DigitalSignatureField

Constructs a DigitalSignatureField from a Field.

Calculates the digest of the relevant bytes of the document for this signature field, in order to allow the caller to perform custom signing/processing. Signature field must first be prepared using one of the non-sign overloads (CreateSigDictForCustomSigning/Certification), and then the document must be saved; after that, this function can be called. The ByteRanges that the most recent save has entered into the signature dictionary within this signature field will be used to calculate the digest.

Calculates the digest of the relevant bytes of the document for this signature field, in order to allow the caller to perform custom signing/processing. Signature field must first be prepared using one of the non-sign overloads (CreateSigDictForCustomSigning/Certification), and then the document must be saved; after that, this function can be called. The ByteRanges that the most recent save has entered into the signature dictionary within this signature field will be used to calculate the digest. This overload uses a default algorithm -- SHA-256.

Must be called to prepare a signature for certification, which is done afterwards by calling Save. Throws if document already certified. Default document permission level is e_annotating_formfilling_signing_allowed. Throws if signature field already has a digital signature dictionary.

Must be called to prepare a signature for certification, which is done afterwards by calling Save. Throws if document already certified. Default document permission level is e_annotating_formfilling_signing_allowed. Throws if signature field already has a digital signature dictionary.

Must be called to prepare a signature for certification, which is done afterwards by calling Save. Throws if document already certified. Default document permission level is e_annotating_formfilling_signing_allowed. Throws if signature field already has a digital signature dictionary.

Clears cryptographic signature, if present. Otherwise, does nothing. Do not need to call HasCryptographicSignature before calling this. After clearing, other signatures should still pass validation. Clears the appearance as well.

Frees the native memory of the object. This can be explicity called to control the deallocation of native memory and avoid situations where the garbage collector does not free the object in a timely manner.

Prepares the field for certification without actually performing certification. Useful for custom signing workflows. It is not necessary to call HasCryptographicSignature before calling this function.

Prepares the field for approval signing without actually performing signing. Useful for custom signing workflows. It is not necessary to call HasCryptographicSignature before calling this function.

Frees the native memory of the object. This can be explicity called to control the deallocation of native memory and avoid situations where the garbage collector does not free the object in a timely manner.

Given a successful verification result that required online information to verify trust (trust verification must have been enabled and successful during the verification), embeds data into the PDF document that allows the signature to be verified offline. (This is accomplished using DSS and VRI dictionaries.) When this operation is successfully completed, one of the two components of secure long term validation (LTV) will be in place. The other necessary component of secure long term validation is to make sure to timestamp the document appropriately while the signature is still verifiable to maintain a chain of unexpired secure timestamps attesting to the integrity of the document. The verifiability of the signature should thereafter be maintainable in such a fashion despite any possible certificate expiry, algorithm compromise, or key compromise that would have otherwise rendered it invalid if it were to be verified using a time in the future rather than a securely-signed timestamp-derived time nearer the time of signing (at which which the signature was verifiable without extra data). This function, if given a good verification result, is also capable of making timestamp (DocTimeStamp ETSI.RFC3161) signatures LTV-enabled, which is necessary to do first when you intend to add another timestamp around an already-timestamped document to extend or enhance its verifiability (as described above), as per the PDF 2.0 and ETSI TS 102 778-4 (PAdES Level 4) specifications. It is necessary to save the document incrementally after this function completes successfully in order to actually write the LTV data into the document.

Low-level function belonging to custom-signing APIs. Using low-level inputs that permit incorporation of remote key usage (cloud keystore, Hardware Security Module (HSM) device, etc.), generates bytes representing a Cryptographic Message Syntax (CMS)-format signature encoded in DER. The resulting data can be passed to SaveCustomSignature.

Low-level function belonging to custom-signing APIs. Using low-level inputs that permit incorporation of remote key usage (cloud keystore, Hardware Security Module (HSM) device, etc.), generates bytes representing a Cryptographic Message Syntax (CMS)-format signature encoded in DER. The resulting data can be passed to SaveCustomSignature.

Low-level function belonging to custom-signing APIs. Using low-level inputs that permit incorporation of remote key usage (cloud keystore, Hardware Security Module (HSM) device, etc.), generates bytes representing a Cryptographic Message Syntax (CMS)-format signature encoded in DER. The resulting data can be passed to SaveCustomSignature.

