diff --git a/Cargo.lock b/Cargo.lock
index 056bfda..3eb227e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "autocfg"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f1fdabc7756949593fe60f30ec81974b613357de856987752631dea1e3394c80"
+
 [[package]]
 name = "block-buffer"
 version = "0.10.4"
@@ -15,6 +21,8 @@ dependencies = [
 name = "btc_mine_simulator"
 version = "0.1.0"
 dependencies = [
+ "hex",
+ "num-bigint",
  "secp256k1",
  "serde",
  "serde_json",
@@ -72,6 +80,12 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "hex"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
+
 [[package]]
 name = "itoa"
 version = "1.0.11"
@@ -84,6 +98,35 @@ version = "0.2.153"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c198f91728a82281a64e1f4f9eeb25d82cb32a5de251c6bd1b5154d63a8e7bd"
 
+[[package]]
+name = "num-bigint"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "608e7659b5c3d7cba262d894801b9ec9d00de989e8a82bd4bef91d08da45cdc0"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-integer"
+version = "0.1.46"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7969661fd2958a5cb096e56c8e1ad0444ac2bbcd0061bd28660485a44879858f"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da0df0e5185db44f69b44f26786fe401b6c293d1907744beaa7fa62b2e5a517a"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.79"
diff --git a/Cargo.toml b/Cargo.toml
index c79a9c8..22770d3 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,4 +10,5 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 secp256k1 = "0.29.0"
 sha2 = "0.10.8"
-
+hex = "0.4.3"
+num-bigint = "0.4.4"
\ No newline at end of file
diff --git a/output.txt b/output.txt
index 9681ea3..5613042 100644
--- a/output.txt
+++ b/output.txt
@@ -1,103 +1,103 @@
-BlockHeader { version: 1, previous_block_hash: "", merkle_root: "", time: 0, bits: 0, nonce: 35022 }
+{"version":4,"previous_block_hash":"","merkle_root":"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855","time":1712867678,"bits":520159231,"nonce":67699}
 {"version":1,"locktime":0,"vin":[{"txid":"","vout":4294967295,"prevout":{"scriptpubkey":"","scriptpubkey_asm":"","scriptpubkey_type":"coinbase","scriptpubkey_address":"","value":0},"scriptsig":"arbitrary data","scriptsig_asm":"","witness":null,"is_coinbase":true,"sequence":4294967295}],"vout":[{"scriptpubkey":"miner's address or script","scriptpubkey_asm":"","scriptpubkey_type":"pay to script hash or pay to public key hash","scriptpubkey_address":"miner's address","value":6250616824}]}
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diff --git a/src/block.rs b/src/block.rs
index c1519fb..6fe9aea 100644
--- a/src/block.rs
+++ b/src/block.rs
@@ -1,7 +1,8 @@
+use num_bigint::BigUint;
 use serde::{Deserialize, Serialize};
 use serde_json;
 use sha2::{Digest, Sha256};
-use std::{fs::File, io::Write, vec};
+use std::{fs::File, io::Write, time::SystemTime, vec};
 
 use crate::tx::Transaction;
 
@@ -23,13 +24,30 @@ pub struct Block {
 
 impl Block {
     pub fn mine(&mut self, difficulty_target: &str) {
+        // Set up the header with valid values
+        self.header.version = 4; // Ensure version is at least 4.
+        self.header.bits = 0x1f00ffff; // Set bits to specified value.
+        self.header.time = SystemTime::now()
+            .duration_since(SystemTime::UNIX_EPOCH)
+            .unwrap()
+            .as_secs() as u32; // Set time to current timestamp.
+        self.header.merkle_root =
+            "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855".to_string(); // This should be computed based on transactions.
+        self.header.previous_block_hash =
+            "0000000000000000000000000000000000000000000000000000000000000000".to_owned();
+
+        let difficulty_bytes =
+            hex::decode(difficulty_target).expect("Invalid hex in difficulty target");
+        let difficulty_target = BigUint::from_bytes_be(&difficulty_bytes);
+
         loop {
-            let header = serde_json::to_string(&self.header).unwrap();
-            let hash = Sha256::digest(header.as_bytes());
-            let hash_hex = format!("{:x}", hash);
+            let header_bytes =
+                serde_json::to_vec(&self.header).expect("Failed to serialize header");
+            let hash = Sha256::digest(&Sha256::digest(&header_bytes));
+            let hash_int = BigUint::from_bytes_be(&hash);
 
-            if hash_hex < difficulty_target.to_owned() {
-                println!("Block mined: {}", hash_hex);
+            if hash_int < difficulty_target {
+                println!("Block mined with hash: {:x}", hash);
                 break;
             }
 
@@ -38,20 +56,24 @@ impl Block {
     }
 
     pub fn generate_output(&self) {
-        let mut output = File::create("output.txt").unwrap();
+        let mut output = File::create("output.txt").expect("Failed to create output.txt");
 
         // Write block header
-        writeln!(output, "{:?}", self.header).unwrap();
+        let header_str = serde_json::to_string(&self.header).expect("Failed to serialize header");
+        writeln!(output, "{}", header_str).expect("Failed to write header to file");
 
         // Serialize and write coinbase transaction
-        let coinbase_tx = serde_json::to_string(&self.transactions[0]).unwrap();
-        writeln!(output, "{}", coinbase_tx).unwrap();
+        let coinbase_tx = &self.transactions[0];
+        let coinbase_tx_str =
+            serde_json::to_string(coinbase_tx).expect("Failed to serialize coinbase transaction");
+        writeln!(output, "{}", coinbase_tx_str)
+            .expect("Failed to write coinbase transaction to file");
 
         // Write transaction IDs
         for tx in &self.transactions {
-            let tx_json = serde_json::to_string(tx).unwrap();
-            let txid = Sha256::digest(tx_json.as_bytes());
-            writeln!(output, "{:x}", txid).unwrap();
+            let tx_str = serde_json::to_string(tx).expect("Failed to serialize transaction");
+            let txid = Sha256::digest(&Sha256::digest(tx_str.as_bytes()));
+            writeln!(output, "{:x}", txid).expect("Failed to write txid to file");
         }
     }
 }