Method and device for secure phone banking

Abstract

A small form-factor security device is provided that may be inserted in series with a telephone line to encrypt dual tone multi-frequency (DTMF) tones from a telephone to prevent unauthorized disclosure of sensitive information. A receiving device decrypts the encrypted DTMF tones to receive the original information sent by the telephone. The security device acts as a second factor in a two-factor authentication scheme with a tele-services security server that authenticates the security device.

What is claimed is: 
     
         1 . A method operational on a small form-factor telephone security device, comprising:
 receiving dual tone multi-frequency (DTMF) tones from a telephone over a first communication interface;   encrypting the DTMF tones received from the telephone; and   sending the encrypted DTMF tones to a security server over a second communication interface.   
     
     
         2 . The method of  claim 1  further comprising:
 receiving an activation signal from the security device; and 
 placing the security device into an active mode of operation once the activation signal is received, wherein active mode the security device is configured to
 encrypt DTMF tones received from the telephone are, and 
 allow voice signals to pass through the security device unchanged. 
 
 
     
     
         3 . The method of  claim 1  further comprising:
 passing DTMF tones from the telephone through unchanged between the first communication interface to a second communication interface in a passive mode of operation. 
 
     
     
         4 . The method of  claim 1  further comprising:
 powering the security device upon a call being initiated between the telephone and the security server. 
 
     
     
         5 . The method of  claim 1  further comprising:
 receiving an authentication challenge from the security server; 
 replying to the authentication challenge with an authentication response; and 
 receiving a confirmation indicating that the security server has successfully authenticated the security device. 
 
     
     
         6 . The method of  claim 1  further comprising:
 converting a first DTMF tone received over the first communication interface into a first symbol; 
 pseudorandomly selecting a translation table from a plurality of translation tables; 
 translating the first symbol into a second symbol using the selected translation table; 
 converting the second symbol into a second DTMF tone; and 
 sending the second DTMF tone as the encrypted DTMF tone. 
 
     
     
         7 . The method of  claim 6  further comprising:
 obtaining a pseudorandom number from a keystream generated at the security device; and 
 shuffling symbols in a base translation table based on the pseudorandom number to obtain the selected translation table. 
 
     
     
         8 . The method of  claim 6  further comprising:
 converting DTMF tones received over the first communication interface into associated symbols within a set of symbols; 
 pseudorandomly selecting an associated translation table from a plurality of translation tables for each DTMF tone received; and 
 translating the associated symbol for each DTMF tone received into an encrypted symbol based on its associated translation table. 
 
     
     
         9 . The method of  claim 1  wherein the security device is positioned proximate the telephone and coupled in series between the telephone and the security server. 
     
     
         10 . The method of  claim 1  further comprising:
 detecting the telephone number called by the telephone; 
 encrypting DTMF tones received from the telephone if the telephone number is recognized as an associated secure institution; and 
 passing DTMF tones received from the telephone to the security server unchanged otherwise. 
 
     
     
         11 . A small form-factor telephone security device, comprising:
 means for receiving dual tone multi-frequency (DTMF) tones from a telephone over a first communication interface;   means for encrypting the DTMF tones received from the telephone; and   means for sending the encrypted DTMF tones to a security server over a second communication interface.   
     
     
         12 . The device of  claim 11  further comprising:
 means for receiving an activation signal from the security device; and 
 means for placing the security device into an active mode of operation once the activation signal is received. 
 
     
     
         13 . The method of  claim 11  further comprising:
 means for passing DTMF tones through unchanged between the first communication interface to a second communication interface in a passive mode of operation. 
 
     
     
         14 . The device of  claim 11  further comprising:
 means for converting a first DTMF tone received over the first communication interface into a first symbol; 
 means for pseudorandomly selecting a translation table from a plurality of translation tables; 
 means for translating the first symbol into a second symbol using the selected translation table; 
 means for converting the second symbol into a second DTMF tone; and 
 means for sending the second DTMF tone as the encrypted DTMF tone. 
 
