EcbModeTransform Class

Definition

Namespace

Bodu.Security.Cryptography

Assembly

Bodu.Security.Cryptography.dll

Package

Bodu.Security.Cryptography 1.2.0

Source

EcbModeTransform.cs

Applies the Electronic Codebook (ECB) mode transformation to an underlying IBlockCipher, encrypting or decrypting each block independently with no chaining.

public sealed class EcbModeTransform : IBlockCipherModeTransform, IDisposable

Inheritance

object

EcbModeTransform

Implements

IBlockCipherModeTransform

IDisposable

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Extension Methods

ComparableExtensions.AtLeast<T>(T, T, IComparer<T>)

ComparableExtensions.AtMost<T>(T, T, IComparer<T>)

ComparableExtensions.IsEqualTo<T>(T, T, IComparer<T>)

ComparableExtensions.Max<T>(T, T, IComparer<T>)

ComparableExtensions.Min<T>(T, T, IComparer<T>)

Examples

using System.Security.Cryptography;
using Bodu.Security.Cryptography;

// Most callers should reach for SymmetricAlgorithm.Mode = ECB instead of constructing this directly.
// Direct use is appropriate only inside larger primitives (e.g. wide-block constructions, KDFs).
using IBlockCipher cipher = new AesBlockCipher(key);
IBlockCipherModeTransform ecb = new EcbModeTransform(cipher);
byte[] ciphertext = new byte[plaintext.Length];
int written = ecb.Transform(plaintext, ciphertext, encrypt: true);

Remarks

Encryption computes Cᵢ = E(Pᵢ) and decryption Pᵢ = D(Cᵢ); no initialization vector is used. See panel 1 of the diagram above: each column is entirely self-contained, so the three cells carry no arrows between them.

That independence is exactly what makes ECB insecure for virtually all real-world messages: identical plaintext blocks always yield identical ciphertext blocks, leaking structural information. Prefer CBC, CTR, or an authenticated mode unless ECB is required as a primitive inside a larger construction.

When to use ECB. Only as a building block inside a larger, well-understood construction - for example, encrypting a single fixed-length tweak inside an XTS or wide-block scheme. For protecting arbitrary plaintext, use CbcModeTransform as a baseline, CtrModeTransform when random access or stream-cipher behavior is wanted, or one of the AEAD modes (GcmModeTransform, EaxModeTransform, …) when authentication matters.

Because ECB has no chaining state, the transform is stateless - repeated Transform(ReadOnlySpan<byte>, Span<byte>, bool) calls produce the same result for the same input - and is trivially parallelisable.

Constructors

EcbModeTransform(IBlockCipher)

Initializes a new instance of the EcbModeTransform class that wraps the specified block cipher.

public EcbModeTransform(IBlockCipher cipher)

Parameters

cipher IBlockCipher

The block cipher over which ECB is applied.

Exceptions

ArgumentNullException

Thrown if cipher is null.

Methods

Dispose()

Releases the resources used by this instance. ECB holds no per-message chaining state, so this is a no-op beyond satisfying the IBlockCipherModeTransform contract. The underlying IBlockCipher is not disposed by this type - ownership remains with the caller.

public void Dispose()

Transform(ReadOnlySpan<byte>, Span<byte>, bool)

Transforms input under the mode's chaining strategy and writes the result to output.

public int Transform(ReadOnlySpan<byte> input, Span<byte> output, bool encrypt)

Parameters

input ReadOnlySpan<byte>

The input data to transform. Its length must be a positive multiple of the underlying cipher block size.

output Span<byte>

The destination span. Its length must be greater than or equal to the length of input.

encrypt bool

true to encrypt the input; false to decrypt.

Returns

int

The number of bytes written to output.

Exceptions

ArgumentException

Thrown when input's length is not a multiple of the block size or when output is too small.

Applies to

Product	Versions
.NET	8, 10

See Also

ECB walk-through in the cipher-modes guide