Initial commit.

6 files changed, 632 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e0caea8
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+.idea/
+vendor/
\ No newline at end of file
diff --git a/LICENSE.txt b/LICENSE.txt
new file mode 100644
index 0000000..0630242
--- /dev/null
+++ b/LICENSE.txt
@@ -0,0 +1,48 @@
+The MIT License (MIT)
+
+Copyright (c) 2016 Paragon Initiative Enterprises
+
+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.
+
+------------------------------------------------------------------------------
+This library was based on the work of Steve "Sc00bz" Thomas.
+------------------------------------------------------------------------------
+
+The MIT License (MIT)
+
+Copyright (c) 2014 Steve Thomas
+
+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.
+
diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000..ac4ca92
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,40 @@
+{
+  "name": "paragonie/constant_time_encoding",
+  "description": "Constant-time Implementations of RFC 4648 Base-64 Encoding (original by Steve 'Sc00bz' Thomas)",
+  "keywords": [
+    "base64", "encoding", "rfc4648"
+  ],
+  "license": "MIT",
+  "type": "library",
+  "authors": [
+      {
+        "name":     "Paragon Initiative Enterprises",
+        "email":    "security@paragonie.com",
+        "homepage": "https://paragonie.com",
+        "role":     "Maintainer"
+      },
+      {
+        "name":     "Steve 'Sc00bz' Thomas",
+        "email":    "steve@tobtu.com",
+        "homepage": "https://www.tobtu.com",
+        "role":     "Original Developer"
+      }
+  ],
+  "support": {
+    "issues":   "https://github.com/paragonie/constant_time_encoding/issues",
+    "email":    "info@paragonie.com",
+    "source":   "https://github.com/paragonie/constant_time_encoding"
+  },
+  "require": {
+    "php": "^5.5|^7"
+  },
+  "require-dev": {
+    "phpunit/phpunit": "4.*|5.*",
+    "paragonie/random_compat": "^1.1"
+  },
+  "autoload": {
+    "psr-4": {
+      "ParagonIE\\ConstantTime\\": "src/"
+    }
+  }
+}
\ No newline at end of file
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
new file mode 100644
index 0000000..d6e196a
--- /dev/null
+++ b/phpunit.xml.dist
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit backupGlobals="true"
+         backupStaticAttributes="false"
+         bootstrap="vendor/autoload.php"
+         colors="true"
+         convertErrorsToExceptions="true"
+         convertNoticesToExceptions="true"
+         convertWarningsToExceptions="true"
+         processIsolation="false"
+         stopOnError="false"
+         stopOnFailure="false"
+         syntaxCheck="true"
+>
+    <testsuites>
+        <testsuite name="Unit">
+            <directory>tests</directory>
+        </testsuite>
+    </testsuites>
+    <testsuites>
+        <testsuite name="Constant Time Encoding Test Suite">
+            <directory suffix="Test.php">./tests</directory>
+        </testsuite>
+    </testsuites>
+    <filter>
+        <whitelist processUncoveredFilesFromWhitelist="true">
+            <directory suffix=".php">./src</directory>
+        </whitelist>
+    </filter>
+</phpunit>
\ No newline at end of file
diff --git a/src/Encoding.php b/src/Encoding.php
new file mode 100644
index 0000000..3324b34
--- /dev/null
+++ b/src/Encoding.php
@@ -0,0 +1,498 @@
+<?php
+namespace ParagonIE\ConstantTime;
+
+/**
+ *  Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
+ *
+ *  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.
+ */
+class Encoding
+{
+    /**
+     * Encode into Base64
+     *
+     * Base64 character set "[A-Z][a-z][0-9]+/"
+     *
+     * @param $src
+     * @return string
+     */
+    public static function base64Encode($src)
+    {
+        $dest = '';
+        $srcLen = self::safeStrlen($src);
+        for ($i = 0; $i + 3 <= $srcLen; $i += 3) {
+            $b0 = ord($src[$i]);
+            $b1 = ord($src[$i + 1]);
+            $b2 = ord($src[$i + 2]);
+
+            $dest .=
+                self::base64Encode6Bits(               $b0 >> 2       ) .
+                self::base64Encode6Bits((($b0 << 4) | ($b1 >> 4)) & 63) .
+                self::base64Encode6Bits((($b1 << 2) | ($b2 >> 6)) & 63) .
+                self::base64Encode6Bits(  $b2                     & 63);
+        }
+        if ($i < $srcLen) {
+            $b0 = ord($src[$i]);
+            if ($i + 1 < $srcLen) {
+                $b1 = ord($src[$i + 1]);
+                $dest .=
+                    self::base64Encode6Bits(               $b0 >> 2       ) .
