The EnCase Evidence File Components and Function

The EnCase evidence file arrangement has what is described as “bag-and-tag” information which consists of information pertaining to case in the header of the file. In addition to the case information data, the image file also contains data and file integrity. Data and file integrity are very important when it come to ensuring the integrity and the proper authentication of the evidence image for court purposes. Message Digest 5 (MD5) and Cyclical Redundancy Check (CRC) are two functions that are used to provide these mechanisms within the EnCase evidence file.

MD5 is an algorithm that is used to verify data integrity through the creation of a 128-bit message digest from data input that is claimed to be as unique to that specific data as a fingerprint is to the specific individual. The result of the calculation is a 128-bit hexadecimal value which provides a number of possible values consisting of 2 ^128. This means that the odds of two files having the same MD5 value is 1 in 2^128. Because the chances are statically remote, the forensic community has adopted and accepted MD5 sufficient for forensic authentication.

CRC is similar in function and purpose to the MD5. The CRC algorithm results in a 32-bit hexadecimal value.

An EnCase evidence file has tree major components: the header, the data blocks and the file integrity component (CRC and MD5). The header will appear on the front end of the evidence file and the data blocks follow the header.

Any additional contribution towards this topic will help for those attempting to obtain the EnCE.

The EnCase Evidence File Format

The EnCase Evidence File Format

The EnCase evidence file can also be referred to as a forensic image file. The concept of an image file is where the entire drive contents of a target media is copied to a file and checksum values are calculated to verify the integrity (useful in court cases) of the image file (often referred to as a “hash value”). Forensic images are acquired with the use of software tools such as the UNIX “dd’ and FTK Imager as well as hardware were cloning devices such as the Solo Masster and Logicube’s MD5 have added forensic functionality.

One major difference between the above mentioned techniques to acquire image files and the EnCase image files is the “bag-and-tag” concept. The UNIX “dd” and many of the hardware cloning devices only provide the bit-for-bit information during acquisition. EnCase on the other hand provides the bit-for-bit data as well as additional data such as case information; data block integrity and file integrity to name a few. These functions are built into the EnCase imaging process for interoperability and ease of use. If the same function were to be implemented using the UNIX “dd” or the hardware options, this process would require many different tools and multiple steps to obtain the same results.

My next posting will be on the "EnCase Evidence File Components and Functions".

What are the phases of the EnCE® exam?

What are the phases of the EnCE® exam?
The EnCE® exam has two phases:

• Phase I of the EnCE® exam is a computer-based test administered by Prometric. Students must obtain a grade of 80% or higher to pass and proceed to Phase II.
• Phase II is a practical test requiring students to examines computer evidence that is sent to them via CD-Rom. Students must submit their findings report to the certification coordinator within 60 days and receive a grade of 85% of higher to pass. A 30-day extension may be granted in certain circumstances. Candidates successfully passing Phase I and II of the process are awarded the EnCE® designation.

How much does the EnCE® program cost?
The total cost for the EnCE® program is $200.00(USD) in the USA and $225.00(USD) internationally . This fee is paid to Prometric to take the Phase I computer-based test. When you register for Phase I of your EnCE® test with Prometric, you will notice the price is listed from $750.00 to $1000.00 (USD). After you enter in your voucher number provided by the Guidance Software certification coordinator, the test price will change to the discounted price. EnCE® certification is inexpensive compared to other professional and IT certifications. The cost was intentionally kept low, as Guidance Software understands many users, especially in the public sector, will not be reimbursed for the fee.

What materials can I use to study for the EnCE® computer-based test?
Guidance Software offering free EnCase® Certified Examiner Study Guides for the computer-based test administered by Prometric. All EnCE® candidates whose applications are approved by the Certification Coordinator will receive a free EnCE® Study Guide by mail. The study guide covers the four parts of the test administered by Prometric including: Examining Computer Based Evidence With Encase®, Computer Knowledge, Good Forensic Practices, and Legal.

If your application for the EnCE® program has been approved and you have received a Prometric voucher number, but have not received you EnCE® Study Guide, please fill out our online Study Guide Request or contact the Guidance Software Certification Coordinator at (626) 229-9191, ext. 513, or email us at certification@guidancesoftware.com

We recommend candidates familiarize themselves with information contained in the following publications:

• EnCase® Legal Journal by Guidance Software
• EnCase® User's Manual by Guidance Software

The EnCase® Forensic Methodology Training manuals also serve as helpful study material. The EnCase® Legal Journal can be downloaded in Adobe Acrobat Reader from Guidance Software's Web site. The EnCase® User's Manual can also be downloaded from Guidance Software's Web site (EnCase® software user name and password required). Some suggested resources for the Computer Knowledge and Good Forensic Practices sections are:

• How Computers Work by Ron White
• Handbook of Computer Crime by Eoghan Casey

What topic areas does the EnCE® computer-based test cover?

• Examining computer based evidence with EnCase®
• The EnCase® Evidence File
• EnCase® Concepts
• The EnCase® Environment
• Searching
• File Signature and Hash Analysis
• Computer Knowledge
• Understanding Data and Binary
• The BIOS
• Computer Boot Sequence
• File Allocation Table Systems
• Computer Hardware Concepts
• Good Forensic Practices
• First Response
• Acquisition of Digital Evidence
• Operating System Artifacts
• Legal (North American EnCE® candidates only)

How do I renew my EnCE®?
The EnCE® designation is valid for two years from the date it is earned. EnCase® Certified Examiners are required to earn sixty-four (64) credit hours of documented continuing education in Computer Forensics or Incident Response every two years to maintain their certification. The training should either be from Guidance, your agency, or an accredited source. You can earn one credit hour for each classroom hour of training and 1/2 credit hour for each one hour of instruction as a Computer Forensics or Incident Response curriculum instructor. Your expiration date is listed on your wallet card. In order for training to qualify for renewal it needs within the two year time period. (Example: If you were certified on 1/1/2005, only training taken between 1/1/2005 and 1/1/2007 would qualify for renewal credits.)

If you were not given certificates, please put the following information in a letter.

Date of the Class
Number of hours
Name of the class
Who provided the training
Short description of the class

When you are ready to submit your renewal credit, please fill out the EnCE® Renewal Form, attach renewal documentation and either mail, fax, or scan/email to:

Certification Coordinator
Guidance Software, Inc.
215 N. Marengo Ave. 2nd floor
Pasadena, CA 91101
Email: certification@guidancesoftware.com
Fax: (626) 432-9558

What if my voucher expires or did not finish my Phase II test before the due date?
- If the Phase I voucher expires, simply contact the Certification Coordinator to obtain a new voucher.
- If anyone does not turn in the Phase II practical with in the time allotted them, they will be required to wait 2 month from the date that the test would have been due and then start the EnCE® process over starting at Phase I.

What if I fail the test?
- Anyone who does not obtain a grade of 80% to pass the Phase I test will be required to wait 2 months before a new voucher will be issued.
- Anyone who does not obtain a grade of 85% to pass the Phase II Practical will be required to wait 2 months before they will be allowed to retest. Those who fail the Phase II will be required to start over at Phase I .
- A new application will be needed if organization of personal information has changed during the 2-month wait period.

Contact Guidance Software's EnCE® certification coordinator at:
Guidance Software
Certification Coordinator
215 North Marengo Avenue
Second Floor
Pasadena, CA 91101
Tel: (626) 229-9191 x 513
certification@guidancesoftware.com