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I just had a user tell me his registration key didn't work. It took me quite a while to figure out that he entered the capital letter "O" instead of the number "0".

So I decided that it is best for my registry checker to treat both "O" and "0" as equivalent, so both will work.

I can think of two other possible mixups:

  1. The number "1" and the capital letter "I" and the small letter "l"
  2. The number "5" and the letter "S" or "s".

Are these all of them, or are there others?

Mark Cidade
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lkessler
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  • I don't know whether this applies to your product, but my registration keys are deliberately too big to type - you have to cut and paste them. Issues like this never crop up. – RichieHindle Aug 22 '09 at 18:15
  • Personally, I think very long registration keys cause users more frustration than not. It's fine when they first get the product, but what if they get a new machine and have to reinstall and no longer have the email. If it's printed, it's a real pain to type in again. There are better ways to protect your software than by just making a long registration key. – lkessler Aug 22 '09 at 21:21
  • 0 and o are most likely to get mixed up because they are right next to each other on the keyboard and it is hard to notice the difference in most fonts – Cameron Aug 22 '09 at 21:46

2 Answers2

3

2 and Z or z. Possibly 9 and g, or 8 and B or 6 and G.

wnoise
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  • Unfortunately I just realized that B and 8 are bad ones if you are using the 16 Hex digits: 0..9, A..F – lkessler Nov 22 '09 at 08:57
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A better solution might be to display the registration key using a font that clearly differentiates between O and 0 and I, 1, and l. Alternatively you could rework the registration system so that the user, in the normal case, does not have to directly enter a key.

Ben Hughes
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