How does the encryption algorithm Rijndael work? (Also known by the abbreviation AES)

Attempts to decrypt data into the specified buffer, using ECB mode with the specified padding mode.

Rijndael Class

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The Rijndael and RijndaelManaged types are obsolete. Use Aes instead.

Represents the base class from which all implementations of the Rijndael symmetric encryption algorithm must inherit.

public ref class Rijndael abstract : System::Security::Cryptography::SymmetricAlgorithm
[System.Runtime.Versioning.UnsupportedOSPlatform("browser")] public abstract class Rijndael : System.Security.Cryptography.SymmetricAlgorithm
[System.Runtime.Versioning.UnsupportedOSPlatform("browser")] [System.Obsolete("The Rijndael and RijndaelManaged types are obsolete. Use Aes instead.", DiagnosticId="SYSLIB0022", UrlFormat="https://aka.ms/dotnet-warnings/")] public abstract class Rijndael : System.Security.Cryptography.SymmetricAlgorithm
[System.Obsolete("The Rijndael and RijndaelManaged types are obsolete. Use Aes instead.", DiagnosticId="SYSLIB0022", UrlFormat="https://aka.ms/dotnet-warnings/")] public abstract class Rijndael : System.Security.Cryptography.SymmetricAlgorithm
public abstract class Rijndael : System.Security.Cryptography.SymmetricAlgorithm
[System.Runtime.InteropServices.ComVisible(true)] public abstract class Rijndael : System.Security.Cryptography.SymmetricAlgorithm
[] type Rijndael = class inherit SymmetricAlgorithm
[] [] type Rijndael = class inherit SymmetricAlgorithm
[] type Rijndael = class inherit SymmetricAlgorithm
type Rijndael = class inherit SymmetricAlgorithm
[] type Rijndael = class inherit SymmetricAlgorithm
Public MustInherit Class Rijndael Inherits SymmetricAlgorithm

Inheritance
Attributes

Examples

The following code example uses the Rijndael class to encrypt and then decrypt data.

using System; using System.IO; using System.Security.Cryptography; namespace RijndaelManaged_Example < class RijndaelExample < public static void Main() < try < string original = "Here is some data to encrypt!"; // Create a new instance of the Rijndael // class. This generates a new key and initialization // vector (IV). using (Rijndael myRijndael = Rijndael.Create()) < // Encrypt the string to an array of bytes. byte[] encrypted = EncryptStringToBytes(original, myRijndael.Key, myRijndael.IV); // Decrypt the bytes to a string. string roundtrip = DecryptStringFromBytes(encrypted, myRijndael.Key, myRijndael.IV); //Display the original data and the decrypted data. Console.WriteLine("Original: ", original); Console.WriteLine("Round Trip: ", roundtrip); > > catch (Exception e) < Console.WriteLine("Error: ", e.Message); > > static byte[] EncryptStringToBytes(string plainText, byte[] Key, byte[] IV) < // Check arguments. if (plainText == null || plainText.Length encrypted = msEncrypt.ToArray(); > > > // Return the encrypted bytes from the memory stream. return encrypted; > static string DecryptStringFromBytes(byte[] cipherText, byte[] Key, byte[] IV) < // Check arguments. if (cipherText == null || cipherText.Length > > > return plaintext; > > > 
Imports System.IO Imports System.Security.Cryptography Class RijndaelExample Public Shared Sub Main() Try Dim original As String = "Here is some data to encrypt!" ' Create a new instance of the Rijndael ' class. This generates a new key and initialization ' vector (IV). Using myRijndael = Rijndael.Create() ' Encrypt the string to an array of bytes. Dim encrypted As Byte() = EncryptStringToBytes(original, myRijndael.Key, myRijndael.IV) ' Decrypt the bytes to a string. Dim roundtrip As String = DecryptStringFromBytes(encrypted, myRijndael.Key, myRijndael.IV) 'Display the original data and the decrypted data. Console.WriteLine("Original: ", original) Console.WriteLine("Round Trip: ", roundtrip) End Using Catch e As Exception Console.WriteLine("Error: ", e.Message) End Try End Sub Shared Function EncryptStringToBytes(ByVal plainText As String, ByVal Key() As Byte, ByVal IV() As Byte) As Byte() ' Check arguments. If plainText Is Nothing OrElse plainText.Length  

Remarks

This algorithm supports key lengths of 128, 192, or 256 bits; defaulting to 256 bits. This algorithm supports block sizes of 128, 192, or 256 bits; defaulting to 128 bits (Aes-compatible).

