PDFVerify Class

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The PDFVerify class verifies PDF signatures.

Syntax

securepdf.PDFVerify

Remarks

The PDFVerify class verifies electronic signatures over PDF documents. Basic Adobe and PAdES signatures are supported.

PDFVerify validates each signature from two perspectives: the integrity and validity of the signature itself (i.e., its correspondence to the document data it covers), and the validity and trustworthiness of the signing certificate chain. These two signature aspects are generally independent of each other - the signature may be valid but the chain may not be trusted, or the chain may be trusted but the integrity of the signature may be violated. Under normal circumstances, both the signature and the chain must be valid for the signature to be considered good.

Preparing the Validation

To initiate the validation, first provide the signed PDF document as a file (InputFile), byte array (InputData), or stream (SetInputStream). Then adjust any chain validation parameters as necessary (please see the Chain Validation Setup section for more details) and call the Verify method.

For every signature in the document, PDFVerify will fire the SignatureInfo event, allowing you to specify whether you want the component to validate the signature, the chain, or both.

Once SignatureInfo returns, PDFVerify proceeds to the signature validation routine in accordance with the provided settings.

Validation Results

Upon completion of the validation, the SignatureProcessed event is fired, and the validation results are published here as well as in the following fields of the associated PDFSignature object:

• SignatureValidationResult contains the outcome of the signature validation: valid, corrupted, the signing certificate was missing, or failed.
• ChainValidationResult contains the primary result of the chain validation routine: valid, valid but untrusted, invalid, or undefined.
• ChainValidationDetails provides the details of the factors that contributed to the chain validation result, such as an outdated certificate, a missing CRL, or a missing CA certificate.

Other information about the signature can be accessed via the Signatures property.

Checking Signature Coverage

The PDF format uses incremental updates to introduce changes to the document. This implies that a signature may not cover the whole document, but rather a certain revision of it. Strictly speaking, every signature in a PDF document, apart from potentially the last one, covers just some part of the document. In most cases, that part matches the revision of the document that existed before all the subsequent signatures were added.

Because of these specifics of the PDF format, it is crucially important to understand which part of the document is covered by a specific signature. Use the CoverageEndsAt field of the associated PDFSignature object to establish the scope of a signature. The revision of the document covered by that specific signature ranges from byte 0 to CoverageEndsAt. Alternatively, you can use the GetSignedVersion method to extract the signed revision to a file.

Chain Validation Setup

Chain validation is a sophisticated, multi-faceted procedure that involves a lot of variables. Depending on the configuration of your operating environment, the specifics of the PKI framework being used, and the validation policy you need to follow, you may want to adjust your chain validation parameters to best fit your requirements. A summary of these parameters is given below.

Note that these parameters apply to the Sign and Update methods in PDFSign as well as the Verify method in PDFVerify, as all three methods execute the chain validation procedure (if it is enabled).

Validation Policy

The ValidationPolicy property dictates how thoroughly the chain will be validated. It includes options to control which checks the class will perform, allowing you to tailor the validation process to meet your specific security needs. For example, if it is not essential to check each certificate's revocation status, set this property to vpFullNoRevocation.

Revocation

The revocation aspect of chain validation is controlled by the RevocationCheck property, which allows you to choose between and prioritize revocation origins. Note that OCSP sources are often preferred to CRL endpoints because of their real-time capability and the smaller size of the responses they produce.

Trust

The trust aspect of chain validation is controlled by the TrustSources property, which allows you to specify the locations in which the class will search for trust anchors. Local system stores, your own trusted root certificates (via the TrustedCerts property), and Trusted Lists (via the TrustedLists property) are all supported.

Offline Mode

The OfflineMode property provides the ability to verify the document without contacting online sources. If this property is enabled, the class will only use KnownCerts, TrustedCerts, data structures within the document itself, and revocation and Trusted List data that it previously saved to its internal cache when looking for missing validation material.

Property List

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The following is the full list of the properties of the class with short descriptions. Click on the links for further details.

Method List

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The following is the full list of the methods of the class with short descriptions. Click on the links for further details.

Event List

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The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.

Config Settings

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The following is a list of config settings for the class with short descriptions. Click on the links for further details.

Attachments Property (PDFVerify Class)

A collection of all attached files found in the PDF document.

Syntax

public PDFAttachmentList getAttachments();
public void setAttachments(PDFAttachmentList attachments);

Remarks

This property is used to access the details of all the attached files identified in the document. Use the SaveAttachment method to save attachments from this collection.

This property is not available at design time.

Please refer to the PDFAttachment type for a complete list of fields.

BlockedCerts Property (PDFVerify Class)

The certificates that must be rejected as trust anchors.

Syntax

public CertificateList getBlockedCerts();
public void setBlockedCerts(CertificateList blockedCerts);

Remarks

This property is used to supply a list of compromised or blocked certificates to the class. Note that any chain containing a blocked certificate will fail validation.

