fix: use separator from WordList when decoding (#197)

* fix: use separator from `WordList` when decoding

* docs: changelog

* fix: review comments

* Update tests/bip39.rs

Co-authored-by: Thoralf-M <[email protected]>

* fix: change severity to patch

* fix: spell checking

---------

Co-authored-by: Thoralf-M <[email protected]>

.changes/bip39-decode-separator.md

@@ -0,0 +1,5 @@
+---
+"iota-crypto": patch
+---
+
+Use word separator provided in `WordList` when decoding. Disallow toleration for multiple whitespace when single whitespace is defined as a word separator.

src/keys/bip39.rs

@@ -139,7 +139,9 @@ pub mod wordlist {
         let mut acc = 0;
         let mut i = 0;
         let ms = ms.chars().nfkd().collect::<String>();
-        for ref w in ms.split_whitespace() {
+        let separator = wordlist.separator.chars().nfkd().collect::<String>();
+
+        for ref w in ms.split(&separator) {
             match wordlist.words.iter().position(|v| v == w) {
                 None => return Err(Error::NoSuchWord(w.to_string())),
                 Some(idx) => {

tests/bip39.rs

@@ -66,6 +66,52 @@ fn test_wordlist_codec() {
     }
 }
 
+#[test]
+fn test_mnemonic_phrase_when_separator_is_repeated() {
+    let test_cases = &[
+        // U+3000 separator
+        ("　", true),
+        // whitespace(U+0020) is also allowed as a separator, because U+3000 is normalized to the whitespace
+        (" ", true),
+        (" 　", false),
+        ("  ", false),
+        ("　 ", false),
+        ("　 　", false),
+    ];
+
+    for case in test_cases {
+        let mnemonic_phrase = format!("あいこくしん{}あいこくしん　あいこくしん　あいこくしん　あいこくしん　あいこくしん　あいこくしん　あいこくしん　あいこくしん　あいこくしん　あいこくしん　あおぞら", case.0);
+        assert_eq!(
+            wordlist::decode(&mnemonic_phrase, &wordlist::JAPANESE).is_ok(),
+            case.1,
+            "{}",
+            mnemonic_phrase
+        );
+        assert_eq!(
+            wordlist::verify(&mnemonic_phrase, &wordlist::JAPANESE).is_ok(),
+            case.1,
+            "{}",
+            mnemonic_phrase
+        );
+    }
+}
+
+#[test]
+fn test_mnemonic_phrase_additional_whitespace() {
+    // additional whitespace at the beginning
+    assert!(
+        wordlist::decode(" sand luggage rack used middle crater deal scare high ring swim fish use then video visa can foot clog base quality all elephant retreat", &wordlist::ENGLISH).is_err(),
+    );
+    // additional whitespace in between
+    assert!(
+        wordlist::decode("sand  luggage rack used middle crater deal scare high ring swim fish use then video visa can foot clog base quality all elephant retreat", &wordlist::ENGLISH).is_err(),
+    );
+    // additional whitespace at the end
+    assert!(
+        wordlist::decode("sand luggage rack used middle crater deal scare high ring swim fish use then video visa can foot clog base quality all elephant retreat ", &wordlist::ENGLISH).is_err(),
+    );
+}
+
 // #[test]
 // fn test_wordlist_codec_different_data_different_encodings() {
 // for _ in 0..1000 {