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Validate PDF Signatures

See more PDF Signatures Examples

This example demonstrates how to validate the signatures in a PDF and also shows how to get information from each signature.

Note: This example requires Chilkat v9.5.0.85 or greater.

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Local $bSuccess = False

; This example requires the Chilkat API to have been previously unlocked.
; See Global Unlock Sample for sample code.

$oPdf = ObjCreate("Chilkat.Pdf")

; Load a PDF that has cryptographic signatures to be validated
$bSuccess = $oPdf.LoadFile("qa_data/pdf/sign_testing_1/helloSigned2.pdf")
If ($bSuccess = False) Then
    ConsoleWrite($oPdf.LastErrorText & @CRLF)
    Exit
EndIf

; Each time we verify a signature, information about the signature is written into
; sigInfo (replacing whatever sigInfo previously contained).
$oSigInfo = ObjCreate("Chilkat.JsonObject")
$oSigInfo.EmitCompact = False

; Iterate over each signature and validate each.
Local $iNumSignatures = $oPdf.NumSignatures
Local $bValidated = False
Local $i = 0
While $i < $iNumSignatures
    $bValidated = $oPdf.VerifySignature($i,$oSigInfo)
    ConsoleWrite("Signature " & $i & " validated: " & $bValidated & @CRLF)
    ConsoleWrite($oSigInfo.Emit() & @CRLF)
    $i = $i + 1
Wend

ConsoleWrite("Finished." & @CRLF)

; When VerifySignature validates a signature, a lot of information is deposited into the JSON sigInfo object.
; The information can vary depending on what was included in the signature (for example, various authenticated attributes
; and unauthenticated attributes may or may not be included).
; Here is a sample of the information you'll see.
; 
; The following online tool can be used to generate code to parse any given JSON.
; Generate Parsing Code from JSON

