Cert Lua Reference Documentation

chilkat.Cert

Current Version: 11.7.0

Markdown version of this page for AI tools (v 11.7.0) · all AI docs

Chilkat.Cert

Load, inspect, validate, and use X.509 certificates throughout Chilkat.

Chilkat.Cert is the central certificate object used throughout Chilkat for TLS, S/MIME, PKCS7/CMS, PDF signing, XML signing, code signing, decryption, certificate stores, smart cards, HSMs, PKCS#11, and cloud-based signing. It provides a broad set of features for loading certificates, inspecting certificate fields, checking validity, accessing private keys, building chains, checking revocation status, exporting certificate data, and diagnosing certificate-related problems.

Load certificates

Load public certificates from PEM, DER, Base64, files, strings, binary data, certificate stores, PFX/P12 files, smart cards, and other sources.

Inspect certificate details

Read subject and issuer fields, serial numbers, fingerprints, validity dates, key usage, extensions, SAN values, and other X.509 information.

Private key access

Work with certificates backed by private keys from PFX/P12 files, OS certificate stores, smart cards, HSMs, PKCS#11 modules, or cloud signing providers.

Trust and validation

Build and inspect certificate chains, verify signatures, check expiration, examine trust-related information, and work with revocation data.

Use across Chilkat

Pass Cert objects to other Chilkat classes for TLS client authentication, S/MIME, signing, encryption, decryption, and verification.

Export and diagnostics

Export certificate data in common formats and use detailed diagnostic output to troubleshoot loading, validation, private-key, chain, or store problems.

Common pattern: Use certificate-only formats such as PEM or DER when only the public certificate is needed. Use PFX/P12, an OS certificate store, smart-card loading, PKCS#11 linking, HSM integration, or cloud-signing configuration when a private key operation is required.

Object Creation

local chilkat = require("chilkat")

local cert = chilkat.Cert.new()
local cert = chilkat.Cert.new()

Creates the object (chilkat.Cert() does the same). Lua's garbage collector frees it when it is no longer referenced; cert:dispose() frees it at once, and in Lua 5.4 and later local cert <close> = chilkat.Cert.new() frees it when the block ends. Calling a method of a disposed object raises an error.

Errors

A method that fails returns nil followed by the error text, as io.open does: local body, err = cert:method(...), where err is the object's last_error_text. Wrap the call in assert() to raise an error with that text instead. Methods that answer a question return true or false, numbers are returned as they are (check last_method_success where the description says a value means failure), and property reads and writes never fail for Chilkat reasons.

Misuse raises a Lua error: a wrong argument type or a missing argument (bad argument #1 to ...), an unknown property name, a write to a read-only property, an out-of-range integer, or an object of the wrong class.

Names are Chilkat's in snake_case: QuickGetStr is quick_get_str, LastErrorText is last_error_text. Properties are fields (cert.verbose_logging = true) and methods use the colon (cert:method(...)). Strings are UTF-8; binary data is a Lua string of bytes. Indexes are 0-based, as in every Chilkat API. Unlocking: call chilkat.unlock_bundle("...") once at startup.

Properties

AuthorityKeyId
-- strVal is a string (read-only)
local strVal = cert.authority_key_id
Introduced in version 9.5.0.40

The authority key identifier of the certificate in base64 string format. This is only present if the certificate contains the extension OID 2.5.29.35.

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AvoidWindowsPkAccess
-- boolVal is a boolean
local boolVal = cert.avoid_windows_pk_access
cert.avoid_windows_pk_access = boolVal

Applies only when running on a Microsoft Windows operating system. If true, then any method that returns a certificate will not try to also access the associated private key, assuming one exists. This is useful if the certificate was installed with high-security such that a private key access would trigger the Windows OS to display a security warning dialog. The default value of this property is false.

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CertVersion
-- intVal is an integer (read-only)
local intVal = cert.cert_version

The version of the certificate (1, 2, or 3). A value of 0 indicates an error -- the most likely cause being that the certificate object is empty (i.e. was never loaded with a certificate). Note: This is not the version of the software, it is the version of the X.509 certificate object. The version of the Chilkat certificate software is indicated by the Version property.

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DebugLogFilePath
-- strVal is a string
local strVal = cert.debug_log_file_path
cert.debug_log_file_path = strVal

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

  • A timeout property set to 0, indicating an infinite timeout.
  • A hang occurring within an event callback in the application code.
  • An internal bug in the Chilkat code causing the hang.

More Information and Examples
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Expired
-- boolVal is a boolean (read-only)
local boolVal = cert.expired

Has a value of true if the certificate or any certificate in the chain of authority has expired. (This information is not available when running on Windows 95/98 computers.)

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ExtendedKeyUsage
-- strVal is a string (read-only)
local strVal = cert.extended_key_usage
Introduced in version 9.5.0.85

Returns a string containing a comma separated list of keywords with the extended key usages of the certificate. The list of possible extended key usages are:

  • serverAuth - TLS WWW server authentication
  • clientAuth - TLS WWW client authentication
  • codeSigning - Signing of downloadable executable code
  • emailProtection - Email protection
  • timeStamping - Binding the hash of an object to a time
  • OCSPSigning - Signing OCSP responses

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ForClientAuthentication
-- boolVal is a boolean (read-only)
local boolVal = cert.for_client_authentication

true if this certificate can be used for client authentication, otherwise false.

