Digital signatures: the Key (ingredient) of a blockchain

Do you know why you can send a blockchain transaction? Because you digitally sign it.


Without digital signatures there would be no accepted transactions, because nobody would trust that you own the money you want to spend. Therefore there wouldn’t be any consensus of the ledger. And we wouldn’t have blockchains. But digital signatures aren’t only the core of the blockchain infrastructure.  This marvellous cryptographic achievement has so many flavors that blockchains with different digital signature schemes have completely different properties. Why is the Monero blockchain so private? Because it uses linkable ring digital signatures schemes. Why  can companies set up a shared account on the Bitcoin blockchain and be sure no partner will steal any fund? Because they can use threshold digital signatures schemes.


Digital signatures allow the user to sign digital content and are a key ingredient of commerce, software management, fund management in a blockchain and they have major legal implications. For example, with a digital signature you can prove your identity remotely. This facilitates human interactions even in delicate world moments and allows greater trust between people. International standards, such as those developed by NIST, allow the transnationality of procedures. And all this is based on what cryptographers commonly call “key pair”: a pair of huge numbers, one secret and known only to the signer and one public available to all. The secret one allows to sign, the public one allows to verify the signature. Losing the secret key could mean losing your (digital) identity.


Are you afraid somebody can steal your key? Implement a multisignature with 8 keys: now the thief needs to steal 8 keys to steal your funds. And what if you lose one of those 8 keys? Would you be able to retrieve your funds?


If you are interested in more details on the reasons why there is no blockchain without digital signatures, watch this space for the upcoming DLT4All online classes offering a great variety of online modules, including the topic of this article