Encryption definition: What is encryption? (2025 guide)
Encryption is the process of converting readable information into unreadable code to prevent unauthorized access. It transforms your data into scrambled text that can only be decrypted and read by someone with the correct key or password. Understanding encryption is essential for protecting sensitive information in today's digital world, whether you're securing personal documents, business files, or confidential communications.
When you encrypt a file, email, or message, you're using mathematical algorithms to scramble the data into ciphertext—random-looking characters that appear meaningless without the decryption key. This ensures that even if someone intercepts your encrypted data, they cannot read it without the proper key. Encryption protects your information at rest (stored on devices) and in transit (traveling over networks), providing a critical security layer for sensitive data.
What is encryption?
Encryption is a security method that uses cryptographic algorithms to convert plaintext (readable data) into ciphertext (encrypted data). The encrypted data appears as random characters and can only be converted back to readable form using a decryption key or password. This process ensures that only authorized parties can access and read the original information.
Key components of encryption:
- Plaintext: The original, readable data before encryption
- Ciphertext: The encrypted, unreadable data after encryption
- Encryption algorithm: The mathematical formula used to scramble data
- Encryption key: The secret code used to encrypt and decrypt data
- Decryption: The process of converting ciphertext back to plaintext
Encryption works by applying complex mathematical operations to your data using an encryption key. The same key (in symmetric encryption) or a corresponding key (in asymmetric encryption) is required to reverse the process and decrypt the data back to its original form.
How encryption works
Encryption uses cryptographic algorithms to transform data. When you encrypt a file or message, the algorithm takes your plaintext and an encryption key, performs mathematical operations, and produces ciphertext. The process is designed to be one-way without the key—meaning you cannot reverse the encryption without the correct decryption key.
The encryption process:
- Input: You provide plaintext (readable data) and an encryption key
- Algorithm processing: The encryption algorithm performs mathematical operations
- Output: The algorithm produces ciphertext (encrypted, unreadable data)
- Storage or transmission: The ciphertext is stored or transmitted securely
- Decryption: The recipient uses the decryption key to convert ciphertext back to plaintext
Example: When you encrypt a Word document with a password, Microsoft Word uses AES-256 encryption to scramble the file contents. Without the password, the file appears as random characters. With the correct password, Word decrypts the file and displays the original content. Learn more about how to encrypt Word files for practical applications.
Types of encryption
Encryption methods fall into two main categories: symmetric and asymmetric encryption. Each type has different use cases and security characteristics.
Symmetric encryption
Symmetric encryption uses the same key for both encryption and decryption. This means the sender and recipient must share the same secret key to communicate securely.
Characteristics:
- Uses a single shared key for encryption and decryption
- Faster and more efficient for large amounts of data
- Requires secure key distribution
- Common algorithms: AES (Advanced Encryption Standard), DES, 3DES
Use cases: File encryption, full disk encryption, database encryption, and secure file sharing where both parties have the key.
Example: When you create a password-protected ZIP file, the password serves as the encryption key. The same password is used to encrypt and decrypt the archive. For step-by-step instructions, see our guide on how to encrypt a file with a password.
Asymmetric encryption
Asymmetric encryption uses a pair of keys—a public key for encryption and a private key for decryption. The public key can be shared openly, while the private key must be kept secret.
Characteristics:
- Uses two mathematically related keys (public and private)
- More secure for key distribution
- Slower than symmetric encryption
- Common algorithms: RSA, ECC (Elliptic Curve Cryptography), Diffie-Hellman
Use cases: Email encryption (S/MIME, PGP), digital signatures, secure web connections (SSL/TLS), and key exchange for symmetric encryption.
Example: When you visit a secure website (HTTPS), your browser uses the website's public key to encrypt data. Only the website's private key can decrypt it, ensuring secure communication.
Hashing
While not encryption in the traditional sense, hashing is a related cryptographic process that converts data into a fixed-length string of characters.
Characteristics:
- One-way process (cannot be reversed)
- Produces fixed-length output regardless of input size
- Used for data integrity verification and password storage
- Common algorithms: SHA-256, MD5, bcrypt
Use cases: Password storage, digital signatures, data integrity checks, and blockchain technology.
Common encryption algorithms
Different encryption algorithms provide varying levels of security and performance. Understanding these algorithms helps you choose the right encryption method for your needs.
AES (Advanced Encryption Standard)
AES is the most widely used encryption standard today, adopted by governments and organizations worldwide.
- Key sizes: 128-bit, 192-bit, 256-bit
- Security level: Very high (AES-256 is considered unbreakable with current technology)
- Performance: Fast and efficient
- Use cases: File encryption, disk encryption, secure communications, secure file sharing
Why AES-256 is recommended: AES-256 uses 256-bit keys, providing 2^256 possible key combinations. This makes it computationally infeasible to break with brute force attacks using current technology.
RSA (Rivest-Shamir-Adleman)
RSA is a widely used asymmetric encryption algorithm for secure key exchange and digital signatures.
- Key sizes: Typically 2048-bit or 4096-bit
- Security level: High (depends on key size)
- Performance: Slower than symmetric encryption
- Use cases: SSL/TLS certificates, email encryption, digital signatures
ECC (Elliptic Curve Cryptography)
ECC provides the same security as RSA with smaller key sizes, making it more efficient.
