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R&D Centre for Mobile Applications (RDC) FEE, Dept of Telecommunications Engineering Czech Technical University in Prague RDC Technical Report TR-13-4 Internship report Evaluation of Compressibility of the Output of the Information-Concealing Algorithm Julien Mamelli, [email protected] 2nd year student at the Ecole´ des Mines d'Al`es (N^ımes,France) Internship supervisor: Luk´aˇsKencl, [email protected] August 2013 Abstract Compression is a key element to exchange files over the Internet. By generating re- dundancies, the concealing algorithm proposed by Kencl and Loebl [?], appears at first glance to be particularly designed to be combined with a compression scheme [?]. Is the output of the concealing algorithm actually compressible? We have tried 16 compression techniques on 1 120 files, and the result is that we have not found a solution which could advantageously use repetitions of the concealing method. Acknowledgments I would like to express my gratitude to my supervisor, Dr Luk´aˇsKencl, for his guidance and expertise throughout the course of this work. I would like to thank Prof. Robert Beˇst´akand Mr Pierre Runtz, for giving me the opportunity to carry out my internship at the Czech Technical University in Prague. I would also like to thank all the members of the Research and Development Center for Mobile Applications as well as my colleagues for the assistance they have given me during this period. 1 Contents 1 Introduction 3 2 Related Work 4 2.1 Information concealing method . 4 2.2 Archive formats . 5 2.3 Compression algorithms . 5 2.3.1 Lempel-Ziv algorithm . -
The Basic Principles of Data Compression
The Basic Principles of Data Compression Author: Conrad Chung, 2BrightSparks Introduction Internet users who download or upload files from/to the web, or use email to send or receive attachments will most likely have encountered files in compressed format. In this topic we will cover how compression works, the advantages and disadvantages of compression, as well as types of compression. What is Compression? Compression is the process of encoding data more efficiently to achieve a reduction in file size. One type of compression available is referred to as lossless compression. This means the compressed file will be restored exactly to its original state with no loss of data during the decompression process. This is essential to data compression as the file would be corrupted and unusable should data be lost. Another compression category which will not be covered in this article is “lossy” compression often used in multimedia files for music and images and where data is discarded. Lossless compression algorithms use statistic modeling techniques to reduce repetitive information in a file. Some of the methods may include removal of spacing characters, representing a string of repeated characters with a single character or replacing recurring characters with smaller bit sequences. Advantages/Disadvantages of Compression Compression of files offer many advantages. When compressed, the quantity of bits used to store the information is reduced. Files that are smaller in size will result in shorter transmission times when they are transferred on the Internet. Compressed files also take up less storage space. File compression can zip up several small files into a single file for more convenient email transmission. -
Encryption Introduction to Using 7-Zip
IT Services Training Guide Encryption Introduction to using 7-Zip It Services Training Team The University of Manchester email: [email protected] www.itservices.manchester.ac.uk/trainingcourses/coursesforstaff Version: 5.3 Training Guide Introduction to Using 7-Zip Page 2 IT Services Training Introduction to Using 7-Zip Table of Contents Contents Introduction ......................................................................................................................... 4 Compress/encrypt individual files ....................................................................................... 5 Email compressed/encrypted files ....................................................................................... 8 Decrypt an encrypted file ..................................................................................................... 9 Create a self-extracting encrypted file .............................................................................. 10 Decrypt/un-zip a file .......................................................................................................... 14 APPENDIX A Downloading and installing 7-Zip ................................................................. 15 Help and Further Reference ............................................................................................... 18 Page 3 Training Guide Introduction to Using 7-Zip Introduction 7-Zip is an application that allows you to: Compress a file – for example a file that is 5MB can be compressed to 3MB Secure the -
ARC File Revision 3.0 Proposal
ARC file Revision 3.0 Proposal Steen Christensen, Det Kongelige Bibliotek <ssc at kb dot dk> Michael Stack, Internet Archive <stack at archive dot org> Edited by Michael Stack Revision History Revision 1 09/09/2004 Initial conversion of wiki working doc. [http://crawler.archive.org/cgi-bin/wiki.pl?ArcRevisionProposal] to docbook. Added suggested edits suggested by Gordon Mohr (Others made are still up for consideration). This revision is what is being submitted to the IIPC Framework Group for review at their London, 09/20/2004 meeting. Table of Contents 1. Introduction ............................................................................................................................2 1.1. IIPC Archival Data Format Requirements .......................................................................... 2 1.2. Input ...........................................................................................................................2 1.3. Scope ..........................................................................................................................3 1.4. Acronyms, Abbreviations and Definitions .......................................................................... 3 2. ARC Record Addressing ........................................................................................................... 4 2.1. Reference ....................................................................................................................4 2.2. The ari Scheme ............................................................................................................ -