; {
;   "validated": true,
;   "signatureDictionary": {         <--- This is the contents of the PDF Signature Dictionary for this signature.
;     "/ByteRange": [
;       0,
;       154682,
;       170512,
;       3233
;     ],
;     "/Contents": "<hex_data>",
;     "/Filter": "/Adobe.PPKLite",        <--- The meaning of the Signature Dictionary entries are defined in the PDF format specification document.
;     "/M": "D:20201006110216-05'00'",
;     "/Name": "yubikey rsa 1024 authentication",
;     "/Prop_Build": {
;       "/App": {
;         "/Name": "/Adobe#20Acrobat#20Pro#20DC",
;         "/OS": [
;           "/Win"
;         ],
;         "/R": 1313792,
;         "/REx": "2020.012.20048",
;         "/TrustedMode": true
;       },
;       "/Filter": {
;         "/Date": "Sep 11 2020 16:30:54",
;         "/Name": "/Adobe.PPKLite",
;         "/R": 131104,
;         "/V": 2
;       },
;       "/PubSec": {
;         "/Date": "Sep 11 2020 16:30:54",
;         "/NonEFontNoWarn": true,
;         "/R": 131105
;       }
;     },
;     "/SubFilter": "/adbe.pkcs7.detached",
;     "/Type": "/Sig"
;   },
;   "pkcs7": {          <--- This is the content of the CMS signature.
;     "verify": {
;       "certs": [      <--- Each signing certificate is listed here (by issuer common name and signing cert's serail number (in hex))
;         {
;           "issuerCN": "yubikey rsa 1024 authentication",
;           "serial": "66BE58138D761E92BC594A722932657BE26D421F"
;         }
;       ],
;       "digestAlgorithms": [
;         "sha256"
;       ],
;       "signerInfo": [     <--- contains data from each SignerInfo
;         {
;           "cert": {
;             "serialNumber": "66BE58138D761E92BC594A722932657BE26D421F",
;             "issuerCN": "yubikey rsa 1024 authentication",
;             "digestAlgOid": "2.16.840.1.101.3.4.2.1",
;             "digestAlgName": "SHA256"
;           },
;           "contentType": "1.2.840.113549.1.7.1",
;           "messageDigest": "btQOuSEvC31mdRFHtyEUPw8R9NuKfk0XPcQ6Lcmn6pk=",
;           "signingAlgOid": "1.2.840.113549.1.1.11",
;           "signingAlgName": "RSA-SHA256-PKCSV-1_5",
;           "authAttr": {     <--- CMS authenticated attributes are contained here.
;             "1.2.840.113583.1.1.8": {
;               "der": "MAA="
;             },
;             "1.2.840.113549.1.9.3": {
;               "name": "contentType",
;               "oid": "1.2.840.113549.1.7.1"
;             },
;             "1.2.840.113549.1.9.4": {
;               "name": "messageDigest",
;               "digest": "btQOuSEvC31mdRFHtyEUPw8R9NuKfk0XPcQ6Lcmn6pk="
;             }
;           },
;           "unauthAttr": {    <--- CMS unauthenticated attributes are contained here.
;             "1.2.840.113549.1.9.16.2.14": {
;               "name": "timestampToken",
;               "der": "MIIOvAYJKo ... Es/70g=",
;               "verify": {
;                 "digestAlgorithms": [
;                   "sha256"
;                 ],
;                 "signerInfo": [
;                   {
;                     "cert": {
;                       "serialNumber": "04CD3F8568AE76C61BB0FE7160CCA76D",
;                       "issuerCN": "DigiCert SHA2 Assured ID Timestamping CA",
;                       "digestAlgOid": "2.16.840.1.101.3.4.2.1",
;                       "digestAlgName": "SHA256"
;                     },
;                     "contentType": "1.2.840.113549.1.9.16.1.4",
;                     "signingTime": "201006160423Z",
;                     "messageDigest": "Atv5Rj3kidB8IR6CplYiX3o6De/k8SC6JJ6uUPAGO0g=",
;                     "signingAlgOid": "1.2.840.113549.1.1.1",
;                     "signingAlgName": "RSA-PKCSV-1_5",
;                     "authAttr": {
;                       "1.2.840.113549.1.9.3": {
;                         "name": "contentType",
;                         "oid": "1.2.840.113549.1.9.16.1.4"
;                       },
;                       "1.2.840.113549.1.9.5": {
;                         "name": "signingTime",
;                         "utctime": "201006160423Z"
;                       },
;                       "1.2.840.113549.1.9.16.2.12": {
;                         "name": "signingCertificate",
;                         "der": "MBowGDAWBBQDJb1QXtqWMC3CL0+gHkwovig0xQ=="
;                       },
;                       "1.2.840.113549.1.9.4": {
;                         "name": "messageDigest",
;                         "digest": "Atv5Rj3kidB8IR6CplYiX3o6De/k8SC6JJ6uUPAGO0g="
;                       }
;                     }
;                   }
;                 ]
;               },
;               "timestampSignatureVerified": true,
;               "tstInfo": {
;                 "tsaPolicyId": "2.16.840.1.114412.7.1",
;                 "messageImprint": {
;                   "hashAlg": "sha256",
;                   "digest": "gLJtrRWUSDfjzDkF1MfWG1wyHA6FrUJLkWMGRG+eMlA=",
;                   "digestMatches": true
;                 },
;                 "serialNumber": "00CE57E1113970607EF63B1D1160545321",
;                 "genTime": "20201006160423Z"
;               }
;             }
;           }
;         }
;       ],
;       "pkcs7": {
;         "verify": {
;           "certs": [
;             {
;               "issuerCN": "DigiCert SHA2 Assured ID Timestamping CA",
;               "serial": "04CD3F8568AE76C61BB0FE7160CCA76D"
;             },
;             {
;               "issuerCN": "DigiCert Assured ID Root CA",
;               "serial": "0AA125D6D6321B7E41E405DA3697C215"
;             }
;           ]
;         }
;       }
;     }
;   }
; }

; **** The point of this code is to show how to get at each desired piece of information contained in the signature.
; **** If your signature contains additional information not shown here, then you can use the online tool to generate the parse code.
; **** It is likely you're only interested in a few items of information, and therefore you wouldn't copy all of this code, but might
; **** choose to use bits and pieces to get the information you find important.

$oJson = ObjCreate("Chilkat.JsonObject")

; Imagine that the "json" object contains the information obtained by validating a signature...
; The code below was generated using the online tool:  Generate Parsing Code from JSON

$oUnauthAttrTimestampTokenTstInfoGenTime = ObjCreate("Chilkat.DtObj")
$oSigningTime = ObjCreate("Chilkat.DtObj")
$oAuthAttrSigningTimeUtctime = ObjCreate("Chilkat.DtObj")
Local $intVal
Local $strVal
Local $sIssuerCN
Local $serial
Local $sCertSerialNumber
Local $sCertIssuerCN
Local $sCertDigestAlgOid
Local $sCertDigestAlgName
Local $sContentType
Local $sMessageDigest
Local $signingAlgOid
Local $signingAlgName
Local $sAuthAttr1_2_840_113583_1_1_8Der
Local $sAuthAttrContentTypeName
Local $sAuthAttrContentTypeOid
Local $sAuthAttrMessageDigestName
Local $sAuthAttrMessageDigestDigest
Local $sUnauthAttrTimestampTokenName
Local $sUnauthAttrTimestampTokenDer
Local $bUnauthAttrTimestampTokenTimestampSignatureVerified
Local $sUnauthAttrTimestampTokenTstInfoTsaPolicyId
Local $sUnauthAttrTimestampTokenTstInfoMessageImprintHashAlg
Local $sUnauthAttrTimestampTokenTstInfoMessageImprintDigest
Local $bUnauthAttrTimestampTokenTstInfoMessageImprintDigestMatches
Local $sUnauthAttrTimestampTokenTstInfoSerialNumber
Local $iJ
Local $iCount_j
Local $sAuthAttrSigningTimeName
Local $sAuthAttrSigningCertificateName
Local $sAuthAttrSigningCertificateDer

