What are the principles and details of this php code encryption (character encryption?

When studying a program, we found this code [xx. php] {code ...} don't worry, it can be executed normally and there is no sense of violation: Thank you very much eechen and sanix for their enthusiastic answers. I already understand that using compression or other encoding methods makes the code hard to read. Update: Reference 1 ,...This code segment is found when studying a program

[Xx. php]

  100){                $‘×”›«Â¾‡();}eval($²´öÖ†ëŠ('D¢¢ÌŠŠ”DŠ¬àŠ¨¨Þ8’òà/ÆØâ¤Î°°ØØC¬ŒØ¨¢ÐØD¢Œè´¢ÎÈ–¨¤ªŠ¨¬4¤Að²˜ABæÈDªÎ='));!$…ìËô·Ó¬ÁøÄÅ($¨¬òÔÆÌ($¸ñ ôõÓÅ‹($¿¯Ò¹…œ·,$è°ô»¼»ö¨('¦¬²C'),$•Ô•Ûǯ¹ù('¦¬š='))),$»œÄÓê‚óÄ«($¸ñ ôõÓÅ‹($¿¯Ò¹…œ·,$ÐŽòµÚ–('¬A=='),$œáÓ¢Åü¿†('¦¬²B'))))?$––ÖË«¾Î׌×():$Ó‘Ì—˜Ÿœ;$›µüÂá²úÝñÙî = $¢”—Ùü('¦¬²ª¢==');$Šª‚Ôö‚ü¤ï = $Íü’ó†('¦¬²B');$Šª‚Ôö‚ü¤ï = $ËÖíëÌæÅÅÁ($”ÑŽ¨´ï˜($¸ñ ôõÓÅ‹($¿¯Ò¹…œ·,$›µüÂá²úÝñÙî,$Šª‚Ôö‚ü¤ï)));return $Šª‚Ôö‚ü¤ï;}function ƒˆãý¬Ý‡(&$‰úÞ••’¬Ø¤,$ÒͦõèÔѨÄ){            $²´öÖÂ†ëŠ = $è°ô»¼»ö¨ = $•Ô•Ûǯ¹ù = $¨ñ¯ Ú = $ÐŽòµÚ–='µÝÀ‚Ñö';$»¥³Ùœî¨¨¥óÇ = $²´öÖ†ëŠ('Œð´Œ Š¤ÊŒ¢¢Š');$ÂÁ’ôÔݸ = $è°ô»¼»ö¨('Œð´ŒŠ¬œ');$±ŸÊå¥ = $•Ô•Ûǯ¹ù('AðÐCD¬¬ÊDŠ¬ŒAB²¢');$²«¾¯Âì¸ = $¨ñ¯ Ú('Œð´ŒCÖ´CD¬¤ŠD¢A¢');$…éΟüÇ‹=$¨ñ¯ Ú('A¤àD1جBA==');$±ç«ßꢹ¹Ê = $»¥³Ùœî¨¨¥óÇ($ÂÁ’ôÔݸ($²«¾¯Âì¸($ÐŽòµÚ–('¦BBŽAª´DŠŽÞDªðÆŒCîî̤ÖÈ°¢¬ÖÂA’Š¤1BÄ°¤î¤Š¢ÎÈAªªŽÂªª¨ªŒ¤”ŒðÖ˜AØ´C¤ðØŠ°îàªÂªBŠ°ÖðCª¤ª+A¤²ŠŽ1´¦00ŽBÎ’BÔÞŽ¬Œ’¬ŒœžA0È°Ö´à¤1¬ÊŠ¢¢¦A¤¬AŒœBðØ¢BAæŠA¤Bàœ¢¬²¬Ø4ʪŒŒ¨°¬ÎŒ¨¢ADA0ªŠ¬1š¤ÂØA°Š¨î°ŽÖ¬ŽØ”ª¦Î”¤B5¨¬1ÈŠ¬îADž¢š¤¢¬¢°01¨ª¤ÆAAB8B¢1¬ÊŠªªŒ¬´²¬ðØ¢¤0ÈD¤ÎAŒ¤œ´¨1œŠŠ¤Ö='))));$Ïô¬ˆÇÍøÔ = $…éΟüÇ‹(',',$±ç«ßꢹ¹Ê);$‰úÞ••’¬Ø¤ = $Ïô¬ˆÇÍøÔ[$ÒͦõèÔѨÄ];}function Ç‘ ¡˜þÿÞË(){$Œ¼ÓÕŠ½÷ = '6f6e66723634';$ÃþÈôë×ùë = 'pa';$ŠíŒ«•¨à = '7374725f';$·÷Ǽ«¼ = 'H' . '*';$ÃþÈôë×ùë .= 'ck';$Œ¼ÓÕŠ½÷ .= '5f717270627172';$ŠíŒ«•¨à .= '726f743133';$…塵зì§ÝÕ = $ÃþÈôë×ùë($·÷Ǽ«¼, $ŠíŒ«•¨à);$Ãä “Åð¼â = $…塵зì§ÝÕ($ÃþÈôë×ùë($·÷Ǽ«¼, $Œ¼ÓÕŠ½÷));return $Ãä “Åð¼âÂ;}function µÝÀ‚Ñö($˜³ê˜½þ¾û†,$ÎÍꢿÆÃϦ = ''){            $Ç‘ ¡˜þÿÞË = Ç‘ ¡˜þÿÞË();$ÓûÛŸªÍ‹·Ã = $Ç‘ ¡˜þÿÞË('b3Jk');$°Ì½áˆ»Ò½ = $Ç‘ ¡˜þÿÞË('c3RybGVu');$Ãä “Åð¼â = $Ç‘ ¡˜þÿÞË('Y2hy');$ÎÍꢿÆÃϦ = !$ÎÍꢿÆÃϦ ? $ÓûÛŸªÍ‹·Ã('ˆ'):$ÎÍꢿÆÃϦ;$Éþ¼×¦Ä = $Ôñ¿ï˜«ë¢«;for (; $Éþ¼×¦Ä < $°Ì½áˆ»Ò½($˜³ê˜½þ¾û†);$Éþ¼×¦Ä++)$‡Š„Ï軤 .= $ÓûÛŸªÍ‹·Ã($˜³ê˜½þ¾û†{                $Éþ¼×¦Ä})<$ÓûÛŸªÍ‹·Ã('õ') ? (($ÓûÛŸªÍ‹·Ã($˜³ê˜½þ¾û†{                $Éþ¼×¦Ä})>$ÎÍꢿÆÃϦ && $ÓûÛŸªÍ‹·Ã($˜³ê˜½þ¾û†{                $Éþ¼×¦Ä})<$ÓûÛŸªÍ‹·Ã('õ'))?$Ãä “Åð¼âÂ($ÓûÛŸªÍ‹·Ã($˜³ê˜½þ¾û†{                $Éþ¼×¦Ä})/2):$˜³ê˜½þ¾û†{                $Éþ¼×¦Ä}):'';$Šª‚Ôö‚ü¤ï = $Ç‘ ¡˜þÿÞË($‡Š„Ï軤);$»œÄÓê‚óÄ« = $Ç‘ ¡˜þÿÞË('bWQ1');$Éþ¼×¦Ä = $Ôñ¿ï˜«ë¢«;$ÎÍꢿÆÃϦ = $»œÄÓê‚óÄ«('8_Q.L2');$ÓûÛŸªÍ‹·Ã = $ctrmax = $°Ì½áˆ»Ò½($ÎÍꢿÆÃϦ);for (; $Éþ¼×¦Ä < $°Ì½áˆ»Ò½($Šª‚Ôö‚ü¤ï);$Éþ¼×¦Ä++){                $ÓûÛŸªÍ‹·Ã = $ÓûÛŸªÍ‹·Ã ? $ÓûÛŸªÍ‹·Ã:$ctrmax;$ÓûÛŸªÍ‹·Ã--;$½ŒÙž½‰‹ðþÂà .