diff --git a/Cargo.lock b/Cargo.lock
index 4f7718c6..03d55acd 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -873,7 +873,7 @@ dependencies = [
 [[package]]
 name = "frame-benchmarking"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "frame-support",
  "frame-support-procedural",
@@ -910,7 +910,7 @@ dependencies = [
 [[package]]
 name = "frame-support"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "bitflags 1.3.2",
  "environmental",
@@ -943,7 +943,7 @@ dependencies = [
 [[package]]
 name = "frame-support-procedural"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "Inflector",
  "cfg-expr",
@@ -959,7 +959,7 @@ dependencies = [
 [[package]]
 name = "frame-support-procedural-tools"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "frame-support-procedural-tools-derive",
  "proc-macro-crate",
@@ -971,7 +971,7 @@ dependencies = [
 [[package]]
 name = "frame-support-procedural-tools-derive"
 version = "3.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -981,7 +981,7 @@ dependencies = [
 [[package]]
 name = "frame-system"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "frame-support",
  "log",
@@ -1786,7 +1786,7 @@ checksum = "624a8340c38c1b80fd549087862da4ba43e08858af025b236e509b6649fc13d5"
 [[package]]
 name = "pallet-balances"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "frame-benchmarking",
  "frame-support",
@@ -1955,7 +1955,7 @@ dependencies = [
 [[package]]
 name = "pallet-timestamp"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "frame-benchmarking",
  "frame-support",
@@ -1973,7 +1973,7 @@ dependencies = [
 [[package]]
 name = "pallet-vesting"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "frame-benchmarking",
  "frame-support",
@@ -2813,7 +2813,7 @@ checksum = "4dccd0940a2dcdf68d092b8cbab7dc0ad8fa938bf95787e1b916b0e3d0e8e970"
 [[package]]
 name = "sp-api"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "hash-db",
  "log",
@@ -2833,7 +2833,7 @@ dependencies = [
 [[package]]
 name = "sp-api-proc-macro"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "Inflector",
  "blake2",
@@ -2847,7 +2847,7 @@ dependencies = [
 [[package]]
 name = "sp-application-crypto"
 version = "7.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "parity-scale-codec",
  "scale-info",
@@ -2860,7 +2860,7 @@ dependencies = [
 [[package]]
 name = "sp-arithmetic"
 version = "6.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "integer-sqrt",
  "num-traits",
@@ -2874,7 +2874,7 @@ dependencies = [
 [[package]]
 name = "sp-authority-discovery"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "parity-scale-codec",
  "scale-info",
@@ -2887,7 +2887,7 @@ dependencies = [
 [[package]]
 name = "sp-consensus-slots"
 version = "0.10.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "parity-scale-codec",
  "scale-info",
@@ -2899,7 +2899,7 @@ dependencies = [
 [[package]]
 name = "sp-core"
 version = "7.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "array-bytes",
  "bitflags 1.3.2",
@@ -2943,7 +2943,7 @@ dependencies = [
 [[package]]
 name = "sp-core-hashing"
 version = "5.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "blake2b_simd",
  "byteorder",
@@ -2957,7 +2957,7 @@ dependencies = [
 [[package]]
 name = "sp-core-hashing-proc-macro"
 version = "5.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2968,7 +2968,7 @@ dependencies = [
 [[package]]
 name = "sp-debug-derive"
 version = "5.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2978,7 +2978,7 @@ dependencies = [
 [[package]]
 name = "sp-externalities"
 version = "0.13.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "environmental",
  "parity-scale-codec",
@@ -2989,7 +2989,7 @@ dependencies = [
 [[package]]
 name = "sp-inherents"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "async-trait",
  "impl-trait-for-tuples",
@@ -3004,7 +3004,7 @@ dependencies = [
 [[package]]
 name = "sp-io"
 version = "7.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "bytes",
  "ed25519",
@@ -3030,7 +3030,7 @@ dependencies = [
 [[package]]
 name = "sp-keyring"
 version = "7.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "lazy_static",
  "sp-core",
@@ -3041,7 +3041,7 @@ dependencies = [
 [[package]]
 name = "sp-keystore"
 version = "0.13.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "futures",
  "parity-scale-codec",
@@ -3055,7 +3055,7 @@ dependencies = [
 [[package]]
 name = "sp-metadata-ir"
 version = "0.1.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "frame-metadata",
  "parity-scale-codec",
@@ -3066,7 +3066,7 @@ dependencies = [
 [[package]]
 name = "sp-panic-handler"
 version = "5.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "backtrace",
  "lazy_static",
@@ -3076,7 +3076,7 @@ dependencies = [
 [[package]]
 name = "sp-runtime"
 version = "7.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "either",
  "hash256-std-hasher",
@@ -3098,7 +3098,7 @@ dependencies = [
 [[package]]
 name = "sp-runtime-interface"
 version = "7.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "bytes",
  "impl-trait-for-tuples",
@@ -3116,7 +3116,7 @@ dependencies = [
 [[package]]
 name = "sp-runtime-interface-proc-macro"
 version = "6.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "Inflector",
  "proc-macro-crate",
@@ -3128,7 +3128,7 @@ dependencies = [
 [[package]]
 name = "sp-staking"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "parity-scale-codec",
  "scale-info",
@@ -3141,7 +3141,7 @@ dependencies = [
 [[package]]
 name = "sp-state-machine"
 version = "0.13.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "hash-db",
  "log",
@@ -3161,12 +3161,12 @@ dependencies = [
 [[package]]
 name = "sp-std"
 version = "5.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 
 [[package]]
 name = "sp-storage"
 version = "7.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "impl-serde",
  "parity-scale-codec",
@@ -3179,7 +3179,7 @@ dependencies = [
 [[package]]
 name = "sp-timestamp"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "async-trait",
  "futures-timer",
@@ -3194,7 +3194,7 @@ dependencies = [
 [[package]]
 name = "sp-tracing"
 version = "6.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "parity-scale-codec",
  "sp-std",
@@ -3206,7 +3206,7 @@ dependencies = [
 [[package]]
 name = "sp-trie"
 version = "7.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "ahash 0.8.6",
  "hash-db",
@@ -3229,7 +3229,7 @@ dependencies = [
 [[package]]
 name = "sp-version"
 version = "5.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "impl-serde",
  "parity-scale-codec",
@@ -3246,7 +3246,7 @@ dependencies = [
 [[package]]
 name = "sp-version-proc-macro"
 version = "4.0.0-dev"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "parity-scale-codec",
  "proc-macro2",
@@ -3257,7 +3257,7 @@ dependencies = [
 [[package]]
 name = "sp-wasm-interface"
 version = "7.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "anyhow",
  "impl-trait-for-tuples",
@@ -3271,7 +3271,7 @@ dependencies = [
 [[package]]
 name = "sp-weights"
 version = "4.0.0"
-source = "git+https://github.com/paritytech/substrate.git?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-v0.9.42#ff24c60ac7d9f87727ecdd0ded9a80c56e4f4b65"
 dependencies = [
  "parity-scale-codec",
  "scale-info",
diff --git a/primitives/sidechain/src/lib.rs b/primitives/sidechain/src/lib.rs
index a5faac04..86a82554 100644
--- a/primitives/sidechain/src/lib.rs
+++ b/primitives/sidechain/src/lib.rs
@@ -24,9 +24,10 @@ use sp_core::H256;
 #[cfg(feature = "std")]
 use serde::{Deserialize, Serialize};
 