Low-level function belonging to custom-signing APIs. Creates the signedAttributes component of Cryptographic Message Syntax (CMS). The result of this function can then be encrypted by a remote private key (cloud service, Hardware Security Module (HSM) device, etc.), using some external API that returns the bytes of a not-already-CMS-embedded signature value (e.g. RSA PKCS #1 v1.5 format). Following that, CMS generation can be performed using GenerateCMSSignature, after which the resulting signature can be inserted into a resulting signed version of the PDF document using the PDFDoc function SaveCustomSignature.

Low-level function belonging to custom-signing APIs. Creates the signedAttributes component of Cryptographic Message Syntax (CMS). The result of this function can then be encrypted by a remote private key (cloud service, Hardware Security Module (HSM) device, etc.), using some external API that returns the bytes of a not-already-CMS-embedded signature value (e.g. RSA PKCS #1 v1.5 format). Following that, CMS generation can be performed using GenerateCMSSignature, after which the resulting signature can be inserted into a resulting signed version of the PDF document using the PDFDoc function SaveCustomSignature.

Contacts a remote timestamp authority over network, sends CMS digest, receives and verifies timestamp token, combines the timestamp token and the data of an existing CMS-type (adbe.pkcs7.detached or ETSI.CAdES.detached subfilter) main document signature, and then returns that data to the user. This function does not insert the final CMS-type document signature into the document. You must retrieve it from the result using GetData and then pass that to PDFDoc SaveCustomSignature. At least one signing time, whether "M" (see setSigDictTimeOfSigning) or a secure embedded timestamp, is required to be added in order to create a PAdES signature.

Low-level optional function belonging to custom-signing APIs allowing creation of PAdES signatures with key elsewhere, allowing CMS to be generated automatically later. Represents one the components of the functionality of SignDigest which are not key-related. Creates the necessary attribute for a PAdES signature (ETSI.CAdES.detached subfilter type). The result of this function can be passed as a contiguous part of the custom attributes buffer parameter of GenerateCMSSignedAttributes. At least one signing time, whether "M" (see setSigDictTimeOfSigning) or a secure embedded timestamp (see generateContentsWithEmbeddedTimestamp), is also required to be added in order to create a PAdES signature. The result will be either the BER-serialized bytes of an ESS_signing_cert or ESS_signing_cert_V2 CMS Attribute (an ASN.1 SEQUENCE containing the correct OID and ESSCertID or ESSCertIDv2), as is appropriate, depending on what digest algorithm type is provided (see RFC 5035).

Retrieves the ranges of byte indices within the document over which this signature is intended to apply/be verifiable. This function does not verify that the signature is valid over its byte ranges. It merely returns them. This can be useful when a document consists of multiple incremental revisions, the latter of which may or may not have been signed, for telling which revisions were actually signed by which signature. The outputs of this function can also be used to truncate the document at the end of a signed byte range, in order that the signed document revision may be retrieved from a document with later incremental revisions. Of course, to be certain that the signature is valid, it must also then be verified using the verification API. Also, the caller is responsible for making sure that the byte ranges returned from this function actually make sense (i.e. fit inside the document).

Gets a certificate in the certificate chain (Cert entry) of the digital signature dictionary by index. Throws if Cert is not Array or String, throws if index is out of range and Cert is Array, throws if index is > 1 and Cert is string, otherwise retrieves the certificate. Only to be used for old-style adbe.x509.rsa_sha1 signatures; for other signatures, use CMS getter functions instead.

Gets number of certificates in certificate chain (Cert entry of digital signature dictionary). Must call HasCryptographicSignature first and use it to check whether the signature is signed. Only to be used for old-style adbe.x509.rsa_sha1 signatures; for other signatures, use CMS getter functions instead.

Retrieves all constructible certificate paths from an adbe.pkcs7.detached or ETSI.CAdES.detached digital signature. The signer will always be returned if the signature is CMS-based and not corrupt. Must only be called on signed adbe.pkcs7.detached signatures. The order of the certificates in each of the paths returned is as follows: the signer will be first, and issuers come after it in order of the issuer of the previous certificate. The default behaviour is to return a sub-path for each marginal issuer in a max-length path. This function does not verify the paths. It merely extracts certificates and constructs paths. This function only works when the build has support for verification-related APIs.

Should not be called when SubFilter is ETSI.RFC3161 (i.e. on a DocTimeStamp). Returns the contact information of the signer from the digital signature dictionary. Must call HasCryptographicSignature first and use it to check whether the signature is signed.

If HasCryptographicSignature, returns most restrictive permissions found in any reference entries in this digital signature. Returns Lock-resident (i.e. tentative) permissions otherwise. Throws if invalid permission value is found.

