1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
use std::fmt;
use anyhow::Error;
use std::mem;
use unicode_normalization::UnicodeNormalization;
use zeroize::Zeroizing;
use crate::crypto::{gen_random_bytes, sha256_first_byte};
use crate::error::ErrorKind;
use crate::language::Language;
use crate::mnemonic_type::MnemonicType;
use crate::util::{checksum, BitWriter, IterExt};

/// The primary type in this crate, most tasks require creating or using one.
///
/// To create a *new* [`Mnemonic`][Mnemonic] from a randomly generated key, call [`Mnemonic::new()`][Mnemonic::new()].
///
/// To get a [`Mnemonic`][Mnemonic] instance for an existing mnemonic phrase, including
/// those generated by other software or hardware wallets, use [`Mnemonic::from_phrase()`][Mnemonic::from_phrase()].
///
/// You can get the HD wallet [`Seed`][Seed] from a [`Mnemonic`][Mnemonic] by calling [`Seed::new()`][Seed::new()].
/// From there you can either get the raw byte value with [`Seed::as_bytes()`][Seed::as_bytes()], or the hex
/// representation using Rust formatting: `format!("{:X}", seed)`.
///
/// You can also get the original entropy value back from a [`Mnemonic`][Mnemonic] with [`Mnemonic::entropy()`][Mnemonic::entropy()],
/// but beware that the entropy value is **not the same thing** as an HD wallet seed, and should
/// *never* be used that way.
///
/// [`Mnemonic`][Mnemonic] implements [`Zeroize`][Zeroize], so it's bytes will be zeroed when it's dropped.
///
/// [Mnemonic]: ./mnemonic/struct.Mnemonic.html
/// [Mnemonic::new()]: ./mnemonic/struct.Mnemonic.html#method.new
/// [Mnemonic::from_phrase()]: ./mnemonic/struct.Mnemonic.html#method.from_phrase
/// [Mnemonic::entropy()]: ./mnemonic/struct.Mnemonic.html#method.entropy
/// [Seed]: ./seed/struct.Seed.html
/// [Seed::new()]: ./seed/struct.Seed.html#method.new
/// [Seed::as_bytes()]: ./seed/struct.Seed.html#method.as_bytes
///
#[derive(Clone)]
pub struct Mnemonic {
    phrase: Zeroizing<String>,
    lang: Language,
    entropy: Zeroizing<Vec<u8>>,
}

impl Mnemonic {
    /// Generates a new [`Mnemonic`][Mnemonic]
    ///
    /// Use [`Mnemonic::phrase()`][Mnemonic::phrase()] to get an `str` slice of the generated phrase.
    ///
    /// # Example
    ///
    /// ```
    /// use bip39::{Mnemonic, MnemonicType, Language};
    ///
    /// let mnemonic = Mnemonic::new(MnemonicType::Words12, Language::English);
    /// let phrase = mnemonic.phrase();
    ///
    /// println!("phrase: {}", phrase);
    ///
    /// assert_eq!(phrase.split(" ").count(), 12);
    /// ```
    ///
    /// [Mnemonic]: ./mnemonic/struct.Mnemonic.html
    /// [Mnemonic::phrase()]: ./mnemonic/struct.Mnemonic.html#method.phrase
    pub fn new(mtype: MnemonicType, lang: Language) -> Mnemonic {
        let entropy = gen_random_bytes(mtype.entropy_bits() / 8);

        Mnemonic::from_entropy_unchecked(entropy, lang)
    }

    /// Create a [`Mnemonic`][Mnemonic] from pre-generated entropy
    ///
    /// # Example
    ///
    /// ```
    /// use bip39::{Mnemonic, MnemonicType, Language};
    ///
    /// let entropy = &[0x33, 0xE4, 0x6B, 0xB1, 0x3A, 0x74, 0x6E, 0xA4, 0x1C, 0xDD, 0xE4, 0x5C, 0x90, 0x84, 0x6A, 0x79];
    /// let mnemonic = Mnemonic::from_entropy(entropy, Language::English).unwrap();
    ///
    /// assert_eq!("crop cash unable insane eight faith inflict route frame loud box vibrant", mnemonic.phrase());
    /// assert_eq!("33E46BB13A746EA41CDDE45C90846A79", format!("{:X}", mnemonic));
    /// ```
    ///
    /// [Mnemonic]: ../mnemonic/struct.Mnemonic.html
    pub fn from_entropy(entropy: &[u8], lang: Language) -> Result<Mnemonic, Error> {
        // Validate entropy size
        MnemonicType::for_key_size(entropy.len() * 8)?;

        Ok(Self::from_entropy_unchecked(entropy, lang))
    }

    fn from_entropy_unchecked<E>(entropy: E, lang: Language) -> Mnemonic
    where
        E: Into<Vec<u8>>,
    {
        let entropy = Zeroizing::new(entropy.into());
        let wordlist = lang.wordlist();

        let checksum_byte = sha256_first_byte(&entropy);

