add untested faert implementation

libs/vdk/src/faert.ts

@@ -0,0 +1,398 @@
+/**
+ * FÆRT: Fast Æternity Recovery Text
+ *
+ * Reference: https://gitlab.com/zxq9/passgas/-/blob/83607fedb08be5dfd03210e331f9c76125bb3467/fullofbeans
+ *
+ * @module
+ */
+
+export {
+    encode,
+    decode,
+    byte_of_word,
+    check_word,
+    check_byte,
+    words
+}
+
+import * as safe from './safe.js';
+
+
+
+/**
+ * Encode a bytestring into FÆRT
+ */
+function
+encode
+    (bytes : Uint8Array)
+    : string
+{
+    // initial accumulator
+    let words_acc  : Array<string> = [];
+
+    // go along each byte and look up the word
+    // add it to the accumulator
+    for (let this_byte of bytes) {
+        let this_word = words[this_byte];
+        words_acc.push(this_word);
+    }
+
+    // prepend check word to phrase
+    // yes craig it would be faster to do the check byte inline
+    // the usage case here is 64 byte strings
+    // double pass is not a big deal
+    return check_word(bytes) + ' ' + words_acc.join(' ');
+}
+
+
+
+/**
+ * Decode a FAERT string into bytes
+ */
+function
+decode
+    (faert : string)
+    : safe.Safe<Uint8Array, string>
+{
+    let all_words        : Array<string> = faert.split(' ');
+    let input_check_word : string        = all_words[0];
+    let input_words      : Array<string> = all_words.slice(1)
+
+    // accumulator
+    let computed_bytes : Array<number> = [];
+
+    // loop over words and figure out accumulator
+    for (let this_input_word of input_words) {
+        let maybe_this_byte : safe.Safe<number, string> = byte_of_word(this_input_word);
+        // if the word is an allowable word, add it to the accumulator
+        if (maybe_this_byte.ok) {
+            let this_byte : number = maybe_this_byte.result;
+            computed_bytes.push(this_byte);
+        }
+        // error case, propagate the error up the call chain
+        else {
+            return maybe_this_byte;
+        }
+    }
+
+    // at this point, we can assume we correctly decoded all words
+    // compute the check byte
+    let computed_check_word : string = check_word(computed_bytes);
+
+    // check if it is correct
+    // if so, return the computed bytes
+    if (computed_check_word === input_check_word) {
+        return safe.ok(new Uint8Array(computed_bytes));
+    }
+    // otherwise, return an error
+    else {
+        return safe.error('checksum failure! computed check word: ' + computed_check_word + '; input check word: ' + input_check_word);
+    }
+}
+
+
+
+/**
+ * given a word, find its index
+ */
+function
+byte_of_word
+    (word: string)
+    : safe.Safe<number, string>
+{
+    for (let i=0; i<=255, i++) {
+        if (word == words[i])
+            return safe.ok(i);
+    }
+    return safe.error('invalid word: ' + word);
+}
+
+
+
+/**
+ * compute the check word of an array
+ */
+function
+check_word
+    (bytes: Uint8Array)
+    : string
+{
+    return words[check_byte(bytes)];
+}
+
+
+/**
+ * given an array, compute the xor of all the bytes in the array
+ */
+function
+check_byte
+    (bytes: Uint8Array)
+    : number
+{
+    let check_byte = 0;
+    for (let this_byte of bytes) {
+        check_byte ^= this_byte;
+    }
+    return check_byte;
+}
+
+
+
+words = [
+    "able",
+    "abuse",
+    "acquire",
+    "adjust",
+    "agent",
+    "air",
+    "alert",
+    "alpha",
+    "anger",
+    "answer",
+    "any",
+    "argue",
+    "around",
+    "assume",
+    "asthma",
