Digital signature is a framework that is introduced in the blockchain to prove who has done it Transactions in the blockchain are always given digital signatures. By using digital signature it is possible to verify that the sentence made on the Internet is the one created by person himself or herself Digital signature technology is based on the nature of public key cryptography and one-way hash function explained in classes before If you feel that there’s an obscure part about them. You will understand the contents of this lesson easily by reviewing I’ll explain the digital signature procedure with concrete examples consider the case that Mr. A sends the document “Hello” to Mrs. B. Firstly A’original message “Hello” is converted to a hash value.
Then the hash value is encrypted with A’s private key and this is the digital signature A sends an original message “Hello” with the digital signature with A’s public key B receives these and decrypt the digital signature by A’public key If the hash value decrypted by A’s public key matches the hash value of the original message “Hello” We can prove that the original sentence was sent from A himself. This is because person himself has a private key and the document that can be decrypted with his public key is only the one encrypted with his private key if the hash value of the transmitted original sentence and the decrypted digital signature match the original text is not falsified Therefore when the hash value of the decrypted digital signature is different from the hash value of original sentence It is considered that the contents of original sentence has been tampered with If it cannot be decrypted with a public key .
There’s a possibility that a document was created by another person or the digital signature was replaced Since only the remoter himself who owned the private key and signed the digital signature. Even if you know the address of another person it is impossible to sign the digital signature unless you know the private key from which the wallet address is derived In other words, even if you try to make remittance from another’s address without permission digital signature cannot be signed by others, except the owner of the private key and the reminisce by others except the principal will not be made To put it the other way, if your private key is known to someone. Digital signature is signed without permission and reminisce is made from your address So the secret key is never known to others In this way, by giving an electronic signature to the transaction in the blockchain. We guarantee that the remittance side is surely the principle Since it is a technology supporting transactions, which can be said to be the nucleus of the blockchain Let’s keep it in mind after understanding the public key cryptography and the hash function.