# Key Concepts and Techniques

The current version of OPZ utilizes two-party computation protocols, with the key shared between the User and OPZ server.

## Simple Example:

OPZ uses secure two-party computation, which enables two parties (user & OPZ server) to evaluate an arbitrary function f on their respective private inputs $$x,y$$ while revealing nothing but the result $$z=f(x,y)$$

1. **Inputs**: The user has a private input $$x$$ and the OPZ server has a private input $$y$$.
2. **Computation**: A function $$f$$ is computed, where $$f:(X,Y)→ Z$$ and $$X,Y,Z$$ are the domains of $$x,y,$$ and $$z$$ respectively.
3. **Output**: The result of the computation is $$z$$, where $$z=f(x,y)$$.

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## Two-Party Elliptic-Curve **Mechanism**

### MPC Key Generation

Instead of generating a key and then splitting it, an MPC protocol is used to generate the key shares. This ensures the key is never exposed on a single device, greatly reducing the risk of compromise.

{% content-ref url="key-concepts-and-techniques/key-generation" %}
[key-generation](https://whitepaper.opz.io/keyfusion/key-concepts-and-techniques/key-generation)
{% endcontent-ref %}

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### MPC Signing Process

Signing is crucial for securing transactions in our Multi-Party Computation (MPC) wallet. This process involves collaboration between the OPZ server and the user device.

We use two distinct MPC signing processes to adapt to the various requirements of different blockchains:

1. **ECDSA (Elliptic Curve Digital Signature Algorithm)**:

{% content-ref url="key-concepts-and-techniques/ecdsa-signing-process" %}
[ecdsa-signing-process](https://whitepaper.opz.io/keyfusion/key-concepts-and-techniques/ecdsa-signing-process)
{% endcontent-ref %}

2. **Schnorr/EdDSA (Edwards-curve Digital Signature Algorithm)**:

{% content-ref url="key-concepts-and-techniques/schnorr-eddsa-signing" %}
[schnorr-eddsa-signing](https://whitepaper.opz.io/keyfusion/key-concepts-and-techniques/schnorr-eddsa-signing)
{% endcontent-ref %}

By supporting these two key signing protocols, we provide a comprehensive solution adaptable to various blockchain environments.