> For the complete documentation index, see [llms.txt](https://docs.extrachain.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.extrachain.io/exconsensus/block-prove-algorithm-bpa.md).

# Block Prove Algorithm (BPA)

Block Prove Algorithm (BPA):

1. Check digital signature of block via EdDSA algorithm;
2. Check hash link to previous block;
   1. If hash link points to local last block – proceed;
   2. If hash link points to other block – stop Block Prove and start Block Merge;
3. If block with same number is already in local blockchain, stop Block Prove and start Block Merge;
4. If received block is new, check each transaction in block via TVA;
5. If TVA check is successful – add approver signature and distribute approved block.

Block needs to be approved by at least 2 approvers to become “mature”.

![BPA Scheme](/files/-Ma2xUPX-evweCHRvizi)