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ForCodeSigning
-- boolVal is a boolean (read-only)
local boolVal = cert.for_code_signing

true if this certificate can be used for code signing, otherwise false.

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ForSecureEmail
-- boolVal is a boolean (read-only)
local boolVal = cert.for_secure_email

true if this certificate can be used for sending secure email, otherwise false.

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ForServerAuthentication
-- boolVal is a boolean (read-only)
local boolVal = cert.for_server_authentication

true if this certificate can be used for server authentication, otherwise false.

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ForTimeStamping
-- boolVal is a boolean (read-only)
local boolVal = cert.for_time_stamping

true if this certificate can be used for time stamping, otherwise false.

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IntendedKeyUsage
-- intVal is an integer (read-only)
local intVal = cert.intended_key_usage

Bitflags indicating the intended usages of the certificate. The flags are:
Digital Signature: 0x80
Non-Repudiation: 0x40
Key Encipherment: 0x20
Data Encipherment: 0x10
Key Agreement: 0x08
Certificate Signing: 0x04
CRL Signing: 0x02
Encipher-Only: 0x01

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IsRoot
-- boolVal is a boolean (read-only)
local boolVal = cert.is_root

true if this is the root certificate, otherwise false.

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IssuerC
-- strVal is a string (read-only)
local strVal = cert.issuer_c

The certificate issuer's country.

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IssuerCN
-- strVal is a string (read-only)
local strVal = cert.issuer_cn

The certificate issuer's common name.

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IssuerDN
-- strVal is a string (read-only)
local strVal = cert.issuer_dn

The issuer's full distinguished name.

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IssuerE
-- strVal is a string (read-only)
local strVal = cert.issuer_e

The certificate issuer's email address.

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IssuerL
-- strVal is a string (read-only)
local strVal = cert.issuer_l

The certificate issuer's locality, which could be a city, count, township, or other geographic region.

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IssuerO
-- strVal is a string (read-only)
local strVal = cert.issuer_o

The certificate issuer's organization, which is typically the company name.

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IssuerOU
-- strVal is a string (read-only)
local strVal = cert.issuer_ou

The certificate issuer's organizational unit, which is the unit within the organization.

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IssuerS
-- strVal is a string (read-only)
local strVal = cert.issuer_s

The certificate issuer's state or province.

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LastErrorHtml
-- strVal is a string (read-only)
local strVal = cert.last_error_html

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorText
-- strVal is a string (read-only)
local strVal = cert.last_error_text

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorXml
-- strVal is a string (read-only)
local strVal = cert.last_error_xml

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastMethodSuccess
-- boolVal is a boolean
local boolVal = cert.last_method_success
cert.last_method_success = boolVal

Indicates the success or failure of the most recent method call: true means success, false means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.

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OcspUrl
-- strVal is a string (read-only)
local strVal = cert.ocsp_url

If present in the certificate's extensions, returns the OCSP URL of the certificate. (The Online Certificate Status Protocol (OCSP) is an Internet protocol used for obtaining the revocation status of an X.509 digital certificate.)

More Information and Examples
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PrivateKeyExportable
-- boolVal is a boolean (read-only)
local boolVal = cert.private_key_exportable

(Relevant only when running on a Microsoft Windows operating system.) Indicates whether the private key was installed with security settings that allow it to be re-exported.

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Revoked
-- boolVal is a boolean (read-only)
local boolVal = cert.revoked

Deprecated: This property does not check the revocation status of the certificate, and always returns false. Do not use it to decide whether a certificate is revoked.

To check whether a certificate has been revoked, call CheckRevoked (Windows only), which returns 1 (revoked), 0 (not revoked), or -1 (unable to check). Applications on any operating system can also send an OCSP request to the certificate's OcspUrl, if the certificate has one.

(A property cannot do this work because checking revocation can require contacting a CRL distribution point or an OCSP responder over the network, which can take a long time. In some programming languages, properties are evaluated at design time in the IDE.)

Note: Chilkat does not check certificate revocation status during the TLS handshake. Settings such as RequireSslCertVerify verify signatures, expiration, and the chain to a trusted root, but not revocation. To reject a revoked server certificate, the application must check it after connecting.

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Rfc822Name
-- strVal is a string (read-only)
local strVal = cert.rfc822_name

The RFC822 name of the certificate. (The RFC822 name is one part of the Subject Alternative Name extension of a certificate, if it exists. It is often the only part of the SAN.)

If the certificate contains a list of RFC822 names then this property will return the comma separated list of names.

Starting in Chilkat v9.5.0.85, to get the complete Subject Alternative Name extension as XML, use the SubjectAlternativeName property.

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SelfSigned
-- boolVal is a boolean (read-only)
local boolVal = cert.self_signed

true if this is a self-signed certificate, otherwise false.

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SerialDecimal
-- strVal is a string (read-only)
local strVal = cert.serial_decimal
Introduced in version 9.5.0.75

The certificate's serial number as a decimal string.

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SerialNumber
-- strVal is a string (read-only)
local strVal = cert.serial_number

The certificate's serial number as a hexidecimal string.

