Subversion Repositories php_utils

<?php

/*

 * ISO/IEC 7816 Application Identifier decoder for PHP

 * Copyright 2022 Daniel Marschall, ViaThinkSoft

 * Version 2022-09-20

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

include_once __DIR__ . '/gmp_supplement.inc.php';

include_once __DIR__ . '/misc_functions.inc.php';

# ---

/*

#test2('A000000051AABBCC'); // International Registration

#test2('B01234567890'); // Illegal AID (RFU)

#test2('D276000098AABBCCDDEEFFAABBCCDDEE'); // National Registration

#test2('F01234567890'); // Unregistered AID

#test('91234FFF999'); // IIN based AID

#test('51234FFF999'); // IIN based AID

test('E828BD080F014E585031'); // ISO E8-OID 1.0.aaaa

test('E80704007F00070304'); // BSI Illegal E8-OID-AID (with DER Length)

test('E80704007F0007030499'); // BSI Illegal E8-OID-AID + PIX (PIX is never used by BSI; it's just for us to test)

test('E829112233'); // Possible other illegal E8-OID

function test2($aid) {

        while ($aid != '') {

                echo test($aid);

                $aid = substr($aid,0,strlen($aid)-1);

        }

}

function test($aid) {

        $out = _decode_aid($aid);

        $max_key_len = 32; // min width of first column

        foreach ($out as $a) {

                if (is_array($a)) {

                        $max_key_len = max($max_key_len,strlen($a[0]));

                }

        }

        foreach ($out as $a) {

                if (is_array($a)) {

                        echo str_pad($a[0],$max_key_len,' ',STR_PAD_RIGHT).'  '.$a[1]."\n";

                } else {

                        echo $a."\n";

                }

        }

        echo "\n";

}

*/

# ---

function _aid_e8_oid_helper($output_oid,$by,$ii,&$ret,$minmax_measure,$min,$max) {

        if ($minmax_measure == 'ARC') {

                if (($min!=-1) && (count($output_oid)<$min)) return true;  // continue

                if (($max!=-1) && (count($output_oid)>$max)) return false; // stop

        } else if ($minmax_measure == 'DER') {

                if (($min!=-1) && ($ii+1<$min)) return true;  // continue

                if (($max!=-1) && ($ii+1>$max)) return false; // stop

        }

        $byy = $by;

        for ($i=0;$i<=$ii;$i++) array_shift($byy);

        $is_iso_standard = (count($output_oid) >= 3) && ($output_oid[0] == '1') && ($output_oid[1] == '0');

        $s_oid = implode('.',$output_oid);

        if ($is_iso_standard) {

                $std_hf = 'Standard ISO/IEC '.$output_oid[2];

                if (isset($output_oid[3])) $std_hf .= "-".$output_oid[3];

        } else {

                $std_hf = "Unknown Standard"; // should not happen

        }

        $pix = implode(':',$byy);

        if ($pix !== '') {

                $ret[] = array($ii+1,"$std_hf (OID $s_oid)",$pix);

        } else {

                $ret[] = array($ii+1,"$std_hf (OID $s_oid)","");

        }

        return true;

}

function _aid_e8_interpretations($pure_der, $minmax_measure='ARC', $min=-1, $max=-1) {

        $ret = array();

        $output_oid = array();

        $pure_der = strtoupper(str_replace(' ','',$pure_der));

        $pure_der = strtoupper(str_replace(':','',$pure_der));

        $by = str_split($pure_der,2);

        // The following part is partially taken from the DER decoder/encoder by Daniel Marschall:

        // https://github.com/danielmarschall/oidconverter/blob/master/php/OidDerConverter.class.phps

        // (Only the DER "value" part, without "type" and "length")

        $part = 2; // DER part 0 (type) and part 1 (length) not present

        $fSub = 0; // Subtract value from next number output. Used when encoding {2 48} and up

        $ll = gmp_init(0);

        $arcBeginning = true;

        foreach ($by as $ii => $pb) {

                $pb = hexdec($pb);

                if ($part == 2) { // First two arcs

                        $first = floor($pb / 40);