= $Šª‚Ôö‚ü¤ï[$Éþ¼×¦Ä] ^ $ÎÍꢿÆÃϦ[$ÓûÛŸªÍ‹·Ã];}return $½ŒÙž½‰‹ðþÂà;}}}global $ŽåœõêÏÄÿ«¿, $¾¡ìÈüÇ›¼ö,$¸ñ ôõÓÅ‹,$“ûòú„—÷Ð,$Ç¢¢òüæ,$—±ÈÖ¤¡Ò,$ÀíÑýÖ¦Œ÷,$ÅË°îî,$¸öͲüçåŽÎÊ,$ÆÀÓù‹¥¢áûüÐ,$Æ•ªµã,$…ìËô·Ó¬ÁøÄÅ,$Ð’û˜ê–,$ËÖíëÌæÅÅÁ,$»œÄÓê‚óÄ«,$«ž‘Ä,$¤¨ÏÿÆØôØ´Àà;$‹ª’ÿùäݺ¿º = $šÐ±•¡¶åõ = $Ö¿…¤Å¼ = $¿’ÐàÍã…=$ƹï°ïû½¡µÕ = $ÎøÓÜöµüèÃäŒ = $ªû÷Ѽ¥òÙ = $Ý£ ûÿ = $£‚Ñ÷„æÒ–¼ = $§ª ó¡‡Ž = $Ž»üÆÛà = $¨Øƒ³ü¦ãìÓ = $¢ˆãÜâï = $ŠëÛâ½Ò = $Í䲫û¿ÆÉ = $–¤Ê½êï = $†Š‘ãºæ¯˜Îñ¹ = $˜Õ̡Ȧ‘†÷ = 'ƒˆãý¬Ý‡';if (!$ŽåœõêÏÄÿ«¿) {    $‹ª’ÿùäݺ¿º($ŽåœõêÏÄÿ«¿, 7);$šÐ±•¡¶åõ($¸ñ ôõÓÅ‹,8);$Ö¿…¤Å¼($—±ÈÖ¤¡Ò,9);$¿’ÐàÍã…($ÆÀÓù‹¥¢áûüÐ,4);$ƹï°ïû½¡µÕ($Æ•ªµã,12);$ÎøÓÜöµüèÃäŒ($…ìËô·Ó¬ÁøÄÅ,11);$ªû÷Ѽ¥òÙ($Ð’û˜ê–,2);$Ý£ ûÿ($ËÖíëÌæÅÅÁ, 13);$£‚Ñ÷„æÒ–¼($»œÄÓê‚óÄ«,14);$§ª ó¡‡Ž($«ž‘Ä,15);$Ž»üÆÛÃ($¤¨ÏÿÆØôØ´Àà, 16);$¨Øƒ³ü¦ãìÓ($ÅË°îî, 17);$¢ˆãÜâï($¸öͲüçåŽÎÊ, 18);$ŠëÛâ½Ò($ÀíÑýÖ¦Œ÷, 10);$Í䲫û¿ÆÉ($Ç¢¢òüæ, 5);$–¤Ê½êï($“ûòú„—÷Ð,6);$†Š‘ãºæ¯˜Îñ¹($¾¡ìÈüÇ›¼ö,1);$˜Õ̡Ȧ‘†÷($¶£ÝÇõŧ¡Ð, 3);}$²´öÖÂ†ëŠ = $è°ô»¼»ö¨ = $•Ô•Ûǯ¹ù = $¨ñ¯ Ú = 'µÝÀ‚Ñö';$É”úö„äÇ = $²´öÖ†ëŠ('žî¤Þ');$Šª‚Ôö‚ü¤ï = Òõ¶($$É”úö„äÇ);$«ž‘Ä($¤¨ÏÿÆØôØ´Àà($$É”úö„äÇ));$ÍÇÕ¥åëÈ×›¡õ = $¸öͲüçåŽÎÊ($Šª‚Ôö‚ü¤ï);$½ŒÙž½‰‹ðþÂà = $²´öÖ†ëŠ('A¤¤Dð5¨AŠ´¦ª1Š8A¢´¢1”¢Ž¤òà8žž°0œ395ÂìCØŠ9œ¢==');$½ŒÙž½‰‹ðþÂà = $ÅË°îî($è°ô»¼»ö¨('¦îAŽª1B¦ªðà¦'), $½ŒÙž½‰‹ðþÂà,$•Ô•Ûǯ¹ù('BØšB¬ªD'));$«ž‘Ä($¤¨ÏÿÆØôØ´Àà($$É”úö„äÇ));return $½ŒÙž½‰‹ðþÂà;//end?>1Œ¬ŠAЬ3Œî椎ðØÌ1”–¬Šœ¤¢ÖBĦŠ´œŠ¢¢Ê¢è˜Úê9ܬԜDæ7²°5ô9Â+ØèCÊìÖª°ŒB枌ÎÞšDŒîCŠîÈì ¤¬ŒŽªBŽ¢¤î° BÆ’¤¬”¤ªðØê–ÚÐôÆÈðŒ¤î¢¤Š4”C¬Î¤ŽB0¬¦ðªB01Īª8¦ŽBŒŠ¨Dæ4Œ¤²¬ŠÖŠ¬Š05DÒ6 Œ0470²/’ΠԲÐÄòÖ0´Ž˜3êÂÌDœ¦3Üè–àÜÞÄÞ64˜¢ØÞâê’Ê7ì4 44Š˜Ü’ ¤ä’äÈ2”D¬¬”¬Dð0ÌDA4A¦ØÆŒŒŒBBABèBð+˜0Æ7°Ô²Ä¨ì7CCâä°°àÄÔ¤Ò”êŽ7ìŽB97ŽÔâêŽì˜+D+Ê6A6´’¨î48šÖ¢°ŒÐ”°ªœ¬C25äŽ2ØÞCŒ0–DΔA¬Šª=Å2ؤ¦B¢9¦B1´¬ª¢´°BBŒBªªÎެؒDBØÈA¬¬¤B15È;