        // First, create a byte iterator for the given entropy and the first byte of the
        // hash of the entropy that will serve as the checksum (up to 8 bits for biggest
        // entropy source).
        //
        // Then we transform that into a bits iterator that returns 11 bits at a
        // time (as u16), which we can map to the words on the `wordlist`.
        //
        // Given the entropy is of correct size, this ought to give us the correct word
        // count.
        let phrase = Zeroizing::new(entropy
            .iter()
            .chain(Some(&checksum_byte))
            .bits()
            .map(|bits| wordlist.get_word(bits))
            .join(" "));

        Mnemonic {
            phrase,
            lang,
            entropy,
        }
    }

    /// Create a [`Mnemonic`][Mnemonic] from an existing mnemonic phrase
    ///
    /// The phrase supplied will be checked for word length and validated according to the checksum
    /// specified in BIP0039
    ///
    /// # Example
    ///
    /// ```
    /// use bip39::{Mnemonic, Language};
    ///
    /// let phrase = "park remain person kitchen mule spell knee armed position rail grid ankle";
    /// let mnemonic = Mnemonic::from_phrase(phrase, Language::English).unwrap();
    ///
    /// assert_eq!(phrase, mnemonic.phrase());
    /// ```
    ///
    /// [Mnemonic]: ../mnemonic/struct.Mnemonic.html
    pub fn from_phrase(phrase: &str, lang: Language) -> Result<Mnemonic, Error> {
        let phrase = Zeroizing::new(phrase
            .split_whitespace()
            .map(|w| w.nfkd())
            .join::<String>(" "));

        // this also validates the checksum and phrase length before returning the entropy so we
        // can store it. We don't use the validate function here to avoid having a public API that
        // takes a phrase string and returns the entropy directly.
        let entropy = Zeroizing::new(Mnemonic::phrase_to_entropy(&phrase, lang)?);

        let mnemonic = Mnemonic {
            phrase,
            lang,
            entropy,
        };

        Ok(mnemonic)
    }

    /// Validate a mnemonic phrase
    ///
    /// The phrase supplied will be checked for word length and validated according to the checksum
    /// specified in BIP0039.
    ///
    /// # Example
    ///
    /// ```
    /// use bip39::{Mnemonic, Language};
    ///
    /// let test_mnemonic = "park remain person kitchen mule spell knee armed position rail grid ankle";
    ///
    /// assert!(Mnemonic::validate(test_mnemonic, Language::English).is_ok());
    /// ```
    pub fn validate(phrase: &str, lang: Language) -> Result<(), Error> {
        Mnemonic::phrase_to_entropy(phrase, lang)?;

        Ok(())
    }

    /// Calculate the checksum, verify it and return the entropy
    ///
    /// Only intended for internal use, as returning a `Vec<u8>` that looks a bit like it could be
    /// used as the seed is likely to cause problems for someone eventually. All the other functions
    /// that return something like that are explicit about what it is and what to use it for.
    fn phrase_to_entropy(phrase: &str, lang: Language) -> Result<Vec<u8>, Error> {
        let wordmap = lang.wordmap();

        // Preallocate enough space for the longest possible word list
        let mut bits = BitWriter::with_capacity(264);

        for word in phrase.split(" ") {
            bits.push(wordmap.get_bits(&word)?);
        }

        let mtype = MnemonicType::for_word_count(bits.len() / 11)?;

        debug_assert!(
            bits.len() == mtype.total_bits(),
            "Insufficient amount of bits to validate"
        );

        let mut entropy = bits.into_bytes();
        let entropy_bytes = mtype.entropy_bits() / 8;

        let actual_checksum = checksum(entropy[entropy_bytes], mtype.checksum_bits());

        // Truncate to get rid of the byte containing the checksum
        entropy.truncate(entropy_bytes);

        let checksum_byte = sha256_first_byte(&entropy);
        let expected_checksum = checksum(checksum_byte, mtype.checksum_bits());

        if actual_checksum != expected_checksum {
            Err(ErrorKind::InvalidChecksum)?;
        }

        Ok(entropy)
    }

    /// Get the mnemonic phrase as a string reference.
    pub fn phrase(&self) -> &str {
        &self.phrase
    }

    /// Consume the `Mnemonic` and return the phrase as a `String`.
    pub fn into_phrase(mut self) -> String {
        // Create an empty string and swap values with the mnemonic's phrase.
        // This allows `Mnemonic` to implement `Drop`, while still returning the phrase.
        mem::replace(&mut self.phrase, String::new())
    }

    /// Get the original entropy value of the mnemonic phrase as a slice.
    ///
    /// # Example
    ///
    /// ```
    /// use bip39::{Mnemonic, Language};
    ///
    /// let phrase = "park remain person kitchen mule spell knee armed position rail grid ankle";
    ///
    /// let mnemonic = Mnemonic::from_phrase(phrase, Language::English).unwrap();
    ///
    /// let entropy: &[u8] = mnemonic.entropy();
    /// ```
    ///
    /// **Note:** You shouldn't use the generated entropy as secrets, for that generate a new
    /// `Seed` from the `Mnemonic`.
    pub fn entropy(&self) -> &[u8] {
        &self.entropy
    }

