Steganography--for This Dummy

I heard about steganography after the September 11th tragedy. In looking at the hidden writing idea I saw an example in a Target Stores Sept 9th promotion. It required holding a cellophane window on an entry card in front of their decoder (Simply a blue color close to 0033ff, the blue below).


A phrase, "Sorry, You are not a winner.," appeared on each card as it was held in front of the blue light. That is one form of steganography.

Intrigued, I looked further and found an interesting, simple demonstration program at a gold crows site (or old crows if you are familiar with that group. I was an Antique Tiger, myself). The web site has not been updated in several years but the program is still available there. It is called S_Tools and is still being maintained. The three figures below show what it does.


FIGURE 1. Here is a original gif file, 35 kbytes and 8 colors:
Original picture, 33 kbytes

FIGURE 2. And here is the picture with content (a small web page) hidden in it (61 kbytes and 51 colors) Text hidden in this  61 kbyte gif file

FIGURE 3. And finally here is the hidden content exposed. 61 kbytes and 51 colors) The hidden information pictured. 61 kbytes

The central green color is an artifact of the methods used in the original preparation of the picture. Blue, yellow, purple, and red colored dots are at least a portion of the hidden information. A JASC Paint Shop Pro tool, the color replacer, was used to expose the information. By setting the tool to zero tolerance it picked out pixels having the color values 255,255,254 from a broad expanse of 255,255,255 (pure white). These pixels were replaced with blue. Other near white colors were replaced with other contrasting colors. Near black was replaced with yellow. There are other coded pixels I haven't exposed--the number of colors went from 8 to 51. I don't know if the dots are the information or the space between dots is the information or maybe some other scheme is used.

Not only is the contained text hidden, it is scrambled. If you try to decode Figure 2, please use the crypto key "ovk". The amount of hidden text surprised me. The ADDENDUM shows about half of what could be hidden in the 31 kbyte of Figure 1.

I hate to trouble you, but please use the address in the picture below to write to me about this page. I am trying to avoid spam.

Repair for writing Subject: Stegano
Assembled by OVK. Last updated 10/28/2003
Home Page


Read only the heading!!

The hidden content (minus the HTML coding) is shown below. The original web page was 9 kbytes. Don't bother reading it--just scroll down to see the amount of text that can be hidden.



Bicycle-Related Head Injuries

How large is the problem of bicycle-related head injury in the United States? 

  In 1996, 757 bicyclists were killed in crashes with motor vehicles, down 8% since 1985
    and 25% since 1975.1
  In 1996, bicyclists younger than 16 years old accounted for 32% of those killed in
    traffic crashes.1
  According to reports, 96% of bicyclists killed in 1996 were not wearing helmets.1
  Each year about 153,000 children get treatment in hospital emergency departments for
    bicycle-related head injuries.2 
  In 1991, societal costs associated with bicycle-related head injury or death resulting
    from head injury were more than $3 billion.3

How well do bicycle helmets protect against head injury? 

  Bicycle helmets have been shown to reduce the risk for head injury by as much as 85% and
    the risk for brain injury by as much as 88%.4
  It is estimated that 75% of bicycle-related fatalities among children could be prevented
    if all children on bicycles wore helmets.4
  Universal use of bicycle helmets by children aged 4 through 15 years old would prevent
    between 135 and 155 deaths, between 39,000 and 45,000 head injuries, and between 18,000
    and 55,000 scalp and face injuries annually.4
How many bicycle riders wear helmets?

About 18 % of bicyclists wear helmets. Usage appears to be increasing. Just over half
of current users began wearing a helmet during the past 3 years. Among frequent riders,
helmet use appears to increase with age. Getting 50% of bicyclists to wear helmets is a
national health goal for the year 2000.5

What methods are used to get bicyclists to wear helmets? 
  Community education programs.
  School-based education programs. 
  Laws requiring helmet use.
  Discount coupons for bicyclists to buy helmets
  Bicycle rodeos.
  Advocacy of helmet use by admired sports figures.
  "Tickets" for free merchandise given by police to unhelmeted riders if they
    buy a helmet.
Why don’t more people wear helmets? 
  Perhaps the most important reason people do not wear helmets is a lack of appreciation
    for the risk for head injury while bicycling and the effectiveness of helmets in
    preventing such injuries. Many riders believe they need not worry about being injured if
    they are not riding in traffic. 
  Among children, fear of peer derision is a key reason for not wanting to wear helmets.
  Other reasons for not wearing a helmet include high cost, unattractive appearance, and
    lack of ventilation.

