Raziel1234/WebText-3 · Datasets at Hugging Face

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Even without removing the password, most freeware or open source PDF readers ignore the permission "protections" and allow the user to print or make copies of excerpts of the text as if the document were not limited by password protection.[37][38][39]
Beginning with PDF 1.5, Usage rights (UR) signatures are used to enable additional interactive features that are not available by default in a particular PDF viewer application
The signature is used to validate that the permissions have been granted by a bona fide granting authority
For example, it can be used to allow a user:[40]
For example, Adobe Systems grants permissions to enable additional features in Adobe Reader, using public-key cryptography
Adobe Reader verifies that the signature uses a certificate from an Adobe-authorized certificate authority
Any PDF application can use this same mechanism for its own purposes.[40]
Under specific circumstances including non-patched systems of the receiver, the information the receiver of a digital signed document sees can be manipulated by the sender after the document has been signed by the signer.[41]
PAdES (PDF Advanced Electronic Signatures) is a set of restrictions and extensions to PDF and ISO 32000-1[42] making it suitable for advanced electronic signatures
This is published by ETSI as TS 102 778.[43]
PDF files can have file attachments which processors may access and open or save to a local filesystem.[44]
PDF files can contain two types of metadata.[2] The first is the Document Information Dictionary, a set of key/value fields such as author, title, subject, creation and update dates
This is optional and is referenced from an Info key in the trailer of the file
A small set of fields is defined and can be extended with additional text values if required
This method is deprecated in PDF 2.0.
In PDF 1.4, support was added for Metadata Streams, using the Extensible Metadata Platform (XMP) to add XML standards-based extensible metadata as used in other file formats
PDF 2.0 allows metadata to be attached to any object in the document, such as information about embedded illustrations, fonts, and images, as well as the whole document (attaching to the document catalog), using an extensible schema.
PDF documents can also contain display settings, including the page display layout and zoom level in a Viewer Preferences object
Adobe Reader uses these settings to override the user's default settings when opening the document.[45] The free Adobe Reader cannot remove these settings.
PDF files can be created specifically to be accessible to people with disabilities.[46][47][48][49][50] PDF file formats in use as of 2014[update] can include tags, text equivalents, captions, audio descriptions, and more
Some software can automatically produce tagged PDFs, but this feature is not always enabled by default.[51][52] Leading screen readers, including JAWS, Window-Eyes, Hal, and Kurzweil 1000 and 3000 can read tagged PDFs.[53][54] Moreover, tagged PDFs can be re-flowed and magnified for readers with visual impairments
Adding tags to older PDFs and those that are generated from scanned documents can present some challenges.
One of the significant challenges with PDF accessibility is that PDF documents have three distinct views, which, depending on the document's creation, can be inconsistent with each other
The three views are (i) the physical view, (ii) the tags view, and (iii) the content view
The physical view is displayed and printed (what most people consider a PDF document)
The tags view is what screen readers and other assistive technologies use to deliver high-quality navigation and reading experience to users with disabilities
The content view is based on the physical order of objects within the PDF's content stream and may be displayed by software that does not fully support the tags' view, such as the Reflow feature in Adobe's Reader.
PDF/UA, the International Standard for accessible PDF based on ISO 32000-1 was first published as ISO 14289–1 in 2012 and establishes normative language for accessible PDF technology.
Rich Media PDF is a PDF file including interactive content that can be embedded or linked within the file
It can contain images, audio, video content, or buttons
For example, if the interactive PDF is a digital catalog for an E-commerce business, products can be listed on the PDF pages and can be added with images and links to the website and buttons to order directly from the document.
Interactive Forms is a mechanism to add forms to the PDF file format
PDF currently supports two different methods for integrating data and PDF forms
Both formats today coexist in the PDF specification:[40][55][56][57]
AcroForms were introduced in the PDF 1.2 format
AcroForms permit the uses of objects (e.g
text boxes, Radio buttons, etc.) and some code (e.g