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Sha1Thumbprint
-- strVal is a string (read-only)
local strVal = cert.sha1_thumbprint

Hexidecimal string of the SHA-1 thumbprint for the certificate. (This is the SHA1 hash of the binary DER representation of the entire X.509 certificate.)

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SignatureVerified
-- boolVal is a boolean (read-only)
local boolVal = cert.signature_verified

Returns true if the certificate and all certificates in the chain of authority have valid signatures, otherwise returns false.

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SmartCardFailReason
-- intVal is an integer (read-only)
local intVal = cert.smart_card_fail_reason
Introduced in version 10.1.0

Set after calling LoadFromSmartcard. Possible values are:

  • 0 - No failure. The call to LoadFromSmartcard was successful.
  • 1 - No smartcard or USB token was detected.
  • 2 - The SmartCardPin was provided and the PIN login failed. (Note: Chilkat only PIN authenticates if PKCS11 was the chosen means for communicating with the smartcard.)
  • 3 - The certificate matching the specified criteria was not found.
  • 99 - Some other undefined failure. Consult the LastErrorText for more information.

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SmartCardNoDialog
-- boolVal is a boolean
local boolVal = cert.smart_card_no_dialog
cert.smart_card_no_dialog = boolVal
Introduced in version 9.5.0.77

If set to true, then no dialog will automatically popup if the SmartCardPin is incorrect. Instead, the method requiring the private key on the smart card will fail. The default value of this property is false, which means that if the SmartCardPin property is incorrect, a dialog with prompt will be displayed.

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SmartCardPin
-- strVal is a string
local strVal = cert.smart_card_pin
cert.smart_card_pin = strVal
Introduced in version 9.5.0.75

Can be set to the PIN value for a certificate / private key stored on a smart card.

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SubjectAlternativeName
-- strVal is a string (read-only)
local strVal = cert.subject_alternative_name
Introduced in version 9.5.0.85

The subject alternative name (SAN) name of the certificate returned as XML. See the examples linked below.

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SubjectC
-- strVal is a string (read-only)
local strVal = cert.subject_c

The certificate subject's country.

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SubjectCN
-- strVal is a string (read-only)
local strVal = cert.subject_cn

The certificate subject's common name.

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SubjectDN
-- strVal is a string (read-only)
local strVal = cert.subject_dn

The certificate subject's full distinguished name.

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SubjectE
-- strVal is a string (read-only)
local strVal = cert.subject_e

The certificate subject's email address.

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SubjectKeyId
-- strVal is a string (read-only)
local strVal = cert.subject_key_id
Introduced in version 9.5.0.40

The subject key identifier of the certificate in base64 string format. This is only present if the certificate contains the extension OID 2.5.29.14.

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SubjectL
-- strVal is a string (read-only)
local strVal = cert.subject_l

The certificate subject's locality, which could be a city, count, township, or other geographic region.

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SubjectO
-- strVal is a string (read-only)
local strVal = cert.subject_o

The certificate subject's organization, which is typically the company name.

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SubjectOU
-- strVal is a string (read-only)
local strVal = cert.subject_ou

The certificate subject's organizational unit, which is the unit within the organization.

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SubjectS
-- strVal is a string (read-only)
local strVal = cert.subject_s

The certificate subject's state or province.

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TrustedRoot
-- boolVal is a boolean (read-only)
local boolVal = cert.trusted_root

Returns true if the certificate has a trusted root authority, otherwise returns false.

Note: As of version 9.5.0.41, the notion of what your application deems as trusted becomes more specific. The TrustedRoots class/object was added in v9.5.0.0. Prior to this, a certificate was considered to be anchored by a trusted root if the certificate chain could be established to a root (self-signed) certificate, AND if the root certificate was located somewhere in the Windows registry-based certificate stores. There are two problems with this: (1) it's a Windows-only solution. This property would always return false on non-Windows systems, and (2) it might be considered not a strong enough set of conditions for trusting a root certificate.

As of version 9.5.0.41, this property pays attention to the new TrustedRoots class/object, which allows for an application to specificallly indicate which root certificates are to be trusted. Certificates may be added to the TrustedRoots object via the LoadCaCertsPem or AddCert methods, and then activated by calling the TrustedRoots.Activate method. The activated trusted roots are deemed to be trusted in any Chilkat API method/property that needs to make this determination. In addition, the TrustedRoots object has a property named TrustSystemCaRoots, which defaults to true, which allows for backward compatibility. It will trust CA certificates stored in the Windows registry-based certificate stores, or if on Linux, will trust certificates found in /etc/ssl/certs/ca-certificates.crt.

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UncommonOptions
-- strVal is a string
local strVal = cert.uncommon_options
cert.uncommon_options = strVal
Introduced in version 9.5.0.87

This is a catch-all property to be used for uncommon needs. This property defaults to the empty string, and should typically remain empty. Possible comma separated keywords can include:

  • CheckRevokedCacheOnly: Added in v11.2.0. In the CheckRevoked method, prevents network access and only checks the cached revocation information on the local computer.

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ValidFromStr
-- strVal is a string (read-only)
local strVal = cert.valid_from_str

The date (in RFC822 string format) that this certificate becomes (or became) valid. It is a GMT/UTC date that is returned.

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ValidToStr
-- strVal is a string (read-only)
local strVal = cert.valid_to_str

The date (in RFC822 string format) that this certificate expires. It is a GMT/UTC date that is returned.

