function __construct($asc)
{
$found = 0;
// normalize line breaks
$asc = str_replace("\r\n", "\n", $asc);
if (strpos($asc, "-----BEGIN PGP PUBLIC KEY BLOCK-----\n") === false) {
throw new Exception("Missing header block in Public Key");
}
if (strpos($asc, "\n\n") === false) {
throw new Exception("Missing body delimiter in Public Key");
}
if (strpos($asc, "\n-----END PGP PUBLIC KEY BLOCK-----") === false) {
throw new Exception("Missing footer block in Public Key");
}
// get rid of everything except the base64 encoded key
$headerbody = explode("\n\n", str_replace("\n-----END PGP PUBLIC KEY BLOCK-----", "", $asc), 2);
$asc = trim($headerbody[1]);
$len = 0;
$s = base64_decode($asc);
$sa = str_split($s);
for ($i = 0; $i < strlen($s);) {
$tag = ord($sa[$i++]);
// echo 'TAG=' . $tag . '/';
if (($tag & 128) == 0) {
break;
}
if ($tag & 64) {
$tag &= 63;
$len = ord($sa[$i++]);
if ($len > 191 && $len < 224) {
$len = ($len - 192 << 8) + ord($sa[$i++]);
} else {
if ($len == 255) {
$oc1 = isset($sa[++$i]) ? $sa[$i] : NULL;
$oc2 = isset($sa[++$i]) ? $sa[$i] : NULL;
$oc3 = isset($sa[++$i]) ? $sa[$i] : NULL;
$oc4 = isset($sa[++$i]) ? $sa[$i] : NULL;
if ($oc1 !== NULL) {
$len = ord($oc1) * pow(2, 24);
} else {
$len = 0 * pow(2, 24);
}
if ($oc2 !== NULL) {
$len += ord($oc2) * pow(2, 16);
} else {
$len += 0 * pow(2, 16);
}
if ($oc3 !== NULL) {
$len += ord($oc3) * pow(2, 8);
} else {
$len += 0 * pow(2, 8);
}
if ($oc4 !== NULL) {
$len += ord($oc4);
} else {
$len += 0;
}
} else {
if ($len > 223 && $len < 255) {
$len = 1 << ($len & 0x1f);
}
}
}
} else {
$len = $tag & 3;
$tag = $tag >> 2 & 15;
if ($len == 0) {
$len = ord($sa[$i++]);
} else {
if ($len == 1) {
$len = (ord($sa[$i++]) << 8) + ord($sa[$i++]);
} else {
if ($len == 2) {
$oc1 = isset($sa[++$i]) ? $sa[$i] : NULL;
$oc2 = isset($sa[++$i]) ? $sa[$i] : NULL;
$oc3 = isset($sa[++$i]) ? $sa[$i] : NULL;
$oc4 = isset($sa[++$i]) ? $sa[$i] : NULL;
if ($oc1 !== NULL) {
$len = ord($oc1) * pow(2, 24);
} else {
$len = 0 * pow(2, 24);
}
if ($oc2 !== NULL) {
$len += ord($oc2) * pow(2, 16);
} else {
$len += 0 * pow(2, 16);
}
if ($oc3 !== NULL) {
$len += ord($oc3) * pow(2, 8);
} else {
$len += 0 * pow(2, 8);
}
if ($oc4 !== NULL) {
$len += ord($oc4);
} else {
$len += 0;
}
// $len = (ord($sa[$i++])* pow(2,24)) + (ord($sa[$i++]) * pow(2,16)) + (0 * pow(2,8)) + 0;
} else {
$len = strlen($s) - 1;
}
}
}
}
// echo $tag . ' ';
if ($tag == 6 || $tag == 14) {
$k = $i;
$version = ord($sa[$i++]);
$found = 1;
$this->version = $version;
$time = (ord($sa[$i++]) << 24) + (ord($sa[$i++]) << 16) + (ord($sa[$i++]) << 8) + ord($sa[$i++]);
if ($version == 2 || $version == 3) {
$valid = ord($sa[$i++]) << 8 + ord($sa[$i++]);
}
$algo = ord($sa[$i++]);
if ($algo == 1 || $algo == 2) {
$m = $i;
$lm = floor((ord($sa[$i]) * 256 + ord($sa[$i + 1]) + 7) / 8);
$i += $lm + 2;
$mod = substr($s, $m, $lm + 2);
$le = floor((ord($sa[$i]) * 256 + ord($sa[$i + 1]) + 7) / 8);
$i += $le + 2;
$this->public_key = base64_encode(substr($s, $m, $lm + $le + 4));
$this->type = "RSA";
if ($version == 3) {
$this->fp = '';
$this->key_id = bin2hex(substr($mod, strlen($mod) - 8, 8));
} else {
if ($version == 4) {
// https://tools.ietf.org/html/rfc4880#section-12
$headerPos = strpos($s, chr(0x4));
// TODO: is this always the correct starting point for the pulic key packet 'version' field?
