From: Sergi Delgado Segura <sergi.delgado.s@gmail.com>
Date: Mon, 22 Mar 2021 10:14:25 +0000 (+0100)
Subject: Adds zbase32 encoding
X-Git-Tag: v0.0.14~21^2~5
X-Git-Url: http://git.bitcoin.ninja/?a=commitdiff_plain;h=c7f405edf5773e29e58d3a218de2a81d5415d63d;p=rust-lightning

Adds zbase32 encoding
---

diff --git a/lightning/src/util/mod.rs b/lightning/src/util/mod.rs
index 04b77872c..59b46a4f1 100644
--- a/lightning/src/util/mod.rs
+++ b/lightning/src/util/mod.rs
@@ -15,6 +15,7 @@ pub(crate) mod fuzz_wrappers;
 pub mod events;
 pub mod errors;
 pub mod ser;
+pub mod zbase32;
 
 pub(crate) mod byte_utils;
 pub(crate) mod chacha20;
diff --git a/lightning/src/util/zbase32.rs b/lightning/src/util/zbase32.rs
new file mode 100644
index 000000000..19a10cca3
--- /dev/null
+++ b/lightning/src/util/zbase32.rs
@@ -0,0 +1,137 @@
+// This is a modification of base32 encoding to support the zbase32 alphabet.
+// The original piece of software can be found at https://github.com/andreasots/base32
+
+/*
+Copyright (c) 2015 The base32 Developers
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+const ALPHABET: &'static [u8] = b"ybndrfg8ejkmcpqxot1uwisza345h769";
+
+pub fn encode(data: &[u8]) -> String {
+    let mut ret = Vec::with_capacity((data.len() + 3) / 4 * 5);
+
+    for chunk in data.chunks(5) {
+        let buf = {
+            let mut buf = [0u8; 5];
+            for (i, &b) in chunk.iter().enumerate() {
+                buf[i] = b;
+            }
+            buf
+        };
+
+        ret.push(ALPHABET[((buf[0] & 0xF8) >> 3) as usize]);
+        ret.push(ALPHABET[(((buf[0] & 0x07) << 2) | ((buf[1] & 0xC0) >> 6)) as usize]);
+        ret.push(ALPHABET[((buf[1] & 0x3E) >> 1) as usize]);
+        ret.push(ALPHABET[(((buf[1] & 0x01) << 4) | ((buf[2] & 0xF0) >> 4)) as usize]);
+        ret.push(ALPHABET[(((buf[2] & 0x0F) << 1) | (buf[3] >> 7)) as usize]);
+        ret.push(ALPHABET[((buf[3] & 0x7C) >> 2) as usize]);
+        ret.push(ALPHABET[(((buf[3] & 0x03) << 3) | ((buf[4] & 0xE0) >> 5)) as usize]);
+        ret.push(ALPHABET[(buf[4] & 0x1F) as usize]);
+    }
+
+    if data.len() % 5 != 0 {
+        let len = ret.len();
+        let num_extra = 8 - (data.len() % 5 * 8 + 4) / 5;
+        ret.truncate(len - num_extra);
+    }
+
+    String::from_utf8(ret).unwrap()
+}
+
+// ASCII 0-Z
+const INV_ALPHABET: [i8; 43] = [
+    -1, 18, -1, 25, 26, 27, 30, 29, 7, 31, -1, -1, -1, -1, -1, -1, -1,  24, 1, 12, 3, 8, 5, 6, 28,
+    21, 9, 10, -1, 11, 2, 16, 13, 14, 4, 22, 17, 19, -1, 20, 15, 0, 23,
+];
+
+pub fn decode(data: &str) -> Result<Vec<u8>, &'static str> {
+    if !data.is_ascii() {
+        return Err("Data is not zbase32 encoded");
+    }
+
+    let data = data.as_bytes();
+    let output_length = data.len() * 5 / 8;
+    let mut ret = Vec::with_capacity((output_length + 4) / 5 * 5);
+
+    for chunk in data.chunks(8) {
+        let buf = {
+            let mut buf = [0u8; 8];
+            for (i, &c) in chunk.iter().enumerate() {
+                match INV_ALPHABET.get(c.to_ascii_uppercase().wrapping_sub(b'0') as usize) {
+                    Some(&-1) | None => return Err("Data is not zbase32 encoded"),
+                    Some(&value) => buf[i] = value as u8,
+                };
+            }
+            buf
+        };
+        ret.push((buf[0] << 3) | (buf[1] >> 2));
+        ret.push((buf[1] << 6) | (buf[2] << 1) | (buf[3] >> 4));
+        ret.push((buf[3] << 4) | (buf[4] >> 1));
+        ret.push((buf[4] << 7) | (buf[5] << 2) | (buf[6] >> 3));
+        ret.push((buf[6] << 5) | buf[7]);
+    }
+    ret.truncate(output_length);
+    Ok(ret)
+}
+
+mod tests {
+    use super::*;
+
+    const TEST_DATA: &[(&str, &[u8])] = &[
+        ("",       &[]),
+        ("yy",     &[0x00]),
+        ("oy",     &[0x80]),
+        ("tqrey",   &[0x8b, 0x88, 0x80]),
+        ("6n9hq",  &[0xf0, 0xbf, 0xc7]),
+        ("4t7ye",  &[0xd4, 0x7a, 0x04]),
+        ("6im5sdy", &[0xf5, 0x57, 0xbb, 0x0c]),
+        ("ybndrfg8ejkmcpqxot1uwisza345h769", &[0x00, 0x44, 0x32, 0x14, 0xc7, 0x42, 0x54, 0xb6,
+                                                    0x35, 0xcf, 0x84, 0x65, 0x3a, 0x56, 0xd7, 0xc6,
+                                                    0x75, 0xbe, 0x77, 0xdf])
+    ];
+ 
+
+    #[test]
+    fn test_encode() {
+        for &(zbase32, data) in TEST_DATA {
+            assert_eq!(encode(data), zbase32);
+        }
+    }
+
+    #[test]
+    fn test_decode() {
+        for &(zbase32, data) in TEST_DATA {
+            assert_eq!(decode(zbase32).unwrap(), data);
+        }
+    }
+
+    #[test]
+    fn test_decode_wrong() {
+        let WRONG_DATA = &["00", "l1", "?", "="];
+
+        for &data in WRONG_DATA {
+            match decode(data) {
+                Ok(_) => assert!(false, "Data shouldn't be decodable"),
+                Err(_) => assert!(true),
+            }
+        }
+    }
+}
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