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VerboseLogging
-- boolVal is a boolean
local boolVal = cert.verbose_logging
cert.verbose_logging = boolVal

If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
-- strVal is a string (read-only)
local strVal = cert.version

Version of the component/library, such as "10.1.0"

More Information and Examples
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Methods

BuildCertChain
-- cert_chain is a chilkat.CertChain
-- ok is true, or nil and err on failure
local ok, err = cert:build_cert_chain(cert_chain)
Introduced in version 11.0.0

Builds the certificate chain in cert_chain containing all the certificates (including this one), in the chain of authentication to the trusted root (if possible). If this certificate object was loaded from a PFX, then the certiicates contained in the PFX are automatically available for building the certificate chain. The UseCertVault method can be called to provide additional certificates that might be required to build the cert chain. Finally, the TrustedRoots object can be used to provide a way of making trusted root certificates available.

Note: Returns true even if certificate chain is not completed to the root. The certificate chain's ReachesRoot property can be examined to see if the chain was completed to the root.

On Windows systems, the registry-based certificate stores are automatically consulted if needed to locate intermediate or root certificates in the chain. Chilkat searches certificate stores in the following order. See System Store Locations for more information.

  1. Current-User CA Certificate Store
  2. Local-Machine CA Certificate Store
  3. Current-User Root Certificate Store
  4. Local-Machine Root Certificate Store
  5. Current-User MY Certificate Store
  6. Local-Machine MY Certificate Store
  7. Current-User ADDRESSBOOK Certificate Store (if it exists)
  8. Local-Machine ADDRESSBOOK Certificate Store (if it exists)

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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CheckRevoked
-- n is an integer
local n = cert:check_revoked()

Returns 1 if the certificate has been revoked, 0 if not revoked, and -1 if unable to check the revocation status.

Note: This method is only implemented on Windows systems. It uses the underlying Microsoft CertVerifyRevocation Platform SDK function to check the revocation status of a certificate. (Search CertVerifyRevocation to get information about it.) Starting in v11.2.0, the keyword "CheckRevokedCacheOnly" can be included in the UncommonOptions to prevent the Microsoft revocation handler from accessing any network based resources for revocation checking. In other words, just check the cached revocation information on the local computer.

CertVerifyRevocation can use the certificate's CRL distribution points as well as OCSP. If it returns -1, see the LastErrorText. One cause is that the issuing intermediate CA certificate is not present in the Windows certificate store.

Non-Windows (and Windows) applications can send an OCSP request as shown in the example below. Note that some CAs publish revocation status only through CRLs, not OCSP. For example, Let's Encrypt removed the OCSP URL from its certificates in May 2025 and shut down its OCSP responders in August 2025, so an OCSP request is not possible for current Let's Encrypt certificates.

More Information and Examples
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CheckSmartCardPin
-- n is an integer
local n = cert:check_smart_card_pin()
Introduced in version 9.5.0.77

Verifies that the SmartCardPin property setting is correct. Returns 1 if correct, 0 if incorrect, and -1 if unable to check because the underlying CSP does not support the functionality.

More Information and Examples
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ExportCertDerBd
-- cer_data is a chilkat.BinData
-- ok is true, or nil and err on failure
local ok, err = cert:export_cert_der_bd(cer_data)
Introduced in version 9.5.0.70

Exports the digital certificate in ASN.1 DER format to a BinData object.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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ExportCertDerFile
-- path is a string
-- ok is true, or nil and err on failure
local ok, err = cert:export_cert_der_file(path)

Exports the digital certificate to ASN.1 DER format binary file.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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ExportCertPem
-- str is a string, or nil and err on failure
local str, err = cert:export_cert_pem()

Exports the digital certificate to an unencrypted PEM formatted string.

Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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ExportCertPemFile
-- path is a string
-- ok is true, or nil and err on failure
local ok, err = cert:export_cert_pem_file(path)

Exports the digital certificate to an unencrypted PEM formatted file.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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ExportCertXml
-- str is a string, or nil and err on failure
local str, err = cert:export_cert_xml()

Exports a certificate to an XML format where the XML tags are the names of the ASN.1 objects that compose the X.509 certificate. Binary data is either hex or base64 encoded. (The binary data for a bits ASN.1 tag is hex encoded, whereas for all other ASN.1 tags, such as octets, it is base64.)

Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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ExportToPfxBd
-- password is a string
-- include_cert_chain is a boolean
-- pfx_data is a chilkat.BinData
-- ok is true, or nil and err on failure
local ok, err = cert:export_to_pfx_bd(password, include_cert_chain, pfx_data)
Introduced in version 9.5.0.70

Exports the certificate and private key (if available) to pfx_data. The password is what will be required to access the PFX contents at a later time. If include_cert_chain is true, then the certificates in the chain of authority are also included in the PFX.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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ExportToPfxFile
-- pfx_filename is a string
-- pfx_password is a string
-- b_include_cert_chain is a boolean
-- ok is true, or nil and err on failure
local ok, err = cert:export_to_pfx_file(pfx_filename, pfx_password, b_include_cert_chain)

Exports the certificate and private key (if available) to a PFX (.pfx or .p12) file. The output PFX is secured using the pfx_password. If b_include_cert_chain is true, then the certificates in the chain of authority are also included in the PFX output file.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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FindIssuer
-- cert2 is a chilkat.Cert, or nil and err on failure
local cert2, err = cert:find_issuer()

Finds and returns the issuer certificate. If the certificate is a root or self-issued, then the certificate returned is a copy of the caller certificate. (The IsRoot property can be check to see if the certificate is a root (or self-issued) certificate.)

