Ethereum: Determining xprv from xpub and child private key

Decrypting Ethereum Private Keys: xprv vs xpub and Sub-Private Private Keys

Ethereum private keys are a crucial aspect of securing transactions on the network. However, to ensure the integrity and security of your wallet and funds, it is crucial to understand how to decrypt these keys. In this article, we will explain the differences between xprv (extended public key) and xpub (public key), as well as the basic private keys.

What are Ethereum private keys?

Ethereum private keys consist of three parts: “x”, “p”, and “r”. These values ​​represent a pair of coordinates on an elliptic curve used to secure transactions. The value “x” is the extended public key, which consists of two components: “xpub” (public key) and “xprv” (extended public key).

xpub vs xprv

To understand the difference between “xpub” and “xprv”, let’s break down their roles:

• xpub: This is the standard public key format used for Ethereum transactions. It is a unique address that can be used to receive or send funds.

• xprv: This extended public key includes additional information, such as a primary extended public key (“p”) and secondary private keys (“r” and “s”). The “xprv” value is required to create and manage child private keys.

Child Private Keys

A partial private key is a combination of two values: r (red) and s (S). These values ​​are used to obtain the public and private components of an extended public key (“xpub”). When you create a secondary private key, you can use it to generate additional private keys or manage existing ones.

Decrypting xprv from xpub and a secondary private key

To decrypt an Ethereum private key, follow these steps:

• Determine the primary extended public key (p): Find the p value in the private key. This is a unique identifier used to derive the child private keys.

• Extract the secondary private keys (r and s): Take the first two values ​​after the p value. These are the red (r) and blue (s) components, respectively.

• Create the extended public key (xprv): Combine the extracted “r” and “s” values ​​with the primary extended public key (“p”). The resulting xprv value is the new private key.

Example

Let’s say you have an Ethereum private key in the following format:

Where “” is the value of “p” and “” consists of the first two values ​​after ““.

Using this information, you can decrypt the private key as follows:

• Remove the secondary private keys (r and s). Let’s say “” = “(0x0004, x0006)”

• Combine the resulting values ​​with the parent’s extended public key (“p”): “(x0003, x0005)”

Therefore, the decrypted Ethereum private key would be:

x0003
x0005

In summary, understanding how to decrypt “xprv” from “xpub” and the private keys that come with them is essential for managing your Ethereum wallet and ensuring security. By following these steps, you can easily identify and use the child’s private keys to create additional private keys or manage existing ones.