+                    self::base64Encode6Bits((($b0 << 4) | ($b1 >> 4)) & 63) .
+                    self::base64Encode6Bits( ($b1 << 2)               & 63) . '=';
+            } else {
+                $dest .=
+                    self::base64Encode6Bits( $b0 >> 2) .
+                    self::base64Encode6Bits(($b0 << 4) & 63) . '==';
+            }
+        }
+        return $dest;
+    }
+
+    /**
+     * Decode from base64 into binary
+     *
+     * Base64 character set "./[A-Z][a-z][0-9]"
+     *
+     * @param $src
+     * @return bool|string
+     */
+    public static function base64Decode($src)
+    {
+        // Remove padding
+        $srcLen = self::safeStrlen($src);
+        if ($srcLen === 0) {
+            return '';
+        }
+        if (($srcLen & 3) === 0) {
+            if ($src[$srcLen - 1] === '=') {
+                $srcLen--;
+                if ($src[$srcLen - 1] === '=') {
+                    $srcLen--;
+                }
+            }
+        }
+        if (($srcLen & 3) === 1) {
+            return false;
+        }
+
+        $err = 0;
+        $dest = '';
+        for ($i = 0; $i + 4 <= $srcLen; $i += 4) {
+            $c0 = self::base64Decode6Bits(ord($src[$i]));
+            $c1 = self::base64Decode6Bits(ord($src[$i + 1]));
+            $c2 = self::base64Decode6Bits(ord($src[$i + 2]));
+            $c3 = self::base64Decode6Bits(ord($src[$i + 3]));
+
+            $dest .=
+                chr((($c0 << 2) | ($c1 >> 4)) & 0xff) .
+                chr((($c1 << 4) | ($c2 >> 2)) & 0xff) .
+                chr((($c2 << 6) |  $c3      ) & 0xff);
+            $err |= ($c0 | $c1 | $c2 | $c3) >> 8;
+        }
+        if ($i < $srcLen) {
+            $c0 = self::base64Decode6Bits(ord($src[$i]));
+            $c1 = self::base64Decode6Bits(ord($src[$i + 1]));
+            if ($i + 2 < $srcLen) {
+                $c2 = self::base64Decode6Bits(ord($src[$i + 2]));
+                $dest .=
+                    chr((($c0 << 2) | ($c1 >> 4)) & 0xff) .
+                    chr((($c1 << 4) | ($c2 >> 2)) & 0xff) .
+                    chr( ($c2 << 6)               & 0xff);
+                $err |= ($c0 | $c1 | $c2) >> 8;
+            } else {
+                $dest .=
+                    chr((($c0 << 2) | ($c1 >> 4)) & 0xff) .
+                    chr( ($c1 << 4)               & 0xff);
+                $err |= ($c0 | $c1) >> 8;
+            }
+        }
+        if ($err !== 0) {
+            return false;
+        }
+        return $dest;
+    }
+
+    /**
+     * Encode into Base64
+     *
+     * Base64 character set "./[A-Z][a-z][0-9]"
+     * @param $src
+     * @return string
+     */
+    public static function base64EncodeDotSlash($src)
+    {
+        $dest = '';
+        $srcLen = self::safeStrlen($src);
+        for ($i = 0; $i + 3 <= $srcLen; $i += 3) {
+            $b0 = ord($src[$i]);
+            $b1 = ord($src[$i + 1]);
+            $b2 = ord($src[$i + 2]);
+
+            $dest .=
+                self::base64Encode6BitsDotSlash(               $b0 >> 2       ) .
+                self::base64Encode6BitsDotSlash((($b0 << 4) | ($b1 >> 4)) & 63) .
+                self::base64Encode6BitsDotSlash((($b1 << 2) | ($b2 >> 6)) & 63) .
+                self::base64Encode6BitsDotSlash(  $b2                     & 63);
+        }
+        if ($i < $srcLen) {
+            $b0 = ord($src[$i]);
+            if ($i + 1 < $srcLen) {
+                $b1 = ord($src[$i + 1]);
+                $dest .=
+                    self::base64Encode6BitsDotSlash(               $b0 >> 2       ) .
+                    self::base64Encode6BitsDotSlash((($b0 << 4) | ($b1 >> 4)) & 63) .
+                    self::base64Encode6BitsDotSlash( ($b1 << 2)               & 63) . '=';
+            } else {
+                $dest .=
+                    self::base64Encode6BitsDotSlash( $b0 >> 2) .