This property is not available at design time.

Please refer to the Certificate type for a complete list of fields.

DecryptionCert Property (PDFVerify Class)

The decryption certificate.

Syntax

public Certificate getDecryptionCert();
public void setDecryptionCert(Certificate decryptionCert);

Remarks

This property is used to provide the certificate used for decryption. Note that this certificate must have a private key associated with it.

This property is not available at design time.

Please refer to the Certificate type for a complete list of fields.

DocumentCerts Property (PDFVerify Class)

A collection of certificates read from the document during processing.

Syntax

public CertificateList getDocumentCerts();

Remarks

This property is used to access all certificates encountered during document processing and embedded into the signature(s). When signing or verifying, this collection will be populated automatically during chain validation.

This property is read-only and not available at design time.

Please refer to the Certificate type for a complete list of fields.

Firewall Property (PDFVerify Class)

A set of properties related to firewall access.

Syntax

public Firewall getFirewall();
public void setFirewall(Firewall firewall);

Remarks

This is a Firewall-type property, which contains fields describing the firewall through which the class will attempt to connect.

Please refer to the Firewall type for a complete list of fields.

InputData Property (PDFVerify Class)

A byte array containing the PDF document to process.

Syntax

public byte[] getInputData();
public void setInputData(byte[] inputData);

Remarks

This property is used to assign a byte array containing the PDF document to be processed.

This property is not available at design time.

InputFile Property (PDFVerify Class)

The PDF file to process.

Syntax

public String getInputFile();
public void setInputFile(String inputFile);

Default Value

""

Remarks

This property is used to provide a path to the PDF document to be processed.

KnownCerts Property (PDFVerify Class)

A collection of additional certificates for chain validation.

Syntax

public CertificateList getKnownCerts();
public void setKnownCerts(CertificateList knownCerts);

Remarks

This property is used to supply a list of additional certificates to the class that might be needed for chain validation. For instance, intermediary CA certificates may be absent from the standard system locations (or there may be no standard system locations) and therefore should be supplied to the class manually.

The purpose of this certificate collection is roughly equivalent to that of the Intermediate Certification Authorities system store in Windows.

Note: Do not add trust anchors or root certificates to this collection; add them to TrustedCerts instead.

This property is not available at design time.

Please refer to the Certificate type for a complete list of fields.

OfflineMode Property (PDFVerify Class)

Whether the class is operating in offline mode.

Syntax

public boolean isOfflineMode();
public void setOfflineMode(boolean offlineMode);

Default Value

False

Remarks

This property indicates whether the class should operate in offline mode.

In offline mode, the class restricts itself from accessing online Trusted Lists and revocation information sources such as CRLs or OCSP responders. It may be useful to set this property to true if there is a need to verify the completeness of the validation information included within the signature or provided via KnownCerts.

OutputData Property (PDFVerify Class)

A byte array containing the PDF document after processing.

Syntax

public byte[] getOutputData();

Remarks

This property is used to read the byte array containing the produced output after the operation has completed. It will only be set if an output file and output stream have not been assigned via OutputFile and SetOutputStream respectively.

This property is read-only and not available at design time.

OutputFile Property (PDFVerify Class)

The path to a local file where the output will be written.

Syntax

public String getOutputFile();
public void setOutputFile(String outputFile);

Default Value

""

Remarks

This property is used to provide a path where the resulting PDF document will be saved after the operation has completed.

Overwrite Property (PDFVerify Class)

Whether or not the class should overwrite files.

Syntax

public boolean isOverwrite();
public void setOverwrite(boolean overwrite);

Default Value

False

Remarks

This property indicates whether or not the class will overwrite OutputFile, OutputData, or the stream set in SetOutputStream. If set to false, an error will be thrown whenever OutputFile, OutputData, or the stream set in SetOutputStream exists before an operation.

Password Property (PDFVerify Class)

The password to decrypt the document with.

Syntax

public String getPassword();
public void setPassword(String password);

Default Value

""

Remarks

This property is used to provide the user password for decryption. Though it may be different from OwnerPassword, most implementations use the same value for both.

Proxy Property (PDFVerify Class)

A set of properties related to proxy access.

Syntax

public Proxy getProxy();
public void setProxy(Proxy proxy);

Remarks

This property contains fields describing the proxy through which the class will attempt to connect.

Please refer to the Proxy type for a complete list of fields.

RevocationCheck Property (PDFVerify Class)

The kind(s) of revocation check to perform for all chain certificates.

