# Application of deep learning series hash algorithm of comunion blockchain The N in it represents the number of consecutive 0, which should be less than the current block difficulty target value M. the condition for digging a block is that all the first n bits are 0. The greater the N, the greater the difficulty. Suppose that the minimum difficulty corresponds to the maximum target value m, then the block difficulty is: M / M < / P > < p > 1. The version number and the previous block hash are fixed. Taking bitcoin as an example, assuming that the current bitcoin block height is n, if someone wants to dig the next N + 1 block, then the version number must be fixed, and the hash of the previous block must also be fixed. Because in the case of no bifurcation, the current block contains the hash value of the previous block; < / P > < p > that is, the hash value of the N-1 block plus the n block data is used to calculate the n block hash value, and then the n block hash value is regarded as the previous block hash value of the N + 1 block. I hope you can understand it more. < / P > < p > 2? When mining, a packing block must be prepared. When the packing block is formed, the miners will package the transaction into a Merkle root according to their own needs or according to the benefit algorithm. < / P > < p > 3. The time stamp is variable, and there is a time range for mining. The mines excavated within this time range are valid, so they are within the effective time The time can be adjusted at will. < / P > < p > when mining, when it comes to nonce, since the time stamp and Merkle root have been calculated and fixed, it is only necessary to change nonce. At this time, we can take the seven data as a whole. The first six data are X. if we put X in the hash function, we will get a value, such as y value. < / P > < p > because the hash algorithm used in bitcoin network is SHA-256, when y value comes out, 256 strings composed of 0 and 1 will be obtained. After the string comes out, it will be compared with the difficulty value in X. < / P > < p > every time a nonce is passed, a y value will be generated, and the y value will be compared with the difficulty value. If the y value is less than the difficulty value, an effective nonce will be found and the mine will be excavated. < / P > < p > in the Merck tree above, there are four leaf nodes at the bottom of the tree, and there is a hash under the far left h a, which means: TX represents the transaction, and a represents the transaction number. < / P > < p > assuming that the current hash algorithm is SHA-256, HA and Hb will be hashed respectively when the transaction is generated, and two strings composed of 256 zeros and one will be obtained. Similarly, HC and HD will also get corresponding strings, so that the four transactions will form the total Merkel root. < / P > < p > as we all know, in the blockchain, each block is linked up one by one, just like a chain. We through the following pictures, specific analysis. < / P > < p > from the figure, we can see that the chain order increases from bottom to top. The height of the bottom block is 277314. This block contains the hash value of the previous block: 0000 0bdf, 0000 here 0bdf is the hash value of the previous chunk header. Similarly, the hash value of the previous block header contained in block 277315 is 0000 2249, which is also the block header hash value of block 277314, that is: 0000 2249。 Similarly, this is also the case in block 277316, which is what we hope you can understand in the first section. < / P > < p > this ensures that anyone can find the hash value of the previous block contained in a block, that is, its parent block. < / P > < p > now we are talking about a situation where there is no bifurcation of the blockchain. Later, we will analyze in detail what the situation is after the blockchain forks. < / P > < p > through these three blocks, we can find that, to some extent, a blockchain is a hash chain. The newly generated block points to the previous block through the hash value, and the previous block points to the previous block All the way to the genesis block. Through this relationship, these blocks form a chain, which is often referred to as the blockchain. < / P > < p > this is the specific application of hash algorithm in blockchain. You can think in advance why hash algorithm is used in blockchain instead of other algorithms? We will give you answers in the following courses. ASMC, a lithography maker, was one of TSMC’s 14 top suppliers last year