diff --git a/packages/kos/src/chains/icp/mod.rs b/packages/kos/src/chains/icp/mod.rs
index 0d0772a..a46a4ad 100644
--- a/packages/kos/src/chains/icp/mod.rs
+++ b/packages/kos/src/chains/icp/mod.rs
@@ -76,16 +76,51 @@ impl Chain for ICP {
         Ok(addr)
     }
 
-    fn sign_tx(&self, _private_key: Vec<u8>, _tx: Transaction) -> Result<Transaction, ChainError> {
-        todo!()
+    fn sign_tx(
+        &self,
+        private_key: Vec<u8>,
+        mut tx: Transaction,
+    ) -> Result<Transaction, ChainError> {
+        let hex = hex::decode(tx.raw_data.clone()).map_err(|_| ChainError::DecodeRawTx)?;
+        let raw_data_str = String::from_utf8(hex).map_err(|_| ChainError::DecodeRawTx)?;
+
+        let icp_hashes: Vec<String> =
+            serde_json::from_str(raw_data_str.as_str()).map_err(|_| ChainError::DecodeHash)?;
+
+        let mut pvk_bytes = private_key_from_vec(&private_key)?;
+
+        let mut signatures: Vec<String> = Vec::new();
+
+        for hash_hex in icp_hashes {
+            let hash_bytes = hex::decode(&hash_hex).map_err(|_| ChainError::DecodeHash)?;
+
+            let signature = Ed25519::sign(&pvk_bytes, &hash_bytes)?;
+            signatures.push(hex::encode(signature));
+        }
+
+        pvk_bytes.fill(0);
+
+        let signatures_json = tiny_json_rs::encode(signatures);
+
+        tx.signature = signatures_json.into_bytes();
+
+        if tx.tx_hash.is_empty() {
+            tx.tx_hash = Vec::new();
+        }
+
+        Ok(tx)
     }
 
-    fn sign_message(
-        &self,
-        _private_key: Vec<u8>,
-        _message: Vec<u8>,
-    ) -> Result<Vec<u8>, ChainError> {
-        todo!()
+    fn sign_message(&self, private_key: Vec<u8>, message: Vec<u8>) -> Result<Vec<u8>, ChainError> {
+        let public_key = self.get_pbk(private_key.clone())?;
+
+        let signature = self.sign_raw(private_key, message)?;
+
+        let mut signature_bytes = Vec::new();
+        signature_bytes.extend_from_slice(&signature);
+        signature_bytes.extend_from_slice(&public_key);
+
+        Ok(signature_bytes)
     }
 
     fn sign_raw(&self, private_key: Vec<u8>, payload: Vec<u8>) -> Result<Vec<u8>, ChainError> {
@@ -148,8 +183,8 @@ pub fn crc_calc_singletable(buffer: &[u8]) -> u32 {
 
 #[cfg(test)]
 mod test {
-
     use super::*;
+    use crate::crypto::base64::simple_base64_decode;
     #[test]
     fn test_icp_get_address() {
         let icp = ICP {};
@@ -166,4 +201,43 @@ mod test {
             "11d238129427ef0e44d86bd27cb6d9da4d7e8934cb0306a93a540e657082d885"
         );
     }
+
+    #[test]
+    fn test_icp_sign_tx() {
+        let icp = ICP {};
+
+        let mnemonic = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about".to_string();
+        let seed = icp.mnemonic_to_seed(mnemonic, "".to_string()).unwrap();
+        let path = icp.get_path(0, false);
+        let pvk = icp.derive(seed, path).unwrap();
+
+        let raw_data = simple_base64_decode("NWIyMjMwNjEzNjM5MzYzMzMyNjQzNzMyMzYzNTM3MzEzNzM1MzYzNTM3MzMzNzM0MzUzMjMxMzc2NTM1MzYzNjM0Mzk2NjY2MzIzMTMyMzgzMzM2NjYzMDYxMzIzMjM2MzIzNjM3NjYzMzMwNjM2MTMwMzA2NTM4NjUzNDY2MzI2NTM4MzMzNDYyNjEzNjYzMzA2NDMyNjQzODMyMzQzMjM3MzIzNjM5MzAzNzMwMzAyMjJjMjIzMDYxMzYzOTM2MzMzMjY0MzczMjM2MzUzNzMxMzczNTM2MzUzNzMzMzczNDMxNjIzMTM0MzA2MjYyNjQzNzM2MzUzNzMxNjMzMDYxMzMzNDMzMzMzMTMzMzEzODM1MzQzMzM3NjI2NTM4NjIzODYyNjMzNDY0MzU2NTMyMzgzOTM4MzAzMTYxNjU2MTMxMzc2NTYxMzAzNjYxNjYzMjMwNjQzMTY1MzkzNzM1MjI1ZA==").unwrap();
+
+        let tx = Transaction {
+            raw_data,
+            signature: vec![],
+            tx_hash: vec![],
+            options: None,
+        };
+
+        let signed_tx = icp.sign_tx(pvk, tx).unwrap();
+
+        assert_eq!(signed_tx.signature.len(), 263);
+    }
+
+    #[test]
+    fn test_icp_sign_message() {
+        let icp = ICP {};
+
+        let mnemonic = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about".to_string();
+        let seed = icp.mnemonic_to_seed(mnemonic, "".to_string()).unwrap();
+        let path = icp.get_path(0, false);
+
+        let pvk = icp.derive(seed, path).unwrap();
+
+        let message = "Hello, World!".as_bytes().to_vec();
+        let signature = icp.sign_message(pvk, message).unwrap();
+
+        assert_eq!(signature.len(), 96, "Signature length should be 96");
+    }
 }
diff --git a/packages/kos/src/chains/mod.rs b/packages/kos/src/chains/mod.rs
index 80143fe..d7bcd65 100644
--- a/packages/kos/src/chains/mod.rs
+++ b/packages/kos/src/chains/mod.rs
@@ -59,6 +59,8 @@ pub enum ChainError {
     MissingOptions,
     InvalidOptions,
     InvalidHex,
+    DecodeRawTx,
+    DecodeHash,
 }
 
 impl Display for ChainError {
@@ -127,6 +129,12 @@ impl Display for ChainError {
             ChainError::InvalidHex => {
                 write!(f, "invalid hex")
             }
+            ChainError::DecodeRawTx => {
+                write!(f, "decode raw tx")
+            }
+            ChainError::DecodeHash => {
+                write!(f, "decode hash")
+            }
         }
     }
 }
@@ -218,6 +226,8 @@ impl ChainError {
             ChainError::MissingOptions => 21,
             ChainError::InvalidOptions => 22,
             ChainError::InvalidHex => 23,
+            ChainError::DecodeRawTx => 24,
+            ChainError::DecodeHash => 25,
         }
     }
 }
@@ -525,7 +535,7 @@ impl ChainRegistry {
                 constants::ICP,
                 ChainInfo {
                     factory: || Box::new(icp::ICP {}),
-                    supported: false,
+                    supported: true,
                 },
             ),
             (