Govdocs1 – Digital Corpora
Govdocs1 — (nearly) 1 million freely-redistributable files
In recent years a significant amount of forensic research has involved the analysis of files or file fragments. In the absence of such corpora, researchers and students who wish to work with files first need to collect files—a surprisingly difficult task if one wishes a large number of files of many types from a variety of sources. Although many files can be freely downloaded from the web, building and running a high-performance document discovery and downloading tool is not a trivial task. Once files are downloaded they need to be analyzed, characterized and curated. Finally, many corpora that might be assembled cannot be easily redistributed due to privacy or copyright concerns.
For these reasons, we have created and released a corpus of 1 million documents that are freely available for research and may be (to the best of our knowledge) freely redistributed. These documents were obtained by performing searches for words randomly chosen from the Unix dictionary, numbers randomly chosen between 1 and 1 million, and randomized combinations of the two, for documents of specified file types that resided on web servers in the .gov domain using the Yahoo an Google search engines.
Each file in the corpus is presented as a numbered file with a file extension (e.g. 0000001.jpg). The file extension is typically the file extension that was provided to us when the file was downloaded. The file extension is a suggestion—it is not part of the corpus.
We are making the corpus available in several ways:
A set of 1000 directories, with 1000 files in each directory, downloadable from our server at https://downloads.digitalcorpora.org/corpora/files/govdocs1/.
A set of 1000 ZIP files, each with 1000 files, downloadable from our server at https://downloads.digitalcorpora.org/corpora/files/govdocs1/zipfiles/.
A a tar file with 109,282 JPEG pictures from the govdocs1m corpus at https://downloads.digitalcorpora.org/corpora/files/govdocs1/files.jpeg.tar.
As a set of 10 subset “threads” (subset0.zip through subset9.zip), each one containing containing 1000 randomly chosen documents. These subsets were specifically created for to facilitate pilot studies and student research projects with the rationale that it’s easier to work with 1000 files than with 1 million. Students are encouraged to use one subset for development and another subset for testing.
A contextual feature list of data from the digitalcorpora can be found at https://downloads.digitalcorpora.org/corpora/files/2012-feature-list/ 
Other metadata:
MD5 hash values of the ZIP files
SHA1 hash values of the ZIP files
Note: Due to accidental over-collection involving files from the State of California, approximately 13,722 files have been removed from the original corpus of 1 million files.
Metadata
The following metadata is provided for each of the files:
The URL from which the file was downloaded.
The date and time of the download.
The search term that was used.
The search engine that provided the document.
The length and SHA1 of the file.
A Simple Dublin Core for the file.
Unfortunately, the metadata server is currently down.
Malware
Please note that the files in this corpus are verbatim copies of files downloaded from USG webservers. We are aware that some of these files contain malware in the form of JavaScript exploits and Windows malware that was sent to mailing lists (that are now present in the mailing list archives). Although this may trigger some anti-virus programs, the malware will not be removed from the files because it is legitimately part of the corpus.
A malware scan of the govdocs1 directory is now available from https://downloads.digitalcorpora.org/corpora/files/govdocs1/MetascanClientLog_201306281214.txt .
Analysis
Forensic Innovations, Inc., has kindly made available the following analysis of the corpus using its FITools product:
Simple statistical report of the digital corpora.
Citation
Please feel free to let us know if you find this corpus is useful by leaving a comment below. If you decide to use this corpus in published research, the appropriate citation is: Garfinkel, Farrell, Roussev and Dinolt, Bringing Science to Digital Forensics with Standardized Forensic Corpora, DFRWS 2009, Montreal, Canada