From d79d0182a6e981dc6d561dcf87de09978a3be534 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Wed, 26 Dec 2018 11:15:51 +1100
Subject: [PATCH] Implement genesis signature

---
 beacon_chain/genesis/Cargo.toml          |  1 +
 beacon_chain/genesis/src/beacon_block.rs | 15 +++++++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/beacon_chain/genesis/Cargo.toml b/beacon_chain/genesis/Cargo.toml
index f1958eaa7..499333979 100644
--- a/beacon_chain/genesis/Cargo.toml
+++ b/beacon_chain/genesis/Cargo.toml
@@ -7,6 +7,7 @@ edition = "2018"
 [dependencies]
 bls = { path = "../utils/bls"  }
 spec = { path = "../spec"  }
+ssz = { path = "../utils/ssz" }
 types = { path = "../types"  }
 validator_induction = { path = "../validator_induction"  }
 validator_shuffling = { path = "../validator_shuffling"  }
diff --git a/beacon_chain/genesis/src/beacon_block.rs b/beacon_chain/genesis/src/beacon_block.rs
index 9e2c75d24..120903564 100644
--- a/beacon_chain/genesis/src/beacon_block.rs
+++ b/beacon_chain/genesis/src/beacon_block.rs
@@ -1,5 +1,6 @@
-use bls::Signature;
+use bls::{Signature, BLS_AGG_SIG_BYTE_SIZE};
 use spec::ChainSpec;
+use ssz::{encode::encode_length, Decodable, LENGTH_BYTES};
 use types::{BeaconBlock, BeaconBlockBody};
 
 /// Generate a genesis BeaconBlock.
@@ -10,7 +11,7 @@ pub fn genesis_beacon_block(spec: &ChainSpec) -> BeaconBlock {
         state_root: spec.zero_hash,
         randao_reveal: spec.zero_hash,
         candidate_pow_receipt_root: spec.zero_hash,
-        signature: Signature::default(),
+        signature: genesis_signature(),
         body: BeaconBlockBody {
             proposer_slashings: vec![],
             casper_slashings: vec![],
@@ -21,6 +22,16 @@ pub fn genesis_beacon_block(spec: &ChainSpec) -> BeaconBlock {
     }
 }
 
+fn genesis_signature() -> Signature {
+    let mut bytes = encode_length(BLS_AGG_SIG_BYTE_SIZE, LENGTH_BYTES);
+    bytes.append(&mut vec![0; BLS_AGG_SIG_BYTE_SIZE]);
+    let (signature, _) = match Signature::ssz_decode(&bytes, 0) {
+        Ok(sig) => sig,
+        Err(_) => unreachable!(),
+    };
+    signature
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;