Syntax

public int getRevocationCheck();
public void setRevocationCheck(int revocationCheck);

Enumerated values:
  public final static int rcAllCRL = 0;
  public final static int rcAllOCSP = 1;
  public final static int rcAllCRLAndOCSP = 2;
  public final static int rcAnyCRL = 3;
  public final static int rcAnyOCSP = 4;
  public final static int rcAnyCRLOrOCSP = 5;
  public final static int rcAnyOCSPOrCRL = 6;

Default Value

6

Remarks

This property is used to specify the revocation sources and preferences the class will use during chain validation. Revocation checking is necessary to ensure the integrity of the chain and to obtain up-to-date certificate validity and trust information.

Certificate Revocation Lists (CRLs) and Online Certificate Status Protocol (OCSP) responses serve the same purpose of ensuring that the certificate has not been revoked by the Certificate Authority (CA) at the time of use. Depending on the circumstances and security policy requirements, either one or both of the revocation information source types may be used.

Possible values are:

This property controls the way revocation checks are performed for every certificate in the chain. Typically, certificates come with two types of revocation information sources: CRLs (Certificate Revocation Lists) and OCSP responses. CRLs are static objects periodically published by the CA at some online location. OCSP responders are active online services maintained by the CA that can provide up-to-date information on certificate statuses in near real time.

There are some conceptual differences between the two. CRLs are normally larger in size. Their use involves some latency because there is normally a delay between the time at which a certificate was revoked and the time at which the subsequent CRL mentioning that revocation is published. The benefits of CRLs are that the same object can provide statuses for all certificates issued by a particular CA, and that the whole technology is much simpler than OCSP (and thus is supported by more CAs).

This property allows the validation course to be adjusted by including or excluding certain types of revocation sources from the validation process. The rcAnyOCSPOrCRL setting (give preference to the faster OCSP route and only demand one source to succeed) is a good choice for most typical validation environments. The rcAll* modes are much stricter, and may be used in scenarios where bulletproof validity information is essential.

Note: If no CRL or OCSP endpoints are provided by the CA, the revocation check will be considered successful. This is because the CA chose not to supply revocation information for its certificates, meaning they are considered irrevocable.

Note: Within each of the above settings, if any retrieved CRL or OCSP response indicates that the certificate has been revoked, the revocation check fails.

Signatures Property (PDFVerify Class)

A collection of all the signatures and empty fields found in the PDF document.

Syntax

public PDFSignatureList getSignatures();

Remarks

This property is used to access the details of all the signatures and empty signature fields identified in the document.

This property is read-only and not available at design time.

Please refer to the PDFSignature type for a complete list of fields.

TrustedCerts Property (PDFVerify Class)

A collection of trusted certificates for chain validation.

Syntax

public CertificateList getTrustedCerts();
public void setTrustedCerts(CertificateList trustedCerts);

Remarks

This property is used to supply a list of trusted certificates to the class that might be needed for chain validation. For instance, root CA certificates may be absent from the standard system locations (or there may be no standard system locations) and therefore should be supplied to the class manually.

The purpose of this certificate collection is largely the same as that of the Windows Trusted Root Certification Authorities system store.

Use this property with extreme care as it directly affects chain verifiability; a wrong certificate added to the list of trusted certificates may result in bad chains being accepted and forfeited signatures being recognized as genuine. Only add certificates that originate from parties that are known and trusted.

This property is not available at design time.

Please refer to the Certificate type for a complete list of fields.

TrustedLists Property (PDFVerify Class)

A list of known Trusted Lists for chain validation.

Syntax

public String getTrustedLists();
public void setTrustedLists(String trustedLists);

Default Value

"%EUTL%"

Remarks

This property is used to supply a semicolon-separated list of URLs or paths of known Trusted Lists to the class for chain validation.

A Trusted List is an XML document that contains a government-issued list of CAs that have passed regulated compliance checks. When validating the chain, the class will consult the Trusted List to establish certificate trust, ensuring that the CA is legitimate and entitled to issue certificates of the kind being checked.

The default value is the special %EUTL% macro, which, if applicable, instructs the class to check the root certificate against up-to-date versions of the primary EU Trusted Lists from the EU LOTL. Custom values can be appended: component.TrustedLists = "%EUTL%;http://my.company/tsl;c:\tsls\mytsl.xml"; Note: The class will cache all Trusted Lists it downloads and uses during chain validation. This cache is shared between class instances within the same process. If this property contains a URL that is also present in the cache, the class will retrieve the cached data and reuse them in the current validation. If the data are invalid, the class will download a fresh Trusted List and add it to the cache.

TrustSources Property (PDFVerify Class)

The trust sources to use during chain validation.

Syntax

public int getTrustSources();
public void setTrustSources(int trustSources);

Enumerated values:
  public final static int tsManual = 0;
  public final static int tsLocal = 1;
  public final static int tsTrustedLists = 2;
  public final static int tsLocalAndTrustedLists = 3;

Default Value

3

Remarks

This property is used to specify the sources the class will use to establish certificate trust during chain validation.

