C
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.
Chilkat C Downloads
#include <C_CkPdf.h>
#include <C_CkJsonObject.h>
#include <C_CkDtObj.h>
void ChilkatSample(void)
{
BOOL success;
HCkPdf pdf;
HCkJsonObject sigInfo;
int numSignatures;
BOOL validated;
int i;
HCkJsonObject json;
HCkDtObj unauthAttrTimestampTokenTstInfoGenTime;
HCkDtObj signingTime;
HCkDtObj authAttrSigningTimeUtctime;
int intVal;
const char *strVal;
const char *issuerCN;
const char *serial;
const char *certSerialNumber;
const char *certIssuerCN;
const char *certDigestAlgOid;
const char *certDigestAlgName;
const char *contentType;
const char *messageDigest;
const char *signingAlgOid;
const char *signingAlgName;
const char *authAttr1_2_840_113583_1_1_8Der;
const char *authAttrContentTypeName;
const char *authAttrContentTypeOid;
const char *authAttrMessageDigestName;
const char *authAttrMessageDigestDigest;
const char *unauthAttrTimestampTokenName;
const char *unauthAttrTimestampTokenDer;
BOOL unauthAttrTimestampTokenTimestampSignatureVerified;
const char *unauthAttrTimestampTokenTstInfoTsaPolicyId;
const char *unauthAttrTimestampTokenTstInfoMessageImprintHashAlg;
const char *unauthAttrTimestampTokenTstInfoMessageImprintDigest;
BOOL unauthAttrTimestampTokenTstInfoMessageImprintDigestMatches;
const char *unauthAttrTimestampTokenTstInfoSerialNumber;
int j;
int count_j;
const char *authAttrSigningTimeName;
const char *authAttrSigningCertificateName;
const char *authAttrSigningCertificateDer;
const char *signatureDictionary_Contents;
const char *signatureDictionary_Filter;
const char *signatureDictionary_M;
const char *signatureDictionary_Name;
const char *signatureDictionary_Prop_Build_App_Name;
int signatureDictionary_Prop_Build_App_R;
const char *signatureDictionary_Prop_Build_App_REx;
BOOL signatureDictionary_Prop_Build_App_TrustedMode;
const char *signatureDictionary_Prop_Build_Filter_Date;
const char *signatureDictionary_Prop_Build_Filter_Name;
int signatureDictionary_Prop_Build_Filter_R;
int signatureDictionary_Prop_Build_Filter_V;
const char *signatureDictionary_Prop_Build_PubSec_Date;
BOOL signatureDictionary_Prop_Build_PubSec_NonEFontNoWarn;
int signatureDictionary_Prop_Build_PubSec_R;
const char *signatureDictionary_SubFilter;
const char *signatureDictionary_Type;
int count_i;
success = FALSE;
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.
pdf = CkPdf_Create();
// Load a PDF that has cryptographic signatures to be validated
success = CkPdf_LoadFile(pdf,"qa_data/pdf/sign_testing_1/helloSigned2.pdf");
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf));
CkPdf_Dispose(pdf);
return;
}
// Each time we verify a signature, information about the signature is written into
// sigInfo (replacing whatever sigInfo previously contained).
sigInfo = CkJsonObject_Create();
CkJsonObject_putEmitCompact(sigInfo,FALSE);
// Iterate over each signature and validate each.
numSignatures = CkPdf_getNumSignatures(pdf);
validated = FALSE;
i = 0;
while (i < numSignatures) {
validated = CkPdf_VerifySignature(pdf,i,sigInfo);
printf("Signature %d validated: %d\n",i,validated);
printf("%s\n",CkJsonObject_emit(sigInfo));
i = i + 1;
}
printf("Finished.\n");
// 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.
json = CkJsonObject_Create();
// 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 functions returning "const char *" return a pointer to temporary internal memory owned and managed by Chilkat.
// See this example explaining how this memory should be used: const char * functions.
