Question

I am developing a tool where a short pass code is generated. That code will be read to the intended user, so I want to limit my character set to letters that are hard to mistake. Both the reader and the listener will be untrained, so any solution must be transparent to them. I want to be able to just give them the passcode and have it exceedingly unlikely that a letter will be misheard.

First off I have limited my possible character list to those characters that look the similar depending on font, so no l or 1, 0 and O are out, as are S and 5, any others you can think of?

Also, I want to remove letters that sound similar, so G&D and B&P are out. Is there a resource of commonly misheard letters?

I know this will cut down on the possible character count severely, but I do need it because of accessibility issues. Also, the person on the receiving end of the code probably won’t be aware that I am limiting the character set. The fact that I am limiting the characters should be transparent to both the person reading the password and the person hearing it.

Answer 1

After taking the suggestions in other answers I this is the reduced list of characters that I have found to be hard to mistake when spoken or viewed.

fhikorsuwxyFHKLQRUWXY246789

Special thanks to:

• David Hedlund
• Kieren Johnstone
• JNK
• Lobsterm

Without their suggestions I would’t have been able to synthesize this list.