Data Encryption  | AES-256

Supported Algorithms

Name	Description
AES-128	The AES-128 (Advanced Encryption Standard with a 128-bit key) is a widely used symmetric encryption algorithm designed to securely encrypt data. It is part of the AES family, which also includes AES-192 and AES-256, with the number referring to the key length in bits. Features: Key Size: AES-128 uses a 128-bit key for encryption, which provides a balance between security and performance. Block Size: AES operates on fixed-size 128-bit blocks of data (16 bytes), meaning it encrypts 128 bits of plaintext at a time. Symmetric Encryption: AES-128 uses the same key for both encryption and decryption, meaning the sender and receiver must both have the same key. Security: AES-128 is considered highly secure, resistant to all known practical attacks, and is widely used in government, military, and commercial applications. Common Uses: AES-128 is commonly used in a wide range of applications such as VPNs, file encryption, secure communications, and data protection.
AES-192	The AES-192 (Advanced Encryption Standard with a 192-bit key) is a symmetric encryption algorithm that is part of the AES family of encryption standards, which also includes AES-128 and AES-256. Features: Key Size: AES-192 uses a 192-bit key for encryption, providing a higher level of security than AES-128, but with a slight performance tradeoff. Block Size: Like all AES variants, AES-192 operates on 128-bit blocks of data, meaning it encrypts 128 bits of plaintext at a time. Symmetric Encryption: AES-192 is a symmetric encryption algorithm, meaning the same key is used for both encryption and decryption. Security: AES-192 provides strong security, suitable for environments that require higher protection levels than AES-128 but don't need the extra overhead of AES-256. Common Uses: AES-192 is used in scenarios where a higher level of encryption is needed than AES-128 but without the computational cost of AES-256. It is used in high-security applications like secure communications, data encryption and network security protocols.
AES-256	The AES-256 (Advanced Encryption Standard with a 256-bit key) is the most secure variant of the AES encryption family, widely used for encrypting sensitive data. Features: Key Size: AES-256 uses a 256-bit key, offering the highest level of security compared to AES-128 and AES-192. Block Size: AES operates on 128-bit blocks of data (16 bytes), meaning it encrypts 128 bits of plaintext at a time. Symmetric Encryption: AES-256 uses the same key for both encryption and decryption, making it a symmetric encryption algorithm. Security: AES-256 provides exceptional security and is considered resistant to brute-force attacks due to its large key size. It is trusted by governments, military organizations, and enterprises for protecting sensitive information. Common Uses: AES-256 is commonly used in high-security applications, such as military communications, government data protection, financial institutions, cloud storage encryption, and VPNs.
DES	The DES (Data Encryption Standard) is an older symmetric encryption algorithm that was widely used for securing digital data, but is now considered obsolete due to its vulnerability to modern computing power. Features: Key Size: DES uses a 56-bit key for encryption, which is relatively small by today's standards and susceptible to brute-force attacks. Block Size: DES operates on 64-bit blocks of data, meaning it encrypts 64 bits of plaintext at a time. Symmetric Encryption: DES is a symmetric encryption algorithm, meaning the same key is used for both encryption and decryption. Security: Due to its small key size, DES is no longer secure for modern applications. It was broken in the late 1990s by brute-force attacks, making it unsuitable for protecting sensitive data. Common Uses: DES was historically used in financial transactions, government communications, and data storage systems. However, it has been largely replaced by more secure algorithms like AES.
TDES-112	The TDES-112 (Triple Data Encryption Standard with 112-bit key) is an enhanced version of the original DES encryption algorithm, designed to improve security by applying the DES algorithm three times with different keys. Features: Key Size: TDES 112 uses a 112-bit key, achieved by applying the DES algorithm three times using two keys (one key is used twice). Block Size: Like DES, TDES operates on 64-bit blocks of data. Symmetric Encryption: TDES is a symmetric encryption algorithm, meaning the same key is used for both encryption and decryption. Security: TDES 112 is significantly more secure than single DES due to the triple encryption process, but still weaker than modern algorithms like AES. Common Uses: TDES 112 is used in legacy systems, especially in financial applications (e.g., ATM transactions, point-of-sale systems), where backward compatibility with DES is needed but enhanced security is required.
