Do you know what a *nonce* and what different uses does it have in cryptography? In it** development of cryptographic systems**, it is common to use certain numbers that are combined with the original data in order to achieve more secure encryption. There are different types of numbers used for these purposes and each of them has specific and different properties. In this post, we will talk about a type of number that is widely used in cryptographic schemes and is known to be part of systems such as CTR, GMC, and even bitcoin modes. Next,** We will explain to you what a nonce**.

## What is a nonce?

**A number nonce is a random value that is combined with a string of data before being subjected to an encryption function**. He

*nonce*It is used in systems such as CRT or GCM encryption modes of operation and is also famous for being a fundamental part of the bitcoin scheme. The main properties of a

*nonce*are that it must be generated truly randomly and that it must have a specific size, given by the blocks of the system used.

*Nonce in CTR and GMC modes*

*Nonce in CTR and GMC modes*

To understand what is a *nonce*, **It is helpful to understand how this value is used in CRT and GCM block cipher modes.**.

Block cipher mode **CRT or counter** It is a mechanism that allows a series of blocks to be encrypted, all at once, in a relatively secure way. CTR is vulnerable, but there is a secure version known as

**GCM or Galois/Counter mode**. To understand how both work, we will explain CTR mode:

First, **a number is generated nonce**which must be completely random and be half the size of each data block.

**The other half of the block is filled with a number called a «counter.»**which grows progressively according to each block, starting from «00000000», until reaching «99999999», assuming that it is a 16-byte block.

**The combination of**.Finally, to the result of the previous step

*nonce*with the counter is the block that is encrypted with the AES encryption algorithm**an XOR operation is performed with the original plain text block of the message**which produces the final ciphertext block.

## What is a nonce in bitcoin

Now you know what a nonce is and how it works within CTR and GCM encrypted mode (which is a version of CTR, but with HMAC authentication protocols). Next, we will briefly talk about **what role do numbers play nonce inside how bitcoin works**.

To understand how the nonce is used in bitcoin, it is necessary to review the concept of *proof of work* (PoW) or proof of work, which refers to a mechanism to incentivize miners to verify transactions honestly. Furthermore, it is a method that completely prevents them from doing the opposite.

To ensure this, **The function of miners is to generate a random number nonce that, when combined with the data string of a transaction, produces a cryptographic hash function that begins with five zeros**. In this way, proof of work is the computational expense that the miner makes in exchange for a reward.

Thus, thanks to the intelligent use of a *nonce***it would be useless to spend money and energy finding codes to verify fake transactions**. In reality, it is much better to spend those resources on finding random numbers that truly authenticate each transaction.

## How to learn more?

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