JavaScript)
Alongside the standard PDF action types, interactive forms (AcroForms) support submitting, resetting, and importing data
The "submit" action transmits the names and values of selected interactive form fields to a specified uniform resource locator (URL)
Interactive form field names and values may be submitted in any of the following formats, (depending on the settings of the action's ExportFormat, SubmitPDF, and XFDF flags):[40]
The entire document can be submitted rather than individual fields and values, as was defined in PDF 1.4.
AcroForms can keep form field values in external stand-alone files containing key-value pairs
The external files may use Forms Data Format (FDF) and XML Forms Data Format (XFDF) files.[61][59][62] The usage rights (UR) signatures define rights for import form data files in FDF, XFDF, and text (CSV/TSV) formats, and export form data files in FDF and XFDF formats.[40]
In PDF 1.5, Adobe Systems introduced a proprietary format for forms; Adobe XML Forms Architecture (XFA)
Adobe XFA Forms are not compatible with ISO 32000's AcroForms feature, and most PDF processors do not handle XFA content
The XFA specification is referenced from ISO 32000-1/PDF 1.7 as an external proprietary specification and was entirely deprecated from PDF with ISO 32000-2 (PDF 2.0).
Anyone may create applications that can read and write PDF files without having to pay royalties to Adobe Systems; Adobe holds patents to PDF, but licenses them for royalty-free use in developing software complying with its PDF specification.[63]
In November 2019, researchers from Ruhr University Bochum and Hackmanit GmbH published attacks on digitally signed PDFs.[64] They showed how to change the visible content in a signed PDF without invalidating the signature in 21 of 22 desktop PDF viewers and 6 of 8 online validation services by abusing implementation flaws
At the same conference, they additionally showed how to exfiltrate the plaintext of encrypted content in PDFs.[65] In 2021, they showed new so-called shadow attacks on PDFs that abuse the flexibility of features provided in the specification.[66] An overview of security issues in PDFs regarding denial of service, information disclosure, data manipulation, and arbitrary code execution attacks was presented by Jens Müller.[67][68]
Some popular PDF readers have a history of security vulnerabilities that allows PDF files that have been infected with viruses, Trojans, and other malware to inflict damage
Such PDF files can have hidden JavaScript code that might exploit vulnerabilities in a PDF reader, hidden objects executed when the file that hides them is opened, and, less commonly, a malicious PDF can launch malware.[69]
PDF attachments carrying viruses were first discovered in 2001
The virus, named OUTLOOK.PDFWorm or Peachy, uses Microsoft Outlook to send itself as an attached Adobe PDF file
It was activated with Adobe Acrobat, but not with Acrobat Reader.[70]
Over the years, several vulnerabilities have been discovered in various versions of Adobe Reader, [71] which prompted the company to issue security fixes
Vulnerabilities have been discovered in other PDF readers as well
One aggravating factor is that a PDF reader can be configured to start automatically if a web page has an embedded PDF file, providing a vector for attack
If a malicious web page contains an infected PDF file that takes advantage of a vulnerability in the PDF reader, the system may be compromised even if the browser is secure
Some of these vulnerabilities are a result of badly written PDF readers mishandling JavaScript embedded in the PDF file
Disabling JavaScript execution in the PDF reader can help mitigate such future exploits, although it does not protect against exploits in other parts of the PDF viewing software
Some security experts say that JavaScript is not essential for a PDF reader and that the security benefit that comes from disabling JavaScript outweighs any compatibility issues caused.[72] One way of avoiding PDF file exploits is to have a local or web service convert files to another format before viewing.
On March 30, 2010, security researcher Didier Stevens reported an Adobe Reader and Foxit Reader exploit that runs a malicious executable if the user allows it to launch when asked.[73]
PDF streams can have nested filters, which allows one to craft a 5 kilobyte file that unpacks to 1 petabyte in RAM
This can be used to cause a denial of service with implementations that don't guard against this like it was the case with pypdf's CVE-2025-55197
[74][75]
Many PDF viewers are provided free of charge from a variety of sources
Programs to manipulate and edit PDF files are available, usually for purchase
Additionally, most modern web browsers, including Chrome, Firefox, and Safari, include PDF viewing capabilities, replacing browser plugins that were previously created for such purposes.[76]
