Introduce SIGNATURE_LENGTH constant

Schnorr and ECDSA have different signature length.

key/src/ecdsa.rs

@@ -42,6 +42,8 @@ use secp256k1::{key, Error as SecpError, Message as SecpMessage, RecoverableSign
 
 use super::{public_to_address, Address, Error, Message, Private, Public, SECP256K1};
 
+pub const ECDSA_SIGNATURE_LENGTH: usize = 65;
+
 /// Signature encoded as RSV components
 #[repr(C)]
 pub struct ECDSASignature([u8; 65]);

key/src/lib.rs

@@ -43,7 +43,7 @@ use codechain_types::H256;
 #[cfg(feature = "ecdsa")]
 pub use ecdsa::{
     recover_ecdsa as recover, sign_ecdsa as sign, verify_ecdsa as verify, verify_ecdsa_address as verify_address,
-    ECDSASignature as Signature,
+    ECDSASignature as Signature, ECDSA_SIGNATURE_LENGTH as SIGNATURE_LENGTH,
 };
 pub use error::Error;
 pub use exchange::exchange;
@@ -56,6 +56,7 @@ pub use rustc_serialize::hex;
 pub use schnorr::{
     recover_schnorr as recover, sign_schnorr as sign, verify_schnorr as verify,
     verify_schnorr_address as verify_address, SchnorrSignature as Signature,
+    SCHNORR_SIGNATURE_LENGTH as SIGNATURE_LENGTH,
 };
 
 /// 32 bytes long signable message

key/src/schnorr.rs

@@ -26,6 +26,8 @@ use secp256k1::{key, schnorr, Error as SecpError, Message as SecpMessage};
 
 use super::{public_to_address, Address, Error, Message, Private, Public, SECP256K1};
 
+pub const SCHNORR_SIGNATURE_LENGTH: usize = 64;
+
 pub struct SchnorrSignature([u8; 64]);
 
 // manual implementation large arrays don't have trait impls by default.

vm/src/executor.rs

@@ -15,7 +15,7 @@
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 use ccrypto::{blake256, keccak256, ripemd160, sha256};
-use ckey::{verify, Signature};
+use ckey::{verify, Signature, SIGNATURE_LENGTH};
 use ctypes::{H256, H520, Public};
 
 use instruction::{is_valid_unlock_script, Instruction};
@@ -209,7 +209,7 @@ pub fn execute(
             }
             Instruction::ChkSig => {
                 let pubkey = Public::from_slice(stack.pop()?.assert_len(64)?.as_ref());
-                let signature = Signature::from(H520::from(stack.pop()?.assert_len(65)?.as_ref()));
+                let signature = Signature::from(H520::from(stack.pop()?.assert_len(SIGNATURE_LENGTH)?.as_ref()));
                 let result = match verify(&pubkey, &signature, &tx_hash) {
                     Ok(true) => 1,
                     _ => 0,