# Secure and Distributed Secret Key Sharding

Specifically, Distributed Control Rights Management (DCRM) technology will ensure that private keys remain completely secure and secret during the cross-chain mapping process. This is the first time in the world where we can prove that it is possible to manage and control private keys in a distributed manner. FUSION utilizing sharding, homomorphic encryption and zero-knowledge proof technologies in order to realize this function’.

[DCRM ](https://fusiondev.gitbook.io/fusion/learn/fusion-features/dcrm-1)is a patent pending cryptographic technology, and perhaps FUSIONs greatest innovation. DCRM is the mechanism that enables the [Lock-in and Lock-out](https://fusiondev.gitbook.io/fusion/learn/fusion-features/time-lock/lock-in-and-lock-out-lilo) of funds from different blockchains (Bitcoin, Ethereum, and eventually other blockchains) to FUSION.

Currently, if digital assets are in the custody of individuals or exchanges, the corresponding keys that control these assets are are stored in a single centralized location. This single point of failure may be the user, a third party providing the wallet, a centralized exchange or another custodian. Private keys may be compromised by accidental loss, theft, hacking, phishing, and fraud. These unfortunate situations are a common experience for early and even experienced adopters of cryptoassets.

## **SECURE CUSTODY for PRIVATE KEYS**

Control over private keys confers control over digital assets. A secure private key custody solution must not expose private keys in the process of generating, storing or using Locked-in digital assets.

Security concerns for private key sharding:

* If the private key is stored completely in one location, the location becomes a target of attacks. Therefore, in order to ensure the security of the private key, FUSION chooses to shard the private key and store shards (small pieces) on multiples nodes.
* The private key must not be generated as a whole, and then cut into shards. From its inception it must be generated in a distributed manner.
* When a sharded private key is used to sign a transaction, FUSION nodes are unable to collect key shards and compromise the complete private key.

## **TECHNICAL DETAILS**

DCRM uses sharding to achieve secure custody of cryptoassets. The process of dividing a complete key into several parts is called key sharding, and each of these parts is called a key shard. In no place and at no time will the data fragments needed to derive the complete private key appear together.

### **The distributed generation of private keys**

The distributed generation of private keys is accomplished by using multiple FUSION nodes in consensus. Each node only generates and saves part of the private key, and does not transmit and assemble the private key fragments.

In this process, the number of shards is determined according to the key sharding algorithm and virtual node groups are formed to generate the private key according to the algorithm. Virtual node groups are a collection of nodes that hold a particular key shard, ensuring that key shards are always in a state of availability. The algorithm that determines the number of nodes in a group will ensure that the probability is extremely low that most of the nodes holding a key’s shard, are simultaneously offline.

### **Distributed storage**

Key fragments are stored independently by different nodes in the decentralized network. Each node has the capacity to hold many shards of incomplete data that can only be used to assist in validating transaction. In this way, a node is not valuable in and of itself but only in its capacity to cooperate with the broader network.

![](https://4087356848-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MVImKVb73UzNxlmWjZ6%2F-MVhU8gv0paRDd-ZGC4U%2F-MVhXl2kvgB9qPiRefuO%2Fimage.png?alt=media\&token=759711ea-7556-4396-b125-e73809fd936e)

### **Transaction Validation**

To issue a transaction on the FUSION blockchain, the asset owner signs a transaction with their private key shard and FUSION supreme nodes validate the partially signed transaction adding their shard signature. The transaction is considered to be valid when the number of shard signatures reach the signature threshold.

This revolutionary innovation is a key foundational cryptographic technology that facilitates dynamic control of cryptoassets. With this quantum leap in interoperability and security, FUSION paves the way for an inclusive financial system, the Internet of Values.

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