     
     
         15 . The device of  claim 14  further comprising:
 means for obtaining a pseudorandom number from a keystream generated at the security device; and 
 means for shuffling symbols in a base translation table based on the pseudorandom number to obtain the selected translation table. 
 
     
     
         16 . A small form-factor telephone security device, comprising:
 a first communication interface for communicating with a telephone;   a second communication interface for communicating with a security server;   a processing circuit coupled between the first communication interface and the second communication interface, the processing circuit configured to:
 receive dual tone multi-frequency (DTMF) tones from the telephone; 
 encrypt the received DTMF tones; and 
 send the encrypted DTMF tones to the security server. 
   
     
     
         17 . The device of  claim 16  wherein the processing circuit is further configured to
 receive an activation signal from the security device; and 
 place the security device into an active mode of operation once the activation signal is received. 
 
     
     
         18 . The device of  claim 16  the processing circuit is further configured to
 pass DTMF tones through unchanged between the first communication interface to a second communication interface in a passive mode of operation. 
 
     
     
         19 . The device of  claim 16  further comprising:
 a DTMF tone detector coupled to the processing circuit to detect when a DTMF tone is received over the first communication interface; and 
 a DTMF encryption module coupled to the processing circuit to assist the processing circuit in converting a received DTMF tone into an encrypted DTMF tone. 
 
     
     
         20 . The device of  claim 16  wherein the processing circuit is further configured to
 convert a first DTMF tone received over the first communication interface into a first symbol; 
 pseudorandomly select a translation table from a plurality of translation tables; 
 translate the first symbol into a second symbol by using the selected translation table; 
 convert the second symbol into a second DTMF tone; and 
 send the second DTMF tone as the encrypted DTMF tone. 
 
     
     
         21 . The device of  claim 20  wherein the processing circuit is further configured to
 obtain a pseudorandom number from a keystream generated at the security device; and 
 shuffle symbols in a base translation table based on the pseudorandom number to obtain the selected translation table. 
 
     
     
         22 . A machine-readable medium having one or more instructions operational on a security device for securing information transmitted by a telephone, which when executed by a processor causes the processor to:
 receive dual tone multi-frequency (DTMF) tones from the telephone over a first communication interface;   encrypt the DTMF tones received from the telephone; and   sending the encrypted DTMF tones over a second communication interface.   
     
     
         23 . The machine-readable medium of  claim 22  having one or more instructions which when executed by a processor causes the processor to further:
 place the security device into an active mode of operation if an activation signal is received, wherein activation mode received DTMF tones are converted to encrypted DTMF tones; and 
 pass DTMF tones through unchanged between the first communication interface to a second communication interface in a passive mode of operation. 
 
     
     
         24 . The machine-readable medium of  claim 22  having one or more instructions which when executed by a processor causes the processor to further:
 authenticate the security device with a receiving device coupled to the second communication interface. 
 
     
     
         25 . The machine-readable medium of  claim 22  having one or more instructions which when executed by a processor causes the processor to further:
 generate a pseudorandom number; 
 select a translation table from a plurality of translation tables based on the pseudorandom number; and 
 translate a first DTMF tone received from the telephone into a second DTMF tone based on the selected translation table. 
 
     
     
         26 . The machine-readable medium of  claim 25  having one or more instructions which when executed by a processor causes the processor to further:
 generate other pseudorandom numbers for subsequent DTMF tones received from the telephone; 
 select a translation table from the plurality of translation tables for each subsequent DTMF tone received based on the other pseudorandom numbers; and 
 translate each DTMF tone received from the telephone into a other DTMF tones based on their selected translation tables. 
 
     
     
         27 . A method operational on a telephone security server, comprising:
 receiving a call from a dual tone multi-frequency (DTMF)-enabled telephone;   sending an activation signal to a security device associated with the DTMF-enabled telephone to activate encryption of DTMF tones from the telephone;   receiving encrypted DTMF tones from the security device; and   decrypting the received DTMF tones to obtain information sent by the telephone.   
     
