From 3057f1bc95733727f5a6c1134c70f9998fdc8cbb Mon Sep 17 00:00:00 2001
From: Alex Page <alex@anpage.me>
Date: Mon, 19 Jun 2023 02:49:46 -0400
Subject: [PATCH] Fix bink1998 verify

---
 src/bink1998.rs | 15 ++++++---------
 src/key.rs      |  8 ++++----
 2 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/src/bink1998.rs b/src/bink1998.rs
index 3c1061b..1cee8a1 100644
--- a/src/bink1998.rs
+++ b/src/bink1998.rs
@@ -6,7 +6,7 @@ use openssl::{
     sha::sha1,
 };
 
-use crate::{key::unbase24, FIELD_BYTES};
+use crate::{key::base24_decode, FIELD_BYTES};
 
 #[derive(Clone, Copy, Debug)]
 struct ProductKey {
@@ -24,11 +24,7 @@ pub fn verify(
 ) -> Result<bool> {
     let mut num_context = BigNumContext::new()?;
 
-    let p_raw = unbase24(p_key);
-    for byte in &p_raw {
-        print!("{:02X}, ", *byte);
-    }
-    println!();
+    let p_raw = base24_decode(p_key);
     let product_key = unpack(&p_raw)?;
 
     let p_data = product_key.serial << 1 | product_key.upgrade as u32;
@@ -63,7 +59,7 @@ pub fn verify(
 
     let msg_digest = sha1(&msg_buffer);
 
-    let hash: u32 = u32::from_be_bytes(msg_digest[0..4].try_into().unwrap()) & ((1 << 28) - 1);
+    let hash: u32 = u32::from_le_bytes(msg_digest[0..4].try_into().unwrap()) >> 4 & ((1 << 28) - 1);
 
     Ok(hash == product_key.hash)
 }
@@ -82,11 +78,12 @@ pub fn generate(
 fn unpack(p_raw: &[u8]) -> Result<ProductKey> {
     const HASH_LENGTH_BITS: u8 = 28;
     const SERIAL_LENGTH_BITS: u8 = 30;
+    const UPGRADE_LENGTH_BITS: u8 = 1;
+    const EVERYTHING_ELSE: u8 = HASH_LENGTH_BITS + SERIAL_LENGTH_BITS + UPGRADE_LENGTH_BITS;
 
     let mut reader = BitReader::new(p_raw);
     // The signature length is unknown, but everything else is, so we can calculate it
-    let signature_length_bits =
-        (p_raw.len() * 8) as u8 - (HASH_LENGTH_BITS + SERIAL_LENGTH_BITS + 1);
+    let signature_length_bits = (p_raw.len() * 8) as u8 - EVERYTHING_ELSE;
 
     let p_signature = reader.read_u64(signature_length_bits)?;
     let p_hash = reader.read_u32(HASH_LENGTH_BITS)?;
diff --git a/src/key.rs b/src/key.rs
index 583dce8..193acbc 100644
--- a/src/key.rs
+++ b/src/key.rs
@@ -9,7 +9,7 @@ const P_CHARSET: [char; 24] = [
 
 const PK_LENGTH: usize = 25;
 
-pub fn unbase24(cd_key: &str) -> Vec<u8> {
+pub fn base24_decode(cd_key: &str) -> Vec<u8> {
     let p_decoded_key: Vec<u8> = cd_key
         .chars()
         .filter_map(|c| P_CHARSET.iter().position(|&x| x == c).map(|i| i as u8))
@@ -25,7 +25,7 @@ pub fn unbase24(cd_key: &str) -> Vec<u8> {
     y.to_vec()
 }
 
-pub fn base24(byte_seq: &[u8]) -> String {
+pub fn base24_encode(byte_seq: &[u8]) -> String {
     let mut z = BigNum::from_slice(byte_seq).unwrap();
     let mut out: VecDeque<char> = VecDeque::new();
     (0..=24).for_each(|_| out.push_front(P_CHARSET[z.div_word(24).unwrap() as usize]));
@@ -37,9 +37,9 @@ mod tests {
     #[test]
     fn test_base24() {
         let input = "JTW3TJ7PFJ7V9CCMX84V9PFT8";
-        let unbase24 = super::unbase24(input);
+        let unbase24 = super::base24_decode(input);
         println!("{:?}", unbase24);
-        let base24 = super::base24(&unbase24);
+        let base24 = super::base24_encode(&unbase24);
         println!("{}", base24);
         assert_eq!(input, base24);
     }