.NET Core C#
.NET Core C#
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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bool success = false;
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.
Chilkat.Pdf pdf = new Chilkat.Pdf();
// Load a PDF that has cryptographic signatures to be validated
success = pdf.LoadFile("qa_data/pdf/sign_testing_1/helloSigned2.pdf");
if (success == false) {
Debug.WriteLine(pdf.LastErrorText);
return;
}
// Each time we verify a signature, information about the signature is written into
// sigInfo (replacing whatever sigInfo previously contained).
Chilkat.JsonObject sigInfo = new Chilkat.JsonObject();
sigInfo.EmitCompact = false;
// Iterate over each signature and validate each.
int numSignatures = pdf.NumSignatures;
bool validated = false;
int i = 0;
while (i < numSignatures) {
validated = pdf.VerifySignature(i,sigInfo);
Debug.WriteLine("Signature " + Convert.ToString(i) + " validated: " + Convert.ToString(validated));
Debug.WriteLine(sigInfo.Emit());
i = i + 1;
}
Debug.WriteLine("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.
Chilkat.JsonObject json = new 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
Chilkat.DtObj unauthAttrTimestampTokenTstInfoGenTime = new Chilkat.DtObj();
Chilkat.DtObj signingTime = new Chilkat.DtObj();
Chilkat.DtObj authAttrSigningTimeUtctime = new Chilkat.DtObj();
int intVal;
string strVal;
string issuerCN;
string serial;
string certSerialNumber;
string certIssuerCN;
string certDigestAlgOid;
string certDigestAlgName;
string contentType;
string messageDigest;
string signingAlgOid;
string signingAlgName;
string authAttr1_2_840_113583_1_1_8Der;
string authAttrContentTypeName;
string authAttrContentTypeOid;
string authAttrMessageDigestName;
string authAttrMessageDigestDigest;
string unauthAttrTimestampTokenName;
string unauthAttrTimestampTokenDer;
bool unauthAttrTimestampTokenTimestampSignatureVerified;
string unauthAttrTimestampTokenTstInfoTsaPolicyId;
string unauthAttrTimestampTokenTstInfoMessageImprintHashAlg;
string unauthAttrTimestampTokenTstInfoMessageImprintDigest;
bool unauthAttrTimestampTokenTstInfoMessageImprintDigestMatches;
string unauthAttrTimestampTokenTstInfoSerialNumber;
int j;
int count_j;
string authAttrSigningTimeName;
string authAttrSigningCertificateName;
string authAttrSigningCertificateDer;
validated = json.BoolOf("validated");
string signatureDictionary_Contents = json.StringOf("signatureDictionary./Contents");
string signatureDictionary_Filter = json.StringOf("signatureDictionary./Filter");
string signatureDictionary_M = json.StringOf("signatureDictionary./M");
string signatureDictionary_Name = json.StringOf("signatureDictionary./Name");
string signatureDictionary_Prop_Build_App_Name = json.StringOf("signatureDictionary./Prop_Build./App./Name");
int signatureDictionary_Prop_Build_App_R = json.IntOf("signatureDictionary./Prop_Build./App./R");
string signatureDictionary_Prop_Build_App_REx = json.StringOf("signatureDictionary./Prop_Build./App./REx");
bool signatureDictionary_Prop_Build_App_TrustedMode = json.BoolOf("signatureDictionary./Prop_Build./App./TrustedMode");
string signatureDictionary_Prop_Build_Filter_Date = json.StringOf("signatureDictionary./Prop_Build./Filter./Date");
string signatureDictionary_Prop_Build_Filter_Name = json.StringOf("signatureDictionary./Prop_Build./Filter./Name");
int signatureDictionary_Prop_Build_Filter_R = json.IntOf("signatureDictionary./Prop_Build./Filter./R");
int signatureDictionary_Prop_Build_Filter_V = json.IntOf("signatureDictionary./Prop_Build./Filter./V");
string signatureDictionary_Prop_Build_PubSec_Date = json.StringOf("signatureDictionary./Prop_Build./PubSec./Date");
bool signatureDictionary_Prop_Build_PubSec_NonEFontNoWarn = json.BoolOf("signatureDictionary./Prop_Build./PubSec./NonEFontNoWarn");
int signatureDictionary_Prop_Build_PubSec_R = json.IntOf("signatureDictionary./Prop_Build./PubSec./R");
string signatureDictionary_SubFilter = json.StringOf("signatureDictionary./SubFilter");
string signatureDictionary_Type = json.StringOf("signatureDictionary./Type");
i = 0;
int count_i = json.SizeOfArray("signatureDictionary./ByteRange");
while (i < count_i) {
json.I = i;
intVal = json.IntOf("signatureDictionary./ByteRange[i]");
i = i + 1;
}
i = 0;
count_i = json.SizeOfArray("signatureDictionary./Prop_Build./App./OS");
while (i < count_i) {
json.I = i;
strVal = json.StringOf("signatureDictionary./Prop_Build./App./OS[i]");
i = i + 1;
}
i = 0;
count_i = json.SizeOfArray("pkcs7.verify.certs");
while (i < count_i) {
json.I = i;
issuerCN = json.StringOf("pkcs7.verify.certs[i].issuerCN");
serial = json.StringOf("pkcs7.verify.certs[i].serial");
i = i + 1;
}
i = 0;
count_i = json.SizeOfArray("pkcs7.verify.digestAlgorithms");
while (i < count_i) {
json.I = i;
strVal = json.StringOf("pkcs7.verify.digestAlgorithms[i]");
i = i + 1;
}
i = 0;
count_i = json.SizeOfArray("pkcs7.verify.signerInfo");
while (i < count_i) {
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");
unauthAttrTimestampTokenTimestampSignatureVerified = 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");
unauthAttrTimestampTokenTstInfoMessageImprintDigestMatches = 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;
count_j = json.SizeOfArray("pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.digestAlgorithms");
while (j < count_j) {
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 + 1;
}
j = 0;
count_j = json.SizeOfArray("pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo");
while (j < count_j) {
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 = j + 1;
}
i = i + 1;
}
i = 0;
count_i = json.SizeOfArray("pkcs7.verify.pkcs7.verify.certs");
while (i < count_i) {
json.I = i;
issuerCN = json.StringOf("pkcs7.verify.pkcs7.verify.certs[i].issuerCN");
serial = json.StringOf("pkcs7.verify.pkcs7.verify.certs[i].serial");
i = i + 1;
}