Public key cryptography is an encryption technology that uses cryptographic “keys,” which are really just very long, randomly generated numbers that are guaranteed to be unique.
The keys serve as an input for the algorithm that encrypts data. Because the keys are unique, the encrypted file you create using your key will be different from the encrypted file that someone else creates using their key, even if you both use the exact same encryption software and algorithm. This means that the keys also serve as a way to digitally “sign” the file to prove that it came from the person who holds the keys — and only that person.
The keys come in pairs: a public key and a private key. These keys are different but mathematically related. Whatever is encrypted using the private key can be decrypted only by its corresponding public key, and vice versa. You can’t decrypt data using the same key that encrypted it — you must have the other key in the pair.
As its name implies, the public key is typically placed on a publicly accessible server and made available to anyone who wants it. The private key remains securely in the sole possession of the keys’ owner, protected from the outside world in the Trusted Platform Module (TPM) / Secure Enclave of their device.
If someone encrypts something using your public key, only you can decrypt it using your private key — even if the encrypted data file and the public key that encrypted it are publicly available.
BlockID solutions use public key cryptography to protect the user’s identity data by encrypting and digitally signing it. The data is also signed when it’s verified by a trusted third-party certification service using BlockID Verify (so that you know it has been verified and by whom) and when it’s exchanged between you and the user.