Hashing vs Encryption: What is the difference?

Hashing and encryption are two common methods used in cryptography to protect data. While related, they serve different purposes and have some key differences. This article will provide an in-depth look at hashing and encryption, how they work, when to use each one, and the main advantages and disadvantages of each.

How Hashing Works

Hashing is the process of converting any arbitrary amount of data into a fixed-size string of characters called a hash value or hash. This is done using a mathematical algorithm known as a hash function.

Here’s an overview of how hashing works:

• The hash function takes input data of any size, like a text document or binary file.
• It runs the data through the hashing algorithm to generate a hash value or digest that represents the data.
• The hash is usually a short string of hexadecimal characters like 3fe2301bfe03a7619b733427510b6629.
• The same input will always generate the same hash output, but any change to the input data should drastically change the hash.
• Hashes are one-way functions, meaning you cannot reconstruct the original data from the hash.

The main purposes of hashing are:

• To quickly identify data by condensing it into a smaller representation. Looking up hashes is much faster than comparing complete data.
• To detect duplicate data by comparing hashes rather than full data. If two hashes are equal, the data is most likely the same.
• For data integrity checks to identify changes or corruption by re-running hashes on data and comparing to stored hashes. If the hashes differ, the data has been altered.

Some common hash functions are MD5 and the SHA family (SHA-1, SHA-2, SHA-3).

Hash Properties

Hash functions have several important properties:

• Deterministic – Same input always gives the same output hash
• Fast computation – Hashing is fast to compute, even for large data
• One-way function – Unable to reverse the hashing process to find the original input
• Unique – Unique hashes for different inputs (with negligible collisions)
• Fixed size – Hash length is constant regardless of input size
• Avalanche effect – Small changes in input drastically change the hash

These make hashing well-suited for quick lookup, data integrity, and fingerprinting data. However, because hashes cannot be reversed, they do not suit applications like encrypted storage and communication.

How Encryption Works

Encryption is the process of encoding data in such a way that only authorized parties can read it. This is done by running the data through a mathematical algorithm using a secret key. Here are the basics of how encryption works:

• The original understandable data is called plaintext. This could be text, binary data, or any digital asset.
• An encryption algorithm and key are used on the plaintext to scramble and encode it into ciphertext that looks like random gibberish.
• Only those with the secret decryption key can decrypt the ciphertext back into readable plaintext.
• Common encryption algorithms are AES, Blowfish, RSA, and others. Keys are usually long binary numbers.
• The decryption key must match the encryption key used to return to the original plaintext.

The main purposes of encryption are:

• Maintain data confidentiality by ensuring only authorized users can read data.
• Protect data integrity by detecting changes to encrypted data.
• Secure communication by encrypting messages only the intended recipient can decrypt.
• Regulatory compliance for data security standards.

Unlike hashing, encryption supports two-way conversion so data can be reversed from ciphertext back into plaintext for authorized users.

Encryption Methods

There are two main types of encryption:

Symmetric-Key Encryption

• Uses a shared secret key for both encryption and decryption.
• Relies on keeping the symmetric key secure.
• Fast performance and simple implementation.
• Used for bulk data encryption and message transmission.

Public-Key Encryption

• Uses a public key for encryption and private key for decryption.
• Public key can be widely distributed without compromising security.
• Enables secure communication without prior exchange of secret keys.
• Used for digital signatures, secure communication, and data integrity.

Both methods have trade-offs between convenience vs security. Many systems use a hybrid approach with both shared secret keys and public key pairs.

Comparing Hashing vs Encryption

Hashing and encryption are related techniques but have some fundamental differences:

In summary:

• Hashing is one-way and produces a fingerprint or digest instead of encrypted data. Hashing algorithms are faster and simpler than encryption.
• Encryption provides two-way transformation using keys. It produces encrypted ciphertext from plaintext and vice versa. Works for securely transmitting confidential data.

Here are some examples highlighting the difference:

Input Data: "Hello World"

Hashing: 
b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9

Encryption: 
857389ejriue83847r7eje8383jrm3kcnq93jcne923kcne9e8342

The hash is a one-way fingerprint that cannot be reversed. Encryption produces ciphertext that requires the key to decrypt back into the original plaintext.

When to Use Hashing vs Encryption

Use encryption when:

• You need to protect the confidentiality of data.
• You need to control access to data using secure keys.
• You want to securely transmit data between parties.
• Data needs to be reversible to plaintext.

Use hashing when:

• You want to identify data via fingerprints for lookup/comparison.
• You want to detect duplicate data.
• You want to verify data integrity and detect tampering.
• Reversing the hash is not required.

Here are some examples of when to use each method:

Encryption is used for:

• Encrypting databases
• Secure communication
• Storing passwords, keys, sensitive data
• Digital signatures on documents

Hashing is used for:

• File fingerprinting
• Data duplication checks
• File integrity verification
• Password storage in databases
• Data validation/integrity checks
• Digital fingerprints and signatures

For data security:

• Encrypt the data for confidentiality
• Hash the encrypted data to detect tampering

For system security:

• Hash passwords before storing them to protect them
• Use encryption keys to control access to resources

So in summary, use hashing when you need to match data or verify integrity, and encryption when you need to securely transmit or store confidential data.

