genesis state

Publish to genesis.json:

  • The remote attestation proof that the Enclave is genuine
  • consensus_seed_exchange_pubkey
  • consensus_io_exchange_pubkey