What is the difference between Encryption and Signing? Why should you use digital signatures?

Threats loom ever present in our digital world, which is why methods of securing data are constantly advancing. Tactics like encryption are used every day on sensitive data-at-rest or in-motion. Encryption is the process of putting data in the form of plaintext into an encryption algorithm, and producing a ciphertext. Ciphertext is a form of data where all the patterns of letters that create words in the plaintext are scrambled into a new text that cannot be read without decrypting the data. Encryption uses a key to ensure the ciphertext cannot be deciphered by anyone but the authorized recipient.

Signing of data works to authenticate the sender of the data and tends to implement a form of encryption in its process. The process of signing emails, sensitive data, and other information has become necessary, as it verifies the identity of the sender and ensures the data has not been altered in transit. If a Man in the Middle attack occurred and the data was altered or compromised by the attacker, the recipient of the information would know that this has occurred. The attacker could alter the data, but as they do not have the key used by the sender to sign the data, the recipient of the data will know not to trust the sent data when analyzing the key and data.

How does digital signing work?

The process of digital signing works similarly to encryption. Encryption comes in two types, asymmetric and symmetric encryption. The process of asymmetric encryption works by creating a key pair with a public and private key. The private key is kept secret from everyone but the creator of the key, while the public key is available to everyone. The data is encrypted with the private key, and decrypted when needed with the public key. Symmetric encryption only uses one key for both encryption and decryption. As asymmetric encryption is more secure than symmetric encryption, it tends to be used more often. When sending data to a recipient, the correct method of encryption is to encrypt the data with the recipient’s public key, as this means only the owner of the key pair can decrypt that data.

Digital signing works oppositely. The data is signed by hashing the message with a hashing algorithm and the sender’s private key. This produces a hash digest, which can only be recreated through use of one of the keys in the key pair created by the sender. The recipient then receives the message, the hash digest, and the public key, if they did not already have it. The recipient then uses the sender’s public key to hash the message they have received. If the resulting hash digest matches the hash digest that has been sent along with the message, then the identity of the sender has been confirmed. This also confirms that the data has not been changed in transit. However, signing alone does not ensure the data has not been intercepted and read.

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Encryption and Signing

To protect data from compromise and authenticate the sender at the same time, encryption and digital signing are used together. They are also both used in tandem to fulfill compliance standards for companies. Standards, like the Federal Information Processing Standards (FIPS) or the General Data Protection Regulation (GDPR), require companies to protect data as securely as possible along with authenticating data received from others. Encryption and digital signing ensures these standards are reached, and that users can be secure in the knowledge that data that is sent to and from them will not be compromised.

Confidential or sensitive data should always be encrypted and signed for its own safety. The use of encryption and signing together ensures that the main goals of cryptography, Confidentiality, Integrity, Authenticity, and Non-Repudiation are all met. Confidentiality and integrity are reached when data is encrypted asymmetrically, as only the intended recipient can decrypt the message. Non-repudiation and authenticity occur due to digital signing. Non-repudiation means that using the technique of digital signing, the sender of any information cannot, in the future, say they did not send the data, as the use of their private key confirms that they sent the data.

Common Encryption and Signing Algorithms

Symmetric Encryption Algorithms:

Asymmetric Encryption Algorithms:

Signing Algorithms:

  • RSA
  • ElGamal Encryption System
  • Digital Signing Algorithm (DSA)