Dart
Dart
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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import 'package:chilkat/chilkat.dart';
void main() {
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.
final pdf = CkPdf();
// Load a PDF that has cryptographic signatures to be validated
try {
pdf.loadFile('qa_data/pdf/sign_testing_1/helloSigned2.pdf');
} on ChilkatException catch (e) {
print(e.lastErrorText);
return;
}
// Each time we verify a signature, information about the signature is written into
// sigInfo (replacing whatever sigInfo previously contained).
final sigInfo = CkJsonObject();
sigInfo.emitCompact = false;
// Iterate over each signature and validate each.
final numSignatures = pdf.numSignatures;
var validated = false;
var i = 0;
while (i < numSignatures) {
validated = true;
try {
pdf.verifySignature(i, sigInfo);
} on ChilkatException {
validated = false;
}
print('Signature $i validated: $validated');
print(sigInfo.emit());
i++;
}
print('Finished.');
// 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.
final json = CkJsonObject();
// 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
final unauthAttrTimestampTokenTstInfoGenTime = CkDtObj();
final signingTime = CkDtObj();
final authAttrSigningTimeUtctime = CkDtObj();
var intVal = 0;
var strVal = '';
var issuerCN = '';
var serial = '';
var certSerialNumber = '';
var certIssuerCN = '';
var certDigestAlgOid = '';
var certDigestAlgName = '';
var contentType = '';
var messageDigest = '';
var signingAlgOid = '';
var signingAlgName = '';
var authAttr1_2_840_113583_1_1_8Der = '';
var authAttrContentTypeName = '';
var authAttrContentTypeOid = '';
var authAttrMessageDigestName = '';
var authAttrMessageDigestDigest = '';
var unauthAttrTimestampTokenName = '';
var unauthAttrTimestampTokenDer = '';
var unauthAttrTimestampTokenTstInfoTsaPolicyId = '';
var unauthAttrTimestampTokenTstInfoMessageImprintHashAlg = '';
var unauthAttrTimestampTokenTstInfoMessageImprintDigest = '';
var unauthAttrTimestampTokenTstInfoSerialNumber = '';
var j = 0;
var countJ = 0;
var authAttrSigningTimeName = '';
var authAttrSigningCertificateName = '';
var authAttrSigningCertificateDer = '';
validated = json.boolOf('validated');
final signatureDictionaryContents = json.stringOf('signatureDictionary./Contents');
final signatureDictionaryFilter = json.stringOf('signatureDictionary./Filter');
final signatureDictionaryM = json.stringOf('signatureDictionary./M');
final signatureDictionaryName = json.stringOf('signatureDictionary./Name');
final signatureDictionaryPropBuildAppName = json.stringOf('signatureDictionary./Prop_Build./App./Name');
final signatureDictionaryPropBuildAppR = json.intOf('signatureDictionary./Prop_Build./App./R');
final signatureDictionaryPropBuildAppREx = json.stringOf('signatureDictionary./Prop_Build./App./REx');
final signatureDictionaryPropBuildFilterDate = json.stringOf('signatureDictionary./Prop_Build./Filter./Date');
final signatureDictionaryPropBuildFilterName = json.stringOf('signatureDictionary./Prop_Build./Filter./Name');
final signatureDictionaryPropBuildFilterR = json.intOf('signatureDictionary./Prop_Build./Filter./R');
final signatureDictionaryPropBuildFilterV = json.intOf('signatureDictionary./Prop_Build./Filter./V');
final signatureDictionaryPropBuildPubSecDate = json.stringOf('signatureDictionary./Prop_Build./PubSec./Date');
final signatureDictionaryPropBuildPubSecR = json.intOf('signatureDictionary./Prop_Build./PubSec./R');
final signatureDictionarySubFilter = json.stringOf('signatureDictionary./SubFilter');
final signatureDictionaryType = json.stringOf('signatureDictionary./Type');
i = 0;
var countI = json.sizeOfArray('signatureDictionary./ByteRange');
while (i < countI) {
json.i = i;
intVal = json.intOf('signatureDictionary./ByteRange[i]');
i++;
}
i = 0;
countI = json.sizeOfArray('signatureDictionary./Prop_Build./App./OS');
while (i < countI) {
json.i = i;
strVal = json.stringOf('signatureDictionary./Prop_Build./App./OS[i]');
i++;
}
i = 0;
countI = json.sizeOfArray('pkcs7.verify.certs');
while (i < countI) {
json.i = i;
issuerCN = json.stringOf('pkcs7.verify.certs[i].issuerCN');
serial = json.stringOf('pkcs7.verify.certs[i].serial');
i++;
}
i = 0;
countI = json.sizeOfArray('pkcs7.verify.digestAlgorithms');
while (i < countI) {
json.i = i;
strVal = json.stringOf('pkcs7.verify.digestAlgorithms[i]');
i++;
}
i = 0;
countI = json.sizeOfArray('pkcs7.verify.signerInfo');
while (i < countI) {
json.i = i;
