ZeroPadding Class

Definition

Namespace

Bodu.Security.Cryptography

Assembly

Bodu.Security.Cryptography.dll

Package

Bodu.Security.Cryptography 1.2.0

Source

ZeroPadding.cs

Implements zero-byte padding, appending 0x00 bytes until the input aligns with the cipher block size.

public sealed class ZeroPadding : IPaddingStrategy

Inheritance

object

ZeroPadding

Implements

IPaddingStrategy

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 Bodu.Security.Cryptography;

// Caller is responsible for tracking the original plaintext length -
// Unpad here returns the padded buffer unchanged.
IPaddingStrategy padding = new ZeroPadding();
byte[] padded = padding.Pad(plaintext, blockSize: 128); // 128 bits = 16 bytes

Remarks

Zero padding is not self-describing and cannot be unambiguously removed when the plaintext itself may end in zero bytes. Use this strategy only when the original plaintext length is recorded out-of-band or the data is known never to contain trailing zeros.

When to choose zero padding. Pick zero padding only when the surrounding format already records the plaintext length explicitly (e.g. a length-prefixed protocol frame or fixed-size record), or when the plaintext is text that cannot legitimately contain trailing 0x00 bytes. For ordinary length-recoverable padding pick Pkcs7Padding; for AEAD modes that handle alignment internally pick NoPadding.

Constructors

ZeroPadding()

public ZeroPadding()

Properties

StripsPaddingOnUnpad

Gets a value indicating whether Unpad(ReadOnlySpan<byte>, int) inspects the final block and may return fewer bytes than it received. Self-describing schemes such as PKCS#7, ANSI X.923, ISO 10126 and ISO/IEC 7816-4 return true; pass-through schemes such as zero padding and no padding return false.

public bool StripsPaddingOnUnpad { get; }

Property Value

bool

Remarks

Streaming block-cipher transforms use this flag to decide whether the final ciphertext block must be deferred during decryption so that padding validation and removal can happen at the stream boundary.

Methods

Pad(ReadOnlySpan<byte>, int)

Pads the input with zero bytes to align its length to a multiple of the block size.

public byte[] Pad(ReadOnlySpan<byte> input, int blockSize)

Parameters

input ReadOnlySpan<byte>

The input data to pad.

blockSize int

The block size in bits. Must be a positive multiple of 8.

Returns

byte[]

The padded input.

Exceptions

ArgumentOutOfRangeException

Thrown if blockSize is not a positive multiple of 8.

Unpad(ReadOnlySpan<byte>, int)

Returns the input as-is. Zero padding cannot be safely removed unless the original length is known.

public byte[] Unpad(ReadOnlySpan<byte> input, int blockSize)

Parameters

input ReadOnlySpan<byte>

The padded input.

blockSize int

The block size in bits. Must be a positive multiple of 8.

Returns

byte[]

The original input with zero padding preserved.

Remarks

The method does not remove trailing zeros because it cannot distinguish between padding and legitimate data.

Applies to

Product	Versions
.NET	8, 10