There are many software options for creating PDFs, including the PDF printing capabilities built into macOS, iOS,[77] and most Linux distributions
Much document processing software including LibreOffice, Microsoft Office 2007 (if updated to SP2) and later,[78] WordPerfect 9, and Scribus can export documents in PDF
There are many PDF print drivers for Microsoft Windows, the pdfTeX typesetting system, the DocBook PDF tools, applications developed around Ghostscript and Adobe Acrobat itself as well as Adobe InDesign, Adobe FrameMaker, Adobe Illustrator, Adobe Photoshop, that allow a "PDF printer" to be set up, which when selected sends output to a PDF file instead of a physical printer
Google's online office suite Google Docs allows uploading and saving to PDF
Some web apps offer free PDF editing and annotation tools.
The Free Software Foundation was "developing a free, high-quality and fully functional set of libraries and programs that implement the PDF file format and associated technologies to the ISO 32000 standard", as one of its high priority projects.[79][80] In 2011, however, the GNU PDF project was removed from the list of "high priority projects" due to the maturation of the Poppler library,[81] which has enjoyed wider use in applications such as Evince with the GNOME desktop environment
Poppler is based on Xpdf[82][83] code base
There are also commercial development libraries available as listed in List of PDF software.
The Apache PDFBox project of the Apache Software Foundation is an open source Java library, licensed under the Apache License, for working with PDF documents.[84]
Raster image processors (RIPs) are used to convert PDF files into a raster format suitable for imaging onto paper and other media in printers, digital production presses and prepress in a process known as rasterization
RIPs capable of processing PDF directly include the Adobe PDF Print Engine[85] from Adobe Systems and Jaws[86] and the Harlequin RIP from Global Graphics.
In 1993, the Jaws raster image processor from Global Graphics became the first shipping prepress RIP that interpreted PDF natively without conversion to another format
The company released an upgrade to its Harlequin RIP with the same capability in 1997.[87]
Agfa-Gevaert introduced and shipped Apogee, the first prepress workflow system based on PDF, in 1997.
Many commercial offset printers have accepted the submission of press-ready PDF files as a print source, specifically the PDF/X-1a subset and variations of the same.[88] The submission of press-ready PDF files is a replacement for the problematic need for receiving collected native working files.
In 2006, PDF was widely accepted as the standard print job format at the Open Source Development Labs Printing Summit
It is supported as a print job format by the Common Unix Printing System and desktop application projects such as GNOME, KDE, Firefox, Thunderbird, LibreOffice and OpenOffice have switched to emit print jobs in PDF.[89]
Some desktop printers also support direct PDF printing, which can interpret PDF data without external help.
PDF was selected as the "native" metafile format for macOS (originally called Mac OS X), replacing the PICT format of the earlier classic Mac OS
The imaging model of the Quartz graphics layer is based on the model common to Display PostScript and PDF, leading to the nickname Display PDF
The Preview application can display PDF files, as can version 2.0 and later of the Safari web browser.[90][91] System-level support for PDF allows macOS applications to create PDF documents automatically, provided they support the OS-standard printing architecture
The files are then exported in PDF 1.3 format according to the file header
When taking a screenshot under Mac OS X versions 10.0 through 10.3, the image was also captured as a PDF; later versions save screen captures as a PNG file, though this behavior can be set back to PDF if desired.
Adobe Acrobat is one example of proprietary software that allows the user to annotate, highlight, and add notes to already created PDF files
One UNIX application available as free software (under the GNU General Public License) is PDFedit
The freeware Foxit Reader, available for Microsoft Windows, macOS and Linux, allows annotating documents
Tracker Software's PDF-XChange Viewer allows annotations and markups without restrictions in its freeware alternative
Apple's macOS's integrated PDF viewer, Preview, does also enable annotations as does the open-source software Skim, with the latter supporting interaction with LaTeX, SyncTeX, and PDFSync and integration with BibDesk reference management software
Freeware Qiqqa can create an annotation report that summarizes all the annotations and notes one has made across their library of PDFs
The Text Verification Tool exports differences in documents as annotations and markups.
There are also web annotation systems that support annotation in pdf and other document formats

