> For the complete documentation index, see [llms.txt](https://davidjosearaujo.gitbook.io/online-courses/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://davidjosearaujo.gitbook.io/online-courses/blockchain-security/beyond-the-basics/advanced-cryptography-in-blockchain/multisignatures.md).

# Multisignatures

Digital signatures are heavily used in the blockchain

**Some transactions may need to be authorized by multiple parties** (High-value transactions, signing contracts, etc)

Algorithms exist that **require multiple secret keys** to generate a digital signature:

* **Based on Shamir's Secret Sharing**
* At least K of a set of N users to participate to create a valid signature