Establishing trust for a particular certificate, when either signing or verifying, involves building a chain up to a valid trust anchor. This trust anchor is a root certificate that typically resides on the local system. If the certificate does not eventually chain up to a valid trust anchor, the chain is considered untrusted and therefore invalid.

Possible values are:

ValidationFlags Property (PDFVerify Class)

Additional chain validation settings.

Syntax

public int getValidationFlags();
public void setValidationFlags(int validationFlags);

Default Value

0

Remarks

This property is used to specify additional settings that affect the overall flow of the chain validation.

Its value should be provided as a bitmask of the following flags:

ValidationPolicy Property (PDFVerify Class)

The level at which to perform chain validation.

Syntax

public int getValidationPolicy();
public void setValidationPolicy(int validationPolicy);

Enumerated values:
  public final static int vpNone = 0;
  public final static int vpFull = 1;
  public final static int vpFullNoTrust = 2;
  public final static int vpFullNoRevocation = 3;
  public final static int vpBestEffort = 4;

Default Value

1

Remarks

This property is used to specify the overall validation policy the class will follow.

Possible values are:

Validation Policy Heuristics

The choice of validation policy will depend on the scenario for which the chain is validated.

Creating a new signature:

• For a basic signature with or without a timestamp, chain validation is not required, so it is recommended to use vpNone. This policy may also be used in test environments or on offline systems.
• For an LTV signature, use vpFull or vpFullNoTrust depending on whether trust checks are necessary in the current environment. If the signature is being created in an environment that does not match the prospective validation environment, consider vpFullNoTrust to validate the chain properly and fully without expecting good trust.

Updating or extending an existing signature:

• When updating a basic signature to LTV, similarly use vpFull or vpFullNoTrust as above.
• When extending an LTV signature, similarly use vpFull or vpFullNoTrust as above.

Validating an existing signature:

• For basic signature validation, use vpFullNoRevocation if trust checks, but not revocation checks, are necessary in the current environment. This policy may also be used on offline systems if the trust anchor is already available to the class.
• For archival validation, use vpFull to validate the chain properly and fully. This policy expects the trust anchor and all the revocation material to be available.

ValidationTime Property (PDFVerify Class)

The time point at which the signature should be validated.

Syntax

public String getValidationTime();
public void setValidationTime(String validationTime);

Default Value

""

Remarks

This property is used to specify the moment in time at which the signature validity should be established. The time should be provided in UTC in yyyyMMddHHmmssZ format.

Leave this property empty to stick to the default time point. The class will then prioritize:

• The signature creation time if the signature contains a signature timestamp (ValidatedSigningTime), or
• The local time included in the signature by the signer (ClaimedSigningTime).

Note: The validity of the same signature may differ depending on the time point chosen due to temporal changes in chain validities, revocation statuses, and timestamp times.

Close Method (PDFVerify Class)

Closes an opened PDF document.

Syntax

public void close();

Remarks

This method is used to close the previously opened document specified in InputFile, InputData, or SetInputStream. It should always be preceded by a call to the Open method.

Example: component.InputFile = "input.pdf"; component.Open(); // Some operation component.Close();

If any changes are made to the document, they will be saved automatically to OutputFile, OutputData, or the stream set in SetOutputStream when this method is called. To configure this saving behavior, set the SaveChanges configuration setting.

Config Method (PDFVerify Class)

Sets or retrieves a configuration setting.

Syntax

public String config(String configurationString);

Remarks

Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Encrypted Method (PDFVerify Class)

Checks whether a PDF document is encrypted.

Syntax

public boolean encrypted();

Remarks

This method is used to determine whether or not the document specified in InputFile, InputData, or SetInputStream is encrypted. It will return false if the document is pseudo-encrypted with an empty password.

Example: component.InputFile = "input.pdf"; if (component.Encrypted()) { // Set Password or DecryptionCert } component.Open(); // Some operation component.Close(); Note: If the document is not already opened, this method will open it, perform the operation, then close it.

GetPageProperty Method (PDFVerify Class)

Retrieves the value of a page property.

Syntax

public String getPageProperty(int page, String property);

Remarks

This method is used to read general information about the pages of the document specified in InputFile, InputData, or SetInputStream, such as their dimensions and content positioning details.

The Page parameter specifies the page to read information about, and the Property parameter specifies the page property to read. The latter can take one of the following values:

Note: Each page property is only populated once the document has been loaded, which is reported by the DocumentInfo event.

Example: int pageCount = 0; component.OnDocumentInfo += (s, e) => { pageCount = e.PageCount; }; component.InputFile = "input.pdf"; component.Open(); for (int i = 1; i <= pageCount; i++) component.GetPageProperty(i, "Height"); component.Close(); The page properties can be used to adjust the position of the signature widget based on the page dimensions. For example: int x = int.Parse(pdfsign.GetPageProperty(1, "Width")) - 100; int y = int.Parse(pdfsign.GetPageProperty(1, "Height")) - 100; pdfsign.SetWidgetProperty("OffsetX", x.ToString()); pdfsign.SetWidgetProperty("OffsetY", y.ToString()); Note: If the document is not already opened, this method will open it, perform the operation, then close it.