+    "aunt",
+    "awkward",
+    "balcony",
+    "barrel",
+    "because",
+    "behave",
+    "bicycle",
+    "bike",
+    "blind",
+    "blouse",
+    "bonus",
+    "bottom",
+    "breeze",
+    "brother",
+    "bubble",
+    "burger",
+    "butter",
+    "can",
+    "cannon",
+    "cargo",
+    "catalog",
+    "caught",
+    "century",
+    "chaos",
+    "chicken",
+    "churn",
+    "cinnamon",
+    "clever",
+    "clock",
+    "clown",
+    "collect",
+    "conduct",
+    "convince",
+    "correct",
+    "cradle",
+    "crane",
+    "crime",
+    "cross",
+    "crystal",
+    "curve",
+    "daughter",
+    "debris",
+    "decrease",
+    "deny",
+    "deputy",
+    "despair",
+    "diesel",
+    "dinner",
+    "distance",
+    "document",
+    "donate",
+    "drama",
+    "drink",
+    "dutch",
+    "earth",
+    "educate",
+    "elbow",
+    "employ",
+    "endless",
+    "enlist",
+    "enter",
+    "equal",
+    "eternal",
+    "example",
+    "exhibit",
+    "exotic",
+    "faculty",
+    "famous",
+    "fault",
+    "feature",
+    "fiber",
+    "filter",
+    "firm",
+    "flame",
+    "flush",
+    "follow",
+    "forward",
+    "frame",
+    "fringe",
+    "future",
+    "game",
+    "gate",
+    "gift",
+    "glare",
+    "glow",
+    "goat",
+    "grab",
+    "grief",
+    "guilt",
+    "hand",
+    "hawk",
+    "health",
+    "hen",
+    "hire",
+    "honey",
+    "hover",
+    "hurry",
+    "hybrid",
+    "impose",
+    "inch",
+    "inherit",
+    "injury",
+    "install",
+    "iron",
+    "jazz",
+    "joke",
+    "just",
+    "kit",
+    "kitchen",
+    "language",
+    "laundry",
+    "leader",
+    "lend",
+    "leopard",
+    "license",
+    "live",
+    "lobster",
+    "lounge",
+    "magnet",
+    "mail",
+    "mansion",
+    "mass",
+    "math",
+    "media",
+    "message",
+    "metal",
+    "misery",
+    "mix",
+    "more",
+    "mountain",
+    "museum",
+    "mutual",
+    "narrow",
+    "nerve",
+    "next",
+    "note",
+    "obey",
+    "obtain",
+    "offer",
+    "once",
+    "orange",
+    "ostrich",
+    "over",
+    "owner",
+    "palace",
+    "patch",
+    "pave",
+    "pen",
+    "phrase",
+    "piece",
+    "pizza",
+    "plunge",
+    "polar",
+    "pool",
+    "power",
+    "pretty",
+    "private",
+    "protect",
+    "pulp",
+    "purity",
+    "quit",
+    "quote",
+    "raise",
+    "razor",
+    "recall",
+    "region",
+    "relief",
+    "rent",
+    "rescue",
+    "review",
+    "ride",
+    "risk",
+    "roof",
+    "rough",
+    "saddle",
+    "salmon",
+    "sand",
+    "scene",
+    "scrub",
+    "season",
+    "seek",
+    "series",
+    "shed",
+    "shoe",
+    "sick",
+    "silent",
+    "situate",
+    "skill",
+    "slide",
+    "slush",
+    "snack",
+    "solar",
+    "soul",
+    "special",
+    "sphere",
+    "spot",
+    "spy",
+    "stairs",
+    "stereo",
+    "strategy",
+    "stuff",
+    "success",
+    "sunny",
+    "surge",
+    "swear",
+    "symptom",
+    "tail",
+    "ten",
+    "tent",
+    "theme",
+    "thumb",
+    "tiny",
+    "toe",
+    "tooth",
+    "topic",
+    "trade",
+    "trash",
+    "trophy",
+    "truly",
+    "tumble",
+    "typical",
+    "uncle",
+    "unfair",
+    "until",
+    "upper",
+    "useless",
+    "van",
+    "venue",
+    "video",
+    "visa",
+    "vocal",
+    "walk",
+    "waste",
+    "wedding",
+    "weekend",
+    "wide",
+    "winner",
+    "wise",
+    "wood",
+    "wrist",
+    "zero"
+]