AES Encrypt Online

Symmetric-Key Encryption

This AES encrypt online tool supports AES, DES, 3DES, RC4, and Rabbit for client-side encrypt/decrypt testing—plaintext never leaves your browser. Symmetric-key algorithms use the same key (or trivially related keys) for both encryption and decryption. This makes them much faster than asymmetric algorithms, but key distribution becomes the primary challenge.

DES

DES (Data Encryption Standard) is a block cipher with a 56-bit key and a 64-bit block size. Published in 1977, it was gradually replaced by 3DES in the 2000s and by AES in the 2010s. See DES on Wikipedia.

3DES

3DES (Triple DES, also written TripleDES) is a block cipher that applies the DES algorithm three times to each data block, effectively increasing the key strength. See 3DES on Wikipedia.

AES

AES (Advanced Encryption Standard), also known as the Rijndael cipher, is a block cipher with a 128-bit block size and key lengths of 128, 192, or 256 bits. It is the current international standard for symmetric encryption. See AES on Wikipedia.

RC4

RC4 (Rivest Cipher 4) is a stream cipher. In 2015, RFC 7465 prohibited the use of RC4 in all versions of TLS. See RC4 on Wikipedia.

Rabbit

Rabbit is a stream cipher published in 2003. See Rabbit cipher on Wikipedia.

How to Use

Encrypting Text

1. Enter your plaintext in the Text input field on the left
2. Select an encryption algorithm: DES, 3DES, AES, RC4, or Rabbit
3. Enter your encryption key (leaving it empty uses an empty string as the key)
4. Click the Encrypt button — the ciphertext appears in the Cipher field on the right

Decrypting Text

1. Paste the ciphertext into the Cipher field on the right
2. Make sure the algorithm and key match those used during encryption
3. Click the Decrypt button — the decrypted plaintext appears on the left

If decryption fails, the most likely cause is a mismatched algorithm or key. Double-check both and try again.

Choosing an Algorithm

AES (recommended) — The current gold standard for symmetric encryption. Strong security and excellent performance. When in doubt, use AES.

3DES — An enhanced version of DES with better security, but slower than AES. Still found in some legacy systems.

DES — The original encryption standard with only a 56-bit key, no longer considered secure. Use it only for learning purposes.

RC4 — A fast stream cipher, but known security vulnerabilities have led to its ban in TLS (RFC 7465).

Rabbit — A lightweight stream cipher suitable for performance-sensitive scenarios.

Important Notes

• Encryption and decryption require the same algorithm and key — mismatches will produce garbled output or errors
• Key strength directly affects security — use a sufficiently complex key
• All encryption and decryption happens in the browser. Your data is never sent to any server

FAQ

Q: What is the difference between symmetric and asymmetric encryption?

Symmetric encryption uses the same key for both encryption and decryption. It is fast and efficient, making it suitable for encrypting large volumes of data. Common algorithms include AES and DES. Asymmetric encryption uses a key pair — a public key for encryption and a private key for decryption (or vice versa for signing). It provides stronger key exchange security but is much slower. Common algorithms include RSA and ECC. In practice, the two are often combined: asymmetric encryption exchanges a symmetric key, which is then used to encrypt the actual data (as in the TLS handshake).

Q: Should I use AES, DES, or 3DES?

For any modern application, AES is the clear choice. DES has only a 56-bit key, making it vulnerable to brute-force attacks — it has been considered insecure for over two decades. 3DES improves on DES by applying the algorithm three times, but it is slow and cumbersome to manage. AES supports 128, 192, or 256-bit keys, offers excellent security and performance, and is the internationally recognized symmetric encryption standard.

Q: How does key length affect security?

Key length determines the difficulty of a brute-force attack. AES-128 has 2¹²⁸ possible key combinations — virtually impossible to crack with current computing power. AES-256 offers even stronger security and is considered resistant to potential quantum computing threats. Longer keys do require slightly more computation, but for most applications AES-128 is more than sufficient. High-security contexts (military, government) may prefer AES-256.

Q: What is the difference between a block cipher and a stream cipher?

A block cipher encrypts data in fixed-size blocks (e.g. AES uses 128-bit blocks) and requires a mode of operation (CBC, CTR, GCM) to handle data larger than one block. A stream cipher encrypts data bit-by-bit or byte-by-byte, generating a keystream that is XORed with the plaintext. Block ciphers are more widely standardized and versatile; stream ciphers offer lower latency, making them suitable for real-time communication. Notably, AES in CTR mode effectively functions as a stream cipher.

Q: Is this tool suitable for production use?

This tool is designed for learning, testing, and quick verification of encryption logic. It is not recommended for encrypting sensitive data in production. Production systems should use security-audited libraries (such as the Web Crypto API or OpenSSL) and perform encryption on the server side. Browser-based encryption carries inherent key-exposure risks, and real-world cryptographic implementations require additional considerations like initialization vectors, authenticated encryption modes, and secure key management.