+                    self::base64Encode6BitsDotSlash(($b0 << 4) & 63) . '==';
+            }
+        }
+        return $dest;
+    }
+
+    /**
+     * Decode from base64 to raw binary
+     *
+     * Base64 character set "./[A-Z][a-z][0-9]"
+     *
+     * @param $src
+     * @return bool|string
+     */
+    public static function base64DecodeDotSlash($src)
+    {
+        // Remove padding
+        $srcLen = self::safeStrlen($src);
+        if ($srcLen === 0) {
+            return '';
+        }
+        if (($srcLen & 3) === 0) {
+            if ($src[$srcLen - 1] === '=') {
+                $srcLen--;
+                if ($src[$srcLen - 1] === '=') {
+                    $srcLen--;
+                }
+            }
+        }
+        if (($srcLen & 3) == 1) {
+            return false;
+        }
+
+        $err = 0;
+        $dest = '';
+        for ($i = 0; $i + 4 <= $srcLen; $i += 4) {
+            $c0 = self::base64Decode6BitsDotSlash(ord($src[$i]));
+            $c1 = self::base64Decode6BitsDotSlash(ord($src[$i + 1]));
+            $c2 = self::base64Decode6BitsDotSlash(ord($src[$i + 2]));
+            $c3 = self::base64Decode6BitsDotSlash(ord($src[$i + 3]));
+
+            $dest .=
+                chr((($c0 << 2) | ($c1 >> 4)) & 0xff) .
+                chr((($c1 << 4) | ($c2 >> 2)) & 0xff) .
+                chr((($c2 << 6) |  $c3      ) & 0xff);
+            $err |= ($c0 | $c1 | $c2 | $c3) >> 8;
+        }
+        if ($i < $srcLen) {
+            $c0 = self::base64Decode6BitsDotSlash(ord($src[$i]));
+            $c1 = self::base64Decode6BitsDotSlash(ord($src[$i + 1]));
+            if ($i + 2 < $srcLen) {
+                $c2 = self::base64Decode6BitsDotSlash(ord($src[$i + 2]));
+                $dest .=
+                    chr((($c0 << 2) | ($c1 >> 4)) & 0xff) .
+                    chr((($c1 << 4) | ($c2 >> 2)) & 0xff) .
+                    chr( ($c2 << 6)               & 0xff);
+                $err |= ($c0 | $c1 | $c2) >> 8;
+            } else {
+                $dest .=
+                    chr((($c0 << 2) | ($c1 >> 4)) & 0xff) .
+                    chr( ($c1 << 4)               & 0xff);
+                $err |= ($c0 | $c1) >> 8;
+            }
+        }
+        if ($err !== 0) {
+            return false;
+        }
+        return $dest;
+    }
+
+    /**
+     * Encode into Base64
+     *
+     * Base64 character set "[.-9][A-Z][a-z]" or "./[0-9][A-Z][a-z]"
+     * @param $src
+     * @return string
+     */
+    public static function base64EncodeDotSlashOrdered($src)
+    {
+        $dest = '';
+        $srcLen = self::safeStrlen($src);
+        for ($i = 0; $i + 3 <= $srcLen; $i += 3) {
+            $b0 = ord($src[$i]);
+            $b1 = ord($src[$i + 1]);
+            $b2 = ord($src[$i + 2]);
+
+            $dest .=
+                self::base64Encode6BitsDotSlashOrdered(               $b0 >> 2       ) .
+                self::base64Encode6BitsDotSlashOrdered((($b0 << 4) | ($b1 >> 4)) & 63) .
+                self::base64Encode6BitsDotSlashOrdered((($b1 << 2) | ($b2 >> 6)) & 63) .
+                self::base64Encode6BitsDotSlashOrdered(  $b2                     & 63);
+        }
+        if ($i < $srcLen) {
+            $b0 = ord($src[$i]);
+            if ($i + 1 < $srcLen) {
+                $b1 = ord($src[$i + 1]);
+                $dest .=
+                    self::base64Encode6BitsDotSlashOrdered(               $b0 >> 2       ) .
+                    self::base64Encode6BitsDotSlashOrdered((($b0 << 4) | ($b1 >> 4)) & 63) .
+                    self::base64Encode6BitsDotSlashOrdered( ($b1 << 2)               & 63) . '=';
+            } else {
+                $dest .=
+                    self::base64Encode6BitsDotSlashOrdered( $b0 >> 2) .