                        $second = $pb % 40;

                        if ($first > 2) {

                                $first = 2;

                                $output_oid[] = $first;

                                if (!_aid_e8_oid_helper($output_oid, $by, $ii, $ret, $minmax_measure, $min, $max)) break;

                                $arcBeginning = true;

                                if (($pb & 0x80) != 0) {

                                        // 2.48 and up => 2+ octets

                                        // Output in "part 3"

                                        if ($pb == 0x80) {

                                                throw new Exception("Encoding error. Illegal 0x80 paddings. (See Rec. ITU-T X.690, clause 8.19.2)\n");

                                        } else {

                                                $arcBeginning = false;

                                        }

                                        $ll = gmp_add($ll, ($pb & 0x7F));

                                        $fSub = 80;

                                        $fOK = false;

                                } else {

                                        // 2.0 till 2.47 => 1 octet

                                        $second = $pb - 80;

                                        $output_oid[] = $second;

                                        if (!_aid_e8_oid_helper($output_oid, $by, $ii, $ret, $minmax_measure, $min, $max)) break;

                                        $arcBeginning = true;

                                        $fOK = true;

                                        $ll = gmp_init(0);

                                }

                        } else {

                                // 0.0 till 0.37 => 1 octet

                                // 1.0 till 1.37 => 1 octet

                                $output_oid[] = $first;

                                $output_oid[] = $second;

                                if (!_aid_e8_oid_helper($output_oid, $by, $ii, $ret, $minmax_measure, $min, $max)) break;

                                $arcBeginning = true;

                                $fOK = true;

                                $ll = gmp_init(0);

                        }

                        $part++;

                } else { //else if ($part == 3) { // Arc three and higher

                        if (($pb & 0x80) != 0) {

                                if ($arcBeginning && ($pb == 0x80)) {

                                        throw new Exception("Encoding error. Illegal 0x80 paddings. (See Rec. ITU-T X.690, clause 8.19.2)");

                                } else {

                                        $arcBeginning = false;

                                }

                                $ll = gmp_mul($ll, 0x80);

                                $ll = gmp_add($ll, ($pb & 0x7F));

                                $fOK = false;

                        } else {

                                $fOK = true;

                                $ll = gmp_mul($ll, 0x80);

                                $ll = gmp_add($ll, $pb);

                                $ll = gmp_sub($ll, $fSub);

                                $output_oid[] = gmp_strval($ll, 10);

                                if (!_aid_e8_oid_helper($output_oid, $by, $ii, $ret, $minmax_measure, $min, $max)) break;

                                // Happens only if 0x80 paddings are allowed

                                // $fOK = gmp_cmp($ll, 0) >= 0;

                                $ll = gmp_init(0);

                                $fSub = 0;

                                $arcBeginning = true;

                        }

                }

        }

        return $ret;

}

function _aid_e8_length_usage($aid) {

        // Return true if $aid is most likely E8+Length+OID  (not intended by ISO)

        // Return false if $aid is most likely E8+OID     (defined by ISO for their OID 1.0)

        // Return null if it is ambiguous

        assert(substr($aid,0,2) === 'E8');

        $len = substr($aid,2,2);

        $rest = substr($aid,4);

        $rest_num_bytes = floor(strlen($rest)/2);

        $is_e8_len_oid = false;

        $is_e8_oid = false;

        // There are not enough following bytes, so it cannot be E8+Length+OID. It must be E8+OID

        if ($len > $rest_num_bytes) $is_e8_oid = true;

        // E8 00 ... must be E8+OID, with OID 0.0.xx (recommendation), because Length=0 is not possible

        if ($len == 0) $is_e8_oid = true;

        // E8 01 ... must be E8+Length+OID, because OID 0.1 (question) was never used

        if ($len == 1) $is_e8_len_oid = true;

        // E8 02 refers to OID 0.2 (administration) but could also refer to a length

        //if ($len == 2) return null;

