In digital signatures, which key is used to encrypt the hash value?

In digital signatures, the hash value is encrypted using the private key of the signer. This process ensures that only the owner of the private key can create a signature that can be verified by others. When the hash value is encrypted, it becomes the digital signature itself. The corresponding public key is then used by the recipient to decrypt the signature. This verification process ensures the integrity and authenticity of the message, confirming that it was not altered and that it truly originates from the owner of the associated private key.

Using the private key for encryption is fundamental in public key cryptography: it allows the recipient to trust the authenticity of the signed message because only the legitimate owner of the private key could have generated it. The use of the public key for decryption further enhances security, as it allows anyone to verify the signature without needing to have access to the private key.