+                    self::base64Encode6BitsDotSlashOrdered(($b0 << 4) & 63) . '==';
+            }
+        }
+        return $dest;
+    }
+
+
+    /**
+     * Decode from base64 to raw binary
+     *
+     * Base64 character set "[.-9][A-Z][a-z]" or "./[0-9][A-Z][a-z]"
+     *
+     * @param $src
+     * @return bool|string
+     */
+    public static function base64DecodeDotSlashOrdered($src)
+    {
+        // Remove padding
+        $srcLen = self::safeStrlen($src);
+        if ($srcLen === 0) {
+            return '';
+        }
+        if (($srcLen & 3) === 0) {
+            if ($src[$srcLen - 1] === '=') {
+                $srcLen--;
+                if ($src[$srcLen - 1] === '=') {
+                    $srcLen--;
+                }
+            }
+        }
+        if (($srcLen & 3) == 1) {
+            return false;
+        }
+
+        $err = 0;
+        $dest = '';
+        for ($i = 0; $i + 4 <= $srcLen; $i += 4) {
+            $c0 = self::base64Decode6BitsDotSlashOrdered(ord($src[$i]));
+            $c1 = self::base64Decode6BitsDotSlashOrdered(ord($src[$i + 1]));
+            $c2 = self::base64Decode6BitsDotSlashOrdered(ord($src[$i + 2]));
+            $c3 = self::base64Decode6BitsDotSlashOrdered(ord($src[$i + 3]));
+
+            $dest .=
+                chr((($c0 << 2) | ($c1 >> 4)) & 0xff) .
+                chr((($c1 << 4) | ($c2 >> 2)) & 0xff) .
+                chr((($c2 << 6) |  $c3      ) & 0xff);
+            $err |= ($c0 | $c1 | $c2 | $c3) >> 8;
+        }
+        if ($i < $srcLen) {
+            $c0 = self::base64Decode6BitsDotSlashOrdered(ord($src[$i]));
+            $c1 = self::base64Decode6BitsDotSlashOrdered(ord($src[$i + 1]));
+            if ($i + 2 < $srcLen) {
+                $c2 = self::base64Decode6BitsDotSlashOrdered(ord($src[$i + 2]));
+                $dest .=
+                    chr((($c0 << 2) | ($c1 >> 4)) & 0xff) .
+                    chr((($c1 << 4) | ($c2 >> 2)) & 0xff) .
+                    chr( ($c2 << 6)               & 0xff);
+                $err |= ($c0 | $c1 | $c2) >> 8;
+            } else {
+                $dest .=
+                    chr((($c0 << 2) | ($c1 >> 4)) & 0xff) .
+                    chr( ($c1 << 4)               & 0xff);
+                $err |= ($c0 | $c1) >> 8;
+            }
+        }
+        if ($err !== 0) {
+            return false;
+        }
+        return $dest;
+    }
+
+    /**
+     *
+     * Base64 character set:
+     * [A-Z]      [a-z]      [0-9]      +     /
+     * 0x41-0x5a, 0x61-0x7a, 0x30-0x39, 0x2b, 0x2f
+     *
+     * @param $src
+     * @return int
+     */
+    protected static function base64Decode6Bits($src)
+    {
+        $ret = -1;
+
+        // if ($src > 0x40 && $src < 0x5b) $ret += $src - 0x41 + 1; // -64
+        $ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 64);
+
+        // if ($src > 0x60 && $src < 0x7b) $ret += $src - 0x61 + 26 + 1; // -70
+        $ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 70);
+
+        // if ($src > 0x2f && $src < 0x3a) $ret += $src - 0x30 + 52 + 1; // 5
+        $ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 5);
+
+        // if ($src == 0x2b) $ret += 62 + 1;
+        $ret += (((0x2a - $src) & ($src - 0x2c)) >> 8) & 63;
+
+        // if ($src == 0x2f) ret += 63 + 1;
+        $ret += (((0x2e - $src) & ($src - 0x30)) >> 8) & 64;
+
+        return $ret;
+    }
+
+    /**
+     * @param $src
+     * @return string
+     */
+    protected static function base64Encode6Bits($src)
+    {
+        $diff = 0x41;
+
+        // if ($src > 25) $diff += 0x61 - 0x41 - 26; // 6
+        $diff += ((25 - $src) >> 8) & 6;
+
+        // if ($src > 51) $diff += 0x30 - 0x61 - 26; // -75
+        $diff -= ((51 - $src) >> 8) & 75;
+
