1 files changed, 175 insertions, 0 deletions
diff --git a/src/Base64.php b/src/Base64.php
new file mode 100644
index 0000000..477e848
--- /dev/null
+++ b/src/Base64.php
@@ -0,0 +1,175 @@
+<?php
+namespace ParagonIE\ConstantTime;
+
+abstract class Base64
+{
+    /**
+     * Encode into Base64
+     *
+     * Base64 character set "[A-Z][a-z][0-9]+/"
+     *
+     * @param string $src
+     * @return string
+     */
+    public static function encode($src)
+    {
+        $dest = '';
+        $srcLen = Core::safeStrlen($src);
+        for ($i = 0; $i + 3 <= $srcLen; $i += 3) {
+            $chunk = \unpack('C*', Core::safeSubstr($src, $i, 3));
+            $b0 = $chunk[1];
+            $b1 = $chunk[2];
+            $b2 = $chunk[3];
+
+            $dest .=
+                self::encode6Bits(               $b0 >> 2       ) .
+                self::encode6Bits((($b0 << 4) | ($b1 >> 4)) & 63) .
+                self::encode6Bits((($b1 << 2) | ($b2 >> 6)) & 63) .
+                self::encode6Bits(  $b2                     & 63);
+        }
+        if ($i < $srcLen) {
+            $chunk = \unpack('C*', Core::safeSubstr($src, $i, $srcLen - $i));
+            $b0 = $chunk[1];
+            if ($i + 1 < $srcLen) {
+                $b1 = $chunk[2];
+                $dest .=
+                    self::encode6Bits(               $b0 >> 2       ) .
+                    self::encode6Bits((($b0 << 4) | ($b1 >> 4)) & 63) .
+                    self::encode6Bits( ($b1 << 2)               & 63) . '=';
+            } else {
+                $dest .=
+                    self::encode6Bits( $b0 >> 2) .
+                    self::encode6Bits(($b0 << 4) & 63) . '==';
+            }
+        }
+        return $dest;
+    }
+
+    /**
+     * decode from base64 into binary
+     *
+     * Base64 character set "./[A-Z][a-z][0-9]"
+     *
+     * @param $src
+     * @return bool|string
+     * @throws \RangeException
+     */
+    public static function decode($src)
+    {
+        // Remove padding
+        $srcLen = Core::safeStrlen($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) {
+            $chunk = \unpack('C*', Core::safeSubstr($src, $i, 4));
+            $c0 = self::decode6Bits($chunk[1]);
+            $c1 = self::decode6Bits($chunk[2]);
+            $c2 = self::decode6Bits($chunk[3]);
+            $c3 = self::decode6Bits($chunk[4]);
+
+            $dest .= \pack(
+                'CCC',
+                ((($c0 << 2) | ($c1 >> 4)) & 0xff),
+                ((($c1 << 4) | ($c2 >> 2)) & 0xff),
+                ((($c2 << 6) |  $c3      ) & 0xff)
+            );
+            $err |= ($c0 | $c1 | $c2 | $c3) >> 8;
+        }
+        if ($i < $srcLen) {
+            $chunk = \unpack('C*', Core::safeSubstr($src, $i, $srcLen - $i));
+            $c0 = self::decode6Bits($chunk[1]);
+            $c1 = self::decode6Bits($chunk[2]);
+
+            if ($i + 2 < $srcLen) {
+                $c2 = self::decode6Bits($chunk[3]);
+                $dest .= \pack(
+                    'CC',
+                    ((($c0 << 2) | ($c1 >> 4)) & 0xff),
+                    ((($c1 << 4) | ($c2 >> 2)) & 0xff)
+                );
+                $err |= ($c0 | $c1 | $c2) >> 8;
+            } elseif($i + 1 < $srcLen) {
+                $dest .= \pack(
+                    'C',
+                    ((($c0 << 2) | ($c1 >> 4)) & 0xff)
+                );
+                $err |= ($c0 | $c1) >> 8;
+            }
+        }
+        if ($err !== 0) {
+            throw new \RangeException(
+                'base64decode() only expects characters in the correct base64 alphabet'
+            );
+        }
+        return $dest;
+    }
+
+    /**
+     *
+     * Base64 character set:
+     * [A-Z]      [a-z]      [0-9]      +     /
+     * 0x41-0x5a, 0x61-0x7a, 0x30-0x39, 0x2b, 0x2f
+     *
+     * @param $src
+     * @return int
+     */
+    protected static function decode6Bits($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 $src
+     * @return string
+     */
+    protected static function encode6Bits($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 \pack('C', $src + $diff);
+    }
+}