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AES Encryption
Tool Description
AES Encryption is an online AES encryption/decryption tool supporting AES-128 / AES-192 / AES-256 key sizes, ECB / CBC / CFB / OFB / CTR cipher modes, PKCS#5 / PKCS#7 / ISO 9797-1 / ANSI X.923 / ISO 10126 / Zero Padding / No Padding padding schemes, and Base64 / Hex / Latin1 / UTF-8 output encodings. All operations run locally in your browser — no data is ever uploaded to any server.
How to Use
- Select Mode
Select the operation mode: Encrypt or Decrypt
- Enter Key
Enter or generate a key, and choose the key size: AES-128 (128-bit), AES-192 (192-bit), or AES-256 (256-bit)
- Configure Algorithm
Choose the cipher mode (ECB / CBC / CFB / OFB / CTR). Non-ECB modes require an IV (16 bytes)
- Set Parameters
Select the padding scheme and output encoding, then paste or type your text in the input area
- Run Conversion
Click "Encrypt" or "Decrypt" to execute. The result appears on the right — copy or download as needed
Use Cases
- Data Protection: Encrypt sensitive data (e.g. user information, API keys, config files) with AES before storage or transmission
- Frontend-Backend Communication: Encrypt request parameters in client-server interactions to prevent plaintext leaks, widely used in web and mobile applications
- Compliance Encryption: Meet security compliance requirements such as GDPR and information security standards for data transmission and storage encryption
Core Advantages
- Completely Free
The tool gives you free daily uses, so everyday light encrypt/decrypt needs are covered at zero cost — no payment required to experience the full feature set.
- Local Processing
All encryption and decryption run locally in your browser. Plaintext, keys, and ciphertext are never uploaded to any server, maximizing your data privacy.
- Full Algorithm Coverage
Supports AES-128 / 192 / 256 key sizes, ECB / CBC / CFB / OFB / CTR cipher modes, and six padding schemes — flexible for a wide range of scenarios.
- Easy to Use
A clean, intuitive interface with no software to install — open the page and use it instantly, including one-click random key generation and result export.
- Instant Results
Processing happens locally and finishes instantly with no server round-trip. Results display on the right side in real time and can be copied or downloaded with one click.
- Cross-Platform
Runs in any modern browser, so Windows, macOS, Linux, and mobile browsers all work without worrying about system compatibility.
Cipher Modes
Different cipher modes determine how data blocks relate to each other, affecting security and applicable scenarios:
| Mode | Full Name | IV Required | Description |
|---|---|---|---|
| ECB | Electronic Codebook | No | Each block encrypted independently; identical plaintext produces identical ciphertext — not recommended for long text |
| CBC | Cipher Block Chaining | Yes | Each block depends on the previous ciphertext block; high security, the most commonly used mode |
| CFB | Cipher Feedback | Yes | Turns a block cipher into a stream cipher; suitable for real-time encryption |
| OFB | Output Feedback | Yes | Turns a block cipher into a stream cipher; errors do not propagate |
| CTR | Counter Mode | Yes | Turns a block cipher into a stream cipher; supports parallel processing with good performance |
Padding Schemes
When the plaintext length is not a multiple of the block size (16 bytes), padding is needed for alignment:
- PKCS#5 / PKCS#7 - Most common; pads with the number of missing bytes (e.g. 5 missing bytes → 0x05 0x05 0x05 0x05 0x05)
- ISO 9797-1 - First byte is 0x80, the rest are 0x00
- ANSI X.923 - Last byte marks the padding length, the rest are 0x00
- ISO 10126 - Last byte marks the padding length, the rest are random bytes
- Zero Padding - Pads with 0x00 to block size; if the plaintext is already aligned, no padding is added
- No Padding - No padding; plaintext length must be an exact multiple of the block size (16 bytes)
Key Size
The AES key size determines encryption strength — more bits means stronger security:
- AES-128 (128-bit) - Standard AES, 16-byte key, 10 rounds — best balance of security and performance
- AES-192 (192-bit) - Enhanced AES, 24-byte key, 12 rounds — security level between 128 and 256
- AES-256 (256-bit) - Strongest AES, 32-byte key, 14 rounds — highest security, ideal for highly sensitive scenarios
AES vs. DES Comparison
AES is the most widely used symmetric encryption algorithm today, with significant advantages over DES:
| Dimension | AES | DES |
|---|---|---|
| Block Size | 128-bit | 64-bit |
| Key Length | 128/192/256 bit | 56 bit (effective) |
| Encryption Rounds | 10/12/14 轮 | 16 轮 |
| Security | Extremely high, no known practical attack | Low, 56-bit can be brute-forced |
| Standardization | Global standard (NIST), recommended | Legacy standard, no longer recommended |
FAQ
An IV (Initialization Vector) is a random starting value used in encryption to ensure the same plaintext produces different ciphertext across multiple encryptions. ECB mode does not need an IV; all other modes (CBC, CFB, OFB, CTR) require one. For AES, the IV must be exactly 16 bytes.
Yes. When decrypting, you must use the exact same key, cipher mode, padding scheme, and output encoding that were used for encryption; otherwise, decryption will fail or produce garbage output.
AES-128 is recommended for most scenarios — it offers the best performance with sufficient security. AES-256 is ideal for high-security requirements (e.g. finance, government). AES-192 is rarely used and generally not needed. Note that AES-256 requires a 32-byte key.
AES is recommended. AES is the next-generation encryption standard defined by NIST, with a 128-bit block size and longer keys (128/192/256 bits), offering far greater security than DES. DES's 56-bit key is insecure against modern computing power. AES is the globally accepted symmetric encryption standard.
Possible causes: ① the key is incorrect; ② the cipher mode or padding scheme does not match what was used for encryption; ③ the output encoding is wrong (e.g. if encrypted with Base64 output, select Base64 for decryption too); ④ the input is not valid encrypted data.
No. All encryption/decryption operations run entirely in your browser. Your keys and data never leave your device.
Yes. The tool uses UTF-8 encoding to process text and can correctly encrypt and decrypt Chinese, Japanese, Korean, and any other Unicode characters.
An AES encryption tool is an online symmetric encryption tool for encrypting and decrypting text with AES. It supports multiple key sizes, cipher modes, and padding schemes, with all operations running locally in the browser — ideal for quickly securing sensitive text.
Because all processing runs locally in the browser, it is very fast and most text finishes almost instantly. For very long text, the browser processes it in one pass and generally will not noticeably lag; for extremely large content, splitting it into several runs is recommended.
Yes, mobile is supported. The tool runs in a web page, so mobile browsers (iOS Safari, Android Chrome, etc.) can open and use it directly. The layout is responsive, so you can encrypt and decrypt anytime, anywhere.
This tool uses pure browser-local computation and never uploads data to a server, so its privacy protection is on par with ordinary local software. Compared with third-party software that requires installation and may bundle plugins or collect data, local online computation is lighter and more transparent.
The tool gives you free daily uses, so everyday light encrypt/decrypt needs are covered at zero cost; for higher quotas or more frequent use, a membership unlocks more benefits. Using the basic features requires no registration or login — just open the page and start.
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