Why can a message encrypted with the public key only be decrypted?

Why can a message encrypted with the public key only be decrypted?

Not true, the message can also be decrypted with the Public Key. A so called “one way function with back door” is applyed for the encryption. 3. The Public Key contains a special function which is used to encrypt the message and which can only be reversed by the appropriate Private Key.

Would anything happen if you encrypt the hash value of your message with your public key when signing it?

A private key can be used to decrypt a message that was encrypted using the correspoding public key, or to sign a message; but a private key cannot be used to encrypt a message. By the same logic, the notion of signing a message with the public key is also fundamentally incorrect.

Can I decrypt with a public key?

What is public key encryption? Data encrypted with the public key can only be decrypted with the private key, and data encrypted with the private key can only be decrypted with the public key. Public key encryption is also known as asymmetric encryption.

Do you need private key to encrypt?

Only the owner of the private key can encrypt data so that the public key decrypts it; meanwhile, anyone can encrypt data with the public key, but only the owner of the private key can decrypt it. Therefore, anyone can send data securely to the private key owner.

How is PGP used to encrypt an email?

Each public key is bound to an email address. The sender will encrypt the message with the recipient’s public PGP key and the sender’s signature. When the recipient receives the message, they must use their passphrase (private key) in order to decrypt the message.

Can a key be encrypted in GnuPG?

GnuPG does not support encrypting to a recipient specified by a key file. The key must be imported in advance, and the recipient defined with either his mail address or key ID. I’d recommend to use a cleaner approach as expected by GnuPG and hard-code either the key’s fingerprint, or a user ID given by that key and import it as usual.

Where can I find the recipient’s public key?

As far as I know, the recipient’s public key IDs, key Validity dates, name, and email address are embedded in the GPG ASCII Armor file ( GnuPG Manual ) So using pub key file / Key ID / Name / Email to identify which public key to use should all be equivalent. BUT I don’t have access to a linux machine right now, so can’t check.

How to import a user ID into GnuPG?

I’d recommend to use a cleaner approach as expected by GnuPG and hard-code either the key’s fingerprint, or a user ID given by that key and import it as usual. If you really do not want to import the key, you could do following as workaround (which actually imports the key, but to a temporary GnuPG home directory):