Dialog-based voiceprint security for business transactions

1. A system for securing a transaction, comprising:

an authentication server configured to:

receive, over an authentication request application programming interface, a request to authenticate an enrolled user of a client device based on a voiceprint of said user, said request originating at a third party other than said user and comprising an identification of said user and a network address of said client device;

instruct said client device at said network address to instantiate an interactive signature collection applet configured to present to said user a random signature string and record said random signature string as the user speaks said random signature string;

receive said recorded signature string and a device signature of said client device from said interactive signature collection applet;

recognize said recorded signature string using an acoustic model selected based at least in part on the device signature of said client device;

compare said recorded signature string with a stored voiceprint of said user; and

authenticate or reject said user based on a result of said comparison; and

wherein said random signature string is generated subsequent to said authentication server receiving said request; and

wherein said system is configured to initiate a telephone call to said client device and present said random signature string to said user via said telephone call.

2. The system of claim 1 , wherein said third party comprises a server running a business application.

3. The system of claim 2 , wherein said server running said business application comprises a telephony server.

4. The system of claim 1 , wherein said request is received over one of a data network and a voice network.

5. The system of claim 1 , wherein said authentication server is configured to communicate with said client device over one of a data network and a voice network.

6. The system of claim 1 , wherein said authentication server receives said request by receiving signaling comprising said identification of said user, said network address of said client device and said device signature of said client device.

7. The system of claim 1 , wherein said interactive signature collection applet is configured to:

present to said user said random signature string;

prompt said user to speak said random signature string;

record a spoken signature string as an audio file using device-specific recording objects;

gather said device signature by reading a configuration of said client device; and

send said audio file and said device signature to said authentication server.

8. The system of claim 1 , wherein said interactive signature collection applet is configured to report an authentication result to the user.

9. The system of claim 1 , wherein said interactive signature collection applet is one of:

pre-installed on said client device; and

served up from said authentication server.

10. The system of claim 1 , wherein said interactive signature collection applet is software and device-specific.

11. The system of claim 1 , wherein said client device includes:

a software environment capable of running said interactive signature collection applet;

sufficient memory to run said applet;

audio recording capabilities;

readable device configuration data; and

capability to send said recorded signature string and said device configuration data.

12. The system of claim 1 , wherein said client device comprises one of:

a personal computer;

a WAP (wireless access protocol) telephone;

a PDA (personal digital assistant); and

a telephone configured to instantiate said interactive signature collection applet.

13. A system for securing a transaction, comprising:

an authentication server configured to:

receive a request to authenticate an enrolled user of a client device based on a voiceprint of said user from a third party other than said user, said request comprising an identification of said user and a network address of said client device;

instruct said client device at said network address to instantiate an interactive signature collection applet configured to present to said user a random signature string and record said random signature string as the user speaks said random signature string;

receive said recorded signature string from said interactive signature collection applet;

recognize said recorded signature string;

compare said recorded signature string with a stored voiceprint of said user; and

authenticate or reject said user based on a result of said comparison; and

wherein said random signature string is generated subsequent to said authentication server receiving said request; and

wherein said system is configured to initiate a telephone call to said client device and present said random signature string to said user via said telephone call.

14. The system of claim 1 , wherein said interactive signature collection applet is configured to render a dialog box on said client device to present said random signature string to said user.

15. The system of claim 1 , wherein said authentication server is further configured to:

determine a recognition confidence level based at least in part on a comparison of said recognized recorded signature string and said random signature string;

determine a verification confidence level based at least in part on said comparison of said recorded signature string with said stored voiceprint of said user; and

authenticate said user when said recognition confidence level exceeds a threshold recognition confidence level and said verification confidence level exceeds a threshold verification confidence level.

16. The system of claim 15 , wherein said interactive signature collection applet is configured to present a new random signature string to said user when one of:

said recognition confidence level exceeds said threshold recognition confidence level and said verification confidence level does not exceed said threshold verification confidence level; and

said verification confidence level exceeds said threshold verification confidence level and said recognition confidence level does not exceed said threshold recognition confidence level.

17. A method comprising:

receiving, over an authentication request application programming interface, a request to authenticate an enrolled user of a client device based on a voiceprint of said user, said request originating at a third party other than said user and comprising an identification of said user and a network address of said client device;

instructing said client device at said network address to instantiate an interactive signature collection applet configured to present to said user a random signature string and record said random signature string as the user speaks said random signature string;

initiating a telephone call to said client device and presenting said random signature string to said user via said telephone call;

receiving said recorded signature string and a device signature of said client device from said interactive signature collection applet;

recognizing said recorded signature string using an acoustic model selected based at least in part on the device signature of said client device;

comparing said recorded signature string with a stored voiceprint of said user; and

authenticating or rejecting said user responsive to said comparison;

wherein said random signature string is generated subsequent to receiving said request.

18. The method of claim 17 , further comprising:

determining a recognition confidence level based at least in part on a comparison of said recognized recorded signature string and said random signature string;

determining a verification confidence level based at least in part on said comparison of said recorded signature string with said stored voiceprint of said user; and

authenticating said user when said recognition confidence level exceeds a threshold recognition confidence level and said verification confidence level exceeds a threshold verification confidence level.

19. The method of claim 18 , wherein said interactive signature collection applet is configured to present a new random signature string to said user when one of:

said recognition confidence level exceeds said threshold recognition confidence level and said verification confidence level does not exceed said threshold verification confidence level; and

said verification confidence level exceeds said threshold verification confidence level and said recognition confidence level does not exceed said threshold recognition confidence level.

20. The method of claim 17 , wherein said interactive signature collection applet is software and device-specific.