+pub type SidechainBlockNumber = u64;
 #[derive(PartialEq, Eq, Clone, Encode, Decode, Debug, Copy, Default, TypeInfo)]
 #[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
 pub struct SidechainBlockConfirmation {
-	pub block_number: u64,
+	pub block_number: SidechainBlockNumber,
 	pub block_header_hash: H256,
 }
diff --git a/sidechain/src/lib.rs b/sidechain/src/lib.rs
index 5624d062..e0f5a141 100644
--- a/sidechain/src/lib.rs
+++ b/sidechain/src/lib.rs
@@ -21,7 +21,7 @@ use enclave_bridge_primitives::ShardIdentifier;
 use frame_support::dispatch::DispatchResultWithPostInfo;
 use frame_system::{self};
 use pallet_enclave_bridge::Pallet as EnclaveBridge;
-use sidechain_primitives::SidechainBlockConfirmation;
+use sidechain_primitives::{SidechainBlockConfirmation, SidechainBlockNumber};
 use sp_core::H256;
 use sp_std::{prelude::*, str, vec};
 
@@ -29,7 +29,7 @@ pub use crate::weights::WeightInfo;
 
 // Disambiguate associated types
 pub type AccountId<T> = <T as frame_system::Config>::AccountId;
-pub type ShardBlockNumber = (ShardIdentifier, u64);
+pub type ShardAndBlockNumber = (ShardIdentifier, SidechainBlockNumber);
 
 pub use pallet::*;
 
