From 3bfb55ece2f70fc9b1969a2ec9c55f7a00358b90 Mon Sep 17 00:00:00 2001
From: Andreas Grois <andi@grois.info>
Date: Tue, 11 Oct 2022 23:31:21 +0200
Subject: Refactor base_conversion. Fix hmac byte bug.

Moved the basis conversion into a submodule, to ease the upcoming
rewrite.
Add a couple of new integration tests.
Fix a bug caused by misreading the PasswordMaker Pro HMAC code.
---
 src/passwordmaker/base_conversion/mod.rs | 65 ++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 src/passwordmaker/base_conversion/mod.rs

(limited to 'src/passwordmaker/base_conversion/mod.rs')

diff --git a/src/passwordmaker/base_conversion/mod.rs b/src/passwordmaker/base_conversion/mod.rs
new file mode 100644
index 0000000..705917a
--- /dev/null
+++ b/src/passwordmaker/base_conversion/mod.rs
@@ -0,0 +1,65 @@
+use std::convert::TryInto;
+
+use self::remainders::CalcRemainders;
+
+mod remainders;
+mod remainders_impl;
+
+/// Converts an input to a different base (which fits in usize). Returns the digits starting at the most significant one.
+pub(super) trait BaseConversion {
+    // return type is subject to change. Hopefully soon the math will be rewritten, so we can skip the Vec and IntoIter.
+    // will have to remain an ExactSizeIterator though.
+    fn convert_to_base(self, base : usize) -> std::iter::Rev<std::vec::IntoIter<usize>>;
+}
+
+impl<const N : usize, T> BaseConversion for T where T : ToI32Array<Output = [u32;N]>{
+    fn convert_to_base(self, base : usize) -> std::iter::Rev<std::vec::IntoIter<usize>> {
+        self.to_int_array().calc_remainders(base).collect::<Vec<_>>().into_iter().rev()
+    }
+}
+
+impl BaseConversion for [u8;16]{
+    fn convert_to_base(self, base : usize) -> std::iter::Rev<std::vec::IntoIter<usize>> {
+        u128::from_be_bytes(self).calc_remainders(base as u128).map(|ll| ll as usize).collect::<Vec<_>>().into_iter().rev()
+    }
+}
+
+
+
+// Rust 1.52 only has a very limited support for const generics. This means, we'll have to live with this not-too-constrained solution...
+// Well, it's private, so no big loss.
+trait ToI32Array {
+    type Output;
+    fn to_int_array(self) -> Self::Output;
+}
+
+//this could of course be done in a generic manner, but it's ugly without array_mut, which we don't have in Rust 1.52.
+//Soo, pedestrian's approach :D 
+impl ToI32Array for [u8;20] {
+    type Output = [u32; 5];
+    fn to_int_array(self) -> [u32; 5] {
+        [
+            u32::from_be_bytes(self[0..4].try_into().unwrap()),
+            u32::from_be_bytes(self[4..8].try_into().unwrap()),
+            u32::from_be_bytes(self[8..12].try_into().unwrap()),
+            u32::from_be_bytes(self[12..16].try_into().unwrap()),
+            u32::from_be_bytes(self[16..20].try_into().unwrap()),
+        ]
+    }
+}
+
+impl ToI32Array for [u8;32] {
+    type Output = [u32; 8];
+    fn to_int_array(self) -> [u32; 8] {
+        [
+            u32::from_be_bytes(self[0..4].try_into().unwrap()),
+            u32::from_be_bytes(self[4..8].try_into().unwrap()),
+            u32::from_be_bytes(self[8..12].try_into().unwrap()),
+            u32::from_be_bytes(self[12..16].try_into().unwrap()),
+            u32::from_be_bytes(self[16..20].try_into().unwrap()),
+            u32::from_be_bytes(self[20..24].try_into().unwrap()),
+            u32::from_be_bytes(self[24..28].try_into().unwrap()),
+            u32::from_be_bytes(self[28..32].try_into().unwrap()),
+        ]
+    }
+}
\ No newline at end of file
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