Returns a new object, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead. The returned object is independent of this one.

More Information and Examples
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GetEncoded
-- str is a string, or nil and err on failure
local str, err = cert:get_encoded()

Returns a base64 encoded string representation of the certificate's binary DER format, which can be passed to SetFromEncoded to recreate the certificate object.

Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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GetExtensionAsText
-- oid is a string
-- str is a string, or nil and err on failure
local str, err = cert:get_extension_as_text(oid)
Introduced in version 9.5.0.89

Returns the certificate extension data as a string. This method should only be called for those extensions with text values NOT stored as binary ASN.1. In most cases, applications should call GetExtensionAsXml because most extensions contain ASN.1 values that need to be decoded..

Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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GetExtensionAsXml
-- oid is a string
-- str is a string, or nil and err on failure
local str, err = cert:get_extension_as_xml(oid)
Introduced in version 9.5.0.49

Returns the certificate extension data in XML format (converted from ASN.1). The oid is an OID, such as the ones listed here: http://www.alvestrand.no/objectid/2.5.29.html

Note: In many cases, the data within the XML is returned base64 encoded. An application may need to take one further step to base64 decode the information contained within the XML.

Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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GetExtensionBd
-- oid is a string
-- bd is a chilkat.BinData
-- ok is true, or nil and err on failure
local ok, err = cert:get_extension_bd(oid, bd)
Introduced in version 9.5.0.96

Returns the certificate extension data specified by oid in bd.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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GetIssuer
-- issuer is a chilkat.Cert
-- ok is true, or nil and err on failure
local ok, err = cert:get_issuer(issuer)
Introduced in version 11.0.0

Finds and returns the issuer certificate in issuer. If the certificate is a root or self-issued, then the certificate returned is a copy of the caller certificate. (The IsRoot property can be check to see if the certificate is a root (or self-issued) certificate.)

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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GetPrivateKey
-- priv_key is a chilkat.PrivateKey
-- ok is true, or nil and err on failure
local ok, err = cert:get_private_key(priv_key)
Introduced in version 11.0.0

Loads the priv_key with the certificate's private key, if it exists. Returns false if the certificate has no associated private key.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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GetPrivateKeyPem
-- str is a string, or nil and err on failure
local str, err = cert:get_private_key_pem()

Exports the certificate's private key to a PEM string (if the private key is available).

Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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GetPubKeyDer
-- prefer_pkcs1 is a boolean
-- bd is a chilkat.BinData
-- ok is true, or nil and err on failure
local ok, err = cert:get_pub_key_der(prefer_pkcs1, bd)
Introduced in version 9.5.0.92

Loads the bd with the certificate's public key in ASN.1 DER format. If the key type (such as RSA) supports both PKCS1 and PKCS8 formats, then prefer_pkcs1 selects which format to return.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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GetPublicKey
-- pub_key is a chilkat.PublicKey
-- ok is true, or nil and err on failure
local ok, err = cert:get_public_key(pub_key)
Introduced in version 11.0.0

Loads the pub_key with the certificate's public key.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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GetSignature
-- bd is a chilkat.BinData
-- ok is true, or nil and err on failure
local ok, err = cert:get_signature(bd)
Introduced in version 9.5.0.92

Loads the bd with the certificate's signature.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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GetSpkiFingerprint
-- hash_alg is a string
-- encoding is a string
-- str is a string, or nil and err on failure
local str, err = cert:get_spki_fingerprint(hash_alg, encoding)
Introduced in version 9.5.0.55

Returns the SPKI Fingerprint suitable for use in pinning. (See RFC 7469.) An SPKI Fingerprint is defined as the output of a known cryptographic hash algorithm whose input is the DER-encoded ASN.1 representation of the Subject Public Key Info (SPKI) of an X.509 certificate. The hash_alg specifies the hash algorithm and may be sha256, sha384, sha512, sha1, md2, md5, haval, ripemd128, ripemd160,ripemd256, or ripemd320. The encoding specifies the encoding, and may be base64, hex, or any of the encoding modes specified in the article at the link below.

Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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GetSubjectPart
-- part_name_or_oid is a string
-- str is a string, or nil and err on failure
local str, err = cert:get_subject_part(part_name_or_oid)
Introduced in version 9.5.0.85

Returns a part of the certificate's subject by name or OID. The part_name_or_oid can be a part name, such as CN, O, OU, E, S, L, C, or SERIALNUMBER, or it can be an OID such as 2.5.4.3.

Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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HashOf
-- part is a string
-- hash_alg is a string
-- encoding is a string
-- str is a string, or nil and err on failure
local str, err = cert:hash_of(part, hash_alg, encoding)
Introduced in version 9.5.0.75

Returns an encoded hash of a particular part of the certificate. The part may be one of the following:

  • IssuerDN
  • IssuerPublicKey
  • SubjectDN
  • SubjectPublicKey

The hash_alg is the name of the hash algorithm, such as sha1, sha256, sha384, sha512, md5, etc. The encoding is the format to return, such as hex, base64, etc.

Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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HasPrivateKey
-- flag is true or false
local flag = cert:has_private_key()

Returns true if a private key associated with the certificate is available.

Returns true or false: an answer, not a success flag.

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IsEcdsa
-- flag is true or false
local flag = cert:is_ecdsa()
Introduced in version 10.1.0

Returns true if certificate is ECDSA-based (i.e. has an ECDSA key).

Returns true or false: an answer, not a success flag.

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IsRsa
-- flag is true or false
local flag = cert:is_rsa()
Introduced in version 10.1.0

Returns true if certificate is RSA-based (i.e. has an RSA key).

Returns true or false: an answer, not a success flag.

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LinkPkcs11
-- session is a chilkat.Pkcs11
-- ok is true, or nil and err on failure
local ok, err = cert:link_pkcs11(session)
Introduced in version 9.5.0.96

Links to the certificate's private key located on an HSM (smart card, token, or cloud HSM). Once linked, the certificate can be used for signing where the signing occurs on the HSM. See the example below for more detailed information.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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LoadByCommonName
-- cn is a string
-- ok is true, or nil and err on failure
local ok, err = cert:load_by_common_name(cn)

This method searches for a certificate with the specified common name (CN) on different operating systems. - On Windows, it searches the Local Machine and Current User certificate stores. - On macOS and iOS, it searches the Default and System Keychains. If the certificate is found, it is loaded and ready for use.

Note: Chilkat v10.0.0 or later is needed for Apple Keychain.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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LoadByEmailAddress
-- email_address is a string
-- ok is true, or nil and err on failure
local ok, err = cert:load_by_email_address(email_address)

This method searches for a certificate with the specified email address on different operating systems. - On Windows, it searches the Local Machine and Current User certificate stores. - On macOS and iOS, it searches the Default and System Keychains. If the certificate is found, it is loaded and ready for use.

Note: Chilkat v10.0.0 or later is needed for Apple Keychain.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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LoadByIssuerAndSerialNumber
-- issuer_cn is a string
-- serial_number is a string
-- ok is true, or nil and err on failure
local ok, err = cert:load_by_issuer_and_serial_number(issuer_cn, serial_number)

This method searches for a certificate with the specified issuer common name (issuer_cn) and serial number (serial_number) on different operating systems. - On Windows, it searches the Local Machine and Current User certificate stores. - On macOS and iOS, it searches the Default and System Keychains. If the certificate is found, it is loaded and ready for use.

Note: Chilkat v10.0.0 or later is needed for Apple Keychain.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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LoadBySubjectOid
-- oid is a string
-- value is a string
-- ok is true, or nil and err on failure
local ok, err = cert:load_by_subject_oid(oid, value)
Introduced in version 9.5.0.85

This method searches for a certificate containing a subject part matching the oid and value. On Windows, it searches the Local Machine and Current User certificate stores. - On macOS and iOS, it searches the Default and System Keychains. If the certificate is found, it is loaded and ready for use.

Note: Chilkat v10.0.0 or later is needed for Apple Keychain.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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LoadByThumbprint
-- thumbprint is a string
-- encoding is a string
-- ok is true, or nil and err on failure
local ok, err = cert:load_by_thumbprint(thumbprint, encoding)
Introduced in version 9.5.0.83

This method searches for a certificate with the specified thumbprint. The thumbprint is passed as a string using the encoding specified by encoding (such as base64, hex, etc.).

On Windows, it searches the Local Machine and Current User certificate stores. - On macOS and iOS, it searches the Default and System Keychains. If the certificate is found, it is loaded and ready for use.

Note: Chilkat v10.0.0 or later is needed for Apple Keychain.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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LoadFromBase64
-- encoded_cert is a string
-- ok is true, or nil and err on failure
local ok, err = cert:load_from_base64(encoded_cert)

Loads an ASN.1 or DER encoded certificate represented in a Base64 string.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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LoadFromBd
-- cert_bytes is a chilkat.BinData
-- ok is true, or nil and err on failure
local ok, err = cert:load_from_bd(cert_bytes)
Introduced in version 9.5.0.70

Loads an X.509 certificate from data contained in cert_bytes.

Note: The cert_bytes may contain the certificate in any format. It can be binary DER (ASN.1), PEM, Base64, etc. Chilkat will automatically detect the format.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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LoadFromFile
-- path is a string
-- ok is true, or nil and err on failure
local ok, err = cert:load_from_file(path)

Loads a certificate from a .cer, .crt, .p7b, or .pem file. This method accepts certificates from files in any of the following formats:
1. DER encoded binary X.509 (.CER)
2. Base-64 encoded X.509 (.CER)
3. Cryptographic Message Syntax Standard - PKCS #7 Certificates (.P7B)
4. PEM format
This method decodes the certificate based on the contents if finds within the file, and not based on the file extension. If your certificate is in a file having a different extension, try loading it using this method before assuming it won't work. This method does not load .p12 or .pfx (PKCS #12) files.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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LoadFromSmartcard
-- cert_spec is a string
-- ok is true, or nil and err on failure
local ok, err = cert:load_from_smartcard(cert_spec)
Introduced in version 9.5.0.77

Important: It's important to set the SmartCardPin property before calling this method.

