A method for improving the security of user secret authentication data during authentication transactions comprising: storing, within an authentication database of an authentication computer system, at least data records and user text-string registries; generating scrambled secret authentication data by determining text-strings and associating each of the text-strings with a different item of information in the secret authentication data, wherein at least one of the text-strings is included in a user text-string registry and at least one of the text-strings is a new text-string not included in the user text-string registry; displaying the determined text-strings and the associated different items of information of the secret authentication data on a communications device; capturing voice biometric data from a user with the communications device as the result of reciting the text-strings corresponding to the items of information included in the secret authentication data of the user; and conducting an authentication (64, 74) transaction with the captured voice biometric data using the authentication computer system to authenticate the user when a transformation of the recited text-strings into items of information corresponds to the secret authentication data stored for the user and the biometric data of the recited text-strings that are stored in the user text-string registry matches the enrollment data for the same text-strings of the user stored therein, and adding said at least one new text-string to the text-string registry and the captured biometric data of said at least one new text-string to the enrollment data record of the user after successfully authenticating the user such that said at least one new text-string can be used as an authentication text-string in a future authentication transaction. storing, within an authentication database of an authentication computer system, at least data records and user text-string registries; generating scrambled secret authentication data by determining text-strings and associating each of the text-strings with a different item of information in the secret authentication data, wherein at least one of the text-strings is included in a user text-string registry and at least one of the text-strings is a new text-string not included in the user text-string registry; displaying the determined text-strings and the associated different items of information of the secret authentication data on a communications device; capturing voice biometric data from a user with the communications device as the result of reciting the text-strings corresponding to the items of information included in the secret authentication data of the user; and conducting an authentication (64, 74) transaction with the captured voice biometric data using the authentication computer system to authenticate the user when a transformation of the recited text-strings into items of information corresponds to the secret authentication data stored for the user and the biometric data of the recited text-strings that are stored in the user text-string registry matches the enrollment data for the same text-strings of the user stored therein, and adding said at least one new text-string to the text-string registry and the captured biometric data of said at least one new text-string to the enrollment data record of the user after successfully authenticating the user such that said at least one new text-string can be used as an authentication text-string in a future authentication transaction.