Should not be called when SubFilter is ETSI.RFC3161 (i.e. on a DocTimeStamp). Returns the Location of the signature from the digital signature dictionary. Must call HasCryptographicSignature first and use it to check whether the signature is signed.

Returns the fully-qualified names of all fields locked by this signature using the field permissions feature. Retrieves from the digital signature dictionary if the form field HasCryptographicSignature. Otherwise, retrieves from the Lock entry of the digital signature form field. Result is invalidated by any field additions or removals. Does not take document permissions restrictions into account.

Should not be called when SubFilter is ETSI.RFC3161 (i.e. on a DocTimeStamp). Returns the Reason for the signature from the digital signature dictionary. Must call HasCryptographicSignature first and use it to check whether the signature is signed.

Retrieves the SDF Obj of the digital signature field.

Should not be called when SubFilter is ETSI.RFC3161 (i.e. on a DocTimeStamp). Returns the name of the signer of the signature from the digital signature dictionary. Must call HasCryptographicSignature first and use it to check whether the signature is signed.

Returns the signing certificate. Must only be called on signed adbe.pkcs7.detached or ETSI.CAdES.detached signatures. This function does not verify the signature. It merely extracts the claimed signing certificate. This function only works when the build has support for verification-related APIs.

Should not be called when SubFilter is ETSI.RFC3161 (i.e. on a DocTimeStamp). Returns the "M" entry from the digital signature dictionary, which represents the signing date/time. Must call HasCryptographicSignature first and use it to check whether the signature is signed.

Returns the SubFilter type of the digital signature. Specification says that one must check the SubFilter before using various getters. Must call HasCryptographicSignature first and use it to check whether the signature is signed.

Returns whether the digital signature field has been cryptographically signed. Checks whether there is a digital signature dictionary in the field and whether it has a Contents entry. Must be called before using various digital signature dictionary-related functions. Does not check validity - will return true even if a valid hash has not yet been generated (which will be the case after [Certify/Sign]OnNextSave[WithCustomHandler] has been called on the signature but even before Save is called on the document).

Returns whether the field has a visible appearance. Can be called without checking HasCryptographicSignature first, since it operates on the surrounding Field dictionary, not the "V" entry (i.e. digital signature dictionary). Performs the zero-width+height check, the Hidden bit check, and the NoView bit check as described by the PDF 2.0 specification, section 12.7.5.5 "Signature fields".

Returns whether or not this signature is a certification.

Returns whether this digital signature field is locked against modifications by any digital signatures. Can be called when this field is unsigned.

Should not be called when SubFilter is ETSI.RFC3161 (i.e. on a DocTimeStamp). Sets the ContactInfo entry in the digital signature dictionary. Must create a digital signature dictionary first using [Certify/Sign]OnNextSave[WithCustomHandler]. If this function is called on a digital signature field that has already been cryptographically signed with a valid hash, the hash will no longer be valid, so do not call Save (to sign/create the hash) until after you call this function, if you need to call this function in the first place. Essentially, call this function after [Certify/Sign]OnNextSave[WithCustomHandler] and before Save.

Sets the digital signature logging filename, and enables the logging. This function is expected to be called only once. Subsequent calls to the function will have no effect.

Sets the document locking permission level for this digital signature field. Call only on unsigned signatures, otherwise a valid hash will be invalidated.

Tentatively sets which fields are to be locked by this digital signature upon signing. It is not necessary to call HasCryptographicSignature before using this function. Throws if non-empty array of field names is passed along with FieldPermissions Action == e_lock_all.

Should not be called when SubFilter is ETSI.RFC3161 (i.e. on a DocTimeStamp). Sets the Location entry in the digital signature dictionary. Must create a digital signature dictionary first using [Certify/Sign]OnNextSave[WithCustomHandler]. If this function is called on a digital signature field that has already been cryptographically signed with a valid hash, the hash will no longer be valid, so do not call Save (to sign/create the hash) until after you call this function, if you need to call this function in the first place. Essentially, call this function after [Certify/Sign]OnNextSave[WithCustomHandler] and before Save.

Sets the preferred digest algorithm to use when signing this field. This is done by setting DigestMethod in the Seed Value dictionary. This function can be called before a signature field is even prepared for signing. In practice, PDF processor applications may or may not actually use this value to determine which algorithm to use; we currently do not.

