Registry sketch and implementation for EVM chains

Cargo.toml

@@ -3,6 +3,7 @@ resolver = "2"
 
 members = [
     "contracts/semi-bridge",
+    "contracts/registry",
 ]
 
 exclude = [
@@ -19,3 +20,5 @@ ink_lang = { git = "https://github.com/Phala-Network/ink.git", branch = "advtest
 ink_lang_codegen = { git = "https://github.com/Phala-Network/ink.git", branch = "advtest-3.4.0" }
 ink_lang_ir = { git = "https://github.com/Phala-Network/ink.git", branch = "advtest-3.4.0" }
 ink_lang_macro = { git = "https://github.com/Phala-Network/ink.git", branch = "advtest-3.4.0" }
+
+signature = { git = "https://github.com/RustCrypto/traits.git", tag = "signature-v1.3.1" }

contracts/registry/Cargo.toml

@@ -0,0 +1,62 @@
+[package]
+name = "index_registry"
+version = "0.1.0"
+authors = ["Phala Network"]
+edition = "2021"
+license = "Apache 2.0"
+homepage = "https://phala.network/"
+repository = "https://github.com/Phala-Network/index-contract"
+
+[dependencies]
+hex-literal = "0.3"
+ink_primitives = { version = "3", default-features = false }
+ink_metadata = { version = "3", default-features = false, features = ["derive"], optional = true }
+ink_env = { version = "3", default-features = false }
+ink_storage = { version = "3", default-features = false }
+ink_lang = { version = "3", default-features = false }
+
+scale = { package = "parity-scale-codec", version = "3.1", default-features = false, features = ["derive"] }
+scale-info = { version = "2.1", default-features = false, features = ["derive"], optional = true }
+xcm = { git = "https://github.com/paritytech/polkadot", branch = "release-v0.9.29", default-features = false }
+phala-pallet-common = { git = "https://github.com/Phala-Network/khala-parachain", tag = "v0.1.18", default-features = false }
+
+pink-extension = { version = "0.1.0", default-features = false }
+pink-web3 = { git = "https://github.com/Phala-Network/pink-web3.git", branch = "pink", default-features = false, features = ["pink"]}
+
+index = { path = "../../index", default-features = false }
+
+[dev-dependencies]
+hex-literal = "0.3"
+pink-extension-runtime = "0.1.3"
+dotenv = "0.15.0"
+
+[profile.release]
+overflow-checks = false     # Disable integer overflow checks.
+lto = false                 # Enable full link-time optimization.
+
+[lib]
+name = "evm_chain"
+path = "src/lib.rs"
+crate-type = [
+	# Used for normal contract Wasm blobs.
+	"cdylib",
+    # Used for ABI generation.
+    "rlib",
+]
+
+[features]
+default = ["std"]
+std = [
+    "ink_metadata/std",
+    "ink_env/std",
+    "ink_storage/std",
+    "ink_primitives/std",
+    "scale/std",
+    "scale-info/std",
+    "xcm/std",
+    "phala-pallet-common/std",
+    "pink-extension/std",
+    "pink-web3/std",
+    "index/std",
+]
+ink-as-dependency = []