$delim = chr(0x1) . chr(0x0);
// TODO: is this the correct delimiter for the end of the public key packet?
$delimPos = strpos($s, $delim) + (3 - $headerPos);
// echo "POSITION: $delimPos\n";
// this does not work, tried it with RSA 1024 and RSA 4096 keys generated by GnuPG v2 (2.0.29) on Windows running Apache and PHP 5.6.3
// $pkt = chr(0x99) . chr($delimPos >> 8) . chr($delimPos & 255) . substr($s, $headerPos, $delimPos);
// this is the original signing string which seems to have only worked for key lengths of 1024 or less
$pkt = chr(0x99) . chr($len >> 8) . chr($len & 255) . substr($s, $k, $len);
// use this for now
$fp = sha1($pkt);
$this->fp = $fp;
$this->key_id = substr($fp, strlen($fp) - 16, 16);
// uncomment to debug the start point for the signing string
// for ($ii = 5; $ii > -1; $ii--) {
// $pkt = chr(0x99) . chr($ii >> 8) . chr($ii & 255) . substr($s, $headerPos, $ii);
// $fp = sha1($pkt);
// echo "LENGTH=" . $headerPos . '->' . $ii . " CHR(" . ord(substr($s,$ii, 1)) . ") = " . substr($fp, strlen($fp) - 16, 16) . "\n";
// }
// echo "\n";
// uncomment to debug the end point for the signing string
// for ($ii = strlen($s); $ii > 1; $ii--) {
// $pkt = chr(0x99) . chr($ii >> 8) . chr($ii & 255) . substr($s, $headerPos, $ii);
// $fp = sha1($pkt);
// echo "LENGTH=" . $headerPos . '->' . $ii . " CHR(" . ord(substr($s,$ii, 1)) . ") = " . substr($fp, strlen($fp) - 16, 16) . "\n";
// }
} else {
throw new Exception('GPG Key Version ' . $version . ' is not supported');
}
}
$found = 2;
} else {
if (($algo == 16 || $algo == 20) && $version == 4) {
$m = $i;
$lp = floor((ord($sa[$i]) * 256 + ord($sa[$i + 1]) + 7) / 8);
$i += $lp + 2;
$lg = floor((ord($sa[$i]) * 256 + ord($sa[$i + 1]) + 7) / 8);
$i += $lg + 2;
$ly = floor((ord($sa[$i]) * 256 + ord($sa[$i + 1]) + 7) / 8);
$i += $ly + 2;
$this->public_key = base64_encode(substr($s, $m, $lp + $lg + $ly + 6));
// TODO: should this be adjusted as it was for RSA (above)..?
$pkt = chr(0x99) . chr($len >> 8) . chr($len & 255) . substr($s, $k, $len);
$fp = sha1($pkt);
$this->fp = $fp;
$this->key_id = substr($fp, strlen($fp) - 16, 16);
$this->type = "ELGAMAL";
$found = 3;
} else {
$i = $k + $len;
}
}
} else {
if ($tag == 13) {
$this->user = substr($s, $i, $len);
$i += $len;
} else {
$i += $len;
}
}
}
if ($found < 2) {
throw new Exception("Unable to parse Public Key");
// $this->version = "";
// $this->fp = "";
// $this->key_id = "";
// $this->user = "";
// $this->public_key = "";
}
}
