Class SignatureUtil

Namespace

iText.Signatures

Assembly

itext.sign.dll

Utility class that provides several convenience methods concerning digital signatures.

public class SignatureUtil

Inheritance

object

SignatureUtil

Inherited Members

object.GetType()

object.MemberwiseClone()

object.ToString()

object.Equals(object)

object.Equals(object, object)

object.ReferenceEquals(object, object)

object.GetHashCode()

Constructors

SignatureUtil(PdfDocument)

Creates a SignatureUtil instance.

public SignatureUtil(PdfDocument document)

Parameters

document PdfDocument

PdfDocument to be inspected

Remarks

Creates a SignatureUtil instance. Sets the acroForm field to the acroForm in the PdfDocument. iText will create a new AcroForm if the PdfDocument doesn't contain one.

Methods

DoesSignatureFieldExist(string)

Checks whether a name exists as a signature field or not.

public virtual bool DoesSignatureFieldExist(string name)

Parameters

name string

name of the field

Returns

bool

boolean does the signature field exist

Remarks

Checks whether a name exists as a signature field or not. It checks both signed fields and blank signatures.

ExtractRevision(string)

Extracts a revision from the document.

public virtual Stream ExtractRevision(string field)

Parameters

field string

the signature field name

Returns

Stream

an InputStream covering the revision. Returns null if it's not a signature field

GetBlankSignatureNames()

Gets the field names that have blank signatures.

public virtual IList<string> GetBlankSignatureNames()

Returns

IList<string>

List containing the field names that have blank signatures

GetRevision(string)

Get signed document revision number, which corresponds to the provided signature name.

public virtual int GetRevision(string field)

Parameters

field string

signature name

Returns

int

int revision number

GetSignature(string)

Get PdfSignature dictionary based on the provided name.

public virtual PdfSignature GetSignature(string name)

Parameters

name string

signature name

Returns

PdfSignature

PdfSignature instance corresponding to the provided name. null otherwise

GetSignatureDictionary(string)

Gets the signature dictionary, the one keyed by /V.

public virtual PdfDictionary GetSignatureDictionary(string name)

Parameters

name string

the field name

Returns

PdfDictionary

the signature dictionary keyed by /V or null if the field is not a signature

GetSignatureFormFieldDictionary(string)

public virtual PdfDictionary GetSignatureFormFieldDictionary(string name)

Parameters

name string

Returns

PdfDictionary

GetSignatureNames()

Gets the field names that have signatures and are signed.

public virtual IList<string> GetSignatureNames()

Returns

IList<string>

List containing the field names that have signatures and are signed

GetTotalRevisions()

Get the amount of signed document revisions.

public virtual int GetTotalRevisions()

Returns

int

int amount of signed document revisions

GetTranslatedFieldName(string)

Get field name, translated using XFA, if any present in the document.

public virtual string GetTranslatedFieldName(string name)

Parameters

name string

field name to be translated

Returns

string

translated field name if XFA is present, original name otherwise

ReadSignatureData(string)

Prepares an PdfPKCS7 instance for the given signature.

public virtual PdfPKCS7 ReadSignatureData(string signatureFieldName)

Parameters

signatureFieldName string

the signature field name

Returns

PdfPKCS7

a PdfPKCS7 instance which can be used to fetch additional info about the signature and also to perform integrity check of data signed by the given signature field.

Remarks

Prepares an PdfPKCS7 instance for the given signature. This method handles signature parsing and might throw an exception if signature is malformed.

The returned PdfPKCS7 can be used to fetch additional info about the signature and also to perform integrity check of data signed by the given signature field.

Prepared PdfPKCS7 instance calculates digest based on signature's /ByteRange entry. In order to check that /ByteRange is properly defined and given signature indeed covers the current PDF document revision please use SignatureCoversWholeDocument(string) method.

SignatureCoversWholeDocument(string)

Checks if the signature covers the entire document (except for signature's Contents) or just a part of it.

public virtual bool SignatureCoversWholeDocument(string name)

Parameters

name string

the signature field name

Returns

bool

true if the signature covers the entire document, false if it doesn't

Remarks

Checks if the signature covers the entire document (except for signature's Contents) or just a part of it.

If this method does not return true it means that signature in question does not cover the entire contents of current PdfDocument . Such signatures cannot be considered as verifying the PDF document, because content that is not covered by signature might have been modified since the signature creation.