Rijndael Encryption and Decryption online tool enables users to encrypt and decrypt text using the Rijndael algorithm, which is the basis for the Advanced Encryption Standard (AES).
The Rijndael algorithm
is a symmetric key encryption algorithm that became the
Advanced
Encryption Standard (AES) after replacing the older and weaker Data
Encryption Standard (DES).
It was designed by two Belgian cryptographers, Joan Daemen and Vincent Rijmen, and
was selected as the AES by the National Institute of Standards and Technology (NIST)
in 2001.
Below is an online tool to encrypt and decrypt any text or password with Rijndael
algorithm. AES is a United States federal standard,
FIPS 197, which is a subset of Rijndael.
Here is the other tool for AES
encryption and decryption online.
Rijndael Encryption
Base64
Hex
⚠️ Plain-text keys are weak. Use Hex/Base64 or PBKDF2-derived keys
for stronger security.
Rijndael Decryption
Plain-Text
Base64
We do not store, log any key you enter.
This tool is intended for personal and educational use.
We suggest not to use online tools to protect real production secrets.
Rijndael Key Features
The Advanced Encryption Standard (AES) and Rijndael are both symmetric block cipher
algorithms.
Rijndael and AES differ only in the range of supported values for the block length
and cipher key length. AES is just a variant of Rijndael.
Block Size: It supports a fixed block size of 128 bits.
Key Sizes: It supports key sizes of 128, 192, and 256 bits.
Symmetric Cipher: AES is a symmetric key cipher, meaning the
same key is used for both encryption and decryption.
Structure: It uses a substitution-permutation network (SPN) structure.
Rijndael Encryption Process
Key Expansion: The cipher key is expanded into an array of key
schedule words.
This array is used in each round of the encryption process.
Initial Round:
AddRoundKey: Each byte of the state is combined with a
round key using bitwise XOR.
Rounds
SubBytes: A non-linear substitution step where each
byte is replaced with another according to a lookup table (S-box).
ShiftRows: A transposition step where the last three
rows of the state are shifted cyclically a certain number of steps.
MixColumns: A mixing operation that operates on the
columns of the state, combining the four bytes in each column.
AddRoundKey: The state is combined with a round key.
Final Round (without MixColumns):
SubBytes
ShiftRows
AddRoundKey
Rijndael Decryption Process
The decryption process of Rijndael essentially reverses the encryption process, using
inverse operations:
Key Expansion: Same as in encryption.
Initial Round:
AddRoundKey
Rounds:
InvShiftRows: The inverse of the ShiftRows step.
InvSubBytes: The inverse of the SubBytes step.
AddRoundKey
InvMixColumns: The inverse of the MixColumns step.
Final Round (without InvMixColumns):
InvShiftRows
InvSubBytes
AddRoundKey
Rijndael vs AES – Key Differences
Feature
Rijndael (General Cipher)
AES (Advanced Encryption Standard)
Algorithm Origin
Designed by Joan Daemen & Vincent Rijmen
Standardized version of Rijndael by NIST
Block Size
Variable: 128, 160, 192, 224, 256 bits
Fixed: 128 bits (16 bytes)
Key Sizes
128, 192, 256 bits
128, 192, 256 bits
Standardization
General-purpose block cipher
FIPS 197 (Official encryption standard)
Interoperability
Limited, depends on library support
Very high, supported everywhere
Library Support
Partial (e.g., Bouncy Castle)
Universal (Java, OpenSSL, browsers, hardware)
IV Size (CBC / CFB)
Same as block size
16 bytes (128 bits)
Padding Rules
Required for CBC when plaintext is not block-aligned
AES is a specific and standardized configuration of Rijndael that uses a fixed
128-bit block size. While Rijndael supports multiple block sizes, only the
128-bit variant is widely used and standardized as AES.
Security and Efficiency
AES is widely used due to its strong security and efficiency. It is implemented in
hardware and software across a range of applications, from securing internet traffic
(SSL/TLS)
to encrypting data stored on devices.
Applications
Internet Security: SSL/TLS for secure web communications.
File Encryption: Tools like BitLocker, VeraCrypt, and many
others use AES.
Wireless Security: WPA2 for Wi-Fi security uses AES.
Disk Encryption: AES is used in full-disk encryption solutions.
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