System and method for management of plaintext data in a mobile data processing device

Abstract

A handheld data processing device includes stored data that is intended to be kept secure from unauthorized access. The handheld data processing device includes applications that store such secure data and which make use of plaintext data corresponding to the secure data. An identifier is defined to be associated with defined plaintext data. When the handheld data processing device is placed in a locked or secure state, code executable on the device is able to search for plaintext identifiers. Code executable on the device is consequently able to display to the user whether plaintext data is stored on the device or not.

1 . A method that provides for a secure state on a mobile device, the method comprising:
 generating plain-text data from encrypted data when the encrypted data is requested by an application on the mobile device;   retrievably storing the decrypted plain-text data in memory on the mobile device;   generating an identifier, the identifier associable with the generated plain-text data and comprising an indicator that the associated plain-text data is confidential;   detecting an indication that the mobile device is to enter a secure state;   retrieving and using the identifier to identify the associated plain-text data as confidential and delete the associated plain-text data from the mobile device memory; and   using a next identifier to identify and delete a next confidential plain-text data, if a next identifier comprising confidential plain-text data exists, until no undeleted confidential plain-text data is identified using identifiers.   
     
     
         2 . The method of  claim 1  further comprising, after retrieving the identifier, displaying an indication that confidential plain-text data exists in the memory of the mobile device, and, when there is no undeleted confidential plain-text data identifiable using identifiers, one of: undisplaying the indication, displaying a next indicator there is no more confidential plain-text data in memory, or, both undisplaying the indication and displaying the next indicator. 
     
     
         3 . The method of  claim 1  wherein storing the plaintext data in association with the identifier comprises storing the plaintext data and the associated identifier in a data object in the device memory. 
     
     
         4 . The method of  claim 1 , wherein the identifier comprises at least one bit in a byte array associated with the plaintext data. 
     
     
         5 . The method of  claim 1 , further comprising clearing plaintext data associated with a predetermined security level in response to a request from an application to release the plaintext content prior to receiving the request for the mobile data processing device to enter the secure state. 
     
     
         6 . The method of  claim 1 , further comprising, upon receipt of a request from an application to write plaintext data stored in the device memory to a persistent memory, writing the requested plaintext data to the persistent memory upon determining that the requested plaintext data is not associated with an identifier indicating that the plaintext data is intended to be treated in a secure fashion. 
     
     
         7 . The method of  claim 1  wherein identifies are table entries. 
     
     
         8 . A method that provides for a secure state on a mobile device, the method comprising:
 generating plain-text data from encrypted data if the encrypted data is requested by an application on the mobile device;   retrievably storing the decrypted plain-text data in memory on the mobile device;   generating an identifier, the identifier associable with the generated plain-text data and comprising an indicator that the associated plain-text data is security related;   generating a next identifier associable with plain-text data generated by the application, if and when there is any plain-text data generated by the application to be classified as security related, the next identifier comprising an indicator that the associated plain-text data is security related;   detecting an indication that the mobile device is to enter a secure state;   using the identifier and any next identifiers to determine if there is any associated plain-text data that is security related; and   resetting the mobile device if it was determined there is security related plain-text data.   
     
     
         9 . The method of  claim 7  where indicators further comprise a security level. 
     
     
         10 . The method of  claim 8  where the resetting of the mobile device only occurs when at least one identifier comprises a preselected security level. 
     
     
         11 . A method that provides for a secure state on a mobile device, the method comprising:
 generating plain-text data by an application running on the mobile device, or, generating plaintext data from encrypted data when the encrypted data is requested by the application;   retrievably storing the plain-text data in memory on the mobile device;   generating an identifier, the identifier associable with the generated plain-text data and comprising an indicator that the associated plain-text data is security related;   detecting an indication that the mobile device is to enter a secure state;   retrieving and using the identifier to identify the associated plain-text data that is security related and delete the security related plain-text data from the mobile device memory; and   using a next identifier to identify and delete a next confidential plain-text data, if a next identifier comprising security related plain-text data exists, until no undeleted confidential plain-text data is identified using identifiers.   
     
     
         12 . The method of  claim 11  further comprising, after retrieving the identifier, displaying an indication that confidential plain-text data exists in the memory of the mobile device, and, when there is no undeleted confidential plain-text data identifiable using identifiers, one of: undisplaying the indication, displaying a next indicator there is no more confidential plain-text data in memory, or, both undisplaying the indication and displaying the next indicator. 
     
     
         13 . The method of  claim 11  wherein storing the plaintext data in association with the identifier comprises storing the plaintext data and the associated identifier in a data object in the device memory. 
     
     
         14 . The method of  claim 11  wherein the identifier comprises at least one bit in a byte array associated with the plaintext data, or, the identifiers are table entries. 
     
     
         15 . The method of  claim 11  further comprising, upon receipt of a request from an application to write plaintext data stored in the device memory to a persistent memory, writing the requested plaintext data to the persistent memory upon determining that the requested plaintext data is not associated with an identifier indicating that the plaintext data is intended to be treated in a secure fashion. 
     
     
         16 . The method of  claim 11  where the security level of an indicator further comprising a plurality of security levels, and the clearing plaintext data associated with the indicator depends on the security level of the indicator.