base32ct: fix broken encoding of unpadded base32 (#1421)

Fixes #943 #1420
RustCrypto · May 28, 2024 · ae4e6a1 · ae4e6a1
1 parent 57d08ba
commit ae4e6a1
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Showing 2 changed files with 120 additions and 1 deletion.
diff --git a/base32ct/src/encoding.rs b/base32ct/src/encoding.rs
@@ -226,7 +226,7 @@ impl<T: Alphabet> Encoding for T {
         } else if Self::PADDED {
             ((bytes.len() - 1) / 5 + 1) * 8
         } else {
-            (bytes.len() * 8) / 5 + 1
+            (bytes.len() * 8 + 4) / 5
         }
     }
 }
@@ -258,3 +258,74 @@ fn remove_padding(mut input: &[u8]) -> Result<&[u8]> {
 
     Ok(input)
 }
+
+#[cfg(all(test, feature = "alloc"))]
+mod tests {
+    use crate::{Base32, Base32Unpadded, Encoding};
+
+    struct LenData {
+        fourty_bit_groups_len: usize,
+        last_group_len: usize,
+        padding_len: usize,
+    }
+
+    fn get_len_data(data_len: usize) -> LenData {
+        // More information about the calculation can be found at
+        // https://www.rfc-editor.org/rfc/rfc4648#section-6
+        let fourty_bit_groups_len = data_len / 5 * 8;
+        let (last_group_len, padding_len) = match data_len % 5 {
+            0 => (0, 0),
+            1 => (2, 6),
+            2 => (4, 4),
+            3 => (5, 3),
+            4 => (7, 1),
+            _ => unreachable!(),
+        };
+
+        LenData {
+            fourty_bit_groups_len,
+            last_group_len,
+            padding_len,
+        }
+    }
+
+    #[test]
+    fn unpadded_encoded_len() {
+        let mut buf = vec![];
+        assert_eq!(Base32Unpadded::encoded_len(&buf), 0);
+
+        for _ in 0..10 {
+            buf.push(b'a');
+            let LenData {
+                fourty_bit_groups_len,
+                last_group_len,
+                padding_len: _,
+            } = get_len_data(buf.len());
+
+            assert_eq!(
+                Base32Unpadded::encoded_len(&buf),
+                fourty_bit_groups_len + last_group_len
+            );
+        }
+    }
+
+    #[test]
+    fn padded_encoded_len() {
+        let mut buf = vec![];
+        assert_eq!(Base32::encoded_len(&buf), 0);
+
+        for _ in 0..10 {
+            buf.push(b'a');
+            let LenData {
+                fourty_bit_groups_len,
+                last_group_len,
+                padding_len,
+            } = get_len_data(buf.len());
+
+            assert_eq!(
+                Base32::encoded_len(&buf),
+                fourty_bit_groups_len + last_group_len + padding_len,
+            );
+        }
+    }
+}
diff --git a/base32ct/tests/vectors.rs b/base32ct/tests/vectors.rs
@@ -23,6 +23,18 @@ const LOWER_PADDED_VECTORS: &[TestVector] = &[
         decoded: &[32, 7],
         encoded: "eadq====",
     },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56],
+        encoded: "ci2fm===",
+    },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56, 0x78, 0x9a],
+        encoded: "ci2fm6e2",
+    },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc],
+        encoded: "ci2fm6e2xq======",
+    },
 ];
 
 const LOWER_UNPADDED_VECTORS: &[TestVector] = &[
@@ -38,6 +50,18 @@ const LOWER_UNPADDED_VECTORS: &[TestVector] = &[
         decoded: &[32, 7],
         encoded: "eadq",
     },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56],
+        encoded: "ci2fm",
+    },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56, 0x78, 0x9a],
+        encoded: "ci2fm6e2",
+    },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc],
+        encoded: "ci2fm6e2xq",
+    },
 ];
 
 const UPPER_PADDED_VECTORS: &[TestVector] = &[
@@ -53,6 +77,18 @@ const UPPER_PADDED_VECTORS: &[TestVector] = &[
         decoded: &[32, 7],
         encoded: "EADQ====",
     },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56],
+        encoded: "CI2FM===",
+    },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56, 0x78, 0x9a],
+        encoded: "CI2FM6E2",
+    },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc],
+        encoded: "CI2FM6E2XQ======",
+    },
 ];
 
 const UPPER_UNPADDED_VECTORS: &[TestVector] = &[
@@ -68,6 +104,18 @@ const UPPER_UNPADDED_VECTORS: &[TestVector] = &[
         decoded: &[32, 7],
         encoded: "EADQ",
     },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56],
+        encoded: "CI2FM",
+    },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56, 0x78, 0x9a],
+        encoded: "CI2FM6E2",
+    },
+    TestVector {
+        decoded: &[0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc],
+        encoded: "CI2FM6E2XQ",
+    },
 ];
 
 #[test]