+        // if ($src > 61) $diff += 0x2b - 0x30 - 10; // -15
+        $diff -= ((61 - $src) >> 8) & 15;
+
+        // if ($src > 62) $diff += 0x2f - 0x2b - 1; // 3
+        $diff += ((62 - $src) >> 8) & 3;
+
+        return chr($src + $diff);
+    }
+
+    /**
+     * Base64 character set:
+     * ./         [A-Z]      [a-z]     [0-9]
+     * 0x2e-0x2f, 0x41-0x5a, 0x61-0x7a, 0x30-0x39
+     *
+     * @param $src
+     * @return int
+     */
+    protected static function base64Decode6BitsDotSlash($src)
+    {
+        $ret = -1;
+
+        // if ($src > 0x2d && $src < 0x30) ret += $src - 0x2e + 1; // -45
+        $ret += (((0x2d - $src) & ($src - 0x30)) >> 8) & ($src - 45);
+
+        // if ($src > 0x40 && $src < 0x5b) ret += $src - 0x41 + 2 + 1; // -62
+        $ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 62);
+
+        // if ($src > 0x60 && $src < 0x7b) ret += $src - 0x61 + 28 + 1; // -68
+        $ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 68);
+
+        // if ($src > 0x2f && $src < 0x3a) ret += $src - 0x30 + 54 + 1; // 7
+        $ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 7);
+
+        return $ret;
+    }
+
+    /**
+     * @param $src
+     * @return string
+     */
+    protected static function base64Encode6BitsDotSlash($src)
+    {
+        $src += 0x2e;
+
+        // if ($src > 0x2f) $src += 0x41 - 0x30; // 17
+        $src += ((0x2f - $src) >> 8) & 17;
+
+        // if ($src > 0x5a) $src += 0x61 - 0x5b; // 6
+        $src += ((0x5a - $src) >> 8) & 6;
+
+        // if ($src > 0x7a) $src += 0x30 - 0x7b; // -75
+        $src -= ((0x7a - $src) >> 8) & 75;
+
+        return chr($src);
+    }
+
+    /**
+     * Base64 character set:
+     * [.-9]      [A-Z]      [a-z]
+     * 0x2e-0x39, 0x41-0x5a, 0x61-0x7a
+     * @param $src
+     * @return int
+     */
+    protected static function base64Decode6BitsDotSlashOrdered($src)
+    {
+        $ret = -1;
+
+        // if ($src > 0x2d && $src < 0x3a) ret += $src - 0x2e + 1; // -45
+        $ret += (((0x2d - $src) & ($src - 0x3a)) >> 8) & ($src - 45);
+
+        // if ($src > 0x40 && $src < 0x5b) ret += $src - 0x41 + 12 + 1; // -52
+        $ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 52);
+
+        // if ($src > 0x60 && $src < 0x7b) ret += $src - 0x61 + 38 + 1; // -58
+        $ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 58);
+
+        return $ret;
+    }
+
+    /**
+     * Base64 character set:
+     * [.-9]      [A-Z]      [a-z]
+     * 0x2e-0x39, 0x41-0x5a, 0x61-0x7a
+     * @param $src
+     * @return string
+     */
+    protected static function base64Encode6BitsDotSlashOrdered($src)
+    {
+        $src += 0x2e;
+
+        // if ($src > 0x39) $src += 0x41 - 0x3a; // 7
+        $src += ((0x39 - $src) >> 8) & 7;
+
+        // if ($src > 0x5a) $src += 0x61 - 0x5b; // 6
+        $src += ((0x5a - $src) >> 8) & 6;
+
+        return chr($src);
+    }
+
+    /**
+     * Safe string length
+     *
+     * @ref mbstring.func_overload
+     *
+     * @param string $str
+     * @return int
+     */
+    public static function safeStrlen($str)
+    {
+        if (\function_exists('mb_strlen')) {
+            return \mb_strlen($str, '8bit');
+        } else {
+            return \strlen($str);
+        }
+    }
+}
diff --git a/tests/EncodingTest.php b/tests/EncodingTest.php
new file mode 100644
index 0000000..556c5a5
--- /dev/null
+++ b/tests/EncodingTest.php
@@ -0,0 +1,15 @@
+<?php
+use \ParagonIE\ConstantTime\Encoding;
+
+class EncodingTest extends PHPUnit_Framework_TestCase
+{
+    public function testBasicEncoding()
+    {
+        $str = random_bytes(33);
+        $enc = base64_encode($str);
+        $this->assertEquals(
+            $str,
+            Encoding::base64Decode($enc)
+        );
+    }
+}
\ No newline at end of file