Steganography and Vulnerabilities in Popular Archives Formats.| Nyxengine Nyx.Reversinglabs.Com
Hiding in the Familiar: Steganography and Vulnerabilities in Popular Archives Formats.| NyxEngine nyx.reversinglabs.com Contents Introduction to NyxEngine ............................................................................................................................ 3 Introduction to ZIP file format ...................................................................................................................... 4 Introduction to steganography in ZIP archives ............................................................................................. 5 Steganography and file malformation security impacts ............................................................................... 8 References and tools .................................................................................................................................... 9 2 Introduction to NyxEngine Steganography1 is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message, a form of security through obscurity. When it comes to digital steganography no stone should be left unturned in the search for viable hidden data. Although digital steganography is commonly used to hide data inside multimedia files, a similar approach can be used to hide data in archives as well. Steganography imposes the following data hiding rule: Data must be hidden in such a fashion that the user has no clue about the hidden message or file's existence. This can be achieved by -
Improved Neural Network Based General-Purpose Lossless Compression Mohit Goyal, Kedar Tatwawadi, Shubham Chandak, Idoia Ochoa
JOURNAL OF LATEX CLASS FILES, VOL. 14, NO. 8, AUGUST 2015 1 DZip: improved neural network based general-purpose lossless compression Mohit Goyal, Kedar Tatwawadi, Shubham Chandak, Idoia Ochoa Abstract—We consider lossless compression based on statistical [4], [5] and generative modeling [6]). Neural network based data modeling followed by prediction-based encoding, where an models can typically learn highly complex patterns in the data accurate statistical model for the input data leads to substantial much better than traditional finite context and Markov models, improvements in compression. We propose DZip, a general- purpose compressor for sequential data that exploits the well- leading to significantly lower prediction error (measured as known modeling capabilities of neural networks (NNs) for pre- log-loss or perplexity [4]). This has led to the development of diction, followed by arithmetic coding. DZip uses a novel hybrid several compressors using neural networks as predictors [7]– architecture based on adaptive and semi-adaptive training. Unlike [9], including the recently proposed LSTM-Compress [10], most NN based compressors, DZip does not require additional NNCP [11] and DecMac [12]. Most of the previous works, training data and is not restricted to specific data types. The proposed compressor outperforms general-purpose compressors however, have been tailored for compression of certain data such as Gzip (29% size reduction on average) and 7zip (12% size types (e.g., text [12] [13] or images [14], [15]), where the reduction on average) on a variety of real datasets, achieves near- prediction model is trained in a supervised framework on optimal compression on synthetic datasets, and performs close to separate training data or the model architecture is tuned for specialized compressors for large sequence lengths, without any the specific data type. -
Financial Statements
ANNUAL REPORT FLYHT AEROSPACE SOLUTIONS LTD. Table of Contents Commonly used Financial Terms and Aviation Acronyms ..................................................................................................... 3 Letter to Shareholders ............................................................................................................................................................. 4 Management Discussion & Analysis ....................................................................................................................................... 5 Non-GAAP Financial Measures .......................................................................................................................................... 5 Forward-Looking Statements .............................................................................................................................................. 5 FLYHT Overview ................................................................................................................................................................. 6 Trends and Economic Factors .......................................................................................................................................... 11 Environmental, Social and Corporate Governance .......................................................................................................... 13 2020 Contracts, Achievements and Activities ................................................................................................................. -
GNU CPIO GNU Cpio 2.5 June 2002