Loads a certificate and its associated private key (if available) from a connected USB token or smart card. This function works on Windows, Linux, MacOS, iOS, and Alpine Linux. If multiple USB tokens and/or smartcards are connected to the system, then each will be searched and the first matching certificate will be loaded.

The cert_spec can have the following formats and values:

  • Empty String: Passing the empty string is the most common way to call this function. Pass the empty string when only one HSM (USB token or smart card) is connected to the system, and it contains only one certificate with a private key. The HSM can contain other certificates, but Chilkat will automatically choose and load the certificate that has the associated private key also located on the HSM.
  • cn=<cert subject common name>: Finds and loads the certificate having the specified subject common name (CN).
  • subjectdn_withtags=<distinguished name with tags>: Finds and loads the certificate having the specified DN with tags. For example, subjectdn_withtags=C=US, O=Example Corporation, OU=IT Department, CN=www.example.com
  • subjectdn=<distinguished name without tags>: Finds and loads the certificate having the specified DN without tags. For example, subjectdn=US, California, San Francisco, Example Corp, Engineering, www.example.com, support@example.com
  • issuercn=<subject hex serial:issuer common name>: Finds and loads the certificate having the specified hex serial number and an issuer with the specified common name. For example, 01020304: Let's Encrypt Authority X1
  • serial=<hex serial number>: Finds and loads the certificate having the specified hexidecimal serial number.
  • thumbprint=<hex SHA1 thumbprint>: Finds and loads the certificate having the specified hexidecimal SHA1 thumbprint.
  • policyoid=<certificate policy OID>: Finds and loads the certificate having a policy OID equal to the specified value, such as 2.16.840.1.101.2.1.11.39.
  • o=<subject organization>: Finds and loads the certificate having the O subject part equal to the specified value.
  • c=<subject country>: Finds and loads the certificate having the C subject part equal to the specified value.
  • l=<subject locality>: Finds and loads the certificate having the L subject part equal to the specified value.
  • ou=<subject organizational unit>: Finds and loads the certificate having the OU subject part equal to the specified value.
  • st=<subject state>: Finds and loads the certificate having the ST subject part equal to the specified value.
  • e=<subject email>: Finds and loads the certificate having the E subject part equal to the specified value.

On Windows systems, cert_spec can specify a CSP (Cryptographic Service Provider) name, such as YubiHSM Key Storage Provider. This option is retained for legacy support, as Chilkat initially handled USB tokens and smartcards only on Windows via CSPs. Chilkat now supports HSMs across multiple platforms (Windows, Linux, macOS, iOS, Alpine Linux) and uses various methods to communicate with HSMs, including PKCS11, macOS Keychain services, Windows ScMinidriver, MsCNG, and legacy Windows CryptoAPI. Chilkat automatically detects the HSM make/model and selects the optimal communication method.

Some possible CSP values are:

  • Microsoft Smart Card Key Storage Provider
  • Microsoft Base Smart Card Crypto Provider
  • Bit4id Universal Middleware Provider
  • YubiHSM Key Storage Provider (starting in v9.5.0.83)
  • SafeSign Standard Cryptographic Service Provider
  • SafeSign Standard RSA and AES Cryptographic Service Provider
  • eToken Base Cryptographic Provider
  • cryptoCertum3 CSP
  • FTSafe ePass1000 RSA Cryptographic Service Provider
  • SecureStoreCSP
  • EnterSafe ePass2003 CSP v2.0
  • Gemalto Classic Card CSP
  • PROXKey CSP India V1.0
  • PROXKey CSP India V2.0
  • TRUST KEY CSP V1.0
  • Watchdata Brazil CSP V1.0
  • Luna Cryptographic Services for Microsoft Windows
  • Luna SChannel Cryptographic Services for Microsoft Windows
  • Safenet RSA Full Cryptographic Provider
  • nCipher Enhanced Cryptographic Provider
  • MySmartLogon NFC CSP
  • NFC Connector Enterprise
  • ActivClient Cryptographic Service Provider
  • EnterSafe ePass2003 CSP v1.0
  • Oberthur Card Systems Cryptographic Provider
  • Athena ASECard Crypto CSP
  • many others...

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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LoadPem
-- str_pem is a string
-- ok is true, or nil and err on failure
local ok, err = cert:load_pem(str_pem)
Introduced in version 9.5.0.49

Loads the certificate from a PEM string.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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LoadPfxBd
-- pfx_data is a chilkat.BinData
-- password is a string
-- ok is true, or nil and err on failure
local ok, err = cert:load_pfx_bd(pfx_data, password)
Introduced in version 9.5.0.70

Loads the certificate from the PFX contained in pfx_data. Note: If the PFX contains multiple certificates, the 1st certificate in the PFX is loaded.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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LoadPfxFile
-- pfx_path is a string
-- password is a string
-- ok is true, or nil and err on failure
local ok, err = cert:load_pfx_file(pfx_path, password)

Loads a PFX file. Note: If the PFX contains multiple certificates, the 1st certificate in the PFX is loaded.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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PemFileToDerFile
-- from_path is a string
-- to_path is a string
-- ok is true, or nil and err on failure
local ok, err = cert:pem_file_to_der_file(from_path, to_path)

