Encode key as base58

js/base-x-3.0.5.1.js

@@ -0,0 +1,148 @@
+// base-x encoding / decoding
+// based on https://github.com/cryptocoinjs/base-x 3.0.5
+// modification: removed Buffer dependency and node.modules entry
+// Copyright (c) 2018 base-x contributors
+// Copyright (c) 2014-2018 The Bitcoin Core developers (base58.cpp)
+// Distributed under the MIT software license, see the accompanying
+// file LICENSE or http://www.opensource.org/licenses/mit-license.php.
+
+var baseX = function base (ALPHABET) {
+  if (ALPHABET.length >= 255) throw new TypeError('Alphabet too long')
+
+  const BASE_MAP = new Uint8Array(256)
+  BASE_MAP.fill(255)
+
+  for (let i = 0; i < ALPHABET.length; i++) {
+    const x = ALPHABET.charAt(i)
+    const xc = x.charCodeAt(0)
+
+    if (BASE_MAP[xc] !== 255) throw new TypeError(x + ' is ambiguous')
+    BASE_MAP[xc] = i
+  }
+
+  const BASE = ALPHABET.length
+  const LEADER = ALPHABET.charAt(0)
+  const FACTOR = Math.log(BASE) / Math.log(256) // log(BASE) / log(256), rounded up
+  const iFACTOR = Math.log(256) / Math.log(BASE) // log(256) / log(BASE), rounded up
+
+  function encode (source) {
+    if (source.length === 0) return ''
+
+    // Skip & count leading zeroes.
+    let zeroes = 0
+    let length = 0
+    let pbegin = 0
+    const pend = source.length
+
+    while (pbegin !== pend && source[pbegin] === 0) {
+      pbegin++
+      zeroes++
+    }
+
+    // Allocate enough space in big-endian base58 representation.
+    const size = ((pend - pbegin) * iFACTOR + 1) >>> 0
+    const b58 = new Uint8Array(size)
+
+    // Process the bytes.
+    while (pbegin !== pend) {
+      let carry = source[pbegin]
+
+      // Apply "b58 = b58 * 256 + ch".
+      let i = 0
+      for (let it = size - 1; (carry !== 0 || i < length) && (it !== -1); it--, i++) {
+        carry += (256 * b58[it]) >>> 0
+        b58[it] = (carry % BASE) >>> 0
+        carry = (carry / BASE) >>> 0
+      }
+
+      if (carry !== 0) throw new Error('Non-zero carry')
+      length = i
+      pbegin++
+    }
+
+    // Skip leading zeroes in base58 result.
+    let it = size - length
+    while (it !== size && b58[it] === 0) {
+      it++
+    }
+
+    // Translate the result into a string.
+    let str = LEADER.repeat(zeroes)
+    for (; it < size; ++it) str += ALPHABET.charAt(b58[it])
+
+    return str
+  }
+
+  function decodeUnsafe (source) {
+    if (typeof source !== 'string') throw new TypeError('Expected String')
+    if (source.length === 0) return ''
+
+    let psz = 0
+
+    // Skip leading spaces.
+    if (source[psz] === ' ') return
+
+    // Skip and count leading '1's.
+    let zeroes = 0
+    let length = 0
+    while (source[psz] === LEADER) {
+      zeroes++
+      psz++
+    }
+
+    // Allocate enough space in big-endian base256 representation.
+    const size = (((source.length - psz) * FACTOR) + 1) >>> 0 // log(58) / log(256), rounded up.
+    const b256 = new Uint8Array(size)
+
+    // Process the characters.
+    while (source[psz]) {
+      // Decode character
+      let carry = BASE_MAP[source.charCodeAt(psz)]
+
+      // Invalid character
+      if (carry === 255) return
+
+      let i = 0
+      for (let it = size - 1; (carry !== 0 || i < length) && (it !== -1); it--, i++) {
+        carry += (BASE * b256[it]) >>> 0
+        b256[it] = (carry % 256) >>> 0
+        carry = (carry / 256) >>> 0
+      }
+
+      if (carry !== 0) throw new Error('Non-zero carry')
+      length = i
+      psz++
+    }
+
+    // Skip trailing spaces.
+    if (source[psz] === ' ') return
+
+    // Skip leading zeroes in b256.
+    let it = size - length
+    while (it !== size && b256[it] === 0) {
+      it++
+    }
+
+    var vch = [];
+
+    let j = zeroes
+    while (it !== size) {
+      vch[j++] = b256[it++]
+    }
+
+    return vch
+  }
+
+  function decode (string) {
+    const buffer = decodeUnsafe(string)
+    if (buffer) return buffer
+
+    throw new Error('Non-base' + BASE + ' character')
+  }
+
+  return {
+    encode: encode,
+    decodeUnsafe: decodeUnsafe,
+    decode: decode
+  }
+}