Which of these functions of public and private keys is correct?
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Private key verifies the digital signatures and public key creates the digital signature.
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Public key verifies the digital signatures and private key creates the digital signature.
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Private key and public key are used to verify the digital signatures.
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Private key and public key are used to create the digital signatures.
A digital signature in its simplest description is a hash of the data that is subsequently encrypted with the signer's private key. Since that is something only the signer has, that is where the trust comes from. EVERYONE has access to the signer's public key. So, to validate a digital signature, the recipient (1) calculates a hash of the same data, (2) decrypts the digital signature using the sender's PUBLIC key, and (3) compares the 2 hash values. If they match, the signature is considered valid. If they don't match, it either means that a different key was used to sign it, or that the data has been altered. Thus, public key helps in verification. The private key is used to encrypt the hash. The encrypted hash along with other information, such as the hashing algorithm, is the digital signature. Thus, it helps in creating the electronic signature.