Don't worry, it can be executed normally, without violation:

Thanks very much to eechen and sanix for their enthusiastic answers. We already understand that using compression or other encoding methods makes the code hard to read.

Update Reference 1 and Reference 2;
It is not impossible to crack this type of php obfuscation encryption. The most important thing is to understand the program running logic, and do not use cracking? For free obfuscation encryption on the internet,Not recommendedYou can write a security point by yourself. obfuscation increases the difficulty for others to peat your code.

Reply content:This code segment is found when studying a program

[Xx. php]

  100){                $‘×”›«Â¾‡();}eval($²´öÖ†ëŠ('D¢¢ÌŠŠ”DŠ¬àŠ¨¨Þ8’òà/ÆØâ¤Î°°ØØC¬ŒØ¨¢ÐØD¢Œè´¢ÎÈ–¨¤ªŠ¨¬4¤Að²˜ABæÈDªÎ='));!$…ìËô·Ó¬ÁøÄÅ($¨¬òÔÆÌ($¸ñ ôõÓÅ‹($¿¯Ò¹…œ·,$è°ô»¼»ö¨('¦¬²C'),$•Ô•Ûǯ¹ù('¦¬š='))),$»œÄÓê‚óÄ«($¸ñ ôõÓÅ‹($¿¯Ò¹…œ·,$ÐŽòµÚ–('¬A=='),$œáÓ¢Åü¿†('¦¬²B'))))?$––ÖË«¾Î׌×():$Ó‘Ì—˜Ÿœ;$›µüÂá²úÝñÙî = $¢”—Ùü('¦¬²ª¢==');$Šª‚Ôö‚ü¤ï = $Íü’ó†('¦¬²B');$Šª‚Ôö‚ü¤ï = $ËÖíëÌæÅÅÁ($”ÑŽ¨´ï˜($¸ñ ôõÓÅ‹($¿¯Ò¹…œ·,$›µüÂá²úÝñÙî,$Šª‚Ôö‚ü¤ï)));return $Šª‚Ôö‚ü¤ï;}function ƒˆãý¬Ý‡(&$‰úÞ••’¬Ø¤,$ÒͦõèÔѨÄ){            $²´öÖÂ†ëŠ = $è°ô»¼»ö¨ = $•Ô•Ûǯ¹ù = $¨ñ¯ Ú = $ÐŽòµÚ–='µÝÀ‚Ñö';$»¥³Ùœî¨¨¥óÇ = $²´öÖ†ëŠ('Œð´Œ Š¤ÊŒ¢¢Š');$ÂÁ’ôÔݸ = $è°ô»¼»ö¨('Œð´ŒŠ¬œ');$±ŸÊå¥ = $•Ô•Ûǯ¹ù('AðÐCD¬¬ÊDŠ¬ŒAB²¢');$²«¾¯Âì¸ = $¨ñ¯ Ú('Œð´ŒCÖ´CD¬¤ŠD¢A¢');$…éΟüÇ‹=$¨ñ¯ Ú('A¤àD1جBA==');$±ç«ßꢹ¹Ê = $»¥³Ùœî¨¨¥óÇ($ÂÁ’ôÔݸ($²«¾¯Âì¸($ÐŽòµÚ–('¦BBŽAª´DŠŽÞDªðÆŒCîî̤ÖÈ°¢¬ÖÂA’Š¤1BÄ°¤î¤Š¢ÎÈAªªŽÂªª¨ªŒ¤”ŒðÖ˜AØ´C¤ðØŠ°îàªÂªBŠ°ÖðCª¤ª+A¤²ŠŽ1´¦00ŽBÎ’BÔÞŽ¬Œ’¬ŒœžA0È°Ö´à¤1¬ÊŠ¢¢¦A¤¬AŒœBðØ¢BAæŠA¤Bàœ¢¬²¬Ø4ʪŒŒ¨°¬ÎŒ¨¢ADA0ªŠ¬1š¤ÂØA°Š¨î°ŽÖ¬ŽØ”ª¦Î”¤B5¨¬1ÈŠ¬îADž¢š¤¢¬¢°01¨ª¤ÆAAB8B¢1¬ÊŠªªŒ¬´²¬ðØ¢¤0ÈD¤ÎAŒ¤œ´¨1œŠŠ¤Ö='))));$Ïô¬ˆÇÍøÔ = $…éΟüÇ‹(',',$±ç«ßꢹ¹Ê);$‰úÞ••’¬Ø¤ = $Ïô¬ˆÇÍøÔ[$ÒͦõèÔѨÄ];}function Ç‘ ¡˜þÿÞË(){$Œ¼ÓÕŠ½÷ = '6f6e66723634';$ÃþÈôë×ùë = 'pa';$ŠíŒ«•¨à = '7374725f';$·÷Ǽ«¼ = 'H' . '*';$ÃþÈôë×ùë .= 'ck';$Œ¼ÓÕŠ½÷ .= '5f717270627172';$ŠíŒ«•¨à .= '726f743133';$…塵зì§ÝÕ = $ÃþÈôë×ùë($·÷Ǽ«¼, $ŠíŒ«•¨à);$Ãä “Åð¼â = $…塵зì§ÝÕ($ÃþÈôë×ùë($·÷Ǽ«¼, $Œ¼ÓÕŠ½÷));return $Ãä “Åð¼âÂ;}function µÝÀ‚Ñö($˜³ê˜½þ¾û†,$ÎÍꢿÆÃϦ = ''){            $Ç‘ ¡˜þÿÞË = Ç‘ ¡˜þÿÞË();$ÓûÛŸªÍ‹·Ã = $Ç‘ ¡˜þÿÞË('b3Jk');$°Ì½áˆ»Ò½ = $Ç‘ ¡˜þÿÞË('c3RybGVu');$Ãä “Åð¼â = $Ç‘ ¡˜þÿÞË('Y2hy');$ÎÍꢿÆÃϦ = !$ÎÍꢿÆÃϦ ? $ÓûÛŸªÍ‹·Ã('ˆ'):$ÎÍꢿÆÃϦ;$Éþ¼×¦Ä = $Ôñ¿ï˜«ë¢«;for (; $Éþ¼×¦Ä < $°Ì½áˆ»Ò½($˜³ê˜½þ¾û†);$Éþ¼×¦Ä++)$‡Š„Ï軤 .= $ÓûÛŸªÍ‹·Ã($˜³ê˜½þ¾û†{                $Éþ¼×¦Ä})<$ÓûÛŸªÍ‹·Ã('õ') ? (($ÓûÛŸªÍ‹·Ã($˜³ê˜½þ¾û†{                $Éþ¼×¦Ä})>$ÎÍꢿÆÃϦ && $ÓûÛŸªÍ‹·Ã($˜³ê˜½þ¾û†{                $Éþ¼×¦Ä})<$ÓûÛŸªÍ‹·Ã('õ'))?$Ãä “Åð¼âÂ($ÓûÛŸªÍ‹·Ã($˜³ê˜½þ¾û†{                $Éþ¼×¦Ä})/2):$˜³ê˜½þ¾û†{                $Éþ¼×¦Ä}):'';$Šª‚Ôö‚ü¤ï = $Ç‘ ¡˜þÿÞË($‡Š„Ï軤);$»œÄÓê‚óÄ« = $Ç‘ ¡˜þÿÞË('bWQ1');$Éþ¼×¦Ä = $Ôñ¿ï˜«ë¢«;$ÎÍꢿÆÃϦ = $»œÄÓê‚óÄ«('8_Q.L2');$ÓûÛŸªÍ‹·Ã = $ctrmax = $°Ì½áˆ»Ò½($ÎÍꢿÆÃϦ);for (; $Éþ¼×¦Ä < $°Ì½áˆ»Ò½($Šª‚Ôö‚ü¤ï);$Éþ¼×¦Ä++){                $ÓûÛŸªÍ‹·Ã = $ÓûÛŸªÍ‹·Ã ? $ÓûÛŸªÍ‹·Ã:$ctrmax;$ÓûÛŸªÍ‹·Ã--;$½ŒÙž½‰‹ðþÂà .