@@ -60,6 +60,7 @@ pub mod pallet {
 		/// a sidechain block has been finalized
 		FinalizedSidechainBlock {
 			shard: ShardIdentifier,
+			block_number: SidechainBlockNumber,
 			block_header_hash: H256,
 			validateer: T::AccountId,
 		},
@@ -76,12 +77,7 @@ pub mod pallet {
 	#[pallet::storage]
 	#[pallet::getter(fn latest_sidechain_block_confirmation)]
 	pub type LatestSidechainBlockConfirmation<T: Config> =
-		StorageMap<_, Blake2_128Concat, ShardIdentifier, SidechainBlockConfirmation, ValueQuery>;
-
-	#[pallet::storage]
-	#[pallet::getter(fn sidechain_block_finalization_candidate)]
-	pub type SidechainBlockFinalizationCandidate<T: Config> =
-		StorageMap<_, Blake2_128Concat, ShardIdentifier, u64, ValueQuery>;
+		StorageMap<_, Blake2_128Concat, ShardIdentifier, SidechainBlockConfirmation, OptionQuery>;
 
 	#[pallet::call]
 	impl<T: Config> Pallet<T> {
@@ -92,7 +88,7 @@ pub mod pallet {
 			origin: OriginFor<T>,
 			shard: ShardIdentifier,
 			block_number: u64,
-			next_finalization_candidate_block_number: u64,
+			_next_finalization_candidate_block_number: u64, //fixme: can be removed next time we introduce breaking changes
 			block_header_hash: H256,
 		) -> DispatchResultWithPostInfo {
 			let sender = ensure_signed(origin)?;
@@ -103,7 +99,8 @@ pub mod pallet {
 					<frame_system::Pallet<T>>::block_number(),
 				)?;
 
-			// TODO: Simple logic for now: only accept blocks from first registered enclave.
+			// TODO: Simple but robust logic for now:
+			// accept all blocks from first registered enclave for shard as long as blocknumber monotonically increases.
 			if sender != shard_status[0].signer {
 				log::debug!(
 					"Ignore block confirmation from registered enclave with index > 1: {:?}",
@@ -111,22 +108,12 @@ pub mod pallet {
 				);
 				return Ok(().into())
 			}
-			let finalization_candidate_block_number =
-				<SidechainBlockFinalizationCandidate<T>>::try_get(shard).unwrap_or(1);
-
-			ensure!(
-				block_number == finalization_candidate_block_number,
-				<Error<T>>::ReceivedUnexpectedSidechainBlock
-			);
-			ensure!(
-				next_finalization_candidate_block_number > finalization_candidate_block_number,
-				<Error<T>>::InvalidNextFinalizationCandidateBlockNumber
-			);
-
-			<SidechainBlockFinalizationCandidate<T>>::insert(
-				shard,
-				next_finalization_candidate_block_number,
-			);
+			if let Some(ancestor) = Self::latest_sidechain_block_confirmation(shard) {
+				ensure!(
+					ancestor.block_number < block_number,
+					<Error<T>>::ReceivedUnexpectedSidechainBlock
+				);
+			}
 			Self::finalize_block(
 				shard,
 				SidechainBlockConfirmation { block_number, block_header_hash },
@@ -145,13 +132,16 @@ impl<T: Config> Pallet<T> {
 	) {
 		<LatestSidechainBlockConfirmation<T>>::insert(shard, confirmation);
 		let block_header_hash = confirmation.block_header_hash;
+		let block_number = confirmation.block_number;
 		log::debug!(
-			"Imported sidechain block confirmed with shard {:?}, block header hash {:?}",
+			"Imported sidechain block {} confirmed with shard {:?}, block header hash {:?}",
+			block_number,
 			shard,
 			block_header_hash
 		);
 		Self::deposit_event(Event::FinalizedSidechainBlock {
 			shard,
+			block_number,
 			block_header_hash,
 			validateer: sender.clone(),
 		});
diff --git a/sidechain/src/tests.rs b/sidechain/src/tests.rs
index b9d0c9bc..8e63db75 100644
--- a/sidechain/src/tests.rs
+++ b/sidechain/src/tests.rs
@@ -33,31 +33,6 @@ fn get_signer(pubkey: &[u8; 32]) -> AccountId {
 	test_utils::get_signer(pubkey)
 }
 
