NdsForge.NdsModcrypt Class Reference

Applies the DSi AES-CTR transform with little-endian counter advancement. Encryption and decryption are the same operation; overloads support isolated buffers, arbitrary slices, and bounded caller-owned streams. More...

Static Public Member Functions
static byte[]	Transform (ReadOnlySpan< byte > data, NdsModcryptContext context, NdsModcryptArea area, long byteOffset=0)
	Transforms an independent buffer using one area from an immutable header-derived context.
static byte[]	Transform (ReadOnlySpan< byte > data, ReadOnlySpan< byte > key, ReadOnlySpan< byte > initialCounter, long byteOffset=0)
	Transforms an independent buffer using explicit AES normal-key and initial-counter bytes.
static async ValueTask	TransformAsync (Stream source, Stream destination, long length, NdsModcryptContext context, NdsModcryptArea area, long byteOffset=0, CancellationToken cancellationToken=default)
	Transforms exactly length bytes without closing either stream. If a late source truncation occurs, already completed chunks remain in the destination so callers can diagnose progress.
static async ValueTask	TransformAsync (Stream source, Stream destination, long length, ReadOnlyMemory< byte > key, ReadOnlyMemory< byte > initialCounter, long byteOffset=0, CancellationToken cancellationToken=default)
	Transforms an exact stream interval with explicit normal-key and counter material. This overload is useful for tooling that obtains counters outside a parsed image while preserving bounded, allocation-stable I/O.

Static Public Attributes
const int	BlockSize = 16
	Defines the AES-128 key, counter, and keystream block width imposed by the cartridge format.

Detailed Description

Applies the DSi AES-CTR transform with little-endian counter advancement. Encryption and decryption are the same operation; overloads support isolated buffers, arbitrary slices, and bounded caller-owned streams.

Definition at line 9 of file NdsModcrypt.cs.

Member Function Documentation

Transform() [1/2]

byte[] NdsForge.NdsModcrypt.Transform ( ReadOnlySpan< byte > data, NdsModcryptContext context, NdsModcryptArea area, long byteOffset = 0 )

inlinestatic

Transforms an independent buffer using one area from an immutable header-derived context.

Parameters

data	Ciphertext or plaintext bytes beginning at byteOffset .
context	Resolved key material and HMAC-derived counters.
area	First or second modcrypt area.
byteOffset	Logical byte offset within that area, allowing correct unaligned slice processing.

Returns

A new array; the input and context remain unchanged.

Definition at line 22 of file NdsModcrypt.cs.

Transform() [2/2]

byte[] NdsForge.NdsModcrypt.Transform ( ReadOnlySpan< byte > data, ReadOnlySpan< byte > key, ReadOnlySpan< byte > initialCounter, long byteOffset = 0 )

inlinestatic

Transforms an independent buffer using explicit AES normal-key and initial-counter bytes.

Parameters

data	Ciphertext or plaintext bytes beginning at byteOffset .
key	Exactly sixteen bytes containing a normal AES key.
initialCounter	Exactly sixteen bytes in DSi counter order.
byteOffset	Logical byte offset from the beginning of the encrypted area.

Returns

A transformed copy suitable for encryption or decryption.

Definition at line 38 of file NdsModcrypt.cs.

TransformAsync() [1/2]

async ValueTask NdsForge.NdsModcrypt.TransformAsync ( Stream source, Stream destination, long length, NdsModcryptContext context, NdsModcryptArea area, long byteOffset = 0, CancellationToken cancellationToken = default )

inlinestatic

Transforms exactly length bytes without closing either stream. If a late source truncation occurs, already completed chunks remain in the destination so callers can diagnose progress.

Parameters

source	Readable stream positioned at the requested area slice.
destination	Writable stream receiving the same number of transformed bytes.
length	Exact number of bytes to consume; trailing source bytes are left unread.
context	Resolved key material and both initial counters.
area	First or second modcrypt area.
byteOffset	Logical slice offset within the selected area.
cancellationToken	Cancels reads, cryptographic chunk processing, or writes.

Returns

A task-like value that completes after exactly length bytes have been transformed.

Definition at line 63 of file NdsModcrypt.cs.

TransformAsync() [2/2]

async ValueTask NdsForge.NdsModcrypt.TransformAsync ( Stream source, Stream destination, long length, ReadOnlyMemory< byte > key, ReadOnlyMemory< byte > initialCounter, long byteOffset = 0, CancellationToken cancellationToken = default )

inlinestatic

Transforms an exact stream interval with explicit normal-key and counter material. This overload is useful for tooling that obtains counters outside a parsed image while preserving bounded, allocation-stable I/O.

Parameters

source	Readable stream positioned at the requested encrypted or plaintext slice.
destination	Distinct writable stream receiving exactly length bytes.
length	Exact byte count; a shorter source raises EndOfStreamException.
key	Exactly sixteen bytes containing a normal AES key.
initialCounter	Exactly sixteen initial counter bytes.
byteOffset	Logical source position relative to the area's first byte.
cancellationToken	Cancels reads, cryptographic chunk processing, or writes.

Returns

A task-like value that completes after exactly length bytes have been transformed.

Definition at line 95 of file NdsModcrypt.cs.

Member Data Documentation

BlockSize

const int NdsForge.NdsModcrypt.BlockSize = 16

static

Defines the AES-128 key, counter, and keystream block width imposed by the cartridge format.

Definition at line 12 of file NdsModcrypt.cs.

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The documentation for this class was generated from the following file:

• src/NdsForge/Modcrypt/NdsModcrypt.cs