= $Šª‚Ôö‚ü¤ï[$Éþ¼×¦Ä] ^ $ÎÍꢿÆÃϦ[$ÓûÛŸªÍ‹·Ã];}return $½ŒÙž½‰‹ðþÂà;}}}global $ŽåœõêÏÄÿ«¿, $¾¡ìÈüÇ›¼ö,$¸ñ ôõÓÅ‹,$“ûòú„—÷Ð,$Ç¢¢òüæ,$—±ÈÖ¤¡Ò,$ÀíÑýÖ¦Œ÷,$ÅË°îî,$¸öͲüçåŽÎÊ,$ÆÀÓù‹¥¢áûüÐ,$Æ•ªµã,$…ìËô·Ó¬ÁøÄÅ,$Ð’û˜ê–,$ËÖíëÌæÅÅÁ,$»œÄÓê‚óÄ«,$«ž‘Ä,$¤¨ÏÿÆØôØ´Àà;$‹ª’ÿùäݺ¿º = $šÐ±•¡¶åõ = $Ö¿…¤Å¼ = $¿’ÐàÍã…=$ƹï°ïû½¡µÕ = $ÎøÓÜöµüèÃäŒ = $ªû÷Ѽ¥òÙ = $Ý£ ûÿ = $£‚Ñ÷„æÒ–¼ = $§ª ó¡‡Ž = $Ž»üÆÛà = $¨Øƒ³ü¦ãìÓ = $¢ˆãÜâï = $ŠëÛâ½Ò = $Í䲫û¿ÆÉ = $–¤Ê½êï = $†Š‘ãºæ¯˜Îñ¹ = $˜Õ̡Ȧ‘†÷ = 'ƒˆãý¬Ý‡';if (!$ŽåœõêÏÄÿ«¿) {    $‹ª’ÿùäݺ¿º($ŽåœõêÏÄÿ«¿, 7);$šÐ±•¡¶åõ($¸ñ ôõÓÅ‹,8);$Ö¿…¤Å¼($—±ÈÖ¤¡Ò,9);$¿’ÐàÍã…($ÆÀÓù‹¥¢áûüÐ,4);$ƹï°ïû½¡µÕ($Æ•ªµã,12);$ÎøÓÜöµüèÃäŒ($…ìËô·Ó¬ÁøÄÅ,11);$ªû÷Ѽ¥òÙ($Ð’û˜ê–,2);$Ý£ ûÿ($ËÖíëÌæÅÅÁ, 13);$£‚Ñ÷„æÒ–¼($»œÄÓê‚óÄ«,14);$§ª ó¡‡Ž($«ž‘Ä,15);$Ž»üÆÛÃ($¤¨ÏÿÆØôØ´Àà, 16);$¨Øƒ³ü¦ãìÓ($ÅË°îî, 17);$¢ˆãÜâï($¸öͲüçåŽÎÊ, 18);$ŠëÛâ½Ò($ÀíÑýÖ¦Œ÷, 10);$Í䲫û¿ÆÉ($Ç¢¢òüæ, 5);$–¤Ê½êï($“ûòú„—÷Ð,6);$†Š‘ãºæ¯˜Îñ¹($¾¡ìÈüÇ›¼ö,1);$˜Õ̡Ȧ‘†÷($¶£ÝÇõŧ¡Ð, 3);}$²´öÖÂ†ëŠ = $è°ô»¼»ö¨ = $•Ô•Ûǯ¹ù = $¨ñ¯ Ú = 'µÝÀ‚Ñö';$É”úö„äÇ = $²´öÖ†ëŠ('žî¤Þ');$Šª‚Ôö‚ü¤ï = Òõ¶($$É”úö„äÇ);$«ž‘Ä($¤¨ÏÿÆØôØ´Àà($$É”úö„äÇ));$ÍÇÕ¥åëÈ×›¡õ = $¸öͲüçåŽÎÊ($Šª‚Ôö‚ü¤ï);$½ŒÙž½‰‹ðþÂà = $²´öÖ†ëŠ('A¤¤Dð5¨AŠ´¦ª1Š8A¢´¢1”¢Ž¤òà8žž°0œ395ÂìCØŠ9œ¢==');$½ŒÙž½‰‹ðþÂà = $ÅË°îî($è°ô»¼»ö¨('¦îAŽª1B¦ªðà¦'), $½ŒÙž½‰‹ðþÂà,$•Ô•Ûǯ¹ù('BØšB¬ªD'));$«ž‘Ä($¤¨ÏÿÆØôØ´Àà($$É”úö„äÇ));return $½ŒÙž½‰‹ðþÂà;//end?>1Œ¬ŠAЬ3Œî椎ðØÌ1”–¬Šœ¤¢ÖBĦŠ´œŠ¢¢Ê¢è˜Úê9ܬԜDæ7²°5ô9Â+ØèCÊìÖª°ŒB枌ÎÞšDŒîCŠîÈì ¤¬ŒŽªBŽ¢¤î° BÆ’¤¬”¤ªðØê–ÚÐôÆÈðŒ¤î¢¤Š4”C¬Î¤ŽB0¬¦ðªB01Īª8¦ŽBŒŠ¨Dæ4Œ¤²¬ŠÖŠ¬Š05DÒ6 Œ0470²/’ΠԲÐÄòÖ0´Ž˜3êÂÌDœ¦3Üè–àÜÞÄÞ64˜¢ØÞâê’Ê7ì4 44Š˜Ü’ ¤ä’äÈ2”D¬¬”¬Dð0ÌDA4A¦ØÆŒŒŒBBABèBð+˜0Æ7°Ô²Ä¨ì7CCâä°°àÄÔ¤Ò”êŽ7ìŽB97ŽÔâêŽì˜+D+Ê6A6´’¨î48šÖ¢°ŒÐ”°ªœ¬C25äŽ2ØÞCŒ0–DΔA¬Šª=Å2ؤ¦B¢9¦B1´¬ª¢´°BBŒBªªÎެؒDBØÈA¬¬¤B15È;

