Cryptography is a method of protecting information and communications through the use of codes that allow only the sender and receiver of a message to view its contents. In cryptography, an original message in plaintext is changed by means of an algorithm into something that is unreadable, known as ciphertext.
Cryptography provides confidentiality, integrity, authentication for sensitive information while it is stored (at rest), traveling across a network (in transit), and existing in memory (in use). Two main types of cryptosystems enforce confidentiality: symmetric and asymmetric cryptosystems.
Symmetric vs. Asymmetric Cryptography
Cryptography’s approach uses a secret key for both encryption and decryption. Data is changed into a format that cannot be read or interpreted by someone who does not have the key used to encrypt it during this phase. Symmetric cryptography is based on a single shared key that all parties are privy to and can utilize to encrypt and decrypt data. Asymmetric cryptography encrypts and decrypts a message using a pair of similar keys. Anybody can use a public key to encrypt a document so that only the recipient can decrypt it with their private key. A private key is only known to the party that generated it.
- Confidentiality: confidentiality means that only the intended recipient can decrypt and thus read the message.
- Non-repudiation: non-repudiation means the sender of the message cannot backtrack and deny their reasons for sending the message.
- Integrity: integrity is the idea that the information contained within the message cannot be tampered with while in storage or transit.
- Authenticity: authenticity ensures that both the sender and recipient can confirm each other’s identities and the destination of the message.
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