I bought Utilitech #0141224 7 day digital in wall timer. I have just 2 wires at the junction box both of which are painted over but assume one could be black and other white. The 7 day digital timer has red, black, white, and green leads. There is not wire in the junction box for green ground lead. So how do I hook up the timer? I tried attaching the red and white wires from the timer together and into one of the wires from junction box but my front porch light comes off and on at 60 Hz blinks. So tried hooking black to black and white to other wire in the junction box but then could not switch the outside light on with the on/off button.

If your box contains 2 and only 2 wires, then the Utilitec timer will not work.
You need the Intermatic ST01C or EJ500 timers that operate with a battery.

I have tested the Intermatic and Utilitec timers:
http://waterheatertimer.org/Program-wire-Utilitec-0141224.html
http://waterheatertimer.org/ST01C-program.html#wire
Do not connect white and red wires together on any timer, but thank you for solving the problem why lights blink when connecting timers.

Now lets look at your wires.
Scrape paint off the wires so you can identify white and black.
According to your information, the black wire inside box will connect to timer-black wire.
The red wire always goes to Load (your light, fan, motor)
The white wire is necessary to complete a circuit so the clock inside timer will operate.
The timer has a clock just like your alarm clock, and it needs to connect back to neutral busbar in breaker box.
This is why the battery-operated timers will work with two wires, the clock runs on battery.
The Utilitec timer-white wire is the wire that goes to Neutral
The timer-white wire is supposed to connect to the other white wires that are twisted together and covered with a wire nut ... but some boxes do not have this neutral wire
To work-around, the timer-white wire can also connect to a bare ground wire.
The bare ground wire also connects to Neutral busbar in breaker box

If you do not have a neutral or ground wire as described above, then you need the battery-powered ST01C or EJ500 Intermatic timers.
See if you can pull some more of the wire into your box ... there might be a ground wire that was cut off and pulling more wire might reveal a ground wire. This will salvage the project.
Aplus is one of many places that sell the Intermatic timer
http://www.aplussupply.com/intermatic/timer.htm

For more about electric wiring:
http://waterheatertimer.org/See-inside-main-breaker-box.html
http://waterheatertimer.org/B220C.html