        // E8 03 refers to OID 0.3 (network-operator) but could also refer to a length

        //if ($len == 3) return null;

        // E8 04 refers to OID 0.4 (identified-organization) but could also refer to a length

        //if ($len == 4) return null;

        // E8 05 refers to OID 0.5 (r-recommendation) but could also refer to a length

        //if ($len == 5) return null;

        // E8 06-08 refers to OID 0.6-8, which are not defined, E8+Length+OID

        if (($len >= 6) && ($len <= 8)) $is_e8_len_oid = true;

        // E8 09 refers to OID 0.9, which can be an OID or a Length

        if ($len == 9) {

                // The only legal child of OID 0.9 is OID 0.9.2342 ($len=09, $rest=9226); then it is E8+OID

                // An OID beginning with DER encoding 9226 would be 2.2262, which is very unlikely

                if (substr($rest,0,4) === '9226') {

                        // 09 92 26 is OID 0.9.2342, which is a valid OID (the only valid OID) => valid OID

                        // 92 26 would be OID 2.2262 which is most likely not a valid OID      => invalid Len

                        $is_e8_oid = true;

                } else {

                        // Any other child inside 0.9 except for 2342 is illegal, so it must be length

                        $is_e8_len_oid = true;

                }

        }

        // E8 10-14 refers to OID 0.10-14 which is not defined. Therefore it must be E8+Length+OID

        if (($len >= 10) && ($len <= 14)) $is_e8_len_oid = true;

        // If E8+Length+OID, then Len can max be 14, because E8 takes 1 byte, length takes 1 byte, and AID must be max 16 bytes

        if ($len > 14) $is_e8_oid = true;

        // There is at least one case where the usage of E8+Length+OID is known:

        //    Including the DER Encoding "Length" is not defined by ISO but used illegally

        //    by German BSI (beside the fact that ISO never allowed anyone else to use E8-AIDs outside

        //    of OID arc 1.0),

        //    e.g. AID E80704007F00070302 defined by "BSI TR-03110" was intended to represent 0.4.0.127.0.7.3.2

        //                                "more correct" would have been AID E804007F00070302

        //         AID E80704007F00070304 defined by "BSI TR-03109-2" was intended to represent 0.4.0.127.0.7.3.4

        //                                "more correct" would have been AID E804007F00070304

        if (substr($rest,0,10) == '04007F0007'/*0.4.0.127.0.7*/) $is_e8_len_oid = $len <= 14;

        // Now conclude

        if (!$is_e8_oid &&  $is_e8_len_oid) return true/*E8+Length+OID*/;

        if ( $is_e8_oid && !$is_e8_len_oid) return false/*E8+OID*/;

        return null/*ambiguous*/;

}

function decode_aid($aid,$compact=true) {

        $sout = '';

        if (strtolower(substr($aid,0,2)) == '0x') $aid = substr($aid,2);

        $out = _decode_aid($aid);

        if ($compact) {

                $max_key_len = 0;

                foreach ($out as $a) {

                        if (is_array($a)) {

                                $max_key_len = max($max_key_len,strlen($a[0]));

                        }

                }

        } else {

                $max_key_len = 32; // 16 bytes

        }

        foreach ($out as $a) {

                if (is_array($a)) {

                        $sout .= str_pad($a[0],$max_key_len,' ',STR_PAD_RIGHT).'   '.$a[1]."\n";

                } else {

                        $sout .= $a."\n";

                }

        }

        return $sout;

}

function _is_bcd($num) {

        return preg_match('@^[0-9]+$@', $num, $m);

}

function _decode_aid($aid) {

        // based on https://github.com/thephpleague/iso3166/blob/main/src/ISO3166.php

        // commit 26 July 2022

        // Generated using:

        /*

        $x = new ISO3166();

        $bla = $x->all();

        foreach ($bla as $data) {

                $out[] = "\t\$iso3166['".$data['numeric']."'] = \"".$data['name']."\";\n";

        }

        */

        $iso3166['004'] = "Afghanistan";

        $iso3166['248'] = "Åland Islands";

