12. The non-transitory computer-usable storage medium of claim 11 , where the user-encoded target length of the target string comprises a user-maintained selection time of a symbol of the sub-sequence, and where the embodied computer program code configured, when executed by a computer, for detecting, via a user input device as part of user entry of a sub-sequence of a sequence of symbols of a target string, a user-encoded target length of the target string comprises computer executable instructions configured, when executed by the computer, for: detecting, during user entry of the symbol of the sub-sequence, a user-maintained press of an input key that enters the symbol of the sub-sequence for a defined duration of time that corresponds to a defined target length; and setting the target length as the defined target length that corresponds to the defined duration of time for which the user-maintained press of the input key that enters the symbol of the sub-sequence was detected.
12. The non-transitory computer-usable storage medium of claim 11 , where the user-encoded target length of the target string comprises a user-maintained selection time of a symbol of the sub-sequence, and where the embodied computer program code configured, when executed by a computer, for detecting, via a user input device as part of user entry of a sub-sequence of a sequence of symbols of a target string, a user-encoded target length of the target string comprises computer executable instructions configured, when executed by the computer, for: detecting, during user entry of the symbol of the sub-sequence, a user-maintained press of an input key that enters the symbol of the sub-sequence for a defined duration of time that corresponds to a defined target length; and setting the target length as the defined target length that corresponds to the defined duration of time for which the user-maintained press of the input key that enters the symbol of the sub-sequence was detected. 13. The non-transitory computer-usable storage medium of claim 12 , where the user input device comprises a keyboard and the input key comprises one key of the keyboard, and where the embodied computer program code configured, when executed by the computer, for detecting, during user entry of the symbol of the sub-sequence, a user-maintained press of an input key that enters the symbol of the sub-sequence for a defined duration of time that corresponds to a defined target length comprises computer executable instructions configured, when executed by the computer, for: measuring an activation time of the input key of a keyboard that enters the symbol of the sub-sequence; and dividing the measured activation time of the input key by a unit of time that defines a single character, with a resulting quotient of the division corresponding to the defined target length.