Rijndael Encryption and Decryption Online

Rijndael Encryption and Decryption Online

Rijndael is a symmetric block cipher that was selected as the Advanced Encryption Standard (AES). This tool allows you to encrypt and decrypt text using the Rijndael algorithm with various block and key sizes. ⓘ AES Tool

💡 Did you know? Rijndael supports block sizes of 128, 192, and 256 bits, while AES standardized only on 128-bit blocks. This tool implements the full Rijndael specification.

🔒 Rijndael Encryption

128-bit = 16 chars 192-bit = 24 chars 256-bit = 32 chars
Key length must match the selected key size

🔓 Rijndael Decryption

Key length must match the selected key size
⚠ Make sure to use the same key, IV, mode, and block size that were used during encryption.

🛡 Features

🔒 Multiple Key Sizes

Support for 128-bit, 192-bit, and 256-bit key lengths providing varying levels of security.

📦 Variable Block Sizes

Unlike AES, Rijndael supports 128, 192, and 256-bit block sizes for enhanced flexibility.

🔄 Multiple Modes

CBC, ECB, and CTR modes supported. CBC recommended for most use cases.

💻 Client-Side Processing

All encryption/decryption happens in your browser. No data is sent to any server.

📋 Multiple Output Formats

Export encrypted data as Base64 or Hexadecimal for easy sharing and storage.

⚡ Fast & Free

Instant encryption and decryption with no usage limits or registration required.

About Rijndael Cipher

Rijndael (pronounced "rain-dahl") is a family of ciphers with different key and block sizes. It was designed by Belgian cryptographers Joan Daemen and Vincent Rijmen and submitted to the AES selection process in 1998.

In 2001, Rijndael was selected as the Advanced Encryption Standard (AES) by NIST. However, AES only uses 128-bit blocks, while the original Rijndael specification supports block sizes of 128, 192, and 256 bits.

Rijndael vs AES Comparison

Feature Rijndael AES
Block Sizes 128, 192, 256 bits 128 bits only
Key Sizes 128, 192, 256 bits 128, 192, 256 bits
Rounds (128-bit block) 10, 12, or 14 10, 12, or 14
Standardization Original specification NIST standard (FIPS-197)
Usage Specialized applications Universal encryption standard

How Rijndael Works

Rijndael operates on a 4×4 to 4×8 column-major order array of bytes, called the state. The cipher performs a series of linked operations including:

  1. SubBytes - A non-linear substitution step using an S-box
  2. ShiftRows - A transposition step that shifts rows cyclically
  3. MixColumns - A linear mixing operation on state columns
  4. AddRoundKey - XOR operation with a subkey derived from the cipher key

The number of rounds depends on key and block size:

When to Use Rijndael over AES

💡 Tip: For most applications, using AES (Rijndael with 128-bit blocks) is recommended as it's the industry standard and has the widest software/hardware support.
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