        $iso3166['008'] = "Albania";

        $iso3166['012'] = "Algeria";

        $iso3166['016'] = "American Samoa";

        $iso3166['020'] = "Andorra";

        $iso3166['024'] = "Angola";

        $iso3166['660'] = "Anguilla";

        $iso3166['010'] = "Antarctica";

        $iso3166['028'] = "Antigua and Barbuda";

        $iso3166['032'] = "Argentina";

        $iso3166['051'] = "Armenia";

        $iso3166['533'] = "Aruba";

        $iso3166['036'] = "Australia";

        $iso3166['040'] = "Austria";

        $iso3166['031'] = "Azerbaijan";

        $iso3166['044'] = "Bahamas";

        $iso3166['048'] = "Bahrain";

        $iso3166['050'] = "Bangladesh";

        $iso3166['052'] = "Barbados";

        $iso3166['112'] = "Belarus";

        $iso3166['056'] = "Belgium";

        $iso3166['084'] = "Belize";

        $iso3166['204'] = "Benin";

        $iso3166['060'] = "Bermuda";

        $iso3166['064'] = "Bhutan";

        $iso3166['068'] = "Bolivia (Plurinational State of)";

        $iso3166['535'] = "Bonaire, Sint Eustatius and Saba";

        $iso3166['070'] = "Bosnia and Herzegovina";

        $iso3166['072'] = "Botswana";

        $iso3166['074'] = "Bouvet Island";

        $iso3166['076'] = "Brazil";

        $iso3166['086'] = "British Indian Ocean Territory";

        $iso3166['096'] = "Brunei Darussalam";

        $iso3166['100'] = "Bulgaria";

        $iso3166['854'] = "Burkina Faso";

        $iso3166['108'] = "Burundi";

        $iso3166['132'] = "Cabo Verde";

        $iso3166['116'] = "Cambodia";

        $iso3166['120'] = "Cameroon";

        $iso3166['124'] = "Canada";

        $iso3166['136'] = "Cayman Islands";

        $iso3166['140'] = "Central African Republic";

        $iso3166['148'] = "Chad";

        $iso3166['152'] = "Chile";

        $iso3166['156'] = "China";

        $iso3166['162'] = "Christmas Island";

        $iso3166['166'] = "Cocos (Keeling) Islands";

        $iso3166['170'] = "Colombia";

        $iso3166['174'] = "Comoros";

        $iso3166['178'] = "Congo";

        $iso3166['180'] = "Congo (Democratic Republic of the)";

        $iso3166['184'] = "Cook Islands";

        $iso3166['188'] = "Costa Rica";

        $iso3166['384'] = "Côte d'Ivoire";

        $iso3166['191'] = "Croatia";

        $iso3166['192'] = "Cuba";

        $iso3166['531'] = "Curaçao";

        $iso3166['196'] = "Cyprus";

        $iso3166['203'] = "Czechia";

        $iso3166['208'] = "Denmark";

        $iso3166['262'] = "Djibouti";

        $iso3166['212'] = "Dominica";

        $iso3166['214'] = "Dominican Republic";

        $iso3166['218'] = "Ecuador";

        $iso3166['818'] = "Egypt";

        $iso3166['222'] = "El Salvador";

        $iso3166['226'] = "Equatorial Guinea";

        $iso3166['232'] = "Eritrea";

        $iso3166['233'] = "Estonia";

        $iso3166['231'] = "Ethiopia";

        $iso3166['748'] = "Eswatini";

        $iso3166['238'] = "Falkland Islands (Malvinas)";

        $iso3166['234'] = "Faroe Islands";

        $iso3166['242'] = "Fiji";

        $iso3166['246'] = "Finland";

        $iso3166['250'] = "France";

        $iso3166['254'] = "French Guiana";

        $iso3166['258'] = "French Polynesia";

        $iso3166['260'] = "French Southern Territories";

        $iso3166['266'] = "Gabon";

        $iso3166['270'] = "Gambia";

        $iso3166['268'] = "Georgia";