TDES-168	The TDES-168 (Triple Data Encryption Standard with 168-bit key) is a more secure variant of the TDES encryption algorithm, offering stronger encryption than TDES 112 by using a 168-bit key (three separate 56-bit DES keys). Features: Key Size: TDES 168 uses a 168-bit key (composed of three 56-bit DES keys), offering stronger security compared to TDES 112, which uses two keys. Block Size: Like DES, TDES operates on 64-bit blocks of data. Symmetric Encryption: TDES is a symmetric encryption algorithm, meaning the same key is used for both encryption and decryption. Security: TDES 168 provides stronger encryption than TDES 112 and DES, but it is still slower and less secure compared to modern encryption algorithms like AES. Common Uses: TDES 168 is used in financial systems, legacy applications, and banking, especially for encrypting card data, ATM transactions and secure communications that need higher security than DES, but cannot yet migrate to AES.
RABBIT	The RABBIT is a stream cipher designed for high-speed encryption, developed by the EU's eSTREAM project as part of its effort to find new and efficient encryption algorithms. Features: Stream Cipher: Rabbit encrypts data one bit or byte at a time, making it suitable for applications requiring fast and lightweight encryption. Key Size: Rabbit uses a 128-bit key and a 128-bit initialization vector (IV) for encryption. Security: Rabbit is designed to offer strong security with high resistance to attacks, such as differential cryptanalysis and linear cryptanalysis. Speed: It is known for its fast performance, particularly in hardware and software implementations, making it ideal for environments where speed is critical, such as real-time communications and data streaming. Common Uses: Rabbit is used in applications that require fast encryption and decryption of large amounts of data, like VPNs, wireless communications, and file encryption.
RC4	The RC4 (Rivest Cipher 4) is a widely used stream cipher developed by Ron Rivest in 1987. It became popular due to its simplicity, speed, and ease of implementation. RC4 encrypts data one byte at a time and uses a variable-length key, typically ranging from 40 bits to 2048 bits. Features: Stream Cipher: RC4 is a stream cipher, meaning it encrypts data sequentially, one bit or byte at a time, rather than in fixed-size blocks. Key Size: The key can vary in length from 40 bits to 2048 bits. Simplicity: RC4 is known for its simplicity and speed in software implementations, making it easy to deploy in various applications. Security: Despite its early popularity, RC4 is now considered cryptographically weak and vulnerable to several attacks, particularly with short key lengths and weak initialization vectors. This led to its deprecation in many security protocols. Common Uses: RC4 was historically used in SSL/TLS for encrypting web traffic, WEP (Wired Equivalent Privacy) for wireless security, and Microsoft's RDP (Remote Desktop Protocol).
RC4-DROP	The RC4-DROP refers to a technique used to mitigate some of the weaknesses in the original RC4 stream cipher. Specifically, it involves discarding a number of initial keystream bytes generated by the key scheduling algorithm (KSA) before starting the actual encryption process. The "DROP" refers to dropping or ignoring the first few bytes of the keystream, which helps reduce certain biases and vulnerabilities present in the early part of the stream. Features: Purpose: The primary goal of RC4 DROP is to improve security by avoiding the biased or predictable initial bytes of the RC4 keystream, which could be exploited by attackers. Keystream Initialization: In standard RC4, the keystream is generated starting from the first byte, but in RC4 DROP, the initial bytes (typically the first 256 or more) are discarded. Security Improvement: By dropping the initial keystream bytes, the technique aims to make the resulting keystream less predictable and reduce the risk of known-plaintext attacks or other weaknesses associated with the early keystream values. Common Uses: RC4 DROP is used in systems that still rely on RC4 but want to mitigate some of its known weaknesses. It is sometimes applied in protocols like TLS or WEP (Wireless Encryption Protocol), although RC4 itself is now considered obsolete and insecure.
RSA-OAEP	The RSA-OAEP (Rivest-Shamir-Adleman with Optimal Asymmetric Encryption Padding) is an enhanced version of the RSA encryption algorithm that includes a secure padding scheme to improve its security. OAEP is used to prevent various attacks, such as chosen-plaintext attacks, by adding randomness and structure to the plaintext before encryption. Features: RSA: A public-key encryption algorithm that uses two keys - one for encryption (public key) and another for decryption (private key). It is widely used for secure data transmission. OAEP Padding: OAEP adds a randomized padding to the plaintext before it is encrypted with RSA. This makes the encryption process more secure by ensuring that even if the same message is encrypted multiple times, the resulting ciphertext will be different each time. Security: OAEP prevents vulnerabilities present in older padding schemes (like PKCS#1 v1.5) and provides semantic security, which ensures that no information about the plaintext can be deduced from the ciphertext under chosen-plaintext attacks. Usage: RSA with OAEP is typically used for key exchange, digital signatures, and public-key encryption in secure communication protocols like SSL/TLS, PGP, and digital certificates. Common Uses: RSA with OAEP is used in modern cryptographic systems to provide enhanced security when encrypting small amounts of data, like symmetric encryption keys in hybrid encryption schemes. It is widely used in SSL/TLS for secure web communications, email encryption, and cryptographic protocols.