GetSignedVersion Method (PDFVerify Class)

Returns the part of a signed PDF document that is covered by the signature.

Syntax

public void getSignedVersion(int signatureIndex);

Remarks

This method is used to retrieve the revision of the document specified in InputFile, InputData, or SetInputStream that is covered by the signature specified by SignatureIndex. The extracted revision will be saved to OutputFile, OutputData, or the stream set in SetOutputStream.

The SignatureIndex parameter is the index of the signature of interest in the Signatures collection.

Example: pdfverify.InputFile = "signed.pdf"; pdfverify.OutputFile = "revision0.pdf"; pdfverify.GetSignedVersion(0); PDF documents often use an incremental update approach, with any changes being appended to the document without altering the existing revision. This may lead to situations where a signature only covers part of the document (one of the past revisions), but not subsequent changes. This method provides a means to extract the revision that is actually certified by the signature.

It is recommended to use this method when validating signatures to make sure the signature covers the byte range it is expected to cover.

An alternative to this method is to check the CoverageEndsAt field of the signature object and match it to the document length.

Note: If the document is not already opened, this method will open it, perform the operation, then close it.

Interrupt Method (PDFVerify Class)

Interrupts the current action.

Syntax

public void interrupt();

Remarks

This method interrupts the current action. It can be used, for example, within the ChainCert event to abort the chain validation procedure.

If there is no action in progress, this method simply returns, doing nothing.

Open Method (PDFVerify Class)

Opens a PDF document for processing.

Syntax

public void open();

Remarks

This method is used to open the document specified in InputFile, InputData, or SetInputStream before performing some operation on it, such as signing, updating, verifying signatures, or removing signatures. When finished, call Close to complete or discard the operation.

It is recommended to use this method (alongside Close) when performing multiple operations on the document at once.

Automatic Decryption Functionality

If this method is called on an encrypted document, the Password or RecipientInfo event will fire (depending on the encryption type) as a notification that the document must be decrypted before processing can continue.

Once the correct decryption material is supplied, the class will then attempt to decrypt the document automatically within this method. When this occurs, the decrypted content is kept in memory so that the document's encrypted status is preserved when it is saved later. Use the Decrypt method to save a decrypted copy of the document instead.

Reset Method (PDFVerify Class)

Resets the class.

Syntax

public void reset();

Remarks

This method is used to reset the class's properties and configuration settings to their default values.

SaveAttachment Method (PDFVerify Class)

Saves a PDF attachment to a file.

Syntax

public void saveAttachment(int index, String fileName);

Remarks

This method is used to retrieve the contents of an attachment from the document specified in InputFile, InputData, or SetInputStream and save it to the file specified by FileName. It does not modify the existence of the Attachments collection's contents.

The Index parameter is the index of the attachment in the Attachments collection to be saved.

The FileName parameter specifies the filename that the attachment will be saved to.

Example: component.InputFile = "input_with_attachment.pdf"; component.Open(); component.SaveAttachment(0, "a.dat"); component.Close(); Example (saving to a stream): component.InputFile = "input_with_attachment.pdf"; component.Attachments[0].OutputStream = myStream; component.SaveAttachment(0, null); // null means use the OutputStream field if it's set Note: If the document is not already opened, this method will open it, perform the operation, then close it.

SetInputStream Method (PDFVerify Class)

Sets the stream containing the PDF document to process.

Syntax

public void setInputStream(java.io.InputStream inputStream);

Remarks

This method is used to set the stream from which the class will read the PDF document to be processed. If an input stream is set before the class attempts to perform operations on the document, the class will read the data from the input stream instead of from the InputFile or InputData properties.

Note: It may be useful to additionally set the CloseInputStreamAfterProcessing configuration setting to true when using input streams.

SetOutputStream Method (PDFVerify Class)

Sets the stream to write the processed document to.

Syntax

public void setOutputStream(java.io.OutputStream outputStream);

Remarks

This method is used to set the stream to which the class will write the resulting PDF document. If an output stream is set before the class attempts to perform operations on the document, the class will write the data to the output stream instead of writing to OutputFile or populating OutputData.

Note: It may be useful to additionally set the CloseOutputStreamAfterProcessing configuration setting to true when using output streams.

Signed Method (PDFVerify Class)

Checks whether a PDF document is signed.

Syntax

public boolean signed();

Remarks

This method is used to determine whether or not the document specified in InputFile, InputData, or SetInputStream is signed. It will return false if the document contains only empty signature fields.

Example: pdfverify.InputFile = "input.pdf"; if (pdfverify.Signed()) { // Configure validation-related properties as desired pdfverify.Verify(); } Note: If the document is not already opened, this method will open it, perform the operation, then close it.

