BlockCipherModeFactory Class

Definition

Namespace: Bodu.Security.Cryptography

Assembly: Bodu.Security.Cryptography.dll

Package: Bodu.Security.Cryptography 1.2.0

Source: BlockCipherModeFactory.cs

Creates IBlockCipherModeTransform instances that wrap an IBlockCipher with a standard chaining mode.

public static class BlockCipherModeFactory

Inheritance: object

BlockCipherModeFactory

Inherited Members: object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Examples

using IBlockCipher cipher = /* construct an IBlockCipher, e.g. an AES wrapper */;
IBlockCipherModeTransform mode = BlockCipherModeFactory.Create(CipherBlockMode.CBC, cipher, iv);
IPaddingStrategy padding = PaddingFactory.Create(PaddingMode.PKCS7);

byte[] padded = padding.Pad(plaintext, cipher.BlockSize);
byte[] ciphertext = new byte[padded.Length];
mode.Transform(padded, ciphertext, encrypt: true);

Remarks

The factory dispatches a CipherModeKind enumeration value to the matching mode-transform implementation. Used internally by every SymmetricAlgorithm in this library when its Mode is set, so that the same enum value selects the appropriate transform regardless of which cipher is in play.

What this factory covers and does not cover. Only the classic confidentiality-only modes (ECB, CBC, CFB, OFB, CTR) are dispatched here. CtsModeTransform and XtsModeTransform have members in the CipherModeKind enumeration (CTS and XTS) but are not dispatched by this factory - their construction shapes differ (XTS requires a second cipher), so they must be constructed directly. Authenticated modes have their own contract and lifecycle - construct an IAeadBlockCipherModeTransform implementation directly, or use the helpers on AeadBlockCipherModeTransformExtensions.

The following example composes a block cipher, a CBC mode transform, and PKCS#7 padding to encrypt a message.

Methods

Create(CipherModeKind, IBlockCipher, byte[]?)

Creates a new IBlockCipherModeTransform instance for the specified block cipher mode.

public static IBlockCipherModeTransform Create(CipherModeKind mode, IBlockCipher cipher, byte[]? iv = null)

Parameters

mode CipherModeKind: The cipher mode to apply (for example CBC, CFB, OFB, ECB, or CTR).
cipher IBlockCipher: The underlying block cipher to wrap.
iv byte[]: The initialization vector or initial counter. Required by all modes except ECB and must have the same length as BlockSize.

Returns

IBlockCipherModeTransform: An IBlockCipherModeTransform that applies mode over cipher.

Exceptions

ArgumentNullException: Thrown if cipher is null.
ArgumentException: Thrown if iv is required but null or of the wrong length.
NotSupportedException: Thrown if mode is not a supported CipherModeKind value.

Applies to

Product	Versions
.NET	8, 10

Table of Contents