The Rijndael class is the predecessor of the Aes algorithm. You should use the Aes algorithm instead of Rijndael. For more information, see the entry The Differences Between Rijndael and AES in the .NET Security blog.

Constructors

Initializes a new instance of Rijndael.

Fields

Represents the block size, in bits, of the cryptographic operation.

Represents the feedback size, in bits, of the cryptographic operation.

Represents the initialization vector (IV) for the symmetric algorithm.

Represents the size, in bits, of the secret key used by the symmetric algorithm.

Represents the secret key for the symmetric algorithm.

Specifies the block sizes, in bits, that are supported by the symmetric algorithm.

Specifies the key sizes, in bits, that are supported by the symmetric algorithm.

Represents the cipher mode used in the symmetric algorithm.

Represents the padding mode used in the symmetric algorithm.

Properties

Gets or sets the block size, in bits, of the cryptographic operation.

Gets or sets the feedback size, in bits, of the cryptographic operation for the Cipher Feedback (CFB) and Output Feedback (OFB) cipher modes.

Gets or sets the initialization vector (IV) for the symmetric algorithm.

Gets or sets the secret key for the symmetric algorithm.

Gets or sets the size, in bits, of the secret key used by the symmetric algorithm.

Gets the block sizes, in bits, that are supported by the symmetric algorithm.

Gets the key sizes, in bits, that are supported by the symmetric algorithm.

Gets or sets the mode for operation of the symmetric algorithm.

Gets or sets the padding mode used in the symmetric algorithm.

Methods

Releases all resources used by the SymmetricAlgorithm class.

Creates a cryptographic object to perform the Rijndael algorithm.

Obsolete.

Creates a cryptographic object to perform the specified implementation of the Rijndael algorithm.

Creates a symmetric decryptor object with the current Key property and initialization vector (IV).

When overridden in a derived class, creates a symmetric decryptor object with the specified Key property and initialization vector (IV).

Creates a symmetric encryptor object with the current Key property and initialization vector (IV).

When overridden in a derived class, creates a symmetric encryptor object with the specified Key property and initialization vector (IV).

Decrypts data using CBC mode with the specified padding mode.

Decrypts data using CBC mode with the specified padding mode.

Decrypts data into the specified buffer, using CBC mode with the specified padding mode.

Decrypts data using CFB mode with the specified padding mode and feedback size.

Decrypts data using CFB mode with the specified padding mode and feedback size.

Decrypts data into the specified buffer, using CFB mode with the specified padding mode and feedback size.

Decrypts data using ECB mode with the specified padding mode.

Decrypts data using ECB mode with the specified padding mode.

Decrypts data into the specified buffer, using ECB mode with the specified padding mode.

Releases all resources used by the current instance of the SymmetricAlgorithm class.

Releases the unmanaged resources used by the SymmetricAlgorithm and optionally releases the managed resources.

Encrypts data using CBC mode with the specified padding mode.

Encrypts data using CBC mode with the specified padding mode.

Encrypts data into the specified buffer, using CBC mode with the specified padding mode.

Encrypts data using CFB mode with the specified padding mode and feedback size.

Encrypts data using CFB mode with the specified padding mode and feedback size.

Encrypts data into the specified buffer, using CFB mode with the specified padding mode and feedback size.

Encrypts data using ECB mode with the specified padding mode.

Encrypts data using ECB mode with the specified padding mode.

Encrypts data into the specified buffer, using ECB mode with the specified padding mode.

Determines whether the specified object is equal to the current object.

When overridden in a derived class, generates a random initialization vector (IV) to use for the algorithm.

When overridden in a derived class, generates a random key (Key) to use for the algorithm.

Gets the length of a ciphertext with a given padding mode and plaintext length in CBC mode.

Gets the length of a ciphertext with a given padding mode and plaintext length in CFB mode.

Gets the length of a ciphertext with a given padding mode and plaintext length in ECB mode.

Serves as the default hash function.

Gets the Type of the current instance.

Creates a shallow copy of the current Object.

Returns a string that represents the current object.

Attempts to decrypt data into the specified buffer, using CBC mode with the specified padding mode.

When overridden in a derived class, attempts to decrypt data into the specified buffer, using CBC mode with the specified padding mode.

Attempts to decrypt data into the specified buffer, using CFB mode with the specified padding mode and feedback size.