Even without removing the password, most freeware or open source PDF readers ignore the permission "protections" and allow the user to print or make copies of excerpts of the text as if the document were not limited by password protection.[37][38][39]

Beginning with PDF 1.5, Usage rights (UR) signatures are used to enable additional interactive features that are not available by default in a particular PDF viewer application

The signature is used to validate that the permissions have been granted by a bona fide granting authority

For example, it can be used to allow a user:[40]

For example, Adobe Systems grants permissions to enable additional features in Adobe Reader, using public-key cryptography

Adobe Reader verifies that the signature uses a certificate from an Adobe-authorized certificate authority

Any PDF application can use this same mechanism for its own purposes.[40]

Under specific circumstances including non-patched systems of the receiver, the information the receiver of a digital signed document sees can be manipulated by the sender after the document has been signed by the signer.[41]

PAdES (PDF Advanced Electronic Signatures) is a set of restrictions and extensions to PDF and ISO 32000-1[42] making it suitable for advanced electronic signatures

This is published by ETSI as TS 102 778.[43]

PDF files can have file attachments which processors may access and open or save to a local filesystem.[44]

PDF files can contain two types of metadata.[2] The first is the Document Information Dictionary, a set of key/value fields such as author, title, subject, creation and update dates

This is optional and is referenced from an Info key in the trailer of the file

A small set of fields is defined and can be extended with additional text values if required

This method is deprecated in PDF 2.0.

In PDF 1.4, support was added for Metadata Streams, using the Extensible Metadata Platform (XMP) to add XML standards-based extensible metadata as used in other file formats

PDF 2.0 allows metadata to be attached to any object in the document, such as information about embedded illustrations, fonts, and images, as well as the whole document (attaching to the document catalog), using an extensible schema.

PDF documents can also contain display settings, including the page display layout and zoom level in a Viewer Preferences object

Adobe Reader uses these settings to override the user's default settings when opening the document.[45] The free Adobe Reader cannot remove these settings.

PDF files can be created specifically to be accessible to people with disabilities.[46][47][48][49][50] PDF file formats in use as of 2014[update] can include tags, text equivalents, captions, audio descriptions, and more

Some software can automatically produce tagged PDFs, but this feature is not always enabled by default.[51][52] Leading screen readers, including JAWS, Window-Eyes, Hal, and Kurzweil 1000 and 3000 can read tagged PDFs.[53][54] Moreover, tagged PDFs can be re-flowed and magnified for readers with visual impairments

Adding tags to older PDFs and those that are generated from scanned documents can present some challenges.

One of the significant challenges with PDF accessibility is that PDF documents have three distinct views, which, depending on the document's creation, can be inconsistent with each other

The three views are (i) the physical view, (ii) the tags view, and (iii) the content view

The physical view is displayed and printed (what most people consider a PDF document)

The tags view is what screen readers and other assistive technologies use to deliver high-quality navigation and reading experience to users with disabilities

The content view is based on the physical order of objects within the PDF's content stream and may be displayed by software that does not fully support the tags' view, such as the Reflow feature in Adobe's Reader.

PDF/UA, the International Standard for accessible PDF based on ISO 32000-1 was first published as ISO 14289–1 in 2012 and establishes normative language for accessible PDF technology.

Rich Media PDF is a PDF file including interactive content that can be embedded or linked within the file

It can contain images, audio, video content, or buttons

For example, if the interactive PDF is a digital catalog for an E-commerce business, products can be listed on the PDF pages and can be added with images and links to the website and buttons to order directly from the document.

Interactive Forms is a mechanism to add forms to the PDF file format

PDF currently supports two different methods for integrating data and PDF forms

Both formats today coexist in the PDF specification:[40][55][56][57]

AcroForms were introduced in the PDF 1.2 format

AcroForms permit the uses of objects (e.g

text boxes, Radio buttons, etc.) and some code (e.g

JavaScript)

Alongside the standard PDF action types, interactive forms (AcroForms) support submitting, resetting, and importing data

The "submit" action transmits the names and values of selected interactive form fields to a specified uniform resource locator (URL)

Interactive form field names and values may be submitted in any of the following formats, (depending on the settings of the action's ExportFormat, SubmitPDF, and XFDF flags):[40]

The entire document can be submitted rather than individual fields and values, as was defined in PDF 1.4.