Encryption Is Not Encoding

Encryption transforms data so that it cannot be read without the correct key. That is what separates it from encoding: Base64 and URL encoding are public, keyless transformations that anyone can reverse instantly, and they provide no confidentiality at all. If you only need to make data safe to transmit as text, use the encoding tool instead.

The security of everything on this page rests entirely on the key. The algorithms are public and well documented — that is a feature, not a weakness. A cipher whose security depends on nobody knowing how it works has never held up in practice.

Symmetric and Asymmetric

Symmetric ciphers

AES, DES, Triple DES, RC4, and Rabbit all use one key for both encryption and decryption. They are fast and handle data of any size, which makes them the workhorses of practical encryption. The difficulty is distribution: both parties need the same secret, and getting it to the other side securely is its own problem.

Asymmetric ciphers

RSA-OAEP uses a key pair — a public key that encrypts and a private key that decrypts. Anyone can encrypt a message to you using your public key, and only you can read it. That solves key distribution, but it is far slower and can only encrypt data smaller than the key size.

Real systems use both. TLS, the protocol securing this page, uses asymmetric cryptography to agree on a symmetric key, then switches to a symmetric cipher for the actual traffic. This is called hybrid encryption, and it takes the key-distribution advantage of one with the speed of the other.

Which Algorithm to Choose

• AES-256 — the default recommendation. It is the current standard, has withstood two decades of analysis, and is used everywhere from disk encryption to government classified material.
• AES-128 and AES-192 — also secure. AES-128 remains well beyond brute-force reach; the larger key sizes provide margin rather than fixing any known weakness.
• Triple DES — legacy. It survives in older financial systems, but it is slow and its 64-bit block size is a genuine limitation. Do not choose it for new work.
• DES — broken. Its 56-bit key was brute-forced in the late 1990s and can now be exhausted quickly. Present here for interoperability with old data, not for protecting anything.
• RC4 — deprecated. Statistical biases in its output led to practical attacks, and it has been prohibited in TLS since 2015.
• RSA-OAEP — the right choice for encrypting a small value, such as a symmetric key or a short credential, to a recipient's public key.

Block Modes

A block cipher encrypts fixed-size blocks, so the mode determines how successive blocks relate to each other. This choice matters as much as the algorithm.

• CBC — each block is combined with the previous ciphertext block before encryption, so identical plaintext blocks produce different output. The common default.
• CFB and OFB — turn a block cipher into a stream cipher, allowing encryption of data that is not a whole number of blocks.
• CTR — encrypts a counter and combines the result with the plaintext. Parallelizable and widely used in modern protocols. CTR Gladman is a variant implementation.
• ECB — encrypts each block independently, with no chaining. This is its weakness: identical plaintext blocks give identical ciphertext, so structure in the original data survives into the output. It should be avoided for anything real.

Padding

Block ciphers need input that fills a whole number of blocks, so shorter data is padded. PKCS7 is the standard choice and is what most systems expect. ANSI X9.23, ISO 10126, and ISO 97971 are alternatives specified by other standards.

Zero padding cannot be unambiguously removed if the data legitimately ends in zero bytes, and "none" requires input that already fills the block exactly. Both are for specific interoperability cases rather than general use.

Common Uses

• Protecting a note or credential — encrypt text before storing it somewhere you do not fully trust.
• Testing interoperability — confirm that two systems agree on algorithm, mode, and padding.
• Learning how ciphers behave — see directly how changing the mode or padding changes the output.
• Decrypting legacy data — read values produced by older systems that used DES or Triple DES.
• Verifying an implementation — check output against a known-good reference before shipping code.

Practical Cautions

• The key is everything. A weak or guessable key defeats any algorithm. Use a long random key — the password generator will produce one.
• Lose the key, lose the data. There is no recovery mechanism. This is the point of encryption, and it cuts both ways.
• Encryption alone does not prove authenticity. These modes protect confidentiality but do not detect tampering. Modern protocols use authenticated encryption, such as AES-GCM, to cover both.
• Match every parameter. Decryption requires the same algorithm, key, mode, and padding. Mismatched settings produce failure or nonsense rather than a helpful error.
• For serious needs, use a vetted tool. A password manager or full-disk encryption handles key management, authentication, and secure storage — concerns beyond what any single-purpose page can address.

Frequently Asked Questions

Is my data or key sent to a server?

No. Encryption and decryption run entirely in your browser. Nothing you type here is transmitted, logged, or stored, and refreshing the page discards it.

Which algorithm should I use?

AES-256 unless you have a specific reason to do otherwise. It is secure, fast, and universally supported. Choose RSA-OAEP only when you need public-key encryption of a small value.

Why is DES still offered if it is broken?

For reading old data. Systems encrypted with DES decades ago still exist, and decrypting their output requires the algorithm. It should never be used to protect anything new.

Can AES-256 be broken?

Not by brute force with any foreseeable technology — the key space is around 10⁷⁷. Real-world compromises come from weak keys, poor implementation, or key theft, not from breaking the cipher itself.

Why does the same input give different output each time?

Because a good cipher introduces randomness, usually through an initialization vector, so that repeated encryption of identical plaintext produces different ciphertext. This is deliberate: it prevents an observer from spotting that the same message was sent twice.

What if decryption returns nothing useful?

Almost always a parameter mismatch — a different key, mode, or padding than was used to encrypt. Decryption with the wrong settings does not report an error; it simply produces meaningless bytes.