Method and system for encoding signatures to authenticate files

• US 20040054906A1
• Filed: 09/09/2003
• Published: 03/18/2004
• Est. Priority Date: 09/12/2002
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Carro, Fernando Incertis
• Granted Patent: US 7,287,164 B2
• Time in Patent Office: Days
• US Class Current: 713/171
• CPC Class Codes: G06F 21/64 Protecting data integrity, e.g. using checksums, certificates or signatures
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

Method and system for verifying the authenticity and integrity of files transmitted through a computer network. Authentication information is encoded in the filename of the file. In a preferred embodiment, authentication information is provided by computing a hash value of the file, computing a digital signature of the hash value using a private key, and encoding the digital signature in the filename of the file at a predetermined position or using delimiters, to create a signed filename. Upon reception of a file, the encoded digital signature is extracted from the signed filename. Then, the encoded hash value of the file is recovered using a public key and extracted digital signature, and compared with the hash value computed on the file. If the decoded and computed hash values are identical, the received file is processed as authentic.

Claims

1. A computer file containing digital data wherein authentication information is encoded in the filename of said computer file at a predetermined position or using delimiters.

2. A method for encoding authentication information in the filename of a computer file containing digital data, said method comprising the steps of:

computing a digital signature of the computer file using a private key of a sender; and

,

encoding said computed digital signature in a filename of said computer file at a predetermined position or using delimiters.

3. The method of claim 2, wherein the step of encoding said computed digital signature includes the step of adding said computed digital signature in the filename just before the file extension, said computed digital signature having a fixed size.

4. The method of claim 2, wherein the step of computing a digital signature is based on a symmetric or public-key algorithm.

5. The method of claim 2, wherein the step of computing a digital signature includes the steps of:

computing a hash value of said computer file; and

computing a digital signature of the computed hash value using the private key of the sender.

6. The method of claim 5, wherein said step of computing a hash value uses a Secure Hash Algorithm or a Message-Digest-5 algorithm.

7. The method of claim 2, further comprising the step of applying said method to files attached or linked to the computer file.

8. Apparatus comprising means adapted for carrying out the method according to claim 2.

9. A computer readable medium comprising program instructions for carrying out the method according to claim 2.

10. A method for authenticating a computer file having a filename comprising authentication information, said method comprising the steps of:

extracting said authentication information from the filename of the computer file at a predetermined position or using delimiters;

recovering an encoded hash value of the computer file by using a public key of a sender of the computer file and the extracted authentication information;

computing a hash value of said computer file using a hash function used by the sender to generate the encoded authentication information;

comparing the encoded and the computed hash values; and

,

if the encoded and the computed hash values are identical, processing the computer file, else, if the encoded and the computed hash values are different, rejecting the computer file.

11. The method of claim 10, further comprising the step of applying said method to files attached or linked to the computer file.

12. Apparatus comprising means adapted for carrying out the method according to claim 10.

13. A computer readable medium comprising program instructions for carrying out the method according to claim 10.