Algorithm Details for: Shift and Count

1. Make a duplicate copy of the cipher text.
2. Allign the copy under the original, only shifted by x places.
3. Record x and the number of coincidences (i.e. where the letters match).
4. Increase x and goto step two until you run out of text to shift.
5. The shift with the most coincidences is a likely guess for the key length.

Alogorithm taken from Trappe & Washington pg 19 (see sources page).