Unsign Method (PDFVerify Class)

Removes a signature from a PDF document.

Syntax

public void unsign(int signatureIndex, int unsignKind);

Remarks

This method is used to remove an existing signature specified by SignatureIndex from the document specified in InputFile, InputData, or SetInputStream. The document with the removed signature will be saved to OutputFile, OutputData, or the stream set in SetOutputStream.

The SignatureIndex parameter is the index of the signature in the Signatures collection to be removed.

The UnsignKind parameter specifies the kind of unsign to perform. Possible values are:

Example: pdfverify.InputFile = "signed.pdf"; pdfverify.OutputFile = "unsigned.pdf"; pdfverify.Open(); int idx = pdfverify.Signatures.Count - 1; pdfverify.Unsign(idx, 0); // uskFull pdfverify.Close(); Note that unsigning is different from GetSignedVersion. The latter returns the revision of the document including the mentioned signature (thus removing anything after that signature was created). Unsign removes the signature completely by carving it out of the document.

Note: SignatureIndex set to -1 removes all signatures in the document.

Note: If the document is not already opened, this method will open it, perform the operation, then close it.

Verify Method (PDFVerify Class)

Verifies a signed PDF document.

Syntax

public void verify();

Remarks

This method is used to validate all signatures in the document specified in InputFile, InputData, or SetInputStream.

This method walks through the signed document and reports every signature via the SignatureInfo event. Subscribe to the event to be notified about the signatures and adjust validation settings on the fly.

Upon completion of this method, the signature details will be published in the Signatures property.

Example: pdfverify.InputFile = "signed.pdf"; pdfverify.Verify(); PDFSignature signature = pdfverify.Signatures[0]; if (signature.SignatureValidationResult == SignatureValidationResults.svrValid) Console.WriteLine("Signature is good"); if (signature.ChainValidationResult == ChainValidationResults.cvrValid) Console.WriteLine("Chain is good"); This method only validates the signatures and does not check their coverage. It is a good idea to use mechanisms such as GetSignedVersion or CoverageEndsAt to ensure that the signature covers the expected document revision.

To control individual signature validation, subscribe to the SignatureInfo event and set the ValidateSignature and ValidateChain parameters accordingly. The results are reported via the SignatureProcessed event.

Use the following properties to adjust chain validation parameters:

• BlockedCerts
• KnownCerts
• OfflineMode
• RevocationCheck
• TrustedCerts
• TrustedLists
• TrustSources
• ValidationFlags
• ValidationPolicy
• ValidationTime

Note: If the document is not already opened, this method will open it, perform the operation, then close it.

ChainCert Event (PDFVerify Class)

Fired when the class encounters a chain certificate.

Syntax

public class DefaultPDFVerifyEventListener implements PDFVerifyEventListener {
  ...
  public void chainCert(PDFVerifyChainCertEvent e) {}
  ...
}

public class PDFVerifyChainCertEvent {
  public byte[] certEncoded;
  public String certSubject;
  public String certIssuer;
  public String validationTime;
  public int validationResult; //read-write
  public int validationDetails; //read-write
}

Remarks

This event is fired once for each certificate encountered during chain validation to report that it is about to be processed. The class will try to retrieve all required chain certificates automatically.

The CertEncoded parameter specifies the PEM (Base64-encoded) public certificate.

The CertSubject and CertIssuer parameters specify the distinguished names of the certificate owner and issuer respectively.

The ValidationTime parameter specifies the time point (in UTC) at which the certificate validity was established.

The ValidationResult parameter reports the outcome of the individual certificate validation and can be one of the following values:

In the case of a failure, the ValidationDetails parameter provides more details on its reasons. Its value is a bitmask of the following flags:

Overridable Chain Validation

While the class will follow the validation rules defined by the X.509 standard to the best of its ability, minor technical issues may arise when validating the chain. The ValidationResult and ValidationDetails parameters can be overridden to relax such requirements on a per-certificate basis.

For example, set ValidationResult to cvrValid and ValidationDetails to 0 in order to:

• Ignore CA or TLS key usage requirements
• Ignore the AuthorityKeyId extension in certificate-issuing CAs (helps with incorrectly renewed certificates)
• Ignore the Basic Constraints or Name Constraints extensions of CA certificates
• Tolerate some weaker algorithms
• Implicitly trust self-signed certificates
• Skip validity period checks for trusted certificates (helps with older devices that have expired root certificates)
• Ignore chain loops (helps with buggy CAs that include subchains that sign themselves)

Based on the adjusted validity of the certificate that is currently being processed, the class will continue or abort the chain validation procedure accordingly as if it had arrived at the chosen validation result itself.

Note: The user code is ultimately responsible for certificate validity decisions made via these two parameters. If their values are modified within this event, the resulting chain validation procedure may deviate from the standard.

