Introduction
Cryptography is a branch of computer science focusing on securely accessing and sending info between two or more parties without using a third party. In practice, these techniques keep info or secrets between parties safe from enemies.
In the big picture, cryptography attempts to construct secure ecosystems that can function with or without the participation of trusted entities. Threshold schemes are one of the most secure approaches for carrying out cryptographic operations.
This article will discuss what are threshold schemes in detail. We will discuss its methodology along with its application. We will also discuss the types of threshold schemes. So without further ado, let’s get started!
What are Threshold Schemes
Threshold cryptography gets its name from the idea that an individual keyholder cannot open a lock on their own. Instead, there must be a certain number of keyholders – a "threshold" number working together to open the lock.
Let’s have a look at a real-life example. In the later 20th century, when nuclear weapons were introduced, the control of nuclear weapons depended upon a similar “two-out-of-three” presence. The three members involved were the Defense Minister, the Defense Ministry, and the President. It means to control nuclear weapons, two out of three members among them should be present.
In threshold schemes, the key is distributed among users such that no single one can deduce the secret without the consent of others. Threshold schemes are complex because keyholders must be able to collaborate without knowing each other's key.
The threshold schemes overcome the flaws in traditional cryptography because we can access the info by using a threshold number of keys, not all of them. We can still access data even if some of the keys are affected or destroyed.
Methodology
Following is the methodology of threshold schemes:
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Let t, w be positive integers, while t ≤ w. Here, t and w are the numbers of key holders.
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A (t, w)-threshold scheme shares a key K among a set of w participants.
- Any t participants can use their keys and find the value of K, but it won't be possible with t − 1 participant.
Application
Threshold schemes provide higher levels of security than many other cryptographic algorithms. As a result, it was adopted by many cryptographic protocols, processes, and applications.
Their applications can be found in various industries, including the Internet of Things, cloud computing, authentication, ad-hoc and sensor networks, etc.
A generalised application can be said as:
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It implements a digital sign technique in which no single component can ever access the signing key.
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Even if one component is compromised. The output, encryption and decryption must be implemented correctly.
- Even though some (but not all) randomness sources are biased or unavailable, they generate unbiased randomness.
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