crc32
GENERATES a VALUE designated as CRC32 polynomial.
CRC32 polynomial is used to test the integrity of a specific DATA.
CRC is the abbreviation for Ciclic Redundance Check.
It is a numeric key for validation using cyclic redundancy.
SHOULD NOT BE CONSIDERED A CRYPTOGRAPHIC CODING KEY
On 32 bit platforms it can result in negative integers, and 64 bit results in positive integers.
You will need to use the %u formatter in the printf or sprintf functions to obtain the unsigned representation of crc32 in DECIMAL FORMAT.
For a representation in HEXADECIMAL, you need to use the %x formatter in the conversion performed by functions printf, sprintf or dechex both to take care of the conversion crc32 which results in an unsigned integer.
64 bit platforms can also return negative integers to larger VALUEs, which would break the HEXADECIMAL conversion.
It was established that the HEXADECIMAL conversion is not broken, being the most common, even in direct DECIMAL comparisons there is a break in 50% of cases when moving from 32 to 64 bit.
For better RESULTS, the use of hash and str_pad functions must be required.
HASH
A HASH function is any function that can be used to map data of arbitrary size to data of a fixed size.
The values returned by a HASH function are called HASH values, HASH codes, digests, or simply hashes.
HASH functions are often used in combination with a HASH table, a common data structure used in computer software for rapid data lookup.
HASH functions accelerate table or database lookup by detecting duplicated records in a large file.
One such application is finding similar stretches in DNA sequences.
They are also useful in cryptography.
A cryptographic HASH function allows one to easily verify that some input data maps to a given HASH value, but if the input data is unknown, it is deliberately difficult to reconstruct it, (or any equivalent alternatives), by knowing the stored HASH value.
This is used for assuring integrity of transmitted data, and is the building block for HMACs, which provide message authentication.
HASH functions are related to, (and often confused with), checksums, check digits, fingerprints, lossy compression, randomization functions, error-correcting codes, and ciphers.
Although the concepts overlap to some extent, each one has its own uses and requirements and is designed and optimized differently.
The HashKeeper database maintained by the American National Drug Intelligence Center, for instance, is more aptly described as a catalogue of file fingerprints than of HASH values.
From Wikipedia, the free encyclopedia.
This function integrates the cast of standard library functions.
Included in this section for being in common use.
<?php
int crc32 ( str $str )
where,
$str = STRING to be calculated the polynomial
?>
$str
STRING to calculate the crc32 polynomial.
EXERCISE
<?php
$str2crc3201 = 'In a collaborative, forward-thinking venture brought together through the merging of like minds.';
$strcrc3201 = crc32($str2crc3201);
echo $strcrc3201 . '<br><br>';
printf("%u", $strcrc3201);
?>
RESULT
'In a collaborative, forward-thinking venture brought together through the merging of like minds.'
crc32 DEC
1678834124
EXERCISE
<?php
// Noticeably different
// of the previous exercise
$str2crc3202 = 'In a collaborative, forward-thinking venture brought together through the merging of like minds. ';
$strcrc3202 = crc32($str2crc3202);
printf("%u", $strcrc3202);
echo '<br><br>';
printf("%x", $strcrc3202);
?>
RESULT
'In a collaborative, forward-thinking venture brought together through the merging of like minds. '
A space was added to the end of the text from the previous exercise.
crc32 DEC:
2077905191
crc32 HEX:
7bda5127
EXERCISE
<?php
$fsvd = PATH2TMPN . 'uulorem.txt';
$fr = file_get_contents($fsvd);
$strass = crc32($fr);
echo 'crc 32 - DEC = ';
printf("%u", $strass);
echo '<br><br>crc 32 - HEX = ';
printf("%x", $strass);
echo '<br><br>' . $fr . '<br><br>';
?>
RESULT
crc32 DEC = 2084863928
crc32 HEX = 7c447fb8
Lorem Ipsum é simplesmente uma simulação de texto da indústria tipográfica e de impressos, e vem sendo utilizado desde o século XVI, quando um impressor desconhecido pegou uma bandeja de tipos e os embaralhou para fazer um livro de modelos de tipos. Lorem Ipsum sobreviveu não só a cinco séculos, como também ao salto para a editoração eletrônica, permanecendo essencialmente inalterado. Se popularizou na década de 60, quando a Letraset lançou decalques contendo passagens de Lorem Ipsum, e mais recentemente quando passou a ser integrado a softwares de editoração eletrônica como Aldus PageMaker.