End to end file-sharing schema using signed Merkle tree randomly originated keys

Patent metadata

Field	Value
Publication number	US-12225113-B2
Application number	US-202217932904-A
Country	US
Kind code	B2
Filing date	Sep 16, 2022
Priority date	Sep 16, 2022
Publication date	Feb 11, 2025
Grant date	Feb 11, 2025

Abstract

A process for transmitting a file from a sender device to a receiver device includes generating a random symmetric session key for the sender device, and randomly selecting a private ephemeral key for the sender device. The private ephemeral key is associated with a corresponding first public key. A public ephemeral key is randomly selected for the receiving device. The public ephemeral key is associated with a corresponding first private key. A random value is generated, an encrypted session key is calculated, and the file is encrypted using symmetric encryption. The sender device includes a first public X509 certificate comprising a second public key and a corresponding second private key that is signed by a service provider, and the receiver device includes a second public X509 certificate comprising a third public key and a corresponding third private key.

First claim

The invention claimed is:

1. A process for transmitting a file from a sender device to a receiver device comprising:
generating a random symmetric session key for the sender device;
randomly selecting a private ephemeral key for the sender device, the private ephemeral key associated with a corresponding first public key;
wherein the receiver device comprises a randomly selected public ephemeral key, the public ephemeral key associated with a corresponding first private key;
generating a random value within a range;
calculating an encrypted session key;
encrypting the file using symmetric encryption; and
transmitting from the sender device to the receiver device a group ID, the encrypted session key, the random value, a sender device ID, a receiver device ID, a hashed file ID, a sender key ID, and a receiver key ID, wherein the receiver device includes a record comprising the random value, the sender device ID, the hashed file ID, and the group ID;
wherein the sender device comprises a first public X509 certificate comprising a second public key and a corresponding second private key that is signed by a service provider;
wherein the receiver device comprises a second public X509 certificate comprising a third public key and a corresponding third private key; and
wherein the encrypted session key is calculated as follows:
encrypted session key=(the random symmetric session key+the random value*the first public key*the first private key+the random value*the second public key*the third public key)/(mod(the range)).

2. The process of claim 1 , comprising receiving the file at the receiver device, and decrypting the file using the random symmetric session key.

3. The process of claim 2 , wherein the random symmetric session key is calculated as follows:
random symmetric session key=the encrypted session key−(the random value*the first public key*the public ephemeral key+the random value*the second public key*the third private key)/(mod(the range)).

4. The process of claim 1 , comprising storing metadata from the file in a signed Merkle Tree structure.

5. The process of claim 1 , wherein the random symmetric session key comprises an Advanced Encryption Standard (AES) key comprising 256 bits.

6. The process of claim 1 , wherein the symmetric encryption comprises AES-GSM with a key derived from the random symmetric session key.

7. The process of claim 6 , comprising:
initializing a first chainkey with the random symmetric session key as chainkey=HMAC_SHA256 (the random symmetric session key, the sender device ID);
creating a file encryption key by concatenating the first chainkey with a name of the file; and
encrypting the file with the AES-GSM and a second chainkey=HMAC_SHA256 (the encrypted session key, the sender device ID).

8. The process of claim 1 , wherein the process comprises a plurality of sending devices, and a different private ephemeral key is selected for each sending device.

9. The process of claim 1 , wherein the process comprises a plurality of receiver devices, and a different public ephemeral key is selected for each receiver device.

10. A non-transitory machine-readable medium comprising instructions that when executed by a processor execute a process for transmitting a file from a sender device to a receiver device comprising:
generating a random symmetric session key for the sender device;
randomly selecting a private ephemeral key for the sender device, the private ephemeral key associated with a corresponding first public key;
wherein the receiver device comprises a randomly selected public ephemeral key, the public ephemeral key associated with a corresponding first private key;
generating a random value within a range;
calculating an encrypted session key;
encrypting the file using symmetric encryption; and
transmitting from the sender device to the receiver device a group ID, the encrypted session key, the random value, a sender device ID, a receiver device ID, a hashed file ID, a sender key ID, and a receiver key ID, wherein the receiver device includes a record comprising the random value, the sender device ID, the hashed file ID, and the group ID;
wherein the sender device comprises a first public X509 certificate comprising a second public key and a corresponding second private key that is signed by a service provider;
wherein the receiver device comprises a second public X509 certificate comprising a third public key and a corresponding third private key,
wherein the symmetric encryption comprises AES-GSM with a key derived from the random symmetric session key; and comprising instructions for:
initializing a first chainkey with the random symmetric session key as chainkey=HMAC_SHA256 (the random symmetric session key, the sender device ID);
creating a file encryption key by concatenating the first chainkey with a name of the file; and
encrypting the file with the AES-GSM and a second chainkey=HMAC_SHA256 (the encrypted session key, the sender device ID).

11. The non-transitory machine-readable medium of claim 10 , comprising instructions for receiving the file at the receiver device, and decrypting the file using the random symmetric session key.

12. The non-transitory machine-readable medium of claim 11 , wherein the random symmetric session key is calculated as follows:
random symmetric session key=the encrypted session key−(the random value*the first public key*the public ephemeral key+the random value*the second public key*the third private key)/(mod(the range)).

13. The non-transitory machine-readable medium of claim 10 , wherein the encrypted session key is calculated as follows:
the encrypted session key=(the random symmetric session key+the random value*the first public key*the first private key+the random value*the second public key*the third public key)/(mod(the range)).

14. The non-transitory machine-readable medium of claim 13 , comprising instructions for storing metadata from the file in a signed Merkle Tree structure.

15. The non-transitory machine-readable medium of claim 10 , wherein the random symmetric session key comprises an Advanced Encryption Standard (AES) key comprising 256 bits.

16. The non-transitory machine-readable medium of claim 10 , wherein the process comprises a plurality of sending devices, and a different private ephemeral key is selected for each sending device; and wherein the process comprises a plurality of receiver devices, and a different public ephemeral key is selected for each receiver device.

17. A system comprising:
a computer processor; and
a computer memory coupled to the computer processor;
wherein the computer processor and the computer memory are operable for:
generating a random symmetric session key for the sender device;
randomly selecting a private ephemeral key for the sender device, the private ephemeral key associated with a corresponding first public key;
wherein the receiver device comprises a randomly selected public ephemeral key, the public ephemeral key associated with a corresponding first private key;
generating a random value within a range;
calculating an encrypted session key;
encrypting the file using symmetric encryption; and
transmitting from the sender device to the receiver device a group ID, the encrypted session key, the random value, a sender device ID, a receiver device ID, a hashed file ID, a sender key ID, and a receiver key ID, wherein the receiver device includes a record comprising the random value, the sender device ID, the hashed file ID, and the group ID;
wherein the sender device comprises a first public

Assignees

• Lenovo Singapore Pte Ltd

Inventors

• Stolbikov Igor
• Rodionov Sergei
• Li Scott Wentao

Classifications

• H04L9/0869

  involving random numbers or seeds · CPC title

• H04L9/3263

  involving certificates, e.g. public key certificate [PKC] or attribute certificate [AC]; Public key infrastructure [PKI] arrangements (network architectures or network communication protocols for supporting authentication of entities using certificates in a packet data network H04L63/0823) · CPC title

• H04L9/0643

  Hash functions, e.g. MD5, SHA, HMAC or f9 MAC · CPC title

• H04L9/0833

  involving conference or group key (network architectures or network communication protocols for key management in group communication in a packet data network H04L63/065) · CPC title

• H04L9/0637

  Modes of operation, e.g. cipher block chaining [CBC], electronic codebook [ECB] or Galois/counter mode [GCM] · CPC title