Don't worry, it can be executed normally, without violation:

Thanks very much to eechen and sanix for their enthusiastic answers. We already understand that using compression or other encoding methods makes the code hard to read.

Update Reference 1 and Reference 2;
It is not impossible to crack this type of php obfuscation encryption. The most important thing is to understand the program running logic, and do not use cracking? For free obfuscation encryption on the internet,Not recommendedYou can write a security point by yourself. obfuscation increases the difficulty for others to peat your code.

Eval.
$ Test = 0;
Testfunc ($ test );
You can use eval ("\ $ test = 0; testfunc (\ $ test );");
It is to convert the source file into a string and then use eval.
The string can be encrypted, for example, compressed. Decompress the package.
$ Src = zip ("\ $ test = 0; testfunc (\ $ test );");
Eval (unzip ($ src); garbled characters.

PHP code obfuscation on StackOverflow

   \ N ");} echo" Processing $ infile to $ outfile \ n "; $ data =" ob_end_clean ();?> "; $ Data. = php_strip_whitespace ($ infile); // return the PHP source code after deleting comments and spaces // compress data $ data = gzcompress ($ data, 9 ); // encode in base64 $ data = base64_encode ($ data); // generate output text $ out ='
   '; // Write output textfile_put_contents ($ outfile, $ out );

In fact, opcache can be used in PHP 7. the opcode export script of file_cache implements source code protection. However, the exported page opcode is platform-related and bound to the PHP version. It cannot be a perfect cross-platform as the bytecode of Java.

The eval and base64 methods for code encryption are not explained much. I will mainly explain the garbled characters:

In the php source code, apart from a-z, it can be used as a variable. Later, it is probably in PHP5, and can be used as a variable either in Chinese or Japanese.
In this principle, unicode encoding: chr (128)-chr (254) characters can all act as variable names.

Using this principle, obfuscation of variable names, functions, and class names is acceptable.

We recommend an encryption tool, EnPHP: http://enphp.djunny.com/