diff --git a/lib/ckb/api.rb b/lib/ckb/api.rb
index 93c031d9..163c1816 100644
--- a/lib/ckb/api.rb
+++ b/lib/ckb/api.rb
@@ -16,7 +16,7 @@ def initialize(host: CKB::RPC::DEFAULT_URL, mode: MODE::TESTNET)
       @rpc = CKB::RPC.new(host: host)
       if mode == MODE::TESTNET
         # Testnet system script code_hash
-        expected_code_hash = "0x9e3b3557f11b2b3532ce352bfe8017e9fd11d154c4c7f9b7aaaa1e621b539a08"
+        expected_code_hash = "0xa4a3d87cd69733562865ddfaf12dd44cf4cd396c4128ff1a5839c2fe48b2a1a1"
         # For testnet chain, we can assume the second cell of the first transaction
         # in the genesis block contains default lock script we can use here.
         system_cell_transaction = genesis_block.transactions.first
diff --git a/lib/ckb/types/input.rb b/lib/ckb/types/input.rb
index dc39fb16..1b7ffce3 100644
--- a/lib/ckb/types/input.rb
+++ b/lib/ckb/types/input.rb
@@ -3,20 +3,20 @@
 module CKB
   module Types
     class Input
-      attr_reader :args, :previous_output, :since
+      attr_reader :block_number, :previous_output, :since
 
-      # @param args [String[]] ["0x..."]
       # @param previous_output [CKB::Types::OutPoint]
       # @param since [String]
-      def initialize(args:, previous_output:, since: "0")
-        @args = args
+      # @param block_number [String]
+      def initialize(previous_output:, since: "0", block_number: "0")
         @previous_output = previous_output
         @since = since.to_s
+        @block_number = block_number.to_s
       end
 
       def to_h
         {
-          args: @args,
+          block_number: block_number,
           previous_output: @previous_output.to_h,
           since: since
         }
@@ -26,7 +26,7 @@ def self.from_h(hash)
         return if hash.nil?
 
         new(
-          args: hash[:args],
+          block_number: hash[:block_number],
           previous_output: OutPoint.from_h(hash[:previous_output]),
           since: hash[:since]
         )
diff --git a/lib/ckb/types/transaction.rb b/lib/ckb/types/transaction.rb
index d4a0e71f..616596ea 100644
--- a/lib/ckb/types/transaction.rb
+++ b/lib/ckb/types/transaction.rb
@@ -30,10 +30,17 @@ def initialize(
       # @param key [CKB::Key]
       # @param tx_hash [String] 0x...
       def sign(key, tx_hash)
-        signature_hex_var = key.sign(tx_hash)
-        signature_size = Utils.hex_to_bin(signature_hex_var).size
-        data = [key.pubkey, signature_hex_var, Utils.bin_to_hex([signature_size].pack("Q<"))]
-        witnesses = inputs.size.times.map do
+        raise "Invalid number of witnesses!" if witnesses.length < inputs.length
+
+        signed_witnesses = witnesses.map do |witness|
+          old_data = witness.data || []
+          blake2b = CKB::Blake2b.new
+          blake2b.update(Utils.hex_to_bin(tx_hash))
+          old_data.each do |datum|
+            blake2b.update(Utils.hex_to_bin(datum))
+          end
+          message = Utils.bin_to_hex(blake2b.digest)
+          data = [key.pubkey, key.sign(message)] + old_data
           Types::Witness.from_h(data: data)
         end
 
@@ -43,7 +50,7 @@ def sign(key, tx_hash)
           deps: deps,
           inputs: inputs,
           outputs: outputs,
-          witnesses: witnesses
+          witnesses: signed_witnesses
         )
       end
 
diff --git a/lib/ckb/wallet.rb b/lib/ckb/wallet.rb
index 05e2022b..dfa7066d 100644
--- a/lib/ckb/wallet.rb
+++ b/lib/ckb/wallet.rb
@@ -75,7 +75,8 @@ def generate_tx(target_address, capacity, data = "0x")
         version: 0,
         deps: [api.system_script_out_point],
         inputs: i.inputs,
-        outputs: outputs
+        outputs: outputs,
+        witnesses: i.witnesses
       )
       tx_hash = api.compute_transaction_hash(tx)
 
@@ -116,7 +117,8 @@ def deposit_to_dao(capacity)
         version: 0,
         deps: [api.system_script_out_point],
         inputs: i.inputs,
-        outputs: outputs
+        outputs: outputs,
+        witnesses: i.witnesses,
       )
       tx_hash = api.compute_transaction_hash(tx)
       send_transaction(tx.sign(key, tx_hash))
@@ -156,11 +158,15 @@ def generate_withdraw_from_dao_transaction(cell_out_point)
         version: 0,
         deps: [{block_hash: current_block.hash}],
         inputs: [
-          Types::Input.new(args: [current_block.hash], previous_output: new_cell_out_point, since: since),
-          Types::Input.new(args: [], previous_output: DAO_ISSUING_OUT_POINT)
+          Types::Input.new(previous_output: new_cell_out_point, since: since),
+          Types::Input.new(previous_output: DAO_ISSUING_OUT_POINT)
         ],
         outputs: [
           Types::Output.new(capacity: output_capacity, lock: lock)
+        ],
+        witnesses: [
+          Types::Witness.new(data: [current_block.hash]),
+          Types::Witness.new(data: []),
         ]
       )
       tx_hash = api.compute_transaction_hash(tx)
@@ -200,15 +206,14 @@ def gather_inputs(capacity, min_capacity, min_charge_capacity)
 
       input_capacities = 0
       inputs = []
-      pubkeys = []
+      witnesses = []
       get_unspent_cells.each do |cell|
         input = Types::Input.new(
           previous_output: cell.out_point,
-          args: [],
           since: "0"
         )
-        pubkeys << pubkey
         inputs << input
+        witnesses << Types::Witness.new(data: [])
         input_capacities += cell.capacity.to_i
 
         diff = input_capacities - capacity
@@ -217,7 +222,7 @@ def gather_inputs(capacity, min_capacity, min_charge_capacity)
 
       raise "Capacity not enough!" if input_capacities < capacity
 
-      OpenStruct.new(inputs: inputs, capacities: input_capacities, pubkeys: pubkeys)
+      OpenStruct.new(inputs: inputs, capacities: input_capacities, witnesses: witnesses)
     end
 
     def pubkey
diff --git a/spec/ckb/types/transaction_spec.rb b/spec/ckb/types/transaction_spec.rb
index 339da7cc..c37751a2 100644
--- a/spec/ckb/types/transaction_spec.rb
+++ b/spec/ckb/types/transaction_spec.rb
@@ -48,7 +48,11 @@
           "data": "0x"
         }
       ],
-      "witnesses": []
+      "witnesses": [
+        {
+          data: []
+        }
+      ]
     }
   end
 
@@ -63,8 +67,7 @@
       {
         data: [
           "0x024a501efd328e062c8675f2365970728c859c592beeefd6be8ead3d901330bc01",
-          "0x304402207c82346909c13b86a97c38a50b4868b52735ca2e7e59b14f99102159c12ff25f0220511ef5974060510e8cb363877843bd85550805f668676771bfc47e36bc5b8aa2",
-          "0x4600000000000000"
+          "0x304402202c643579e47045be050d3842ed9270151af8885e33954bddad0e53e81d1c2dbe02202dc637877a8302110846ebc6a16d9148c106e25f945063ad1c4d4db2b6952408"
         ]
       }
     ])