GNU CPIO GNU cpio 2.5 June 2002 by Robert Carleton Copyright c 1995, 2001, 2002 Free Software Foundation, Inc. This is the first edition of the GNU cpio documentation, and is consistent with GNU cpio 2.5. Published by the Free Software Foundation 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the con- ditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another lan- guage, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Free Software Foundation. Chapter 2: Tutorial 1 1 Introduction GNU cpio copies files into or out of a cpio or tar archive, The archive can be another file on the disk, a magnetic tape, or a pipe. GNU cpio supports the following archive formats: binary, old ASCII, new ASCII, crc, HPUX binary, HPUX old ASCII, old tar, and POSIX.1 tar. The tar format is provided for compatability with the tar program. By default, cpio creates binary format archives, for compatibility with older cpio programs. When extracting from archives, cpio automatically recognizes which kind of archive it is reading and can read archives created on machines with a different byte-order. -
Lossless Compression of Internal Files in Parallel Reservoir Simulation
Lossless Compression of Internal Files in Parallel Reservoir Simulation Suha Kayum Marcin Rogowski Florian Mannuss 9/26/2019 Outline • I/O Challenges in Reservoir Simulation • Evaluation of Compression Algorithms on Reservoir Simulation Data • Real-world application - Constraints - Algorithm - Results • Conclusions 2 Challenge Reservoir simulation 1 3 Reservoir Simulation • Largest field in the world are represented as 50 million – 1 billion grid block models • Each runs takes hours on 500-5000 cores • Calibrating the model requires 100s of runs and sophisticated methods • “History matched” model is only a beginning 4 Files in Reservoir Simulation • Internal Files • Input / Output Files - Interact with pre- & post-processing tools Date Restart/Checkpoint Files 5 Reservoir Simulation in Saudi Aramco • 100’000+ simulations annually • The largest simulation of 10 billion cells • Currently multiple machines in TOP500 • Petabytes of storage required 600x • Resources are Finite • File Compression is one solution 50x 6 Compression algorithm evaluation 2 7 Compression ratio Tested a number of algorithms on a GRID restart file for two models 4 - Model A – 77.3 million active grid blocks 3.5 - Model K – 8.7 million active grid blocks 3 - 15.6 GB and 7.2 GB respectively 2.5 2 Compression ratio is between 1.5 1 compression ratio compression - From 2.27 for snappy (Model A) 0.5 0 - Up to 3.5 for bzip2 -9 (Model K) Model A Model K lz4 snappy gzip -1 gzip -9 bzip2 -1 bzip2 -9 8 Compression speed • LZ4 and Snappy significantly outperformed other algorithms -
The Ark Handbook
The Ark Handbook Matt Johnston Henrique Pinto Ragnar Thomsen The Ark Handbook 2 Contents 1 Introduction 5 2 Using Ark 6 2.1 Opening Archives . .6 2.1.1 Archive Operations . .6 2.1.2 Archive Comments . .6 2.2 Working with Files . .7 2.2.1 Editing Files . .7 2.3 Extracting Files . .7 2.3.1 The Extract dialog . .8 2.4 Creating Archives and Adding Files . .8 2.4.1 Compression . .9 2.4.2 Password Protection . .9 2.4.3 Multi-volume Archive . 10 3 Using Ark in the Filemanager 11 4 Advanced Batch Mode 12 5 Credits and License 13 Abstract Ark is an archive manager by KDE. The Ark Handbook Chapter 1 Introduction Ark is a program for viewing, extracting, creating and modifying archives. Ark can handle vari- ous archive formats such as tar, gzip, bzip2, zip, rar, 7zip, xz, rpm, cab, deb, xar and AppImage (support for certain archive formats depends on the appropriate command-line programs being installed). In order to successfully use Ark, you need KDE Frameworks 5. The library libarchive version 3.1 or above is needed to handle most archive types, including tar, compressed tar, rpm, deb and cab archives. To handle other file formats, you need the appropriate command line programs, such as zipinfo, zip, unzip, rar, unrar, 7z, lsar, unar and lrzip. 5 The Ark Handbook Chapter 2 Using Ark 2.1 Opening Archives To open an archive in Ark, choose Open... (Ctrl+O) from the Archive menu. You can also open archive files by dragging and dropping from Dolphin. -
Bzip2 and Libbzip2, Version 1.0.8 a Program and Library for Data Compression
bzip2 and libbzip2, version 1.0.8 A program and library for data compression Julian Seward, https://sourceware.org/bzip2/ bzip2 and libbzip2, version 1.0.8: A program and library for data compression by Julian Seward Version 1.0.8 of 13 July 2019 Copyright© 1996-2019 Julian Seward This program, bzip2, the associated library libbzip2, and all documentation, are copyright © 1996-2019 Julian Seward. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. • The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. • Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. • The name of the author may not be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DIS- CLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -
Forcepoint DLP Supported File Formats and Size Limits
Forcepoint DLP Supported File Formats and Size Limits Supported File Formats and Size Limits | Forcepoint DLP | v8.8.1 This article provides a list of the file formats that can be analyzed by Forcepoint DLP, file formats from which content and meta data can be extracted, and the file size limits for network, endpoint, and discovery functions. See: ● Supported File Formats ● File Size Limits © 2021 Forcepoint LLC Supported File Formats Supported File Formats and Size Limits | Forcepoint DLP | v8.8.1 The following tables lists the file formats supported by Forcepoint DLP. File formats are in alphabetical order by format group. ● Archive For mats, page 3 ● Backup Formats, page 7 ● Business Intelligence (BI) and Analysis Formats, page 8 ● Computer-Aided Design Formats, page 9 ● Cryptography Formats, page 12 ● Database Formats, page 14 ● Desktop publishing formats, page 16 ● eBook/Audio book formats, page 17 ● Executable formats, page 18 ● Font formats, page 20 ● Graphics formats - general, page 21 ● Graphics formats - vector graphics, page 26 ● Library formats, page 29 ● Log formats, page 30 ● Mail formats, page 31 ● Multimedia formats, page 32 ● Object formats, page 37 ● Presentation formats, page 38 ● Project management formats, page 40 ● Spreadsheet formats, page 41 ● Text and markup formats, page 43 ● Word processing formats, page 45 ● Miscellaneous formats, page 53 Supported file formats are added and updated frequently. Key to support tables Symbol Description Y The format is supported N The format is not supported P Partial metadata