15. The computer system of claim 13 , wherein the first string of characters further includes a third set of one or more characters, further comprising: program instructions, stored on at least one of the one or more computer readable storage media for execution by at least one of the one or more processors, to assign a second substitute character to be used as input for each of the third set of one or more characters; and program instructions, stored on at least one of the one or more computer readable storage media for execution by at least one of the one or more processors, to present an indication of the second substitute character and an indication of when to use the second substitute character to the user.
15. The computer system of claim 13 , wherein the first string of characters further includes a third set of one or more characters, further comprising: program instructions, stored on at least one of the one or more computer readable storage media for execution by at least one of the one or more processors, to assign a second substitute character to be used as input for each of the third set of one or more characters; and program instructions, stored on at least one of the one or more computer readable storage media for execution by at least one of the one or more processors, to present an indication of the second substitute character and an indication of when to use the second substitute character to the user. 16. The computer system of claim 15 , wherein program instructions determine whether the second string of characters substantially matches, within a predetermined threshold, the first string of characters based on the first substitute character assigned to each of the second set of one or more characters comprise: program instructions to determine whether the second string of characters substantially matches, within the predetermined threshold, the first string of characters based on the first substitute character assigned to each of the second set of one or more characters and the second substitute character assigned to each of the third set of one or more characters.