-#[test]
-fn confirm_imported_sidechain_block_invalid_next_finalization_candidate() {
-	new_test_ext().execute_with(|| {
-		Timestamp::set_timestamp(TEST7_TIMESTAMP);
-		let hash = H256::default();
-		let signer7 = get_signer(TEST7_SIGNER_PUB);
-		let shard7 = H256::from_slice(&TEST7_MRENCLAVE);
-
-		let block_number = 1;
-
-		register_ias_enclave7();
-
-		assert_err!(
-			Sidechain::confirm_imported_sidechain_block(
-				RuntimeOrigin::signed(signer7.clone()),
-				shard7,
-				block_number,
-				block_number,
-				hash
-			),
-			Error::<Test>::InvalidNextFinalizationCandidateBlockNumber,
-		);
-	})
-}
-
 #[test]
 fn confirm_imported_sidechain_block_works_for_correct_shard() {
 	new_test_ext().execute_with(|| {
@@ -81,6 +56,7 @@ fn confirm_imported_sidechain_block_works_for_correct_shard() {
 
 		let expected_event = RuntimeEvent::Sidechain(SidechainEvent::FinalizedSidechainBlock {
 			shard: shard7,
+			block_number,
 			block_header_hash: hash,
 			validateer: signer7,
 		});
@@ -122,72 +98,90 @@ fn confirm_imported_sidechain_block_correct_order() {
 		register_ias_enclave7();
 
 		assert_ok!(confirm_sidechain_block7(1, 2, H256::random(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 1);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 2);
+		assert_eq!(
+			Sidechain::latest_sidechain_block_confirmation(shard7)
+				.unwrap_or_default()
+				.block_number,
+			1
+		);
 		assert_ok!(confirm_sidechain_block7(2, 3, H256::random(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 2);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 3);
+		assert_eq!(
+			Sidechain::latest_sidechain_block_confirmation(shard7)
+				.unwrap_or_default()
+				.block_number,
+			2
+		);
 		assert_ok!(confirm_sidechain_block7(3, 4, H256::random(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 3);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 4);
+		assert_eq!(
+			Sidechain::latest_sidechain_block_confirmation(shard7)
+				.unwrap_or_default()
+				.block_number,
+			3
+		);
 		assert_ok!(confirm_sidechain_block7(4, 5, H256::random(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 4);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 5);
+		assert_eq!(
+			Sidechain::latest_sidechain_block_confirmation(shard7)
+				.unwrap_or_default()
+				.block_number,
+			4
+		);
 		assert_ok!(confirm_sidechain_block7(5, 6, H256::random(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 5);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 6);
+		assert_eq!(
+			Sidechain::latest_sidechain_block_confirmation(shard7)
+				.unwrap_or_default()
+				.block_number,
+			5
+		);
 	})
 }
 
 #[test]
-fn confirm_imported_sidechain_block_wrong_next() {
+fn confirm_imported_sidechain_block_outdated_successor_fails() {
 	new_test_ext().execute_with(|| {
 		Timestamp::set_timestamp(TEST7_TIMESTAMP);
 		let shard7 = H256::from_slice(&TEST7_MRENCLAVE);
 
 		register_ias_enclave7();
 
-		assert_ok!(confirm_sidechain_block7(1, 2, H256::random(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 1);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 2);
-		assert_ok!(confirm_sidechain_block7(2, 4, H256::random(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 2);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 4);
+		assert_ok!(confirm_sidechain_block7(11, 42, H256::random(), true));
+		assert_eq!(
+			Sidechain::latest_sidechain_block_confirmation(shard7)
+				.unwrap_or_default()
+				.block_number,
+			11
+		);
+		assert_ok!(confirm_sidechain_block7(22, 42, H256::random(), true));
+		assert_eq!(
+			Sidechain::latest_sidechain_block_confirmation(shard7)
+				.unwrap_or_default()
+				.block_number,
+			22
+		);
+
+		// resubmission must fail
 		assert_err!(
-			confirm_sidechain_block7(3, 4, H256::random(), true),
+			confirm_sidechain_block7(22, 42, H256::random(), true),
 			Error::<Test>::ReceivedUnexpectedSidechainBlock
 		);
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 2);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 4);
-		assert_ok!(confirm_sidechain_block7(4, 5, H256::random(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 4);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 5);
-	})
-}
-
-#[test]
-fn confirm_imported_sidechain_block_outdated() {
-	new_test_ext().execute_with(|| {
-		Timestamp::set_timestamp(TEST7_TIMESTAMP);
-		let shard7 = H256::from_slice(&TEST7_MRENCLAVE);
-
-		register_ias_enclave7();
-
-		assert_ok!(confirm_sidechain_block7(1, 2, H256::random(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 1);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 2);
-		assert_ok!(confirm_sidechain_block7(2, 4, H256::random(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 2);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 4);
+		// outdated blocks must fail
 		assert_err!(
-			confirm_sidechain_block7(2, 4, H256::random(), true),
+			confirm_sidechain_block7(21, 42, H256::random(), true),
 			Error::<Test>::ReceivedUnexpectedSidechainBlock
 		);
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 2);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 4);
-		assert_ok!(confirm_sidechain_block7(4, 5, H256::random(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 4);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard7), 5);
+
+		assert_eq!(
+			Sidechain::latest_sidechain_block_confirmation(shard7)
+				.unwrap_or_default()
+				.block_number,
+			22
+		);
+		assert_ok!(confirm_sidechain_block7(44, 42, H256::random(), true));
+		assert_eq!(
+			Sidechain::latest_sidechain_block_confirmation(shard7)
+				.unwrap_or_default()
+				.block_number,
+			44
+		);
 	})
 }
 
