7zip Compress Shared Files
PDF format support some form of compression internally, most common is Deflate. Some PDF file just leave it uncompress. If the PDF file is already internally compressed, you cannot gain much by recompress it with 7zip or RAR. But if the PDF is internally uncompress, then you can compress it much much better using 7zip or other solid archiver. A file with the 7Z file extension is a 7-Zip Compressed file. It's a bit like a folder on your computer, except that it really acts like a file. Both a folder and a 7Z file can store one or more files, and even other folders. However, unlike folders, this is just a single file with the.7Z extension that serve as a compressed archive of the data. Select all the files you want to archive in one file explorer window. Right click on one of the selected items and navigate to 7-Zip then Add to Archive. Input your settings and destination. Press Ok to begin.
Allows you to specify options for creating or updating an archive.
How to call this dialog box
- In Windows Explorer or in 7-Zip, right-click the file(s) or folder(s) you want to compress.
- Point to 7-Zip, and then click the Add to archive... command item.
Parameters
Specifies compression level. There are 6 levels of compression:
| Value | Meaning |
|---|---|
| Store | Files will be copied to archive without compression. |
| Fastest | Fastest compression. |
| Fast | Fast compression. |
| Normal | Compression with balanced settings. |
| Maximum | Can give a higher compression ratio than Normal level. But it can be slower, and it can require more memory. |
| Ultra | Can give a higher compression ratio than Maximum level. But it can be slower, and it can require more memory. |
Specifies compression method. Each archive format can have its own compression methods:
| Method | Description |
|---|---|
| LZMA | It's base compression method for 7z format. Even old versions of 7-Zip can decompress archives created with LZMA method. It provides high compression ratio and very fast decompression. |
| LZMA2 | Default compression method of 7z format. LZMA2 is LZMA-based compression method. It provides better multithreading support than LZMA. But compression ratio can be worse in some cases. For best compression ratio with LZMA2 use 1 or 2 CPU threads. If you use LZMA2 with more than 2 threads, 7-zip splits data to chunks and compresses these chunks independently (2 threads per each chunk). |
| PPMd | Dmitry Shkarin's PPMdH algorithm with small changes. Usually it provides high compression ratio and high speed for text files. |
| BZip2 | Standard compression method based on BWT algorithm. Usually it provides high speed and pretty good compression ratio for text files. |
| Deflate | Standard compression method of ZIP and GZip formats. Compression ratio is not too high. But it provides pretty fast compressing and decompressing. Deflate method supports only 32 KB dictionary. |
| Deflate64 | Modified version of Deflate algorithm with bigger dictionary (64KB). |
Estimated 7-Zip performance and memory requirements for 2 GHz dual core CPU:
| Method | Level | Dictionary Size | Compressing Speed | Decompressing Speed | Memory for Compressing | Memory for Decompressing |
|---|---|---|---|---|---|---|
| LZMA | fastest | 64 KB | 4.5 MB/s | 15 MB/s | 3 MB | 3 MB |
| fast | 1 MB | 3 MB/s | 10 MB | 3 MB | ||
| normal | 16 MB | 2 MB/s | 186 MB | 18 MB | ||
| maximum | 32 MB | 1.8 MB/s | 376 MB | 34 MB | ||
| ultra | 64 MB | 1.6 MB/s | 709 MB | 66 MB | ||
| PPMD | fast | 4 MB | 1.4 MB/s | 6 MB | ||
| normal | 24MB | 1.2 MB/s | 26 MB | |||
| maximum | 64 MB | 1.0 MB/s | 66 MB | |||
| ultra | 192 MB | 0.9 MB/s | 194 MB | |||
| Deflate | fast | 32 KB | 15 MB/s | 40 MB/s | 3 MB | 2 MB |
| normal | 3.5 MB/s | |||||
| maximum | 1.5 MB/s | 4MB | ||||
| ultra | 0.4 MB/s | |||||
| BZip2 | normal | 900 KB | 3 MB/s | 16 MB/s | 20 MB | 7 MB |
| maximum | 1.2 MB/s | |||||
| ultra | 0.4 MB/s | |||||
Specifies Dictionary size for compression method.
Usually, a higher Dictionary size gives a higher compression ratio. But compressing can be slower and it can require more memory.
Memory (RAM) usage for LZMA compressing is about 11 times more than dictionary size. Memory usage for LZMA decompressing is close to value of dictionary size. Memory usage for PPMd compressing and decompressing is almost equal to dictionary size.
Specifies the length of words, which will be used to find identical sequences of bytes for compression.
Usually for LZMA and Deflate, big Word size gives a little bit better compression ratio and slower compression process. A big Word size parameter can significantly increase compression ratio for files which contain long identical sequences of bytes. For PPMd, the Word size strongly affects both compression ratio and compression/decompression speed.
