A cryptography key pair consists of two related but distinct cryptographic keys:
- Private Key: A secret key that is used to decrypt, sign, or authenticate data. It’s called “private” because it should be kept confidential and secure to prevent unauthorized access.
- Public Key: A publicly accessible key that is used to encrypt, verify, or authenticate data. It’s called “public” because it can be shared freely without compromising the security of the system.
How do key pairs work?
Here’s a simplified overview of how key pairs are used in various cryptographic scenarios:
Encryption
- Alice wants to send a secure message to Bob.
- Bob generates a key pair and shares his public key with Alice.
- Alice uses Bob’s public key to encrypt the message.
- Bob uses his private key to decrypt the message.
Digital Signatures
- Alice wants to send a document to Bob and prove its authenticity.
- Alice generates a key pair and uses her private key to sign the document.
- Bob uses Alice’s public key to verify the signature and ensure the document hasn’t been tampered with.
Authentication
- Alice wants to access a secure system or service.
- The system generates a key pair and shares its public key with Alice.
- Alice uses the system’s public key to encrypt a challenge or password.
- The system uses its private key to decrypt the challenge or password and authenticate Alice.
Key Pair Properties
- Asymmetric: Key pairs are asymmetric, meaning that the private key is not easily derived from the public key.
- Mathematical relationship: The private and public keys are mathematically related, allowing for encryption, decryption, signing, and verification.
- Unique: Each key pair is unique, ensuring that data encrypted with a public key can only be decrypted with the corresponding private key.
Types of Key Pairs
- RSA (Rivest-Shamir-Adleman): A popular algorithm used for encryption, decryption, and digital signatures.
- Elliptic Curve Cryptography (ECC): A more modern algorithm used for encryption, decryption, and digital signatures, offering better security with smaller key sizes.
- Diffie-Hellman (DH): A key exchange algorithm used to establish a shared secret key between two parties.
In summary, cryptography key pairs are a fundamental component of secure online communications, enabling encryption, digital signatures, and authentication. By using a pair of related but distinct keys, key pairs provide a secure way to protect data and ensure its authenticity.