atoponce/lehmer.html

## lehmer.html
<!doctype html>
<html>
  <head>
    <meta charset='utf-8'></meta>
    <title>Lehmer Code</title>
    <style>
      input[type=text] {
        font-family: monospace;
        width: 450px;
      }
    </style>
  </head>
  <body>
    <label for='chars'>Characters (A-Z):</label>
    <br/>
    <input type='text' id='chars' name='chars' />
    <br/>
    <label for='faces'>Digits (1-6):</label>
    <br/>
    <input type='text' id='faces' name='faces' />
    <br/>
    <label for='orien'>Orientations (1-4):</label>
    <br/>
    <input type='text' id='orien' name='orien' />
    <br/>
    <input type='submit' value='Submit' onclick='buildHex()'/>
    <br/>
    <br/>
    <label for='result'>Result:</label>
    <br/>
    <input readonly type='text' id='result' name='result' />
    <br/>
    <p>Give this result to <a href='https://github.com/diracdeltas/niceware'>Niceware</a> for a fun 192-bit 12-word passphrase.</a>
    <script>
      function factorial(n) {
        let result = BigInt(1)

        while (n > 0) {
          result *= BigInt(n)
          n--
        }

        return result
      }

      function calculateLehmer(chars) {
        const arr = chars.split('')
        let lehmer = []
        let counter = 0
        let result = BigInt(0)

        for (let i = 0; i < arr.length; i++) {
          for (let j = i + 1; j < arr.length; j++) {
            if (arr[i] > arr[j]) counter++
          }
          lehmer[i] = counter
          counter = 0
        }

        counter = lehmer.length
        for (let i = 0; i < lehmer.length; i++) {
          counter--
          result += (BigInt(lehmer[i]) * factorial(counter))
        }

        return result
      }

      function calculateDecimal(outcome, possible) {
        const arr = outcome.split('')
        let counter = arr.length
        let result = BigInt(0)

        for (let i = 0; i < arr.length; i++) {
          counter--
          result += BigInt((arr[i] % possible) * possible**counter)
        }

        return result
      }

      function buildHex() {
        const result = document.getElementById('result')

        // The three DiceKeys inputs
        const chars = document.getElementById('chars').value
        const faces = document.getElementById('faces').value
        const orien = document.getElementById('orien').value

        // The calculated results of each set
        const charsDec = calculateLehmer(chars)
        const facesDec = calculateDecimal(faces, 6)
        const orienDec = calculateDecimal(orien, 4)

        // The maxes each set can be
        const charsMax = BigInt(factorial(25)) - 1n
        const facesMax = BigInt(6**25) - 1n
        const orienMax = BigInt(4**25) - 1n

        // The calculated ID of that specific DiceKeys toss
        let permutation = (orienDec * facesMax * charsMax) + (facesDec * charsMax) + charsDec

        // We must keep a uniform distribution. Some tosses must be discarded.
        // 2^198 is about 80% of 2^198.30557612690..., so we lose ~20% tosses.
        if (permutation >= BigInt(2**198)) {
          result.value = 'Result will be biased. Reroll.'
          result.style.color = 'red'
        }
        else {
          permutation = permutation & (BigInt(2**192) - 1n)
          const hex = permutation.toString(16).padStart(48, '0')
          result.value = hex
          result.style.color = 'black'
        }
      }
    </script>
  </body>
</html>
	<!doctype html>
	<html>
	<head>
	<meta charset='utf-8'></meta>
	<title>Lehmer Code</title>
	<style>
	input[type=text] {
	font-family: monospace;
	width: 450px;
	}
	</style>
	</head>
	<body>
	<label for='chars'>Characters (A-Z):</label>
	<br/>
	<input type='text' id='chars' name='chars' />
	<br/>
	<label for='faces'>Digits (1-6):</label>
	<br/>
	<input type='text' id='faces' name='faces' />
	<br/>
	<label for='orien'>Orientations (1-4):</label>
	<br/>
	<input type='text' id='orien' name='orien' />
	<br/>
	<input type='submit' value='Submit' onclick='buildHex()'/>
	<br/>
	<br/>
	<label for='result'>Result:</label>
	<br/>
	<input readonly type='text' id='result' name='result' />
	<br/>
	<p>Give this result to <a href='https://github.com/diracdeltas/niceware'>Niceware</a> for a fun 192-bit 12-word passphrase.</a>
	<script>
	function factorial(n) {
	let result = BigInt(1)

	while (n > 0) {
	result *= BigInt(n)
	n--
	}

	return result
	}

	function calculateLehmer(chars) {
	const arr = chars.split('')
	let lehmer = []
	let counter = 0
	let result = BigInt(0)

	for (let i = 0; i < arr.length; i++) {
	for (let j = i + 1; j < arr.length; j++) {
	if (arr[i] > arr[j]) counter++
	}
	lehmer[i] = counter
	counter = 0
	}

	counter = lehmer.length
	for (let i = 0; i < lehmer.length; i++) {
	counter--
	result += (BigInt(lehmer[i]) * factorial(counter))
	}

	return result
	}

	function calculateDecimal(outcome, possible) {
	const arr = outcome.split('')
	let counter = arr.length
	let result = BigInt(0)

	for (let i = 0; i < arr.length; i++) {
	counter--
	result += BigInt((arr[i] % possible) * possible**counter)
	}

	return result
	}

	function buildHex() {
	const result = document.getElementById('result')

	// The three DiceKeys inputs
	const chars = document.getElementById('chars').value
	const faces = document.getElementById('faces').value
	const orien = document.getElementById('orien').value

	// The calculated results of each set
	const charsDec = calculateLehmer(chars)
	const facesDec = calculateDecimal(faces, 6)
	const orienDec = calculateDecimal(orien, 4)

	// The maxes each set can be
	const charsMax = BigInt(factorial(25)) - 1n
	const facesMax = BigInt(6**25) - 1n
	const orienMax = BigInt(4**25) - 1n

	// The calculated ID of that specific DiceKeys toss
	let permutation = (orienDec * facesMax * charsMax) + (facesDec * charsMax) + charsDec

	// We must keep a uniform distribution. Some tosses must be discarded.
	// 2^198 is about 80% of 2^198.30557612690..., so we lose ~20% tosses.
	if (permutation >= BigInt(2**198)) {
	result.value = 'Result will be biased. Reroll.'
	result.style.color = 'red'
	}
	else {
	permutation = permutation & (BigInt(2**192) - 1n)
	const hex = permutation.toString(16).padStart(48, '0')
	result.value = hex
	result.style.color = 'black'
	}
	}
	</script>
	</body>
	</html>