AcroForms can keep form field values in external stand-alone files containing key-value pairs

The external files may use Forms Data Format (FDF) and XML Forms Data Format (XFDF) files.[61][59][62] The usage rights (UR) signatures define rights for import form data files in FDF, XFDF, and text (CSV/TSV) formats, and export form data files in FDF and XFDF formats.[40]

In PDF 1.5, Adobe Systems introduced a proprietary format for forms; Adobe XML Forms Architecture (XFA)

Adobe XFA Forms are not compatible with ISO 32000's AcroForms feature, and most PDF processors do not handle XFA content

The XFA specification is referenced from ISO 32000-1/PDF 1.7 as an external proprietary specification and was entirely deprecated from PDF with ISO 32000-2 (PDF 2.0).

Anyone may create applications that can read and write PDF files without having to pay royalties to Adobe Systems; Adobe holds patents to PDF, but licenses them for royalty-free use in developing software complying with its PDF specification.[63]

In November 2019, researchers from Ruhr University Bochum and Hackmanit GmbH published attacks on digitally signed PDFs.[64] They showed how to change the visible content in a signed PDF without invalidating the signature in 21 of 22 desktop PDF viewers and 6 of 8 online validation services by abusing implementation flaws

At the same conference, they additionally showed how to exfiltrate the plaintext of encrypted content in PDFs.[65] In 2021, they showed new so-called shadow attacks on PDFs that abuse the flexibility of features provided in the specification.[66] An overview of security issues in PDFs regarding denial of service, information disclosure, data manipulation, and arbitrary code execution attacks was presented by Jens Müller.[67][68]

Some popular PDF readers have a history of security vulnerabilities that allows PDF files that have been infected with viruses, Trojans, and other malware to inflict damage

Such PDF files can have hidden JavaScript code that might exploit vulnerabilities in a PDF reader, hidden objects executed when the file that hides them is opened, and, less commonly, a malicious PDF can launch malware.[69]

PDF attachments carrying viruses were first discovered in 2001

The virus, named OUTLOOK.PDFWorm or Peachy, uses Microsoft Outlook to send itself as an attached Adobe PDF file

It was activated with Adobe Acrobat, but not with Acrobat Reader.[70]

Over the years, several vulnerabilities have been discovered in various versions of Adobe Reader, [71] which prompted the company to issue security fixes

Vulnerabilities have been discovered in other PDF readers as well

One aggravating factor is that a PDF reader can be configured to start automatically if a web page has an embedded PDF file, providing a vector for attack

If a malicious web page contains an infected PDF file that takes advantage of a vulnerability in the PDF reader, the system may be compromised even if the browser is secure

Some of these vulnerabilities are a result of badly written PDF readers mishandling JavaScript embedded in the PDF file

Disabling JavaScript execution in the PDF reader can help mitigate such future exploits, although it does not protect against exploits in other parts of the PDF viewing software

Some security experts say that JavaScript is not essential for a PDF reader and that the security benefit that comes from disabling JavaScript outweighs any compatibility issues caused.[72] One way of avoiding PDF file exploits is to have a local or web service convert files to another format before viewing.

On March 30, 2010, security researcher Didier Stevens reported an Adobe Reader and Foxit Reader exploit that runs a malicious executable if the user allows it to launch when asked.[73]

PDF streams can have nested filters, which allows one to craft a 5 kilobyte file that unpacks to 1 petabyte in RAM

This can be used to cause a denial of service with implementations that don't guard against this like it was the case with pypdf's CVE-2025-55197

[74][75]

Many PDF viewers are provided free of charge from a variety of sources

Programs to manipulate and edit PDF files are available, usually for purchase

Additionally, most modern web browsers, including Chrome, Firefox, and Safari, include PDF viewing capabilities, replacing browser plugins that were previously created for such purposes.[76]