When overridden in a derived class, attempts to decrypt data into the specified buffer, using CFB mode with the specified padding mode and feedback size.

Attempts to decrypt data into the specified buffer, using ECB mode with the specified padding mode.

When overridden in a derived class, attempts to decrypt data into the specified buffer, using ECB mode with the specified padding mode.

Attempts to encrypt data into the specified buffer, using CBC mode with the specified padding mode.

When overridden in a derived class, attempts to encrypt data into the specified buffer, using CBC mode with the specified padding mode.

Attempts to encrypt data into the specified buffer, using CFB mode with the specified padding mode and feedback size.

When overridden in a derived class, attempts to encrypt data into the specified buffer, using CFB mode with the specified padding mode and feedback size.

Attempts to encrypt data into the specified buffer, using ECB mode with the specified padding mode.

When overridden in a derived class, attempts to encrypt data into the specified buffer, using ECB mode with the specified padding mode.

Determines whether the specified key size is valid for the current algorithm.

Explicit Interface Implementations

This API supports the product infrastructure and is not intended to be used directly from your code.

Releases the unmanaged resources used by the SymmetricAlgorithm and optionally releases the managed resources.

Applies to

See also

How does the encryption algorithm Rijndael work? (Also known by the abbreviation AES)

Transferring highly confidential information to a secure location without unauthorized access to that information presents many dangers. Over the centuries, people have made repeated attempts to develop particularly hard-to-decipher secret languages. From ancient Rome to the Second World War to the present day, orders were sent in encrypted form by statesmen and important commanders to deceive the enemy or keep the information out of the hands of unauthorized persons.

Unfortunately, these forms of encryption were usually very easy to crack. For instance, one could easily decipher secret languages, which have arisen from the displacement of letters (e.g., today is a beautiful day = heute ist ein schöner Tag = heu teis teinsch önert ag). The weak point of all sophisticated secret languages is that once the key has been found, any text can be "translated". At least with the use of computers, it has become impossible to keep secret a key attributed to the shifting of letters.

Today, other encryption methods have to be used to avoid sharing confidential information with everyone. In this case, too, again a key is used, which only the sending and the receiving side know. For encryption and decryption, so-called encryption algorithms are used. An encryption algorithm is a mathematical method, according to which the conversion of the data takes place.

Password Depot uses the encryption algorithm Rijndael or AES (Advanced Encryption Standard) to encrypt your confidential data.

This security algorithm is explained in more detail below.

Advanced Encryption Standard, short AES or Rijndael

The US National Bureau of Standards developed a complicated encryption standard called DES (Data Encryption Standard) , which offered unlimited data encryption capabilities. This encryption standard has been largely replaced by Rijndael encryption. The name Rijndael is derived from the names of the Belgian cryptologists and originators of this encryption method, Joan Daemen and Vincent Rijmen. At Rijndael, encryption is done with a 128, 192, or 256-bit key, which provides guaranteed increased security against brute-force attacks. In addition, this encryption method works three times faster than DES in software. This method can be used both for the secure exchange of keys and for the transmission of data with a length of 128 or 256 bits.

AES is approved in the United States for high-level security clearance government documents.

This is how the encryption algorithm Rijndael works

Rijndael encryption is based on byte-by-byte replacement, swap, and XOR.

The procedure looks like this:

  • Rijndael again generates 10 128-bit keys from the 128-bit key.
  • These are stored in 4 x 4 tables.
  • The plaintext is also divided into 4 x 4 tables (each in 128-bit chunks).
  • Each of the 128-bit plaintext pieces is processed in a 10-round process (10 rounds on 128-bit keys, 11 on 192, 13 on 256).
  • Thus, the code is generated after the 10th round.
  • Each individual byte is substituted in an S-box and replaced by the reciprocal over GF (2 8).
  • Subsequently, a modulo 2 matrix is applied bitwise and an XOR operation is performed at 63.
  • The rows of the matrices are now sorted cyclically.
  • Then the columns are exchanged by matrix multiplication via a Galois field (GF) (2 8).
  • An XOR link is applied to the subkey for each round.

The security of this encryption method increases when Rijndael is performed several times with different round keys.

Brute-force attacks

Brute-force attacks are very dangerous because all sorts of keys are used to attack a process. The attacker can spread a virus via the Internet, which secretly tries keys in the background and exchanges the results via a server. With these attacks, you can crack e.g. DES within a very short time. More modern methods, such as BlowFish and Rijndael, are protected against brute-force attacks, as their key length can exceed 128 bits.