Sets the preferred digest algorithm to use when signing this field. This is done by setting DigestMethod in the Seed Value dictionary. This function can be called before a signature field is even prepared for signing. In practice, PDF processor applications may or may not actually use this value to determine which algorithm to use; we currently do not.

Should not be called when SubFilter is ETSI.RFC3161 (i.e. on a DocTimeStamp). Sets the Reason entry in the digital signature dictionary. Must create a digital signature dictionary first using [Certify/Sign]OnNextSave[WithCustomHandler]. If this function is called on a digital signature field that has already been cryptographically signed with a valid hash, the hash will no longer be valid, so do not call Save (to sign/create the hash) until after you call this function, if you need to call this function in the first place. Essentially, call this function after [Certify/Sign]OnNextSave[WithCustomHandler] and before Save.

Adds the "M" key and value, representing the PDF-time-of-signing (not to be confused with embedded timestamps, DocTimeStamps, or CMS signing time), to the digital signature dictionary. The digital signature field must have been prepared for signing first. This function should only be used if no secure embedded timestamping support is available from your signing provider. Useful for custom signing workflows, where signing time is not set automatically by the Apryse SDK, unlike in the usual standard handler signing workflow. A secure embedded timestamp can also be added later and should override this "M" date entry when the signature is read by signature-verifying PDF processor applications. At least one signing time, whether "M" or a secure embedded timestamp (see generateContentsWithEmbeddedTimestamp), is required to be added in order to create a PAdES signature.

Returns a CMS detached signature incorporating a digest that is provided using the provided PKCS #12 key buffer (.pfx). This function is part of the custom signing API, but cannot be used for workflows where the key is not in PFX format or when the signature comes from a source that cannot generate CMS signatures (e.g. Hardware Security Modules (HSM) devices, cloud signing services). In such cases, the low-level parts of the custom signing API should be used instead of this function (e.g. GenerateESSSigningCertPAdESAttribute, GenerateCMSSignedAttributes, GenerateCMSSignature). This function is a shortcut for situations in which use of more low-level custom signing functions is unnecessary. Therefore, this function will generate necessary CMS components, such as signedAttrs, internally. This function does not change the DigitalSignatureField. Call SaveCustomSignature to write a signature to its PDFDoc.

Returns a CMS detached signature incorporating a digest that is provided using the provided PKCS #12 key file (.pfx). This function is part of the custom signing API, but cannot be used for workflows where the key is not in PFX format or when the signature comes from a source that cannot generate CMS signatures (e.g. Hardware Security Modules (HSM) devices, cloud signing services). In such cases, the low-level parts of the custom signing API should be used instead of this function (e.g. GenerateESSSigningCertPAdESAttribute, GenerateCMSSignedAttributes, GenerateCMSSignature). This function is a shortcut for situations in which use of more low-level custom signing functions is unnecessary. Therefore, this function will generate necessary CMS components, such as signedAttrs, internally. This function does not change the DigitalSignatureField. Call SaveCustomSignature to write a signature to its PDFDoc.

Must be called to prepare a signature for signing, which is done afterwards by calling Save. Cannot sign two signatures during one save (throws). Default document permission level is e_annotating_formfilling_signing_allowed. Throws if signature field already has a digital signature dictionary.

Must be called to prepare a signature for signing, which is done afterwards by calling Save. Cannot sign two signatures during one save (throws). Default document permission level is e_annotating_formfilling_signing_allowed. Throws if signature field already has a digital signature dictionary.

Must be called to prepare a signature for signing, which is done afterwards by calling Save. Cannot sign two signatures during one save (throws). Default document permission level is e_annotating_formfilling_signing_allowed. Throws if signature field already has a digital signature dictionary.

Must be called to prepare a secure PDF-embedded timestamp signature (RFC 3161 DocTimeStamp) for signing, which is done afterwards by calling Save on the document with an e_incremental flag. Throws if document is locked by other signatures, if signature is already signed, or if another signature has already been prepared for signing on the next save (because only one signing operation can be done per incremental save). Default document permission level is e_annotating_formfilling_signing_allowed. A failure in timestamp response verification will result in document Save throwing an exception. It is recommended to use TimestampingConfiguration.TestConfiguration with the VerificationOptions ahead of time to avoid this.

Sets the requested SubFilter value (which identifies a signature type) as the only one to use during future signing, overwriting all such previous settings. It is not necessary to call HasCryptographicSignature before calling this function. For example, this function can be used to switch to PAdES signing mode.

Verifies this cryptographic digital signature in the manner specified by the VerificationOptions.