Specifies the size of a solid block. You can also disable solid mode. In solid mode all files will be compressed as continuous data blocks. Usually compressing to a solid archive improves the compression ratio. You can use this option only for 7z archives. The updating of solid .7z archives can be slow, since it can require some recompression.
.Specifies the number of threads for compressing. A big number of threads can speed up compression speed on Multi-Processor systems. Sometimes it can increase speed even on single-core CPU.
Specifies volume sizes in Bytes, Kilobytes (1 Kilobyte = 1024 bytes), Megabytes (1 Megabyte = 1024 Kilobytes) or Gigabytes (1 Gigabyte = 1024 Megabytes). If you specify only {Size}, 7-zip will treat it as bytes. It's possible to specify several values. Example:
The first volume will be 10 KB, the second will be 15 KB, and all others will be 2 MB.
Allows you to specify parameters for compression. See the -m (Method) switch description for more details. Omit the -m prefix (as in -m switch) when using this dialog box.
Examples
uses Delta:4 filter (if you want to compress WAV files).
uses BCJ2 filter (for x86 executables).
Specifies update mode:
| Value | Meaning |
|---|---|
| Add and replace files | Add all specified files to the archive. |
| Update and add files | Update older files in the archive and add files that are new to the archive. |
| Freshen existing files | Update specified files in the archive that are older than the selected disk files. |
| Synchronize files | Replace specified files only if added files are newer. Always add those files, which are not present in the archive. Delete from archive those files, which are not present on the disk. |
Specifies how path names will be stored in archive:
| Value | Meaning |
|---|---|
| Relative pathnames | Store file paths relative to current folder. |
| Full pathnames | Store file paths relative to root of the volume, excluding volume name prefix. |
| Absolute pathnames | Store fully qualified file paths including volume name. |
Specifies compression options:
| Option | Meaning |
|---|---|
| Create SFX archive | Create self-extracting archive. You can use this option only for 7z archives. Look to -sfx (Create SFX archive) switch description for more details about SFX modules. |
| Compress shared files | Compress files open for writing by another applications. |
| Delete files after compression | Delete files after including to archive. So it works like moving files to archive. 7-Zip deletes files at the end of operation and only if archive was successfully created. |
Specifies password and encryption options.
- Enter password
- Specify password here
- Reenter password
- Reenter password here for verification
- Show Password
- Shows Password
- Encryption method
- Specifies the encryption method. For 7z format, it can be only AES-256. For ZIP format you can select ZipCrypto or AES-256. Use ZipCrypto, if you want to get archive compatible with most of the ZIP archivers. AES-256 provides stronger encryption, but now AES-256 is supported only by 7-Zip, WinZip and some other ZIP archivers.
- Encrypt file names
- Enables or disables archive header encryption, including file name encryption.
7-Zip is an open source software used to compress or zip files secured with encryption.
When you send or transfer files that contain Personal Identifiable Information (PII) or other confidential and sensitive data, the files must be encrypted to ensure they are protected from unauthorized disclosure.
For Mac OS instructions, please visit: http://osxdaily.com/2012/01/07/set-zip-password-mac-os-x/
7-Zip, like WinZip, creates a container called archive that holds the files to be protected. That archive can be encrypted and protected with a password. 7-Zip is a free software that creates Zip files that can be opened with WinZip or other similar programs.
To obtain a copy of 7-Zip, please see http://www.7-zip.org/ and select the Download link.
Once the software is installed, please follow these steps to encrypt a file or folder.
Step 1: Right click on the file / folder to be encrypted.
Step 2: Select “7-Zip” then “Add to archive…”
Step 3: In the Add to Archive window change the name of the archive you wish to create.
Step 4: Change the Archive format to “Zip”.
Step 5: Change the Encryption Method to “AES-256”.
There is a trade-off between using AES-256 and ZipCrypto. AES-256 is proven much more secure than ZipCrypto, but if you select AES-256 the recipient of the zip file may have to install 7-zip or another zip program to read the file contents. Selecting ZipCrypto may allow users to open the zip file in Windows without a zip program, but it does not provide adequate protection against attackers with modern cracking tools.
It is strongly recommended to use AES-256 to protect sensitive and confidential data.
Step 6: Enter a Password. Use a strong password with at least 8 characters containing upper and lowercase letters, and a minimum of one number.
Step 7: Select “Ok” to create the encrypted archive file. The new archive file will be located in the same folder as the original.
Free Download Compressed Zip Folder
Best security practices recommend that you do not email the password with the Zip file as it could be intercepted in transit. It is better to call the recipient of the Zip file and convey the password over the phone.