Passport decryption function written in php

Passport decryption function written in php

/** * Passport decryption function * * @ Param string the encrypted string * @ Param string private key (used for decryption and encryption) * * @ Return string result after private key decryption */ Function passport_decrypt ($ txt, $ key ){ // $ Txt results in base64 decoding of the encrypted string, and then together with the private key, // Return value after passport_key () function processing $ Txt = passport_key (base64_decode ($ txt), $ key ); // Variable initialization $ Tmp = ''; // For loop, $ I is an integer starting from 0 to less than $ txt string length For ($ I = 0; $ I <strlen ($ txt); $ I ++ ){ // $ Tmp adds a bit at the end of the string, whose content is the $ I bit of $ txt, // It is the same as the $ I + 1 bits in $ txt. Then $ I = $ I + 1 $ Tmp. = $ txt [$ I] ^ $ txt [++ $ I]; } // Return the value of $ tmp as the result Return $ tmp; } /** * Passport key processing function * * @ Param string the string to be encrypted or to be decrypted * @ Param string private key (used for decryption and encryption) * * @ Return string the processed key */ Function passport_key ($ txt, $ encrypt_key ){ // Assign $ encrypt_key to the value of $ encrypt_key after md5 () $ Encrypt_key = md5 ($ encrypt_key ); // Variable initialization $ Ctr = 0; $ Tmp = ''; // For loop, $ I is an integer starting from 0 to less than $ txt string length For ($ I = 0; $ I <strlen ($ txt); $ I ++ ){ // If $ ctr = $ encrypt_key length, $ ctr is cleared. $ Ctr = strlen ($ encrypt_key )? 0: $ ctr; // $ Tmp adds a bit at the end of the string, whose content is the $ I bit of $ txt, // It is the same or as the $ ctr + 1 of $ encrypt_key. Then $ ctr = $ ctr + 1 $ Tmp. = $ txt [$ I] ^ $ encrypt_key [$ ctr ++]; } // Return the value of $ tmp as the result Return $ tmp; } ?>