## The mining process.

**Mining Bitcoin with pencil and article** Bitcoin mining is a key part of the security of the Bitcoin system. The idea is that Bitcoin miners group a bunch of Bitcoin transactions into a block. Then repeatedly perform a cryptographic operation called hashing. Mining Bitcoin with pencil and article Zillions of times until someone finds it. A special extremely rare hash value. Mining Bitcoin with pencil and article At this point, the block has been mined. Becomes part of the Bitcoin blockchain.

The hashing task itself doesn’t accomplish anything useful in itself. But because finding a successful partnership is so difficult. It ensures that no individual has the resources. Mining Bitcoin with pencil and article To take over the Bitcoin system. For more details on mining. See my** Bitcoin mining article.** A cryptographic hash function takes a block. Of input data and creates a smaller. Unpredictable output.

The hash function is designed so there’s no shortcut to getting the desired output you just have to keep hashing blocks until you find one by brute force that works. For Bitcoin, the hash function is a function called SHA-256. To provide additional security, Bitcoin applies the SHA-256 function twice, a process known as double-SHA-256. In Bitcoin, a successful hash starts with enough zeros.

Just as it is rare to find a phone number or license plate ending in multiple zeros, it is rare to find a hash starting with multiple zeros. But Bitcoin is exponentially harder. **Bitcoin mining example** Currently, a successful hash must start with approximately 17 zeros, so only one out of 1.4×10^{20} hashes will be successful. In other words, finding a successful hash is harder than finding a particular grain of sand out of all the grains of sand on Earth.

The following diagram shows a block in the Bitcoin blockchain along with its hash. The yellow bytes are hashed to generate the block hash. In this case, the resulting hash starts with enough zeros so mining was successful. However, the hash will almost always be unsuccessful. In that case, the miner changes the nonce value or other block contents and tries again.

## The SHA-256 hash algorithm is used by Bitcoin.

The SHA-256 hash algorithm takes input blocks of 512 bits 64 bytes and connects. The details cryptographically, and sires a 256-bit (32 bytes) result. The SHA-256 algorithm consists of a somewhat austere band duplicated 64 terms. **Bitcoin mining lives** The diagram below shows one round, which takes eight 4-byte inputs, A through H, performs a few operations, and generates new values of A through H. The blue boxes mix up the values in non-linear ways that are hard to analyze cryptographically.

Since the algorithm uses several different functions, discovering an attack is more complicated. (If more brutally figure out a mathematical shortcut to generate successful hashes, you could take over Bitcoin mining.) The *Ma* majority box looks at the bits of A, B, and C.** Bitcoin algorithm code** For each position, if the majority of the bits are 0, it outputs 0. Otherwise, it outputs 1. That is, for each position in A, B, and C, look at the number of 1 bit if it is z for one, output 0. If it is two or three, output 1.

The *Σ0* box rotates the bits of A to form three rotated versions, and then sums them together modulo 2. In other words, if the number of 1 bit is odd, the sum is 1; otherwise, it is 0. **Bitcoin mining per day** The three values in the sum are A rotated right by 2 bits, 13 bits, and 22 bits. The *Ch* “choose” box chooses output bits based on the value of input E. If a bit of E is 1, the output bit is the corresponding bit of F.

If a bit of E is 0. The output bit is the corresponding bit of G. The next box *Σ1* rotates and sums the bits of E, similar to *Σ0* except the shifts are 6, 11, and 25 bits. **The red boxes** perform 32-bit addition, generating new values for A and E. The input *W _{t}* is based on the input data, slightly processed.

**The algorithm used in bitcoin**This is where the input block gets fed into the algorithm. The other values pass through unchanged, with the old A value becoming the new B value, the old B value becoming the new C value, and so forth.

## Manual mining.

I perform the first round of hashing to mine a block. Completing this round took me 16 minutes and 45 seconds. To explain what’s on the paper: I’ve written each block. **Bitcoin hash example** A through H in hex on a separate row and put the binary value below. The *major* operation appears below C, and the shifts and *Σ0* appear above the row.

Likewise, the *chosen* operation appears below G and the shifts and *Σ1* above E. The first three red sum boxes. These steps all correspond to the diagram and discussion above. I also manually performed another hash round, the last round to finish hashing the **Bitcoin block**. The zeroes in this hash show that it is a successful hash. Note that the zeroes are at the end of the hash. The reason is that Bitcoin inconveniently reverses all the bytes generated by SHA-256.