DocumentInfo Event (PDFVerify Class)

Fired when the document has been loaded into memory.

Syntax

public class DefaultPDFVerifyEventListener implements PDFVerifyEventListener {
  ...
  public void documentInfo(PDFVerifyDocumentInfoEvent e) {}
  ...
}

public class PDFVerifyDocumentInfoEvent {
  public int pageCount;
  public int signatureCount;
}

Remarks

This event is fired once per document processing routine to report that the document has been processed and loaded into memory.

The handler for this event is a good place to check the document structure and access document-related information such as page number and document file details. These may be useful when preparing the signature. For example, the GetPageProperty method can be used to find the optimal position for the signature widget.

The PageCount parameter reports the number of pages in the document.

The SignatureCount parameter reports the number of signatures in the document.

This event is fired when the Open method is called, but only after Password or RecipientInfo is fired (if applicable) and the document has been decrypted.

This event will populate the Attachments, DocumentCerts, and Signatures collections with any corresponding objects found in the document.

Error Event (PDFVerify Class)

Fired when information is available about errors during data delivery.

Syntax

public class DefaultPDFVerifyEventListener implements PDFVerifyEventListener {
  ...
  public void error(PDFVerifyErrorEvent e) {}
  ...
}

public class PDFVerifyErrorEvent {
  public int errorCode;
  public String description;
}

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class throws an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Log Event (PDFVerify Class)

Fired once for each log message.

Syntax

public class DefaultPDFVerifyEventListener implements PDFVerifyEventListener {
  ...
  public void log(PDFVerifyLogEvent e) {}
  ...
}

public class PDFVerifyLogEvent {
  public int logLevel;
  public String message;
  public String logType;
}

Remarks

This event is fired once for each log message generated by the class. The verbosity is controlled by the LogLevel configuration setting.

The LogLevel parameter indicates the detail level of the message. Possible values are:

The Message parameter is the log message.

The LogType parameter identifies the type of log entry. Possible values are:

• CertValidator
• Font
• HTTP
• PDFInvalidSignature
• PDFRevocationInfo
• Timestamp
• TSL

Password Event (PDFVerify Class)

Fired when the class detects that the PDF document is encrypted with a password.

Syntax

public class DefaultPDFVerifyEventListener implements PDFVerifyEventListener {
  ...
  public void password(PDFVerifyPasswordEvent e) {}
  ...
}

public class PDFVerifyPasswordEvent {
  public boolean available;
  public boolean cancel; //read-write
}

Remarks

This event is fired during document processing to report that the document is encrypted with a password. It may be used to supply the correct decryption password to the Password property.

The Available parameter indicates whether the decryption password is already available to the class or still needs to be set. If this parameter is set to false, the correct password must be provided for the decryption attempt to succeed.

The Cancel parameter determines whether the class will stop firing this event to request a password.

RecipientInfo Event (PDFVerify Class)

Fired for each recipient certificate of the encrypted PDF document.

Syntax

public class DefaultPDFVerifyEventListener implements PDFVerifyEventListener {
  ...
  public void recipientInfo(PDFVerifyRecipientInfoEvent e) {}
  ...
}

public class PDFVerifyRecipientInfoEvent {
  public String issuer;
  public String serialNumber;
  public String subjectKeyIdentifier;
  public boolean available;
  public boolean cancel; //read-write
}

Remarks

This event is fired during document processing for each recipient certificate that the document has been encrypted for (if applicable). It may be used to identify the certificate(s) to load and supply to the DecryptionCert property.

The Issuer parameter specifies the subject of the issuer certificate.

The SerialNumber parameter specifies the serial number of the encryption certificate.

The SubjectKeyIdentifier parameter specifies the X.509 subjectKeyIdentifier extension value of the encryption certificate, encoded as a hex string.

The Available parameter indicates whether the decryption certificate is already available to the class or still needs to be set. If this parameter is set to false, the correct certificate must be provided for the decryption attempt to succeed.

The Cancel parameter determines whether the class will stop firing this event to request a certificate.

Note: The document may be encrypted with more than one certificate (or have "more than one recipient"), in which case each certificate will cause its own invocation of this event.

SignatureInfo Event (PDFVerify Class)

Fired when the class finds a signature in the document.

Syntax

public class DefaultPDFVerifyEventListener implements PDFVerifyEventListener {
  ...
  public void signatureInfo(PDFVerifySignatureInfoEvent e) {}
  ...
}

public class PDFVerifySignatureInfoEvent {
  public int signatureIndex;
  public boolean validateSignature; //read-write
  public boolean validateChain; //read-write
}

Remarks

This event is fired once for each signature found in the document to report that the signature specified by SignatureIndex is about to be validated.

The SignatureIndex parameter is the index of the signature in the Signatures collection.