There are many software options for creating PDFs, including the PDF printing capabilities built into macOS, iOS,[77] and most Linux distributions

Much document processing software including LibreOffice, Microsoft Office 2007 (if updated to SP2) and later,[78] WordPerfect 9, and Scribus can export documents in PDF

There are many PDF print drivers for Microsoft Windows, the pdfTeX typesetting system, the DocBook PDF tools, applications developed around Ghostscript and Adobe Acrobat itself as well as Adobe InDesign, Adobe FrameMaker, Adobe Illustrator, Adobe Photoshop, that allow a "PDF printer" to be set up, which when selected sends output to a PDF file instead of a physical printer

Google's online office suite Google Docs allows uploading and saving to PDF

Some web apps offer free PDF editing and annotation tools.

The Free Software Foundation was "developing a free, high-quality and fully functional set of libraries and programs that implement the PDF file format and associated technologies to the ISO 32000 standard", as one of its high priority projects.[79][80] In 2011, however, the GNU PDF project was removed from the list of "high priority projects" due to the maturation of the Poppler library,[81] which has enjoyed wider use in applications such as Evince with the GNOME desktop environment

Poppler is based on Xpdf[82][83] code base

There are also commercial development libraries available as listed in List of PDF software.

The Apache PDFBox project of the Apache Software Foundation is an open source Java library, licensed under the Apache License, for working with PDF documents.[84]

Raster image processors (RIPs) are used to convert PDF files into a raster format suitable for imaging onto paper and other media in printers, digital production presses and prepress in a process known as rasterization

RIPs capable of processing PDF directly include the Adobe PDF Print Engine[85] from Adobe Systems and Jaws[86] and the Harlequin RIP from Global Graphics.

In 1993, the Jaws raster image processor from Global Graphics became the first shipping prepress RIP that interpreted PDF natively without conversion to another format

The company released an upgrade to its Harlequin RIP with the same capability in 1997.[87]

Agfa-Gevaert introduced and shipped Apogee, the first prepress workflow system based on PDF, in 1997.

Many commercial offset printers have accepted the submission of press-ready PDF files as a print source, specifically the PDF/X-1a subset and variations of the same.[88] The submission of press-ready PDF files is a replacement for the problematic need for receiving collected native working files.

In 2006, PDF was widely accepted as the standard print job format at the Open Source Development Labs Printing Summit

It is supported as a print job format by the Common Unix Printing System and desktop application projects such as GNOME, KDE, Firefox, Thunderbird, LibreOffice and OpenOffice have switched to emit print jobs in PDF.[89]

Some desktop printers also support direct PDF printing, which can interpret PDF data without external help.

PDF was selected as the "native" metafile format for macOS (originally called Mac OS X), replacing the PICT format of the earlier classic Mac OS

The imaging model of the Quartz graphics layer is based on the model common to Display PostScript and PDF, leading to the nickname Display PDF

The Preview application can display PDF files, as can version 2.0 and later of the Safari web browser.[90][91] System-level support for PDF allows macOS applications to create PDF documents automatically, provided they support the OS-standard printing architecture

The files are then exported in PDF 1.3 format according to the file header

When taking a screenshot under Mac OS X versions 10.0 through 10.3, the image was also captured as a PDF; later versions save screen captures as a PNG file, though this behavior can be set back to PDF if desired.

Adobe Acrobat is one example of proprietary software that allows the user to annotate, highlight, and add notes to already created PDF files

One UNIX application available as free software (under the GNU General Public License) is PDFedit

The freeware Foxit Reader, available for Microsoft Windows, macOS and Linux, allows annotating documents

Tracker Software's PDF-XChange Viewer allows annotations and markups without restrictions in its freeware alternative

Apple's macOS's integrated PDF viewer, Preview, does also enable annotations as does the open-source software Skim, with the latter supporting interaction with LaTeX, SyncTeX, and PDFSync and integration with BibDesk reference management software

Freeware Qiqqa can create an annotation report that summarizes all the annotations and notes one has made across their library of PDFs

The Text Verification Tool exports differences in documents as annotations and markups.

There are also web annotation systems that support annotation in pdf and other document formats