Php verification data problems

Php verification data problems PHPcode $ str3 = $ str1. $ str2; // only the checksum of $ str1 and $ str2 are available. // How can I calculate the checksum of $ str3 through crc32, from the data feature value, cyclic redundancy check code can not calculate the original data .. 12 php verification data problems

PHP code

  $ Str3 = $ str1. $ str2; // currently, only the checksum of $ str1 and $ str2 are available. // How can I calculate the checksum of $ str3 through crc32?

------ Solution --------------------
There is no way, from the data feature value, cyclic redundancy check code can not calculate the original data .. 128-bit, 512-bit, or 32-bit data cannot represent an infinite amount of data.

PHP code

Var_dump (crc32 ("86821"), crc32 ("14740600 "));
------ Solution --------------------
Possible!

The CRC algorithm can be clearly stated by referring to the http://blog.csdn.net/sparkliang/article/details/5671510.

You can use the checksum value of $ str1 as the base value and continue to calculate the content of $ str2.