     
         28 . The method of  claim 27  wherein the security device is positioned proximate the telephone and coupled in series between the telephone and the security server. 
     
     
         29 . The method of  claim 27  further comprising:
 sending an authentication challenge to the security device; 
 receiving an authentication response from the security device; and 
 sending a confirmation to the security device if the authentication response is valid for the authentication challenge. 
 
     
     
         30 . The method of  claim 27  wherein decrypting a received DTMF tone results in obtaining part of a number entered by a user of the telephone. 
     
     
         31 . The method of  claim 27  further comprising:
 synchronizing a symbol encryption algorithm between the security server and the security device. 
 
     
     
         32 . The method of  claim 27  wherein decrypting the received DTMF tones includes
 converting a first DTMF tone into a first symbol; 
 translating the first symbol into a second symbol using a pseudorandomly selected symbol-to-symbol reverse translation table; and 
 converting the second symbol into a second DTMF tone. 
 
     
     
         33 . A telephone security server, comprising:
 means for receiving a call from a dual tone multi-frequency (DTMF)-enabled telephone;   means for sending an activation signal to a security device associated with the DTMF-enabled telephone to activate encryption of DTMF tones from the telephone;   means for receiving encrypted DTMF tones from the security device; and   means for decrypting the received DTMF tones to obtain information sent by the telephone.   
     
     
         34 . The telephone security server of  claim 33  further comprising:
 means for sending an authentication challenge to the security device; 
 means for receiving an authentication response from the security device; and 
 means for sending a confirmation to the security device if the authentication response is valid for the authentication challenge. 
 
     
     
         35 . The telephone security server of  claim 33  further comprising:
 means for converting a first DTMF tone into a first symbol; 
 means for translating the first symbol into a second symbol using a pseudorandomly selected symbol-to-symbol reverse translation table; and 
 means for converting the second symbol into a second DTMF tone. 
 
     
     
         36 . A telephone security server, comprising:
 a communication module for receiving telephone calls from dual tone multi-frequency (DTMF) enabled telephones;   a DTMF decryption module for decrypting encrypted DTMF tones; and   a processing circuit coupled to the communication module and the DTMF decryption module, the processing circuit configured to:
 receive encrypted DTMF tones from a security device associated with a DTMF-enabled telephone; and 
 decrypt the received DTMF tones to obtain information sent by the telephone. 
   
     
     
         37 . The server of  claim 36  wherein the processing circuit is further configured to
 receive a call from the DTMF-enabled telephone; and 
 send an activation signal to the security device associated with the DTMF-enabled telephone to activate encryption of DTMF tones from the telephone. 
 
     
     
         38 . The server of  claim 36  further comprising:
 an authentication module to authenticate the security device. 
 
     
     
         39 . The server of  claim 36  wherein the processing circuit is further configured to
 convert a first DTMF tone into a first symbol; 
 translate the first symbol into a second symbol using a pseudorandomly selected symbol-to-symbol reverse translation table; and 
 convert the second symbol into a second DTMF tone. 
 
     
     
         40 . A machine-readable medium having one or more instructions operational on a telephone security server for securing information transmitted from a telephone as dual tone multi-frequency (DTMF) tones, which when executed by a processor causes the processor to:
 authenticate a security device associated with the telephone;   receive encrypted DTMF tones from the security device; and   decrypt the received DTMF tones to obtain information sent by the telephone.   
     
     
         41 . The machine-readable medium of  claim 40  having one or more instructions which when executed by a processor causes the processor to further:
 receive a call from the telephone; and 
 send an activation signal to a security device associated with the telephone to activate encryption of DTMF tones from the telephone. 
 
     
     
         42 . The machine-readable medium of  claim 40  having one or more instructions which when executed by a processor causes the processor to further:
 convert the encrypted DTMF tones into digital symbols; 
 obtain a symbol-to-symbol reverse translation table for each of the digital symbols; and 
 translate each digital symbol using the reverse translation table.