DECENT Technology: Key Distribution for DECENT Development

After spending the first few weeks in China, I will present the direction the DECENT project is taking. DECENT is currently in its initial stages and its full functionality will be extensively documented in:

1. DECENT prototype demonstration video

2. DECENT Whitepaper

3. DECENT Yellow Paper

Let's focus on some interesting features of DECENT core. One of them is DECENT key distribution, which adopts the concept of Shamir's Secret Sharing (SSS), where the key is divided into multiple parts and each participant of the sharing scheme gets a specific part. SSS provides a threshold scheme where only a subset of participants need to decrypt the key.

A quadratic polynomial passing through two points (Wikipedia)

According to Wikipedia:

"You can draw an infinite number of quadratic polynomials through two points, and you can determine a unique quadratic polynomial through three points. This picture is for illustration only - Shamir's scheme uses polynomials over a finite field and is not representative of 2D space."

Shamir's m-out-of-n threshold scheme for key sharing is being implemented in the DECENT core as follows:
author:

1. The author creates the content in the form of a computer file and chooses 2 integers n and m such that n>m>2.

2. The author's application generates a unique AES encryption key and encrypts a portion of the content that is not free to read.

3. The author's application selects a distribution protocol and produces a distribution package that contains free-to-read and encrypted content.

4. Our application splits the encryption key into n shares so that m of them can be used to retrieve the key using Shamir's key sharing algorithm.

5. The author's application finds n suitable publishers.

6. The author's application uses the public key assigned by n publishers to a single publisher to encrypt the n secret key components generated in step 4

7. The author's application generates a content submission transaction that includes all content metadata such as title, synopsis or tags as well as network-related data such as availability, price, publisher list and a shared encrypted list of each selected publisher.

8. The transaction is included in the next block, which can be read by publishers or consumers.

Content Consumers:

1. The content consumer selects the content he wishes to purchase and he downloads the distribution package using the chosen protocol (many are permitted).

2. The content consumer's application generates a "request to buy" transaction, which is included in the next block, which is visible to the publisher.

3. Once the publisher node sees the “Request to Buy” transaction in the blockchain, they decrypt the corresponding share (from the content submission transaction) using their private key and then encrypt it again using the content consumer’s public key.

4. The publisher node generates a transfer key transaction containing the share encrypted with the consumer's key and the transfer proof. This transaction is included in the next block, which is visible to content consumers.

5. When there are enough shares in the blockchain, the content consumer decrypts the share using his or her private key, reconstructs the AES decryption key and decrypts the content.

The DECENT code is available in a private Github repository and will be made available to the public soon.