- Key sizes: 256-bit, 384-bit, 521-bit
- Security level: High (equivalent to larger RSA keys)
- Performance: Faster than RSA
- Use cases: Mobile devices, IoT security, modern SSL/TLS certificates
Encryption in practice
Encryption protects your data in various real-world scenarios, from securing files on your computer to protecting communications over the internet.
File encryption
File encryption protects individual files or entire storage devices from unauthorized access. When you encrypt a file, only someone with the correct password or key can open and read it.
Examples:
- Encrypting Word documents with password protection
- Full disk encryption using FileVault (Mac) or BitLocker (Windows)
- Creating encrypted ZIP archives for file sharing
- Using secure file sharing platforms with built-in encryption
Understanding which files need encryption helps you prioritize security efforts for sensitive documents like financial records, legal contracts, and personal information.
Email encryption
Email encryption protects email messages and attachments from being read by unauthorized parties during transmission or storage.
Methods:
- S/MIME (Secure/Multipurpose Internet Mail Extensions)
- PGP (Pretty Good Privacy)
- Office 365 Message Encryption
- TLS (Transport Layer Security) for email transmission
Benefits: Email encryption ensures that even if your email is intercepted, the content remains unreadable without the decryption key.
Database encryption
Database encryption protects sensitive information stored in databases, such as customer data, financial records, and personal information.
Types:
- Encryption at rest: Data is encrypted when stored in the database
- Encryption in transit: Data is encrypted when transmitted between applications and databases
- Field-level encryption: Specific database fields are encrypted individually
Cloud storage encryption
Cloud storage services use encryption to protect your files stored in the cloud, ensuring that even service providers cannot read your data without the encryption key.
Types:
- Client-side encryption: Files are encrypted on your device before uploading
- Server-side encryption: Files are encrypted by the cloud service provider
- End-to-end encryption: Only you and authorized recipients can decrypt files
Papermark: Secure file sharing with encryption
Papermark is a secure file sharing platform that combines AES-256 encryption with advanced security features to protect your sensitive documents. When you upload files to Papermark, they are automatically encrypted using industry-standard AES-256 encryption, ensuring your data remains protected both in transit and at rest.
Papermark encryption features:
- AES-256 encryption: All files are encrypted with AES-256, the same standard used by governments and financial institutions
- Password protection: Add an additional layer of security with password-protected file sharing
- Access controls: Control who can access your encrypted files with email verification, allowlists, and denylists
- Dynamic watermarking: Add recipient-specific watermarks to encrypted documents to identify unauthorized sharing
- Access tracking: Monitor who accessed your encrypted files and when, even with password protection enabled
- Secure sharing: Share encrypted files via secure links that require passwords and access verification
Papermark makes encryption accessible for businesses and individuals who need to share sensitive documents securely. Unlike basic file encryption tools, Papermark combines encryption with comprehensive access controls, analytics, and the ability to revoke access—making it ideal for sharing encrypted files with clients, partners, or team members.
For step-by-step instructions on using Papermark's encryption features, see our guide on how to encrypt a file with a password.
Why encryption matters
Encryption is essential for protecting sensitive information in today's digital landscape. It provides multiple security benefits and helps comply with data protection regulations.
Protection against unauthorized access
Encryption prevents unauthorized parties from reading your sensitive data, even if they gain access to your files, devices, or network communications. This is crucial for protecting personal information, business secrets, and confidential communications.
Data privacy compliance
Many regulations require encryption for sensitive data, including:
- GDPR (General Data Protection Regulation): Requires encryption for personal data
- HIPAA (Health Insurance Portability and Accountability Act): Requires encryption for health information
- PCI DSS (Payment Card Industry Data Security Standard): Requires encryption for payment card data
Secure communication
Encryption enables secure communication over insecure networks like the internet. It ensures that your messages, files, and data remain private even when transmitted over public networks.
Data integrity
Some encryption methods also provide data integrity verification, ensuring that encrypted data hasn't been tampered with or modified during transmission or storage.
Encryption vs. password protection
While related, encryption and password protection are not the same thing. Understanding the difference helps you choose the right security method.
Password protection: Adds a password requirement to access files or accounts. Simple password protection can sometimes be bypassed or cracked relatively easily.
Encryption: Uses mathematical algorithms to scramble data into unreadable code. Strong encryption (like AES-256) cannot be easily broken even with password cracking tools.
Best practice: Use encryption with password protection for maximum security. The password serves as the encryption key, and the encryption algorithm ensures the data cannot be read without it.
Conclusion
Encryption is a fundamental security technology that protects your sensitive data by converting it into unreadable code. Understanding how encryption works, the different types available, and when to use it helps you make informed decisions about protecting your information. Whether you're encrypting files on your computer, securing email communications, or protecting data in the cloud, encryption provides a critical security layer against unauthorized access.
For practical applications, use encryption to protect sensitive files like financial documents, legal contracts, and personal information. When sharing encrypted files, consider using secure file sharing platforms that combine encryption with password protection, access controls, and detailed analytics for comprehensive security.