Converts a PEM file to a DER file.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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SaveToFile
-- path is a string
-- ok is true, or nil and err on failure
local ok, err = cert:save_to_file(path)

Saves a certificate object to a .cer file.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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SetCloudSigner
-- json is a chilkat.JsonObject
-- ok is true, or nil and err on failure
local ok, err = cert:set_cloud_signer(json)
Introduced in version 9.5.0.96

Provides information for a cloud signing service to do the signing via a remote signing server. Current supported services are AWS KMS, Azure Key Vault, and ARSS (Aruba Remote Signing Service). See the examples below.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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SetFromEncoded
-- encoded_cert is a string
-- ok is true, or nil and err on failure
local ok, err = cert:set_from_encoded(encoded_cert)

Initializes the certificate object from a base64 encoded string representation of the certificate's binary DER format.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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SetPrivateKey
-- priv_key is a chilkat.PrivateKey
-- ok is true, or nil and err on failure
local ok, err = cert:set_private_key(priv_key)

Used to associate a private key with the certificate for subsequent (PKCS7) signature creation or decryption.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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SetPrivateKeyPem
-- priv_key_pem is a string
-- ok is true, or nil and err on failure
local ok, err = cert:set_private_key_pem(priv_key_pem)

Same as SetPrivateKey, but the key is provided in unencrypted PEM format. (Note: The priv_key_pem is not a file path, it is the actual PEM text.)

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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Unload
-- ok is true, or nil and err on failure
local ok, err = cert:unload()
Introduced in version 11.0.0

Unload the certificate, which could mean closing a PKCS11 session if the certificate was loaded from a smart card.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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UploadToCloud
-- json_in is a chilkat.JsonObject
-- json_out is a chilkat.JsonObject
-- ok is true, or nil and err on failure
local ok, err = cert:upload_to_cloud(json_in, json_out)
Introduced in version 9.5.0.96

This is an open-ended method to accomodate uploading the private key to a cloud service, such as AWS KMS, or Azure Key Vault. For details, see the examples below.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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UseCertVault
-- vault is a chilkat.XmlCertVault
-- ok is true, or nil and err on failure
local ok, err = cert:use_cert_vault(vault)
Introduced in version 9.5.0.40

Adds an XML certificate vault to the object's internal list of sources to be searched for certificates for help in building certificate chains and verifying the certificate signature to the trusted root.

Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

More Information and Examples
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VerifySignature
-- flag is true or false
local flag = cert:verify_signature()
Introduced in version 9.5.0.40

Verifies the certificate signature, as well as the signatures of all certificates in the chain of authentication to the trusted root. Returns true if all signatures are verified to the trusted root. Otherwise returns false.

Returns true or false: an answer, not a success flag.

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X509PKIPathv1
-- str is a string, or nil and err on failure
local str, err = cert:x509_pki_pathv1()
Introduced in version 9.5.0.77

Returns the base64 representation of an X509PKIPathv1 containing just the calling certificate. This is typically used in an X.509 Binary Security Token. It is a PKIPath that contains an ordered list of X.509 public certificates packaged in a PKIPath. The X509PKIPathv1 token type may be used to represent a certificate path. (This is sometimes used in XAdES signatures.)

Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.

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Events

All Chilkat methods are synchronous: the call returns when the work is done. During a long-running call, chilkat.Cert reports progress to the functions given to set_event_handler, in a table keyed by event name (plain functions, not methods: closures carry whatever state they need):

cert:set_event_handler({
    percent_done  = function(pct) print(pct .. "%") end,              -- return true to abort
    progress_info = function(name, value) print(name, value) end,
})
cert:set_event_handler({ event_name = function(...) ... end, ... })

Installs the handlers, replacing any installed before; cert:set_event_handler(nil) removes them. The event names are checked when the table is installed: a misspelled one raises an error.

The abort_check handler is called periodically during long operations; percent_done is called when an operation's completion percentage is known; progress_info delivers named progress values. A true return from abort_check or percent_done aborts the running method, which then fails in the usual way (nil, err). An error raised in a handler aborts the method and is raised again from the method call; the object remains usable.

AbortCheck
-- handler: function() ... return abort end -- a true return aborts the method in progress
cert:set_event_handler({ abort_check = function() ... end })

Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.

More Information and Examples

Example

local deadline = os.time() + 30                  -- give up after 30 seconds
cert:set_event_handler({ abort_check = function() return os.time() > deadline end })
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PercentDone
-- handler: function(pct_done) ... return abort end -- a true return aborts
cert:set_event_handler({ percent_done = function(pct_done) ... end })

This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).

The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.

To abort the operation, set the abort output argument to true. This will cause the method to terminate and return a failure status or corresponding failure value.

More Information and Examples

Example

cert:set_event_handler({
    percent_done = function(pct_done)     -- 0 to 100
        print("Percent done: " .. pct_done)
        return false                       -- return true to abort the method in progress
    end,
})
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ProgressInfo
-- handler: function(name, value) ... end
cert:set_event_handler({ progress_info = function(name, value) ... end })

This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.

Note: Some Chilkat methods don't fire any ProgressInfo events.

More Information and Examples

Example

cert:set_event_handler({
    progress_info = function(name, value) print(name .. ": " .. value) end,
})
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