    /// Get the [`Language`][Language]
    ///
    /// [Language]: ../language/struct.Language.html
    pub fn language(&self) -> Language {
        self.lang
    }
}

impl AsRef<str> for Mnemonic {
    fn as_ref(&self) -> &str {
        self.phrase()
    }
}

impl fmt::Display for Mnemonic {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Display::fmt(self.phrase(), f)
    }
}

impl fmt::Debug for Mnemonic {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Debug::fmt(self.phrase(), f)
    }
}

impl fmt::LowerHex for Mnemonic {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        if f.alternate() {
            f.write_str("0x")?;
        }

        for byte in self.entropy() {
            write!(f, "{:02x}", byte)?;
        }

        Ok(())
    }
}

impl fmt::UpperHex for Mnemonic {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        if f.alternate() {
            f.write_str("0x")?;
        }

        for byte in self.entropy() {
            write!(f, "{:02X}", byte)?;
        }

        Ok(())
    }
}

impl From<Mnemonic> for String {
    fn from(val: Mnemonic) -> String {
        val.into_phrase()
    }
}

#[cfg(test)]
mod test {
    use super::*;
    #[cfg(target_arch = "wasm32")]
    use wasm_bindgen_test::*;

    #[cfg_attr(all(target_arch = "wasm32"), wasm_bindgen_test)]
    #[cfg_attr(not(target_arch = "wasm32"), test)]
    fn back_to_back() {
        let m1 = Mnemonic::new(MnemonicType::Words12, Language::English);
        let m2 = Mnemonic::from_phrase(m1.phrase(), Language::English).unwrap();
        let m3 = Mnemonic::from_entropy(m1.entropy(), Language::English).unwrap();

        assert_eq!(m1.entropy(), m2.entropy(), "Entropy must be the same");
        assert_eq!(m1.entropy(), m3.entropy(), "Entropy must be the same");
        assert_eq!(m1.phrase(), m2.phrase(), "Phrase must be the same");
        assert_eq!(m1.phrase(), m3.phrase(), "Phrase must be the same");
    }

    #[cfg_attr(all(target_arch = "wasm32"), wasm_bindgen_test)]
    #[cfg_attr(not(target_arch = "wasm32"), test)]
    fn mnemonic_from_entropy() {
        let entropy = &[
            0x33, 0xE4, 0x6B, 0xB1, 0x3A, 0x74, 0x6E, 0xA4, 0x1C, 0xDD, 0xE4, 0x5C, 0x90, 0x84,
            0x6A, 0x79,
        ];
        let phrase = "crop cash unable insane eight faith inflict route frame loud box vibrant";

        let mnemonic = Mnemonic::from_entropy(entropy, Language::English).unwrap();

        assert_eq!(phrase, mnemonic.phrase());
    }

    #[cfg_attr(all(target_arch = "wasm32"), wasm_bindgen_test)]
    #[cfg_attr(not(target_arch = "wasm32"), test)]
    fn mnemonic_from_phrase() {
        let entropy = &[
            0x33, 0xE4, 0x6B, 0xB1, 0x3A, 0x74, 0x6E, 0xA4, 0x1C, 0xDD, 0xE4, 0x5C, 0x90, 0x84,
            0x6A, 0x79,
        ];
        let phrase = "crop cash unable insane eight faith inflict route frame loud box vibrant";

        let mnemonic = Mnemonic::from_phrase(phrase, Language::English).unwrap();

        assert_eq!(entropy, mnemonic.entropy());
    }

    #[cfg_attr(all(target_arch = "wasm32"), wasm_bindgen_test)]
    #[cfg_attr(not(target_arch = "wasm32"), test)]
    fn mnemonic_format() {
        let mnemonic = Mnemonic::new(MnemonicType::Words15, Language::English);

        assert_eq!(mnemonic.phrase(), format!("{}", mnemonic));
    }

    #[cfg_attr(all(target_arch = "wasm32"), wasm_bindgen_test)]
    #[cfg_attr(not(target_arch = "wasm32"), test)]
    fn mnemonic_hex_format() {
        let entropy = &[
            0x03, 0xE4, 0x6B, 0xB1, 0x3A, 0x74, 0x6E, 0xA4, 0x1C, 0xDD, 0xE4, 0x5C, 0x90, 0x84,
            0x6A, 0x79,
        ];

        let mnemonic = Mnemonic::from_entropy(entropy, Language::English).unwrap();

        assert_eq!(
            format!("{:x}", mnemonic),
            "03e46bb13a746ea41cdde45c90846a79"
        );
        assert_eq!(
            format!("{:X}", mnemonic),
            "03E46BB13A746EA41CDDE45C90846A79"
        );
        assert_eq!(
            format!("{:#x}", mnemonic),
            "0x03e46bb13a746ea41cdde45c90846a79"
        );
        assert_eq!(
            format!("{:#X}", mnemonic),
            "0x03E46BB13A746EA41CDDE45C90846A79"
        );
    }
}