@@ -199,13 +193,19 @@ fn dont_process_confirmation_of_second_registered_enclave() {
 
 		register_ias_enclave(TEST7_SIGNER_PUB, TEST7_CERT);
 		assert_ok!(confirm_sidechain_block(shard7, TEST7_SIGNER_PUB, 1, 2, H256::default(), true));
-		assert_eq!(Sidechain::latest_sidechain_block_confirmation(shard7).block_number, 1);
+		assert_eq!(
+			Sidechain::latest_sidechain_block_confirmation(shard7)
+				.unwrap_or_default()
+				.block_number,
+			1
+		);
 		register_ias_enclave(TEST6_SIGNER_PUB, TEST6_CERT);
 
 		System::reset_events();
 		assert_ok!(confirm_sidechain_block(shard7, TEST6_SIGNER_PUB, 1, 2, H256::default(), false));
 		let expected_event = RuntimeEvent::Sidechain(SidechainEvent::FinalizedSidechainBlock {
 			shard: shard7,
+			block_number: 1,
 			block_header_hash: H256::default(),
 			validateer: get_signer(TEST6_SIGNER_PUB),
 		});
@@ -241,6 +241,7 @@ fn confirm_imported_sidechain_block_works_for_correct_shard_with_updated_fingerp
 
 		let expected_event = RuntimeEvent::Sidechain(SidechainEvent::FinalizedSidechainBlock {
 			shard,
+			block_number: 1,
 			block_header_hash: hash,
 			validateer: enclave_signer.clone(),
 		});
@@ -266,6 +267,7 @@ fn confirm_imported_sidechain_block_works_for_correct_shard_with_updated_fingerp
 
 		let expected_event = RuntimeEvent::Sidechain(SidechainEvent::FinalizedSidechainBlock {
 			shard,
+			block_number: 2,
 			block_header_hash: hash,
 			validateer: enclave_signer.clone(),
 		});
@@ -287,6 +289,7 @@ fn confirm_imported_sidechain_block_works_for_correct_shard_with_updated_fingerp
 
 		let expected_event = RuntimeEvent::Sidechain(SidechainEvent::FinalizedSidechainBlock {
 			shard,
+			block_number: 3,
 			block_header_hash: hash,
 			validateer: enclave_signer,
 		});
@@ -314,6 +317,7 @@ fn two_sidechains_with_different_fingerprint_works() {
 
 		let expected_event = RuntimeEvent::Sidechain(SidechainEvent::FinalizedSidechainBlock {
 			shard: shard1,
+			block_number: 1,
 			block_header_hash: hash1,
 			validateer: enclave_signer1.clone(),
 		});
@@ -337,6 +341,7 @@ fn two_sidechains_with_different_fingerprint_works() {
 
 		let expected_event = RuntimeEvent::Sidechain(SidechainEvent::FinalizedSidechainBlock {
 			shard: shard2,
+			block_number: 1,
 			block_header_hash: hash2,
 			validateer: enclave_signer2.clone(),
 		});
@@ -356,14 +361,12 @@ fn two_sidechains_with_different_fingerprint_works() {
 		assert_eq!(shard_status2[0].last_activity, 2u32);
 		assert_eq!(
 			Sidechain::latest_sidechain_block_confirmation(shard1),
-			SidechainBlockConfirmation { block_number: 1, block_header_hash: hash1 }
+			Some(SidechainBlockConfirmation { block_number: 1, block_header_hash: hash1 })
 		);
 		assert_eq!(
 			Sidechain::latest_sidechain_block_confirmation(shard2),
-			SidechainBlockConfirmation { block_number: 1, block_header_hash: hash2 }
+			Some(SidechainBlockConfirmation { block_number: 1, block_header_hash: hash2 })
 		);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard1), 2);
-		assert_eq!(Sidechain::sidechain_block_finalization_candidate(shard2), 10);
 	})
 }
 
@@ -424,6 +427,7 @@ fn confirm_sidechain_block(
 	if assert_event {
 		let expected_event = RuntimeEvent::Sidechain(SidechainEvent::FinalizedSidechainBlock {
 			shard,
+			block_number,
 			block_header_hash,
 			validateer: signer,
 		});