Hashing Algorithms

There are many standard hashing algorithms, but some of the most common and widely-used include:

MD5

• Produces 128-bit hash value
• Designed for speed and simplicity
• Prone to collisions
• No longer considered cryptographically secure

SHA-1

• Produces 160-bit hash value
• More resilient against collisions than MD5
• Approved for use by US Government up to 2014
• Deprecated due to cryptographic weaknesses

SHA-2

• Current standard approved by NIST
• Variants produce digests of 224, 256, 384 or 512 bits
• Includes SHA-224, SHA-256, SHA-384, SHA-512
• Much stronger against collisions and crypto attacks than MD5 and SHA-1

SHA-3

• Latest member of SHA family
• Produces digests of 224, 256, 384, or 512 bits
• Stronger against attacks than SHA-2
• Became standard in 2015, replacing SHA-2

BLAKE2

• Creates hashes of up to 512 bits
• Faster performance than MD5 and SHA families
• Designed for speed, efficiency, and security
• Gaining popularity as an alternative to SHA-3

When selecting a hashing algorithm, SHA-2 or SHA-3 are usually recommended over older methods like MD5 and SHA-1. The specific variant (SHA-256 vs SHA-512) depends on the desired security level and hash length.

Encryption Algorithms

There are two main classes of encryption algorithms:

Symmetric-Key Algorithms

Some commonly used algorithms include:

• AES (Advanced Encryption Standard) – The most widely adopted symmetric algorithm. Used worldwide by governments, corporations, and individuals. Key sizes of 128, 192 or 256 bits.
• Blowfish – Powerful 64-bit block cipher. Very fast when implemented on 32-bit microprocessors.
• Twofish – A 128-bit block cipher. High security and fast performance across a variety of hardware.
• RC4 (Rivest Cipher 4) – Stream cipher used in popular protocols like TLS. Fast and simple but has weaknesses when incorrectly used.
• DES (Data Encryption Standard) – An older standard that is now considered insecure. 3DES is a more secure variant.

AES is the recommended standard for symmetric encryption today. The key size should be at least 128 bits or higher for strong security.

Public-Key Algorithms

Common algorithms include:

• RSA – Most widely used public-key algorithm based on factoring prime numbers. Highly secure when large keys (2048+ bits) are used.
• ECC (Elliptic Curve Cryptography) – Modern public-key method based on elliptic curve math. Faster performance than RSA with equivalent security.
• Diffie-Hellman – A key exchange protocol that uses discrete logarithms. Enables two parties to securely establish a shared key over an insecure channel.
• DSA (Digital Signature Algorithm) – Used to create and verify digital signatures. Often paired with SHA hash functions.

For public-key encryption, RSA is universally supported. ECC offers faster performance but not as widely adopted. Key size should be at least 2048 bits for RSA or 224 bits for ECC.

Hashing for Password Storage

One very common application of hashing is storing user passwords in a database. Passwords should never be stored in plaintext, only hashed. When a user logs in, you hash their entered password and compare it to the stored hash.

Storing hashed passwords provides protection even if your database is compromised, since attackers cannot recover the original passwords. This prevents password reuse across sites.

Here is the basic process:

1. User creates account with password like mypass123
2. Password is hashed using a salt and algorithm like pbkdf2, bcrypt or scrypt to produce hash: a7f5ba8c0e1020b49da746ae739f1489f75686457c1b433b202b2c2ffa2b220d
3. Only the hash is stored in the database, not the plaintext password
4. User enters mypass123 to log in again
5. Their entered password is hashed using same method. The resulting hash is compared to stored hash.
6. If hashes match, login succeeds. Otherwise failure.

Proper password hashing is crucial for application security. Common algorithms like bcrypt, scrypt, and PBKDF2 apply multiple rounds of salted hashing to protect stored passwords from brute force attacks.

Digital Fingerprints

Hashing can serve as a digital fingerprint for identifying and verifying data. Files, documents, network packets, and other digital assets can have hashes computed to uniquely identify them.

This allows for quick duplicate detection and file integrity verification. By comparing document hashes rather than entire contents, duplication and changes are rapidly detected.

Some examples of hashing for digital fingerprints:

• File integrity checking – Store file hashes to detect unauthorized changes
• Anti-piracy and plagiarism checks – Hash copied media/documents for infringement
• Network traffic analysis – Hash packet contents for intrusion detection
• Forensics – Identify known illegal or restricted files via hashing

Hash-based message authentication codes (HMACs) are also used to verify integrity and authenticity of transmitted data. They combine hashing with secret keys for identity and tampering detection.

Summary of Key Differences

When to Use Each Method

Here are some recommended use cases for hashing vs encryption:

Use Encryption For:

• Securing sensitive data at rest or in transit
• Storing personal info, credentials, passwords
• Protecting databases, files, backups
• Secure communication and messaging
• Digital rights management (DRM)

Use Hashing For:

• Password and credential storage
• Data validation and integrity checks
• File fingerprinting and duplication detection
• Document signing and verification
• Network traffic analysis and forensics
• Blockchain transaction verification

For security best practices:

• Encrypt data for confidentiality
• Hash data to verify integrity
• Hash passwords before storing them

Conclusion

Hashing and encryption provide fundamental cryptographic functionality for securing data.

• Hashing produces fixed-length digests used for fast lookup, data integrity and digital fingerprints. It is irreversible and uses hash functions like SHA and MD5.
• Encryption transforms plaintext into ciphertext for securely transmitting or storing data using keys. It uses encryption algorithms like AES and RSA and can be reversed into original data.

Understanding when to apply hashing versus encryption is important. Use encryption to provide confidentiality and access control. Use hashing when you need to validate data integrity or create unique identifiers and lookups.

By combining both cryptographic methods, systems can implement strong end-to-end security. Properly hashing passwords and validating data integrity provides defense in depth for protecting sensitive information and assets.