.gitignore

@@ -1,4 +1,2 @@
 *.exe
 data/BNC/*
-data/dictionary*
-!data/dictionary.txt

passphrase.nimble

@@ -12,7 +12,6 @@ bin           = @["passphrase"]
 
 requires "nim >= 1.0"
 requires "nimcrypto >= 0.4.8"
-requires "zippy >= 0.7.3"
 
 
 # Tasks n scripts
@@ -33,13 +32,6 @@ task(dictionary, "Generate dictionary from BNC XML files"):
   echo output.strip().splitlines()[^1]
 
 
-task(pack, "Pack dictionary into fixed-width file and compress"):
-  echo "Packing dictionary"
-  echo runCmd("nim c --run src/dictionary.nim data/dictionary.txt data/dictionary.pack")
-
-
 before(build):
   if not fileExists("data/dictionary.txt"):
     dictionaryTask()
-  if not fileExists("data/dictionary.pack"):
-    packTask()

src/dictionary.nim

@@ -1,62 +0,0 @@
-import std/strutils
-import zippy
-
-
-type
-  Dictionary* = object
-    words: string
-    width: uint32
-
-
-proc `[]`*(d: Dictionary, i: Natural): string =
-  let start = i.uint32 * d.width
-  d.words[start ..< start + d.width]
-
-
-proc len*(d: Dictionary): int =
-  result = d.words.len div d.width.int
-
-
-proc addU32(s: var string, i: uint32) =
-  for offset in 0..3:
-    let b = cast[char](i shr (offset * 8))
-    s.add(b)
-
-
-proc getU32(s: string): uint32 =
-  for offset in 0..3:
-    result = result or (cast[uint32](s[offset]) shl (offset * 8))
-
-
-proc pack*(d: Dictionary): string =
-  var data: string
-  data.addU32(d.width)
-  data.add(d.words)
-  data.compress(dataFormat = dfGzip)
-
-
-proc unpack*(p: string): Dictionary =
-  let data = p.uncompress(dataFormat = dfGzip)
-  result.width = data.getU32()
-  result.words = data[4..^1]
-
-
-proc loadWords*(path: string): Dictionary =
-  result.width = 25
-  for word in readFile(path).strip().splitLines():
-    if word.len > 25:
-      continue
-
-    result.words.add(word)
-    for _ in 0..<(25 - word.len):
-      result.words.add(' ')
-
-
-when isMainModule:
-  import std/os
-  echo "Loading words..."
-  let dictionary = loadWords(paramStr(1))
-  echo "Packing dictionary..."
-  let packed = dictionary.pack()
-  writeFile(paramStr(2), packed)
-  echo "Dictionary packed."

src/passphrase.nim

@@ -1,19 +1,45 @@
 import std/[os, strutils]
 import nimcrypto/sysrand
-import dictionary
 
 
-const packed = staticRead("../data/dictionary.pack")
+type Dictionary = object
+  words: string
+  offsets: seq[uint32]
 
 
-proc genPassphrase(dict: Dictionary, length, dictSize: int): string =
+proc `[]`(d: Dictionary, i: Natural): string =
+  # last word has no following start index, so we have to fake it
+  # also strings are indexed with ints
+  let slice = if i == d.offsets.high:
+    d.offsets[i].int .. d.words.high
+  else:
+    d.offsets[i].int ..< d.offsets[i + 1].int
+
+  result = d.words[slice]
+
+
+proc len(d: Dictionary): int =
+  result = d.offsets.len
+
+
+proc loadWords(): Dictionary =
+  for word in staticRead("../data/dictionary.txt").strip().splitLines():
+    let startIdx = result.words.len.uint32
+    result.offsets.add(startIdx)
+    result.words.add(word)
+
+
+const dict = loadWords()
+
+
+proc genPassphrase(length, dictSize: int): string =
   var rands = newSeq[uint64](length)
   discard randomBytes(rands)
 
   var words: seq[string]
   for r in rands:
     let i = r mod dictSize.uint64
-    words.add(dict[i].strip())
+    words.add(dict[i])
   result = words.join(" ")
 
 
@@ -22,8 +48,7 @@ const help = """Usage:
 
 Defaults to length of 4 and dictionary size of 25,000."""
 
-
+proc parseInput(): (int, int) =
-proc parseInput(dictLen: int): (int, int) =
   let params = commandLineParams()
   if "-h" in params or "--help" in params:
     echo help
@@ -42,8 +67,8 @@ proc parseInput(dictLen: int): (int, int) =
   if params.len > 1:
     try:
       dictSize = parseInt(params[1])
-      if dictSize < 100 or dictSize > dictLen:
+      if dictSize < 100 or dictSize > dict.len:
-        quit("Dictionary size must be between 100 and " & $dictLen, 1)
+        quit("Dictionary size must be between 100 and " & $dict.len, 1)
     except ValueError:
       quit('"' & params[1] & "\" is not a valid dictionary size.", 1)
 
@@ -51,6 +76,5 @@ proc parseInput(dictLen: int): (int, int) =
 
 
 when isMainModule:
-  let dict = packed.unpack()
+  let (length, dictSize) = parseInput()
-  let (length, dictSize) = parseInput(dict.len)
+  echo genPassphrase(length, dictSize)
-  echo genPassphrase(dict, length, dictSize)