$bValidated = $oJson.BoolOf("validated")
Local $signatureDictionary_Contents = $oJson.StringOf("signatureDictionary./Contents")
Local $signatureDictionary_Filter = $oJson.StringOf("signatureDictionary./Filter")
Local $signatureDictionary_M = $oJson.StringOf("signatureDictionary./M")
Local $signatureDictionary_Name = $oJson.StringOf("signatureDictionary./Name")
Local $signatureDictionary_Prop_Build_App_Name = $oJson.StringOf("signatureDictionary./Prop_Build./App./Name")
Local $iSignatureDictionary_Prop_Build_App_R = $oJson.IntOf("signatureDictionary./Prop_Build./App./R")
Local $signatureDictionary_Prop_Build_App_REx = $oJson.StringOf("signatureDictionary./Prop_Build./App./REx")
Local $bSignatureDictionary_Prop_Build_App_TrustedMode = $oJson.BoolOf("signatureDictionary./Prop_Build./App./TrustedMode")
Local $signatureDictionary_Prop_Build_Filter_Date = $oJson.StringOf("signatureDictionary./Prop_Build./Filter./Date")
Local $signatureDictionary_Prop_Build_Filter_Name = $oJson.StringOf("signatureDictionary./Prop_Build./Filter./Name")
Local $iSignatureDictionary_Prop_Build_Filter_R = $oJson.IntOf("signatureDictionary./Prop_Build./Filter./R")
Local $iSignatureDictionary_Prop_Build_Filter_V = $oJson.IntOf("signatureDictionary./Prop_Build./Filter./V")
Local $signatureDictionary_Prop_Build_PubSec_Date = $oJson.StringOf("signatureDictionary./Prop_Build./PubSec./Date")
Local $bSignatureDictionary_Prop_Build_PubSec_NonEFontNoWarn = $oJson.BoolOf("signatureDictionary./Prop_Build./PubSec./NonEFontNoWarn")
Local $iSignatureDictionary_Prop_Build_PubSec_R = $oJson.IntOf("signatureDictionary./Prop_Build./PubSec./R")
Local $signatureDictionary_SubFilter = $oJson.StringOf("signatureDictionary./SubFilter")
Local $signatureDictionary_Type = $oJson.StringOf("signatureDictionary./Type")
$i = 0
Local $iCount_i = $oJson.SizeOfArray("signatureDictionary./ByteRange")
While $i < $iCount_i
    $oJson.I = $i
    $intVal = $oJson.IntOf("signatureDictionary./ByteRange[i]")
    $i = $i + 1
Wend
$i = 0
$iCount_i = $oJson.SizeOfArray("signatureDictionary./Prop_Build./App./OS")
While $i < $iCount_i
    $oJson.I = $i
    $strVal = $oJson.StringOf("signatureDictionary./Prop_Build./App./OS[i]")
    $i = $i + 1
Wend
$i = 0
$iCount_i = $oJson.SizeOfArray("pkcs7.verify.certs")
While $i < $iCount_i
    $oJson.I = $i
    $sIssuerCN = $oJson.StringOf("pkcs7.verify.certs[i].issuerCN")
    $serial = $oJson.StringOf("pkcs7.verify.certs[i].serial")
    $i = $i + 1
Wend
$i = 0
$iCount_i = $oJson.SizeOfArray("pkcs7.verify.digestAlgorithms")
While $i < $iCount_i
    $oJson.I = $i
    $strVal = $oJson.StringOf("pkcs7.verify.digestAlgorithms[i]")
    $i = $i + 1
Wend
$i = 0
$iCount_i = $oJson.SizeOfArray("pkcs7.verify.signerInfo")
While $i < $iCount_i
    $oJson.I = $i
    $sCertSerialNumber = $oJson.StringOf("pkcs7.verify.signerInfo[i].cert.serialNumber")
    $sCertIssuerCN = $oJson.StringOf("pkcs7.verify.signerInfo[i].cert.issuerCN")
    $sCertDigestAlgOid = $oJson.StringOf("pkcs7.verify.signerInfo[i].cert.digestAlgOid")
    $sCertDigestAlgName = $oJson.StringOf("pkcs7.verify.signerInfo[i].cert.digestAlgName")
    $sContentType = $oJson.StringOf("pkcs7.verify.signerInfo[i].contentType")
    $sMessageDigest = $oJson.StringOf("pkcs7.verify.signerInfo[i].messageDigest")
    $signingAlgOid = $oJson.StringOf("pkcs7.verify.signerInfo[i].signingAlgOid")
    $signingAlgName = $oJson.StringOf("pkcs7.verify.signerInfo[i].signingAlgName")
    $sAuthAttr1_2_840_113583_1_1_8Der = $oJson.StringOf("pkcs7.verify.signerInfo[i].authAttr.""1.2.840.113583.1.1.8"".der")
    $sAuthAttrContentTypeName = $oJson.StringOf("pkcs7.verify.signerInfo[i].authAttr.""1.2.840.113549.1.9.3"".name")
    $sAuthAttrContentTypeOid = $oJson.StringOf("pkcs7.verify.signerInfo[i].authAttr.""1.2.840.113549.1.9.3"".oid")
    $sAuthAttrMessageDigestName = $oJson.StringOf("pkcs7.verify.signerInfo[i].authAttr.""1.2.840.113549.1.9.4"".name")
    $sAuthAttrMessageDigestDigest = $oJson.StringOf("pkcs7.verify.signerInfo[i].authAttr.""1.2.840.113549.1.9.4"".digest")
