Apparatus for proving original document of electronic mail

• US 20050102499A1
• Filed: 09/24/2004
• Published: 05/12/2005
• Est. Priority Date: 09/25/2003
• Status: Abandoned Application

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kosuga, Masayuki, Nunokami, Hiroyasu
• Application Number:
  US10/948,269
• Publication Number:
  US 20050102499A1
• Time in Patent Office: Days
• US Class Current: 713/152
• CPC Class Codes: G06F 21/64 Protecting data integrity, e.g. using checksums, certificates or signatures
• CPC Class Codes: H04L 51/23 Reliability checks, e.g. acknowledgments or fault reporting
• CPC Class Codes: H04L 63/12 Applying verification of the received information cryptographic mechanisms or cryptographic arrangements for data integrity or data verification H04L9/32

Abstract

An authenticity assurance apparatus for e-mail documents which preserves a transmitted e-mail includes a unit to add a digital signature to an e-mail document and a file attached to it at time of transmitting the mail from a sender and from the apparatus; a unit to check for a mail tampering by using the digital signature at time of receiving the mail by the apparatus and by a recipient; a unit to inform the sender and the recipient of the tampering when detected; a unit to preserve the mail and the associated data on an unoverwritable database; a unit to meet a requirement of integrity by creating and adding a time stamp; a unit to encrypt and preserve the e-mail document and the attached file; and a unit to meet a requirement of confidentiality of the e-mail document by limiting an access to the database.

Claims

1. An authenticity assurance apparatus for e-mail documents for preserving a transmitted e-mail document and a file attached thereto, comprising:

means for detecting a tampering with the e-mail document and the attached file;

means for notifying a sender and a recipient of the tampering when detected;

means for encrypting the e-mail document and the attached file and preserving the encrypted ones in a storage;

means for creating a time stamp signature and attaching the created signature to the e-mail; and

means for restricting an access to the storage in which the e-mail document and the attached file are preserved.

2. An authenticity assurance apparatus for e-mail documents according to claim 1, wherein the tampering detecting means receives digital data containing a body of the e-mail received from a mail sending device and a hash value of the digital data, matches a hashed value of the digital data with the received hash value, and, if not matched, decides that the e-mail has been tampered with.

3. An authenticity assurance apparatus for e-mail documents according to claim 1, wherein the encrypting and preserving means doubly encrypts encrypted data received from the mail sending device by using an encryption key stored in the authenticity assurance apparatus for e-mail documents and then records the doubly encrypted data in the database.

4. An authenticity assurance apparatus for e-mail documents according to claim 1, wherein the time stamp signature is digital data created by encrypting with a private key a combination of hash values of an encrypted mail body received from the mail sending device, a re-converted property made up of data of a destination and a title name, a time recording file for transmission that records a time at which the digital data received from the mail sending device was recorded, and a previously created time stamp signature.

9. A time stamp signature verifying method for verifying the time stamp signature of claim 6 by performing the steps of:

inputting encrypted data of the time stamp signature defined in claim 4;

and

comparing a hash value of data of the encrypted mail body of the received e-mail, the re-converted property and the time recording file for transmission with a corresponding hash value obtained by decrypting the encrypted time stamp signature.

10. An authenticity assurance apparatus for e-mail documents comprising:

an input unit which accepts account information of a user when a request is made for retransmitting a stored e-mail defined in claim 1;

an output unit which when the e-mail is accessible, search and output information on an encrypted property based on information on correspondence between a mail ID and a user ID; and

a retransmission unit which retransmits the mail selected by the user to a device on the user side according to an output result.

5. A mail transmission program for causing a computer that transmits a mail to execute:

a function of duplicating digital data of the mail to be transmitted;

a function of changing destination addresses to which the digital data of the duplicated mails is to be transmitted to an authenticity assurance apparatus for e-mail documents;

a function of encrypting a mail body and an attached file in the digital data; and

a function of transmitting a title name, a destination, the encrypted mail body and attached file, and a mail sender certifying signature to the authenticity assurance apparatus for e-mail documents.

8. A mail transmission program for causing a computer to transmit a mail, according to claim 5,

wherein when a tag is added to the title name of the mail, the program causes the computer to execute

a function of changing destination addresses to which the digital data of the reproduced mails is to be transmitted to the authenticity assurance apparatus for e-mail documents and

a function of adding a recipient'"'"'s address to the title name of each of the duplicated mails

6. A received mail processing program for causing a computer that has received a mail to execute:

a function of verifying a received sender certifying signature by using a signature verifying key;

a function of verifying a received time stamp signature;

a function of, when the verification result is abnormal, outputting to an output device an alert message to inform a recipient of an anomaly; and

a function of, when the verification result is abnormal, returning a warning mail to an authenticity assurance apparatus for e-mail documents as a mail transmission source.

7. A mail transmission/reception acknowledging program for causing computers to execute:

a function of, when informed by a computer that has received a mail that a result of verifying a sender certifying signature or a time stamp signature is abnormal, transmitting a warning mail to a computer that has transmitted the mail and other computers that have received the mail;

a function of, when the sender certifying signature and the time stamp signature are received as a reception acknowledge mail from the computers that received the mail, matching them with information on the sender certifying signature and the time stamp signature already recorded in a storage;

a function of, when the result of verification is abnormal, sending a warning mail to the mail transmitting computer and the mail receiving computers; and

a function of, when it is found that there is no anomaly with all the mail receiving computers, sending to the mail transmitting computer an acknowledge mail containing a message indicating a transmission/reception is successfully completed and a mail ID.