Adler-32 is a fast checksum algorithm used in zlib to verify the results of decompression. It is composed of two sums modulo 65521. Start with s1 = 1 and s2 = 0, then for each byte x, s1 = s1 + x, s2 = s2 + s1. The two sums are combined into a 32-bit value with s1 in the low 16 bits and s2 in the high 16 bits.
Questions tagged [adler32]
39 questions
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Is Adler32 easy to decrypt and why?
I heard that we shouldn't rely on Adler32 and I want to ask why.
Why shouldn't we trust Adler32 to hash ? Is it reversible ? Or can we just see the real text with ease ?
M. Jack
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Fast implementation of rolling hash in PHP
I've implemented the Adler32 rolling hash in PHP, but because ord is so slow (about 1MB per second on my dev machine) to get the integer values of chanters in a string, this solution is unworkable for 100MB+ files.
PHP's mhash function can get a…
Dom
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Convert a hashcode to its binary representation
I compute the hash code for the word "tropical" using the Adler32 algorithm.
The result is the number "260768607"
How can I convert the above number to its binary representation?
Thank you
Panayotis Theodorou
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adler32 java bitwise and of input
I found the code for adler32 here http://developer.classpath.org/doc/java/util/zip/Adler32-source.html
however my update code looks like following
private int a = 1, b = 0;
public void update(byte[] buf, int offset, int len)
{
for (int i =…
user3307582
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adler32 checksum in objective c
I am working on a app which sends data to server with user location info. Server accept this data based on checksum calculation, which is written in java.
Here is the code written in Java:
private static final String CHECKSUM_CONS =…
user3275097
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Generating variations of checksum functions to minimize collisions
My goal is to efficiently perform an exhaustive diff of a directory tree. Given a set of files F, I must compute the equivalence classes EQV = [F₁, F₂, F₃, ... Fₙ] such that fⱼ, fₖ ∈ EQV[i] iff (fⱼ is identical to fₖ) for all i, j, k.
My general…
ealfonso
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different adler32 check sum on objective-c and C#
I'm developing an app in objective-c that send a file and a Adler32 check sum of that file to a web service.
After I send the file to the web server answers saying that the check sum failed.
This is the code that I use to check sum on…
Tony
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Adler-32 in Multilevel Security Environment Safe Practices
I'm implementing a multilevel security environment on several several web servers running Debian. I've done quite a bit of reading on fast hash checking algorithms to compliment the other security components.
It seems Adler-32 is quite fast and…
Mr. Russian
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Cumulative Hashes
I've read before here on SO (EDIT: Incremental Checksums) that there are some checksum algorithms (I think one of those is adler32) that support the following property:
adler32('abc'); // 123
adler32('def'); // 456
adler32('abcdef'); // 579 (123 +…
Alix Axel
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