Class PdfStructureReader

Namespace

SimpleSign.Pdf

Assembly

SimpleSign.Pdf.dll

Reads PDF structure to extract digital signature fields and their metadata. Supports classic xref tables, xref streams (PDF 1.5+), and FlateDecode compression.

public sealed class PdfStructureReader

Inheritance

object

PdfStructureReader

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Fields

MaxPdfSize

Maximum PDF file size supported (200 MB).

public const int MaxPdfSize = 209715200

Field Value

int

Methods

DetectPdfALevelAsync(Stream, ILogger?, CancellationToken)

Detects the PDF/A conformance level by scanning XMP metadata for pdfaid:part and pdfaid:conformance elements.

public static Task<PdfALevel> DetectPdfALevelAsync(Stream pdfStream, ILogger? logger = null, CancellationToken cancellationToken = default)

Parameters

pdfStream Stream

logger ILogger

cancellationToken CancellationToken

Returns

Task<PdfALevel>

GetDocMdpPermissionLevelAsync(Stream, ILogger?, CancellationToken)

Returns the DocMDP permission level from the PDF. 0 = no DocMDP, 1 = no changes allowed, 2 = form filling only, 3 = form filling and annotations.

public static Task<int> GetDocMdpPermissionLevelAsync(Stream pdfStream, ILogger? logger = null, CancellationToken cancellationToken = default)

Parameters

pdfStream Stream

logger ILogger

cancellationToken CancellationToken

Returns

Task<int>

IsDocMdpLockedAsync(Stream, ILogger?, CancellationToken)

Checks if the PDF has a DocMDP certification signature that prohibits further modifications. Returns true if the document is locked (permission level < 3).

public static Task<bool> IsDocMdpLockedAsync(Stream pdfStream, ILogger? logger = null, CancellationToken cancellationToken = default)

Parameters

pdfStream Stream

logger ILogger

cancellationToken CancellationToken

Returns

Task<bool>

IsEncryptedAsync(Stream, ILogger?, CancellationToken)

Checks if the PDF is encrypted. Encrypted PDFs cannot be signed or validated by SimpleSign.

public static Task<bool> IsEncryptedAsync(Stream pdfStream, ILogger? logger = null, CancellationToken cancellationToken = default)

Parameters

pdfStream Stream

logger ILogger

cancellationToken CancellationToken

Returns

Task<bool>

IsLinearized(ReadOnlySpan<byte>)

Detects if the PDF is linearized (§9.9). Linearized PDFs have a Linearized dictionary in the first object. This is informational — linearized PDFs are fully supported for signature operations since we always follow the startxref chain from the end of the file.

public static bool IsLinearized(ReadOnlySpan<byte> data)

Parameters

data ReadOnlySpan<byte>

Returns

bool

ReadSignatureFieldsAsync(Stream, ILogger?, CancellationToken)

Reads all digital signature fields from a PDF stream. Parses the cross-reference table (classic or stream) and scans for /ByteRange dictionaries.

public static Task<IReadOnlyList<PdfSignatureField>> ReadSignatureFieldsAsync(Stream pdfStream, ILogger? logger = null, CancellationToken cancellationToken = default)

Parameters

pdfStream Stream

logger ILogger

cancellationToken CancellationToken

Returns

Task<IReadOnlyList<PdfSignatureField>>

ReadSignedBytesAsync(Stream, PdfByteRange, ILogger?, CancellationToken)

Reads the signed byte ranges from a PDF stream, concatenating both segments. Used to compute the hash for signature verification.

public static Task<byte[]> ReadSignedBytesAsync(Stream pdfStream, PdfByteRange byteRange, ILogger? logger = null, CancellationToken cancellationToken = default)

Parameters

pdfStream Stream

byteRange PdfByteRange

logger ILogger

cancellationToken CancellationToken

Returns

Task<byte[]>