Signature validation consists of two independent stages: cryptographic signature validation and chain validation. The ValidateSignature and ValidateChain parameters determine whether each stage should be included in the validation. They can be overridden to modify the validation policy on a per-signature basis, allowing signatures to be verified individually instead of all at once (via Verify). To skip validation entirely, set both parameters to false.

Use the following properties to adjust chain validation parameters:

• BlockedCerts
• KnownCerts
• OfflineMode
• RevocationCheck
• TrustedCerts
• TrustedLists
• TrustSources
• ValidationFlags
• ValidationPolicy
• ValidationTime

SignatureProcessed Event (PDFVerify Class)

Fired after a signature has been processed.

Syntax

public class DefaultPDFVerifyEventListener implements PDFVerifyEventListener {
  ...
  public void signatureProcessed(PDFVerifySignatureProcessedEvent e) {}
  ...
}

public class PDFVerifySignatureProcessedEvent {
  public int signatureIndex;
  public int signatureValidationResult;
  public int chainValidationResult;
  public int chainValidationDetails;
}

Remarks

This event is fired once for each signature found in the document to report that the signature specified by SignatureIndex has completed validation. It is fired after SignatureInfo if that event's ValidateSignature parameter is set to true.

The SignatureIndex parameter is the index of the signature in the Signatures collection.

Signature validation consists of two independent stages: cryptographic signature validation and chain validation. Separate validation results are reported for each in the SignatureValidationResult and ChainValidationResult parameters.

The former reports the validity of the signature and can be one of the following values:

The latter reports the validity of the chain and can be one of the following values:

In the case of a failure, the ChainValidationDetails parameter provides more details on its reasons. Its value is a bitmask of the following flags:

Note: SignatureValidationResult, ChainValidationResult, and ChainValidationDetails are also available as fields in the PDFSignature type.

SSLServerAuthentication Event (PDFVerify Class)

Fired after the server presents its certificate to the client.

Syntax

public class DefaultPDFVerifyEventListener implements PDFVerifyEventListener {
  ...
  public void SSLServerAuthentication(PDFVerifySSLServerAuthenticationEvent e) {}
  ...
}

public class PDFVerifySSLServerAuthenticationEvent {
  public byte[] certEncoded;
  public String certSubject;
  public String certIssuer;
  public String status;
  public boolean accept; //read-write
}

Remarks

This event is fired during timestamping or chain validation after the server presents its SSL/TLS certificate to the class. It only applies if the TSA, CRL, OCSP, or Trusted List endpoint operates over HTTPS.

During this event, the client can decide whether or not to continue with the connection process. The Accept parameter is a recommendation on whether to continue or close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When the Accept parameter is false, the Status parameter shows why the verification failed (otherwise, Status contains the string OK). If it is decided to continue, you can override and accept the certificate by setting the Accept parameter to true.

SSLStatus Event (PDFVerify Class)

Fired when secure connection progress messages are available.

Syntax

public class DefaultPDFVerifyEventListener implements PDFVerifyEventListener {
  ...
  public void SSLStatus(PDFVerifySSLStatusEvent e) {}
  ...
}

public class PDFVerifySSLStatusEvent {
  public String message;
}

Remarks

This event is fired during timestamping or chain validation for informational and logging purposes only. This event tracks the progress of the SSL/TLS connection. It only applies if the TSA, CRL, OCSP, or Trusted List endpoint operates over HTTPS.

Certificate Type

This is the digital certificate being used.

Remarks

This type describes the current digital certificate. The certificate may be a public or private key. The fields are used to identify or select certificates.

Fields

Constructors

public Certificate();

public Certificate( certificateFile);

public Certificate( encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

Firewall Type

The firewall the class will connect through.

Remarks

When connecting through a firewall, this type is used to specify different properties of the firewall, such as the firewall Host and the FirewallType.

Fields

Constructors

public Firewall();

PDFAttachment Type

This describes the file being attached to the PDF document.

Remarks

This type contains information about the file that is being attached to the document.

Fields

Constructors

public PDFAttachment();

public PDFAttachment( fileName);

public PDFAttachment( fileName,  description);

public PDFAttachment( data,  name,  description);

public PDFAttachment( inputStream,  name,  description);

PDFSignature Type

A container for PDF signature details.

Remarks

This type contains details about the signature. Use it to read information about the signature when processing it.

Fields

Constructors

public PDFSignature();

Proxy Type

The proxy the class will connect to.

Remarks

When connecting through a proxy, this type is used to specify different properties of the proxy, such as the Server and the AuthScheme.

Fields

Constructors

public Proxy();

public Proxy( server,  port);

public Proxy( server,  port,  user,  password);

Config Settings (PDFVerify Class)

The class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

PDFVerify Config Settings

Base Config Settings

Trappable Errors (PDFVerify Class)

PDFVerify Errors

PDF Errors

Parsing Errors

HTTP Errors

TCPClient Errors

SSL Errors

TCP/IP Errors