        $iso3166['276'] = "Germany";

        $iso3166['288'] = "Ghana";

        $iso3166['292'] = "Gibraltar";

        $iso3166['300'] = "Greece";

        $iso3166['304'] = "Greenland";

        $iso3166['308'] = "Grenada";

        $iso3166['312'] = "Guadeloupe";

        $iso3166['316'] = "Guam";

        $iso3166['320'] = "Guatemala";

        $iso3166['831'] = "Guernsey";

        $iso3166['324'] = "Guinea";

        $iso3166['624'] = "Guinea-Bissau";

        $iso3166['328'] = "Guyana";

        $iso3166['332'] = "Haiti";

        $iso3166['334'] = "Heard Island and McDonald Islands";

        $iso3166['336'] = "Holy See";

        $iso3166['340'] = "Honduras";

        $iso3166['344'] = "Hong Kong";

        $iso3166['348'] = "Hungary";

        $iso3166['352'] = "Iceland";

        $iso3166['356'] = "India";

        $iso3166['360'] = "Indonesia";

        $iso3166['364'] = "Iran (Islamic Republic of)";

        $iso3166['368'] = "Iraq";

        $iso3166['372'] = "Ireland";

        $iso3166['833'] = "Isle of Man";

        $iso3166['376'] = "Israel";

        $iso3166['380'] = "Italy";

        $iso3166['388'] = "Jamaica";

        $iso3166['392'] = "Japan";

        $iso3166['832'] = "Jersey";

        $iso3166['400'] = "Jordan";

        $iso3166['398'] = "Kazakhstan";

        $iso3166['404'] = "Kenya";

        $iso3166['296'] = "Kiribati";

        $iso3166['408'] = "Korea (Democratic People's Republic of)";

        $iso3166['410'] = "Korea (Republic of)";

        $iso3166['414'] = "Kuwait";

        $iso3166['417'] = "Kyrgyzstan";

        $iso3166['418'] = "Lao People's Democratic Republic";

        $iso3166['428'] = "Latvia";

        $iso3166['422'] = "Lebanon";

        $iso3166['426'] = "Lesotho";

        $iso3166['430'] = "Liberia";

        $iso3166['434'] = "Libya";

        $iso3166['438'] = "Liechtenstein";

        $iso3166['440'] = "Lithuania";

        $iso3166['442'] = "Luxembourg";

        $iso3166['446'] = "Macao";

        $iso3166['807'] = "North Macedonia";

        $iso3166['450'] = "Madagascar";

        $iso3166['454'] = "Malawi";

        $iso3166['458'] = "Malaysia";

        $iso3166['462'] = "Maldives";

        $iso3166['466'] = "Mali";

        $iso3166['470'] = "Malta";

        $iso3166['584'] = "Marshall Islands";

        $iso3166['474'] = "Martinique";

        $iso3166['478'] = "Mauritania";

        $iso3166['480'] = "Mauritius";

        $iso3166['175'] = "Mayotte";

        $iso3166['484'] = "Mexico";

        $iso3166['583'] = "Micronesia (Federated States of)";

        $iso3166['498'] = "Moldova (Republic of)";

        $iso3166['492'] = "Monaco";

        $iso3166['496'] = "Mongolia";

        $iso3166['499'] = "Montenegro";

        $iso3166['500'] = "Montserrat";

        $iso3166['504'] = "Morocco";

        $iso3166['508'] = "Mozambique";

        $iso3166['104'] = "Myanmar";

        $iso3166['516'] = "Namibia";

        $iso3166['520'] = "Nauru";

        $iso3166['524'] = "Nepal";

        $iso3166['528'] = "Netherlands";

        $iso3166['540'] = "New Caledonia";

        $iso3166['554'] = "New Zealand";

        $iso3166['558'] = "Nicaragua";

        $iso3166['562'] = "Niger";

        $iso3166['566'] = "Nigeria";

        $iso3166['570'] = "Niue";

        $iso3166['574'] = "Norfolk Island";

        $iso3166['580'] = "Northern Mariana Islands";