    $sUnauthAttrTimestampTokenName = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".name")
    $sUnauthAttrTimestampTokenDer = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".der")
    $bUnauthAttrTimestampTokenTimestampSignatureVerified = $oJson.BoolOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".timestampSignatureVerified")
    $sUnauthAttrTimestampTokenTstInfoTsaPolicyId = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".tstInfo.tsaPolicyId")
    $sUnauthAttrTimestampTokenTstInfoMessageImprintHashAlg = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".tstInfo.messageImprint.hashAlg")
    $sUnauthAttrTimestampTokenTstInfoMessageImprintDigest = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".tstInfo.messageImprint.digest")
    $bUnauthAttrTimestampTokenTstInfoMessageImprintDigestMatches = $oJson.BoolOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".tstInfo.messageImprint.digestMatches")
    $sUnauthAttrTimestampTokenTstInfoSerialNumber = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".tstInfo.serialNumber")
    $oJson.DtOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".tstInfo.genTime",False,$oUnauthAttrTimestampTokenTstInfoGenTime)
    $iJ = 0
    $iCount_j = $oJson.SizeOfArray("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.digestAlgorithms")
    While $iJ < $iCount_j
        $oJson.J = $iJ
        $strVal = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.digestAlgorithms[j]")
        $iJ = $iJ + 1
    Wend
    $iJ = 0
    $iCount_j = $oJson.SizeOfArray("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo")
    While $iJ < $iCount_j
        $oJson.J = $iJ
        $sCertSerialNumber = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].cert.serialNumber")
        $sCertIssuerCN = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].cert.issuerCN")
        $sCertDigestAlgOid = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].cert.digestAlgOid")
        $sCertDigestAlgName = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].cert.digestAlgName")
        $sContentType = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].contentType")
        $oJson.DtOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].signingTime",False,$oSigningTime)
        $sMessageDigest = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].messageDigest")
        $signingAlgOid = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].signingAlgOid")
        $signingAlgName = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].signingAlgName")
        $sAuthAttrContentTypeName = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].authAttr.""1.2.840.113549.1.9.3"".name")
        $sAuthAttrContentTypeOid = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].authAttr.""1.2.840.113549.1.9.3"".oid")
        $sAuthAttrSigningTimeName = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].authAttr.""1.2.840.113549.1.9.5"".name")
        $oJson.DtOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].authAttr.""1.2.840.113549.1.9.5"".utctime",False,$oAuthAttrSigningTimeUtctime)
        $sAuthAttrSigningCertificateName = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].authAttr.""1.2.840.113549.1.9.16.2.12"".name")
        $sAuthAttrSigningCertificateDer = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].authAttr.""1.2.840.113549.1.9.16.2.12"".der")
        $sAuthAttrMessageDigestName = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].authAttr.""1.2.840.113549.1.9.4"".name")
        $sAuthAttrMessageDigestDigest = $oJson.StringOf("pkcs7.verify.signerInfo[i].unauthAttr.""1.2.840.113549.1.9.16.2.14"".verify.signerInfo[j].authAttr.""1.2.840.113549.1.9.4"".digest")
        $iJ = $iJ + 1
    Wend
    $i = $i + 1
Wend
$i = 0
$iCount_i = $oJson.SizeOfArray("pkcs7.verify.pkcs7.verify.certs")
While $i < $iCount_i
    $oJson.I = $i
    $sIssuerCN = $oJson.StringOf("pkcs7.verify.pkcs7.verify.certs[i].issuerCN")
    $serial = $oJson.StringOf("pkcs7.verify.pkcs7.verify.certs[i].serial")
    $i = $i + 1
Wend