Method for permanent decryption of selected sections of an encrypted document

• US 7,870,386 B2
• Filed: 04/29/2004
• Issued: 01/11/2011
• Est. Priority Date: 04/29/2004
• Status: Expired due to Fees

• Current Assignee: LinkedIn Corporation (Microsoft Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Forlenza, Randolph Michael, Berstis, Viktors
• Primary Examiner(s): Moazzami; Nasser
• Assistant Examiner(s): McNally; Michael S
• Application Number:
  US10/835,502
• Publication Number:
  US 20050246526A1
• Time in Patent Office: 2,448 Days
• Field of Search: 713/165
• US Class Current: 713/165
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/088 Usage controlling of secret information, e.g. techniques for restricting cryptographic keys to pre-authorized uses, different access levels, validity of crypto-period, different key- or password length, or different strong and weak cryptographic algorithms network architectures or network communication protocols for using time-dependent keys in a packet data network H04L63/068

Abstract

The present invention allows the viewer of a document to select certain portions of an encrypted document for decryption and optionally re-encryption while other portions of the document remain encrypted or as originally created. In this decryption process, the user would use a standard word processing editor technique to highlight (or swipe) portions of a document that the user desires to decrypt. The highlighted area would then be ‘tagged’ with a surrounding attribute indicating that the highlighted area is to be decrypted. This process is similar to the existing word processor capability to highlight areas on a document and then assign rich text attributes, such as BOLD, ITALICS, etc., to those areas.

Claims

1. A method for selective decryption within an encrypted document, said method comprising:

detecting an encrypted portion of a document, said encrypted portion having been selected and marked for decryption, said encrypted portion being an encryption of a text portion of the document, said text portion comprising a known character string that had been added to the text portion prior to the text portion being encrypted;

receiving a selection of a valid key configured to decrypt the encrypted portion;

ascertaining that an attempt to convert the encrypted portion into a decrypted portion of the document by decrypting the encrypted portion using the valid key was successful, said ascertaining comprising determining that the decrypted portion includes the known character string;

in response to said ascertaining, removing the known character string from the decrypted portion; and

after said removing the known character string, displaying the encrypted portion.

2. The method of claim 1, said text portion comprising both said known character string and a random character string that had been added to the text portion prior to the text portion being encrypted, wherein the method further comprises:

in further response to said ascertaining, removing the random character string from the decrypted portion.

3. The method of claim 1, wherein the document comprises multiple copies of the encrypted portion, wherein each copy of the multiple copies is encrypted with a different encryption key, wherein said decrypting the encrypted portion comprises permanently decrypting the encrypted portion resulting in the decrypted portion being permitted to be edited, and wherein the method further comprises:

in response to said ascertaining, removing from the document each copy of the multiple copies of the encrypted portion such that only plain text of the decrypted portion is retained in the document.

4. The method of claim 1, wherein said decrypting the encrypted portion comprises decrypting the encrypted portion resulting in the decrypted portion being in read-only status and not being permitted to be edited.

5. The method of claim 1, wherein the method further comprises:

receiving a selection of multiple keys; and

selecting the key by attempting to decrypt the encrypted portion successively with each key of the multiple keys until said ascertaining has been has been performed with the valid key.

6. The method of claim 1, wherein said receiving the selection of a valid key comprises:

presenting to a user an identification of a plurality of keys previously entered to open a corresponding plurality of documents; and

receiving from the user the selection of the valid key from the plurality of keys.

7. A computer program product, comprising a computer readable storage medium having a computer readable program code stored therein, said program code configured to be executed by a data processing system to implement a method for selective decryption within an encrypted document, said method comprising:

detecting an encrypted portion of a document, said encrypted portion having been selected and marked for decryption, said encrypted portion being an encryption of a text portion of the document, said text portion comprising a known character string that had been added to the text portion prior to the text portion being encrypted;

receiving a selection of a valid key configured to decrypt the encrypted portion;

ascertaining that an attempt to convert the encrypted portion into a decrypted portion of the document by decrypting the encrypted portion using the valid key was successful, said ascertaining comprising determining that the decrypted portion includes the known character string;

in response to said ascertaining, removing the known character string from the decrypted portion;

after said removing the known character string, displaying the decrypted portion.

8. The computer program product of claim 7, said text portion comprising both said known character string and a random character string that had been added to the text portion prior to the text portion being encrypted, wherein the method further comprises:

in further response to said ascertaining, removing the random character string from the decrypted portion.

9. The computer program product of claim 7, wherein the document comprises multiple copies of the encrypted portion, wherein each copy of the multiple copies is encrypted with a different encryption key, wherein said decrypting the encrypted portion comprises permanently decrypting the encrypted portion resulting in the decrypted portion being permitted to be edited, and wherein the method further comprises:

in response to said ascertaining, removing from the document each copy of the multiple copies of the encrypted portion such that only plain text of the decrypted portion is retained in the document.

10. The computer program product of claim 7, wherein said decrypting the encrypted portion comprises decrypting the encrypted portion resulting in the decrypted portion being in read-only status and not being permitted to be edited.

11. The computer program product of claim 7, wherein the method further comprises:

receiving a selection of multiple keys; and

selecting the key by attempting to decrypt the encrypted portion successively with each key of the multiple keys until said ascertaining has been has been performed with the valid key.

12. The computer program product of claim 7, wherein said receiving the selection of a valid key comprises:

presenting to a user an identification of a plurality of keys previously entered to open a corresponding plurality of documents; and

receiving from the user the selection of the valid key from the plurality of keys.

13. A data processing system comprising a computer readable memory unit, said memory unit containing computer readable program code stored therein, said program code configured to be executed in the data processing system to implement a method for selective decryption within an encrypted document, said method comprising:

detecting an encrypted portion of a document, said encrypted portion having been selected and marked for decryption, said encrypted portion being an encryption of a text portion of the document, said text portion comprising a known character string that had been added to the text portion prior to the text portion being encrypted;

receiving a selection of a valid key configured to decrypt the encrypted portion;

ascertaining that an attempt to convert the encrypted portion into a decrypted portion of the document by decrypting the encrypted portion using the valid key was successful, said ascertaining comprising determining that the decrypted portion includes the known character string;

in response to said ascertaining, removing the known character string from the decrypted portion;

after said removing the known character string, displaying the decrypted portion.

14. The system of claim 13, said text portion comprising both said known character string and a random character string that had been added to the text portion prior to the text portion being encrypted, wherein the method further comprises:

in further response to said ascertaining, removing the random character string from the decrypted portion.

15. The system of claim 13, wherein the document comprises multiple copies of the encrypted portion, wherein each copy of the multiple copies is encrypted with a different encryption key, wherein said decrypting the encrypted portion comprises permanently decrypting the encrypted portion resulting in the decrypted portion being permitted to be edited, and wherein the method further comprises:

in response to said ascertaining, removing from the document each copy of the multiple copies of the encrypted portion such that only plain text of the decrypted portion is retained in the document.

16. The system of claim 13, wherein said decrypting the encrypted portion comprises decrypting the encrypted portion resulting in the decrypted portion being in read-only status and not being permitted to be edited.

17. The system of claim 13, wherein the method further comprises:

receiving a selection of multiple keys; and

selecting the key by attempting to decrypt the encrypted portion successively with each key of the multiple keys until said ascertaining has been has been performed with the valid key.

18. The system of claim 13, wherein said receiving the selection of a valid key comprises:

presenting to a user an identification of a plurality of keys previously entered to open a corresponding plurality of documents; and

receiving from the user the selection of the valid key from the plurality of keys.