        $iso3166['578'] = "Norway";

        $iso3166['512'] = "Oman";

        $iso3166['586'] = "Pakistan";

        $iso3166['585'] = "Palau";

        $iso3166['275'] = "Palestine, State of";

        $iso3166['591'] = "Panama";

        $iso3166['598'] = "Papua New Guinea";

        $iso3166['600'] = "Paraguay";

        $iso3166['604'] = "Peru";

        $iso3166['608'] = "Philippines";

        $iso3166['612'] = "Pitcairn";

        $iso3166['616'] = "Poland";

        $iso3166['620'] = "Portugal";

        $iso3166['630'] = "Puerto Rico";

        $iso3166['634'] = "Qatar";

        $iso3166['638'] = "Réunion";

        $iso3166['642'] = "Romania";

        $iso3166['643'] = "Russian Federation";

        $iso3166['646'] = "Rwanda";

        $iso3166['652'] = "Saint Barthélemy";

        $iso3166['654'] = "Saint Helena, Ascension and Tristan da Cunha";

        $iso3166['659'] = "Saint Kitts and Nevis";

        $iso3166['662'] = "Saint Lucia";

        $iso3166['663'] = "Saint Martin (French part)";

        $iso3166['666'] = "Saint Pierre and Miquelon";

        $iso3166['670'] = "Saint Vincent and the Grenadines";

        $iso3166['882'] = "Samoa";

        $iso3166['674'] = "San Marino";

        $iso3166['678'] = "Sao Tome and Principe";

        $iso3166['682'] = "Saudi Arabia";

        $iso3166['686'] = "Senegal";

        $iso3166['688'] = "Serbia";

        $iso3166['690'] = "Seychelles";

        $iso3166['694'] = "Sierra Leone";

        $iso3166['702'] = "Singapore";

        $iso3166['534'] = "Sint Maarten (Dutch part)";

        $iso3166['703'] = "Slovakia";

        $iso3166['705'] = "Slovenia";

        $iso3166['090'] = "Solomon Islands";

        $iso3166['706'] = "Somalia";

        $iso3166['710'] = "South Africa";

        $iso3166['239'] = "South Georgia and the South Sandwich Islands";

        $iso3166['728'] = "South Sudan";

        $iso3166['724'] = "Spain";

        $iso3166['144'] = "Sri Lanka";

        $iso3166['729'] = "Sudan";

        $iso3166['740'] = "Suriname";

        $iso3166['744'] = "Svalbard and Jan Mayen";

        $iso3166['752'] = "Sweden";

        $iso3166['756'] = "Switzerland";

        $iso3166['760'] = "Syrian Arab Republic";

        $iso3166['158'] = "Taiwan (Province of China)";

        $iso3166['762'] = "Tajikistan";

        $iso3166['834'] = "Tanzania, United Republic of";

        $iso3166['764'] = "Thailand";

        $iso3166['626'] = "Timor-Leste";

        $iso3166['768'] = "Togo";

        $iso3166['772'] = "Tokelau";

        $iso3166['776'] = "Tonga";

        $iso3166['780'] = "Trinidad and Tobago";

        $iso3166['788'] = "Tunisia";

        $iso3166['792'] = "Turkey";

        $iso3166['795'] = "Turkmenistan";

        $iso3166['796'] = "Turks and Caicos Islands";

        $iso3166['798'] = "Tuvalu";

        $iso3166['800'] = "Uganda";

        $iso3166['804'] = "Ukraine";

        $iso3166['784'] = "United Arab Emirates";

        $iso3166['826'] = "United Kingdom of Great Britain and Northern Ireland";

        $iso3166['840'] = "United States of America";

        $iso3166['581'] = "United States Minor Outlying Islands";

        $iso3166['858'] = "Uruguay";

        $iso3166['860'] = "Uzbekistan";

        $iso3166['548'] = "Vanuatu";

        $iso3166['862'] = "Venezuela (Bolivarian Republic of)";

        $iso3166['704'] = "Viet Nam";

