All Questions
29
questions
1
vote
1
answer
59
views
Why do i get more 256 false positive in PKZIP Decryption key verification?
I have been trying to brute force Key2 of ZipCrypto with first byte of CRC and last byte of encryption header to see how long would it take but i got more than 2000 valid keys.
From the APPNOTE, Key2 ...
1
vote
1
answer
136
views
Malformed PNG pixel data from deflate "unknown edge cases"
For the past 2 months, I've been implementing a png/deflate decoder, (for various reasons but mainly for learning purposes) but only returns the correct expected data in some cases.
Here in this table,...
- 11
0
votes
1
answer
64
views
How to skip detection of random data when attempting to compress?
Do popular compressors such as gzip, 7z, or others using deflate, detect random data strings and skip attempting to compress said strings for sake of speed?
If so, can I switch off this setting?
...
-1
votes
1
answer
350
views
What's wrong with my PNG IDAT CHUNK datas?
i'm trying for learning purpose to create manually a png file from with OpenGL
All other CHUNKS are okk (IHDR, pHY, IEND).
firstly, I read pixels by Opengl :
int s_width = glutGet(GLUT_SCREEN_WIDTH), ...
0
votes
1
answer
326
views
PNG IDAT chunk data calculation
I'm trying for learning propose to write my own png file in c language.
I have already read the PNG file format specification and i am now able to write a basic PNG(signature, IHDR CHUNK, 1px-IDAT ...
0
votes
1
answer
284
views
puff.c How does the huffman decoding work?
I am trying to decompress a raw DEFLATE data stream in order to understand, how the DEFLATE decompression works. I don't care for performance at the moment. I just want to understand the decompression ...
- 57
0
votes
1
answer
289
views
C - zlib - png crc32/deflate
I'm doing an homework to read a png file through zlib in C and I always have checksum not equal to png crc. How I shoul take from zlib? I've been on it for 5 hours and I'm going crazy.
Thank you for ...
- 1,312
0
votes
1
answer
114
views
Is it always okay to Inflate zlib-wrapped data with the windowBits of 15?
If the zlib-wrapped data to Inflate has, in its zlib header, CINFO (which determines the LZ77 window size) that is other than 7 (the maximum valid), is it okay to Inflate it with the windowBits of 15 (...
- 14k
1
vote
1
answer
453
views
Method of estimating DEFLATE's (zlib) current compressed size without flush
I'm currently writing a program that takes in cachelines (64 bytes, but adjustable), and attempts to fit as many as possible into a 512 byte block (again adjustable).
The issue is that I need to be ...
- 13
0
votes
1
answer
105
views
Using wininet to download deflate XML on Windows MSVC, but gets broken data
This code download deflated XML document https://api.bilibili.com/x/v1/dm/list.so?oid=162677333 and save it to temp.Z, which however seems broken. How is that?
#include <stdio.h>
#include <...
- 1,001
1
vote
1
answer
873
views
ZLib GZIP Returning Z_BUF_ERROR(-5)
I am using the zlib library (compiled from src) to deflate/inflate gzip/zlib/raw bytes. I have created a wrapper class for decompressing and compressing (Compressor/Decompresser). I have also created ...
user10047010
0
votes
1
answer
310
views
Inflate decompression operation success without processing complete compressed data
I am using Software Inflate methods ( Raw deflate method and not GZIP/ZLIB variants )for decompression operations.
Strangely, I noticed the following obseravations
1.) When I pass in a single ...
- 49
3
votes
2
answers
2k
views
Decompressing gzip file to memory using libarchive
I'm trying to decompress programmatically a gzip file into memory and mimic the command gzip -d file.gz using libarchive project.
The file is actually taken from http response with the following ...
- 877
2
votes
1
answer
262
views
Deflate Format: differences between type blocks
I am currently trying to write a compressor and decompressor with the same purpose as the RFC Deflate specification.
I'm not able to understand the difference between how blocks are composed in the ...
- 29
4
votes
1
answer
3k
views
How to Encode and Decode websocket permessage-deflate using zlib library in C?
All
I am trying to encode WebSocket payload using per-message-deflate. I am trying to use some test code but my encoding is not proper can you please help me.
Here is my code:
char a[180] = "{\"...
