What does Cryptographic Key mean?

A cryptographic key is data that is used to lock or unlock cryptographic functions such as encryption, authentication and authorization. Keys are typically designed to be both random and reasonably long such that they are difficult to guess. 

A cryptographic key is a string of bits used by a cryptographic algorithm to transform plain text into cipher text or vice versa. This key remains private and ensures secure communication.

A cryptographic key is the core part of cryptographic operations. Many cryptographic systems include pairs of operations, such as encryption and decryption. A key is a part of the variable data that is provided as input to a cryptographic algorithm to execute this sort of operation. In a properly designed cryptographic scheme, the security of the scheme is dependent on the security of the keys used.

Cryptographic key Explained

Cryptographic keys are symmetric or asymmetric. Symmetric encryption requires only one key, which is used to encrypt and decrypt data. Asymmetric encryption uses two different keys: one for encryption and one for decryption. A certificate authority (CA) provides public/private key pairs using the public key infrastructure. The digital certificate registration authority process begins before the user’s digital certificate status is communicated to the CA.

Cryptographic keys may be further indexed by the purposes for which they are used, which can include data encryption and decryption, digital signature verification, digital signature creation, message authentication, key transport and key wrapping.

The length of a key is normally expressed in bits. A longer key makes it more difficult to crack the encrypted data; however, a longer key results in longer time periods to perform encryption and decryption processes.

The CA provides the keys. The private key is given to the key requester. The public key is made public in an open access directory. Private keys never travel via the Internet and thus remain private.

12 Types of Cryptographic Key

The following are common types of cryptographic key:

Asymmetric Key Pair

A matching public/private key pair whereby anyone can encrypt with the public key but only those who hold the private key can decrypt.


The public key in a asymmetric key pair.


Private keys may be part of a public/private asymmetric key pair. Alternatively, they can be used in symmetric encryption whereby you use the same key to encrypt and decrypt data. Private keys are generally kept secret.

Signature Keys

Keys that are used to generate digital signatures for verifying identity, determining the integrity of data and non-repudiation.

Authentication Keys

Keys that are used to verify identity, communications and data.

Wrapping Keys

Keys that are used to encrypt other keys. For example, it is common to use public/private asymmetric keys for an initial exchange of symmetric private keys. This is done because symmetric encryption is generally faster than public key encryption.

Transport Key

Basically another term for a wrapping key. Transport keys are used to encrypt transport messages that contain other keys.

Key Agreement Key

Another term for keys that are used to exchange other keys.

Ephemeral Key

A temporary key that is typically used to establish other keys.

Transient Key

An asymmetric public/private key pair that is only used once. This may be done in order to implement functionality such as the ability to irrefutably identify the time that a digital signature was created.

Master Key

A key that is used to generate other keys using a key derivation function.

Authorization Keys

Authorization keys are used to provide a privilege. In many cases, these are used to prove that a message has been successfully decrypted. If you encrypt an authorization key with a public key you know that a client is in possession of the corresponding private key because they are able to send the authorization key back to you.

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