Cybersecurity
Encryption Methods Explained: AES, RSA, ECC, and What Comes Next
Encryption turns readable data into ciphertext that only authorized parties can decode. This guide explains AES, RSA, and ECC, why NIST retired Triple DES, the new post-quantum standards, and how encryption applies to business devices and compliance.
Encryption is the process of converting readable data into a scrambled format that cannot be understood without the corresponding key. It is the foundational control behind secure websites, encrypted email, protected file storage, and private communications. Understanding how encryption works and which methods apply to different situations helps you make better decisions about protecting your organization's data.
How Encryption Works
Encryption uses mathematical algorithms and keys to transform plaintext into ciphertext. The algorithm defines the process. The key is the unique value that controls the transformation. Without the correct key, decrypting the ciphertext to recover the original data is computationally infeasible with current technology, assuming a strong algorithm and sufficient key length.
The two primary categories of encryption are symmetric and asymmetric, and each serves different purposes.
Symmetric Encryption
Symmetric encryption uses the same key for both encryption and decryption. The sender and receiver must both possess the key. This approach is fast and efficient, making it well-suited for encrypting large volumes of data. The challenge is key distribution: securely sharing the key with the intended recipient without exposing it during transmission.
AES (Advanced Encryption Standard)
AES is the current standard for symmetric encryption and is widely considered one of the most secure encryption algorithms available. It supports key lengths of 128, 192, or 256 bits. The 256-bit variant is used in government and enterprise environments where the highest level of protection is required. AES encrypts data in fixed-size blocks and is used in everything from full-disk encryption to wireless network security protocols.
DES and Triple DES
DES was the symmetric encryption standard before AES. It uses a 56-bit key, which is far too short to resist modern brute-force attacks, and it has been replaced by AES in current applications. Its successor, Triple DES (3DES), applied the algorithm three times to extend its life. NIST no longer allows it for new protection: under NIST SP 800-131A Rev. 2, Triple DES encryption was deprecated through 2023 and disallowed after December 31, 2023. Decryption is still permitted only to read legacy data. If an older application, VPN, or device still relies on 3DES, plan to replace or reconfigure it.
Asymmetric Encryption
Asymmetric encryption uses a mathematically linked key pair: a public key and a private key. Data encrypted with the public key can only be decrypted with the corresponding private key. The public key can be shared freely, while the private key is kept secret by its owner. This solves the key distribution problem inherent in symmetric encryption.
RSA (Rivest-Shamir-Adleman)
RSA is one of the most widely used asymmetric algorithms. It is used to secure data transmission and digital signatures and is the basis for many digital certificate and public key infrastructure systems. RSA keys of 2048 bits are the current minimum recommended size, with 3072-bit and larger keys used where longer-term protection is needed. RSA is computationally intensive, so it is typically used for signatures or to securely exchange symmetric keys, after which symmetric encryption handles the bulk data.
ECC (Elliptic Curve Cryptography)
ECC is an asymmetric approach that achieves equivalent security to RSA with significantly shorter key lengths. A 256-bit ECC key provides roughly the same protection as a 3072-bit RSA key. This efficiency makes ECC particularly well-suited for mobile devices, embedded systems, and environments where processing power and battery life are constrained. ECC is widely used in modern TLS connections and mobile application security.
What Comes Next: Post-Quantum Cryptography
A large enough quantum computer could break RSA and ECC, the algorithms that protect most key exchanges and digital signatures today. That machine does not exist yet, but data encrypted and stolen now could be decrypted later, so the transition has already started. On August 13, 2024, NIST published its first three post-quantum standards: FIPS 203, which specifies the ML-KEM key-encapsulation mechanism, FIPS 204 for ML-DSA digital signatures, and FIPS 205 for SLH-DSA hash-based signatures. NIST says these can and should be put into use now and that it will deprecate and ultimately remove quantum-vulnerable algorithms from its standards by 2035.
Most businesses will adopt post-quantum protection through updates to browsers, operating systems, VPNs, and cloud services rather than by building anything themselves. The practical step today is to know where your systems use encryption and which vendors will need to update them. Symmetric algorithms such as AES are far less affected by quantum computing and are not the focus of this transition.
Encryption in Practice
Encryption appears throughout everyday digital life. Online shopping and banking rely on TLS encryption to protect data in transit between your browser and the server. Encrypted messaging applications use end-to-end encryption so that only the sender and recipient can read messages. Full-disk encryption on laptops and mobile devices protects stored data if a device is lost or stolen. Email encryption protects message content from interception during delivery.
For a typical business, that translates into a short list of controls:
- Full-disk encryption on every laptop and desktop, such as BitLocker on Windows, with recovery keys stored centrally. Microsoft Intune can enforce BitLocker and back up recovery keys to Microsoft Entra ID.
- Encryption on phones and tablets that access company data, enforced through device management.
- Current TLS for websites, email, and remote access, with outdated protocol versions and ciphers such as 3DES turned off.
- Encrypted email or secure portals for sending sensitive information outside the organization.
- Encrypted backups, with the keys stored separately from the backup data.
Encryption and Compliance
Encryption is also a regulatory expectation. The FTC Safeguards Rule requires covered financial institutions to encrypt all customer information both in transit over external networks and at rest. If encryption is infeasible, the institution may instead use effective alternative compensating controls reviewed and approved by its Qualified Individual. The HIPAA Security Rule lists encryption of electronic protected health information, at rest and in transmission, as an addressable implementation specification, which means a covered entity must implement it when reasonable and appropriate, or document why not and what it does instead.
For organizations, encryption decisions involve selecting the right algorithm and key length for each use case, managing keys securely over their full lifecycle, and ensuring that encryption is applied consistently across all data that requires protection.
If you want to assess how encryption is currently applied in your environment or need help implementing encryption controls that meet your regulatory and business requirements, contact Cyber One Solutions. We help businesses across Texas and Tennessee build data security programs that protect information at rest and in transit.