What is CDC doing about increasing helmet use? 
  CDC develops and disseminates injury control recommendations on bicycle helmets.6
  CDC gives grants to state health departments to implement and evaluate programs that
    promote helmet use.
  CDC gives funds to special injury control centers to promote helmet use.
  CDC collaborates with the National Highway Traffic Safety
    Administration and other federal agencies to promote bicycle safety.
  CDC collaborates with SAFE KIDS and other private and voluntary agencies to promote
    helmet use and bicycle safety.
  CDC provides funds for research to improve helmet design.

How many states have bicycle helmet laws? 
  To date, 15 states and 56 localities have enacted some form of bicycle helmet
    legislation, most of which covers only young riders.7

If all bicyclists wore helmets, what would be the effect? 

  One life would be saved every day.8
  One head injury would be prevented every 4 minutes.7

What health care costs are associated with not wearing a bicycle helmet? 
  Every bicycle helmet saves this country $395 in direct health care costs and other costs
    to society.4
  If 85% of all child cyclists wore bicycle helmets for one year, the savings in medical
    costs would be between $109 million and $142 million.4
  A person who survives a head injury typically needs 5 to 10 years of intensive
    rehabilitation services. The estimated lifetime cost of these services may exceed $4
    million per injured person.4
What are some tips for preventing injuries while bicycling? 
  Always wear a bicycle helmet everywhere you ride. A bicycle helmet is a necessity, not
    an accessory. 
  Wear a bicycle helmet correctly. A bicycle helmet should fit comfortably and snugly, but
    not too tightly. It should sit on top of your head in a level position, and it should not
    rock forward and back or from side to side. Always keep the helmet straps buckled.
  Buy a bicycle helmet that meets or exceeds the safety standards developed by the
    American National Standards Institute (ANSI), the Snell Memorial Foundation, or the
    American Society for Testing and Materials (ASTM).
  Learn the rules of the road and obey all traffic laws. Ride on the right side of the
    road, with the traffic not against it. Use appropriate hand signals. Respect traffic
    signals. Stop at all intersections marked and unmarked. Stop and look both ways before
    entering a street.
  Restrict children to riding on sidewalks and paths until they are 10 years old, able to
    show good riding skills, and able to observe the basic rules of the road.


1. Insurance Institute for Highway Safety (IIHS). Facts 1996 Fatalities: Bicycles.
Arlington (VA): IIHS, 1997.

2. Sosin DM, Sacks JJ, Webb KW. Pediatric head injuries and deaths from bicycling in
the United States. Pediatrics 1996;98(5):868-70.

3. U.S. Consumer Products Safety Commission (CPSC). Bicycle-related head injury or
death. Washington (DC): CPSC, 1994.

4. National Safe Kids Campaign (NSKC). Fact sheet on bicycle injury. Washington (DC):
NSKC, 1997.

5. Public Health Service (PHS). Health People 2000: Midcourse Review. Washington (DC):
PHS, 1996:88-95.

6. CDC. Injury Control Recommendations: Bicycle Helmets. MMWR 44(RR-1)1995.

7. Bicycle Helmet Safety Institute (BHSI). Mandatory helmet laws: summary. Arlington
(VA): BHSI, 1997.

8. Sacks JJ, Holmgreen P, Smith S, Sosin D. Bicycle-associated head injuries and deaths
in the United States from 1984-1988. JAMA 1991;266:3016-8.
November 1997

Top of Page | The
Bike HUB | CDC Home Page
| CDC Search Page  | NCIPC Home Page