        $iso3166['092'] = "Virgin Islands (British)";

        $iso3166['850'] = "Virgin Islands (U.S.)";

        $iso3166['876'] = "Wallis and Futuna";

        $iso3166['732'] = "Western Sahara";

        $iso3166['887'] = "Yemen";

        $iso3166['894'] = "Zambia";

        $iso3166['716'] = "Zimbabwe";

        $out = array();

        $aid = strtoupper($aid);

        $aid = trim($aid);

        $aid = str_replace(' ','',$aid);

        $aid = str_replace(':','',$aid);

        if ($aid == '') {

                $out[] = "INVALID: The AID is empty";

                return $out;

        }

        if (!preg_match('@^[0-9A-F]+$@', $aid, $m)) {

                $out[] = "INVALID: AID has invalid characters. Only A..F and 0..9 are allowed";

                return $out;

        }

        $aid_hf = implode(':',str_split($aid,2));

        if (strlen($aid)%2 == 1) $aid_hf .= '_';

        $out[] = array("$aid", "ISO/IEC 7816 Application Identifier (AID)");

        $out[] = array('', "> $aid_hf <");

        $out[] = array('', c_literal_hexstr($aid));

        if ((strlen($aid) == 32) && (substr($aid,-2) == 'FF')) {

                // Sometimes you read that a 16-byte AID must not end with FF, because it is reserved by ISO.

                // I have only found one official source:

                // ISO/IEC 7816-5 : 1994

                //        Identification cards - Integrated circuit(s) cards with contacts -

                //        Part 5 : Numbering system and registration procedure for application identifiers

                //        https://cdn.standards.iteh.ai/samples/19980/8ff6c7ccc9254fe4b7a8a21c0bf59424/ISO-IEC-7816-5-1994.pdf

                // Quote from clause 5.2:

                //       "The PIX has a free coding. If the AID is 16 bytes long,

                //        then the value 'FF' for the least significant byte is reserved for future use."

                // In the revisions of ISO/IEC 7816, parts of ISO 7816-5 (e.g. the AID categories)

                // have been moved to ISO 7816-4.

                // The "FF" reservation cannot be found in modern versions of 7816-4 or 7816-5.

                /*$out[] = array('',"INVALID: A 16-byte AID must not end with FF. (Reserved by ISO/IEC)");*/

                $out[] = array('',"Note: A 16-byte AID ending with FF was reserved by ISO/IEC 7816-5:1994");

        }

        if (strlen($aid) > 32) {

                $out[] = array('',"INVALID: An AID must not be longer than 16 bytes");

        }

        $category = substr($aid,0,1);

        // Category 0..9

        // RID = ISO/IEC 7812 Issuer Identification Number (IIN 6 or 8 digits)

        // AID = RID + 'FF' + PIX

        $iso7812_category = array();

        $iso7812_category['0'] = 'ISO/TC 68 and other industry assignments';

        $iso7812_category['1'] = 'Airlines';

        $iso7812_category['2'] = 'Airlines, financial and other future industry assignments';

        $iso7812_category['3'] = 'Travel and entertainment';

        $iso7812_category['4'] = 'Banking and financial';

        $iso7812_category['5'] = 'Banking and financial';

        $iso7812_category['6'] = 'Merchandising and banking/financial';

        $iso7812_category['7'] = 'Petroleum and other future industry assignments';

        $iso7812_category['8'] = 'Healthcare, telecommunications and other future industry assignments';

        $iso7812_category['9'] = 'Assignment by national standards bodies';

        foreach ($iso7812_category as $check_cat => $check_cat_name) {

                if ("$category" == "$check_cat") { // comparison as string is important so that "===" works. "==" does not work because 0=='A' for some reason!

                        #$out[] = array($category, "AID based on category $category of ISO/IEC 7812 Issuer Identification Number (IIN)");

                        #$out[] = array('',        "($check_cat = $check_cat_name)");

                        $out[] = array('', "AID based on ISO/IEC 7812 Issuer Identification Number (IIN)");