certSerialNumber = json.stringOf('pkcs7.verify.signerInfo[i].cert.serialNumber');
certIssuerCN = json.stringOf('pkcs7.verify.signerInfo[i].cert.issuerCN');
certDigestAlgOid = json.stringOf('pkcs7.verify.signerInfo[i].cert.digestAlgOid');
certDigestAlgName = json.stringOf('pkcs7.verify.signerInfo[i].cert.digestAlgName');
contentType = json.stringOf('pkcs7.verify.signerInfo[i].contentType');
messageDigest = json.stringOf('pkcs7.verify.signerInfo[i].messageDigest');
signingAlgOid = json.stringOf('pkcs7.verify.signerInfo[i].signingAlgOid');
signingAlgName = json.stringOf('pkcs7.verify.signerInfo[i].signingAlgName');
authAttr1_2_840_113583_1_1_8Der = json.stringOf('pkcs7.verify.signerInfo[i].authAttr."1.2.840.113583.1.1.8".der');
authAttrContentTypeName = json.stringOf('pkcs7.verify.signerInfo[i].authAttr."1.2.840.113549.1.9.3".name');
authAttrContentTypeOid = json.stringOf('pkcs7.verify.signerInfo[i].authAttr."1.2.840.113549.1.9.3".oid');
authAttrMessageDigestName = json.stringOf('pkcs7.verify.signerInfo[i].authAttr."1.2.840.113549.1.9.4".name');
authAttrMessageDigestDigest = json.stringOf('pkcs7.verify.signerInfo[i].authAttr."1.2.840.113549.1.9.4".digest');
unauthAttrTimestampTokenName = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".name');
unauthAttrTimestampTokenDer = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".der');
json.boolOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".timestampSignatureVerified');
unauthAttrTimestampTokenTstInfoTsaPolicyId = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".tstInfo.tsaPolicyId');
unauthAttrTimestampTokenTstInfoMessageImprintHashAlg = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".tstInfo.messageImprint.hashAlg');
unauthAttrTimestampTokenTstInfoMessageImprintDigest = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".tstInfo.messageImprint.digest');
json.boolOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".tstInfo.messageImprint.digestMatches');
unauthAttrTimestampTokenTstInfoSerialNumber = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".tstInfo.serialNumber');
json.dtOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".tstInfo.genTime', false, unauthAttrTimestampTokenTstInfoGenTime);
j = 0;
countJ = json.sizeOfArray('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.digestAlgorithms');
while (j < countJ) {
json.j = j;
strVal = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.digestAlgorithms[j]');
j++;
}
j = 0;
countJ = json.sizeOfArray('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.signerInfo');
while (j < countJ) {
json.j = j;
certSerialNumber = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.signerInfo[j].cert.serialNumber');
certIssuerCN = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.signerInfo[j].cert.issuerCN');
certDigestAlgOid = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.signerInfo[j].cert.digestAlgOid');
certDigestAlgName = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.signerInfo[j].cert.digestAlgName');
contentType = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.signerInfo[j].contentType');
json.dtOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.signerInfo[j].signingTime', false, signingTime);
messageDigest = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.signerInfo[j].messageDigest');
signingAlgOid = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.signerInfo[j].signingAlgOid');
signingAlgName = json.stringOf('pkcs7.verify.signerInfo[i].unauthAttr."1.2.840.113549.1.9.16.2.14".verify.signerInfo[j].signingAlgName');
authAttrContentTypeName = json.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');
authAttrContentTypeOid = json.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');
authAttrSigningTimeName = json.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');
json.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, authAttrSigningTimeUtctime);
authAttrSigningCertificateName = json.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');
authAttrSigningCertificateDer = json.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');
authAttrMessageDigestName = json.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');
authAttrMessageDigestDigest = json.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');
j++;
}
i++;
}
i = 0;
countI = json.sizeOfArray('pkcs7.verify.pkcs7.verify.certs');
while (i < countI) {
json.i = i;
issuerCN = json.stringOf('pkcs7.verify.pkcs7.verify.certs[i].issuerCN');
serial = json.stringOf('pkcs7.verify.pkcs7.verify.certs[i].serial');
i++;
}
}