Password Depot also makes brute-force attacks more difficult with a delay function. This causes the program to remain locked for a few seconds after an incorrectly entered master password.

And one thing is certain: since the key length at Rijndael can vary as desired, this modern security algorithm is considered safe for a very long time from today's perspective.

What Is the Rijndael Algorithm: A Data Scientist's Guide

As a data scientist or software engineer, you may come across various encryption algorithms in your work. One such algorithm that has gained significant popularity is the Rijndael algorithm. In this article, we will explore what the Rijndael algorithm is, how it works, and its significance in the field of data security.

By Saturn Cloud | Tuesday, July 18, 2023 | Miscellaneous

What Is the Rijndael Algorithm: A Data Scientist’s Guide

Rijndael Algorithm

As a data scientist or software engineer, you may come across various encryption algorithms in your work. One such algorithm that has gained significant popularity is the Rijndael algorithm. In this article, we will explore what the Rijndael algorithm is, how it works, and its significance in the field of data security.

Introduction to the Rijndael Algorithm

The Rijndael algorithm is a symmetric key block cipher, named after its creators Vincent Rijmen and Joan Daemen. It was selected as the Advanced Encryption Standard (AES) by the National Institute of Standards and Technology (NIST) in 2001. AES is widely used in various applications, including secure communication, data storage, and authentication.

How Does the Rijndael Algorithm Work?

The Rijndael algorithm operates on blocks of data and uses a symmetric key for both encryption and decryption. It supports three key sizes: 128 bits, 192 bits, and 256 bits, making it highly flexible for different security requirements.

Key Expansion

Before the encryption process begins, the Rijndael algorithm performs a key expansion step to generate a set of round keys. The number of rounds depends on the key size: 10 rounds for a 128-bit key, 12 rounds for a 192-bit key, and 14 rounds for a 256-bit key. Each round key is derived from the original encryption key using a key schedule algorithm.

SubBytes Transformation

In the encryption process, the Rijndael algorithm applies a byte substitution operation called the SubBytes transformation. This step replaces each byte of the input with a corresponding byte from a substitution box (S-box). The S-box is constructed using a combination of algebraic and affine transformations, providing non-linearity and confusion in the cipher.

ShiftRows Transformation

The ShiftRows transformation is another step in the Rijndael algorithm that operates on the state matrix, which represents the input data. It cyclically shifts the rows of the matrix to the left, providing diffusion and spreading the data across different rows.

MixColumns Transformation

The MixColumns transformation further enhances the diffusion of data by performing a matrix multiplication on the columns of the state matrix. This step combines elements from each column, providing diffusion and increasing the complexity of the encryption process.

AddRoundKey Transformation

In each round of encryption, the AddRoundKey transformation applies an XOR operation between the state matrix and the corresponding round key. This step adds the key material to the data, providing confusion and preventing linear attacks.

Why Is the Rijndael Algorithm Important for Data Security?

The Rijndael algorithm, as the AES standard, offers several key advantages for data security:

Strong Encryption

The Rijndael algorithm provides a high level of security due to its complex and well-designed structure. It has undergone extensive analysis and testing by cryptographic experts, making it resistant to various known attacks.

Flexibility

With support for multiple key sizes, the Rijndael algorithm offers flexibility in choosing the appropriate level of security for different applications. This adaptability allows users to balance performance and security based on their specific requirements.

Wide Adoption

As the AES standard, the Rijndael algorithm is widely adopted and implemented in various software and hardware systems. Its widespread use ensures interoperability and compatibility across different platforms and technologies.

Performance Efficiency

The Rijndael algorithm is highly optimized and efficient in terms of performance. It takes advantage of efficient arithmetic operations and parallel processing techniques, making it suitable for resource-constrained environments.

Conclusion

In summary, the Rijndael algorithm, also known as the AES standard, is a powerful symmetric key block cipher widely used for data encryption and security. Its robust design, flexibility, and wide adoption make it an essential tool for data scientists and software engineers working on secure communication, data storage, and authentication. By understanding the inner workings of the Rijndael algorithm, you can make informed decisions about its usage and leverage its capabilities to protect sensitive information effectively.

Remember, when it comes to data security, always stay updated with the latest encryption standards and best practices to ensure the confidentiality and integrity of your data.

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