The security of the blocks is kept by connecting each block to the previous one using hash identifiers. This means that the block data cannot be changed or altered as the hash value will change. Moreover, each data stored in a block is also protected using cryptography. The data can be unlocked by the network participant who created it in the first place. The private key is required to access the data. The transactions that are stored in a block is digital signed and hence once stored cannot be altered, giving the block the required integrity and transparency when needed.