unauthAttrTimestampTokenTstInfoGenTime = CkDtObj_Create();
signingTime = CkDtObj_Create();
authAttrSigningTimeUtctime = CkDtObj_Create();
validated = CkJsonObject_BoolOf(json,"validated");
signatureDictionary_Contents = CkJsonObject_stringOf(json,"signatureDictionary./Contents");
signatureDictionary_Filter = CkJsonObject_stringOf(json,"signatureDictionary./Filter");
signatureDictionary_M = CkJsonObject_stringOf(json,"signatureDictionary./M");
signatureDictionary_Name = CkJsonObject_stringOf(json,"signatureDictionary./Name");
signatureDictionary_Prop_Build_App_Name = CkJsonObject_stringOf(json,"signatureDictionary./Prop_Build./App./Name");
signatureDictionary_Prop_Build_App_R = CkJsonObject_IntOf(json,"signatureDictionary./Prop_Build./App./R");
signatureDictionary_Prop_Build_App_REx = CkJsonObject_stringOf(json,"signatureDictionary./Prop_Build./App./REx");
signatureDictionary_Prop_Build_App_TrustedMode = CkJsonObject_BoolOf(json,"signatureDictionary./Prop_Build./App./TrustedMode");
signatureDictionary_Prop_Build_Filter_Date = CkJsonObject_stringOf(json,"signatureDictionary./Prop_Build./Filter./Date");
signatureDictionary_Prop_Build_Filter_Name = CkJsonObject_stringOf(json,"signatureDictionary./Prop_Build./Filter./Name");
signatureDictionary_Prop_Build_Filter_R = CkJsonObject_IntOf(json,"signatureDictionary./Prop_Build./Filter./R");
signatureDictionary_Prop_Build_Filter_V = CkJsonObject_IntOf(json,"signatureDictionary./Prop_Build./Filter./V");
signatureDictionary_Prop_Build_PubSec_Date = CkJsonObject_stringOf(json,"signatureDictionary./Prop_Build./PubSec./Date");
signatureDictionary_Prop_Build_PubSec_NonEFontNoWarn = CkJsonObject_BoolOf(json,"signatureDictionary./Prop_Build./PubSec./NonEFontNoWarn");
signatureDictionary_Prop_Build_PubSec_R = CkJsonObject_IntOf(json,"signatureDictionary./Prop_Build./PubSec./R");
signatureDictionary_SubFilter = CkJsonObject_stringOf(json,"signatureDictionary./SubFilter");
signatureDictionary_Type = CkJsonObject_stringOf(json,"signatureDictionary./Type");
i = 0;
count_i = CkJsonObject_SizeOfArray(json,"signatureDictionary./ByteRange");
while (i < count_i) {
CkJsonObject_putI(json,i);
intVal = CkJsonObject_IntOf(json,"signatureDictionary./ByteRange[i]");
i = i + 1;
}
i = 0;
count_i = CkJsonObject_SizeOfArray(json,"signatureDictionary./Prop_Build./App./OS");
while (i < count_i) {
CkJsonObject_putI(json,i);
strVal = CkJsonObject_stringOf(json,"signatureDictionary./Prop_Build./App./OS[i]");
i = i + 1;
}
i = 0;
count_i = CkJsonObject_SizeOfArray(json,"pkcs7.verify.certs");
while (i < count_i) {
CkJsonObject_putI(json,i);
issuerCN = CkJsonObject_stringOf(json,"pkcs7.verify.certs[i].issuerCN");
serial = CkJsonObject_stringOf(json,"pkcs7.verify.certs[i].serial");
i = i + 1;
}
i = 0;
count_i = CkJsonObject_SizeOfArray(json,"pkcs7.verify.digestAlgorithms");
while (i < count_i) {
CkJsonObject_putI(json,i);
strVal = CkJsonObject_stringOf(json,"pkcs7.verify.digestAlgorithms[i]");
i = i + 1;
}
i = 0;
count_i = CkJsonObject_SizeOfArray(json,"pkcs7.verify.signerInfo");
while (i < count_i) {
CkJsonObject_putI(json,i);
certSerialNumber = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].cert.serialNumber");
certIssuerCN = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].cert.issuerCN");
certDigestAlgOid = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].cert.digestAlgOid");
certDigestAlgName = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].cert.digestAlgName");
contentType = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].contentType");
messageDigest = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].messageDigest");
signingAlgOid = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].signingAlgOid");
signingAlgName = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].signingAlgName");
authAttr1_2_840_113583_1_1_8Der = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113583.1.1.8\".der");
authAttrContentTypeName = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.3\".name");
authAttrContentTypeOid = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.3\".oid");
authAttrMessageDigestName = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.4\".name");
authAttrMessageDigestDigest = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.4\".digest");
unauthAttrTimestampTokenName = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".name");
unauthAttrTimestampTokenDer = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".der");
unauthAttrTimestampTokenTimestampSignatureVerified = CkJsonObject_BoolOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".timestampSignatureVerified");
unauthAttrTimestampTokenTstInfoTsaPolicyId = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".tstInfo.tsaPolicyId");
unauthAttrTimestampTokenTstInfoMessageImprintHashAlg = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".tstInfo.messageImprint.hashAlg");
unauthAttrTimestampTokenTstInfoMessageImprintDigest = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".tstInfo.messageImprint.digest");
unauthAttrTimestampTokenTstInfoMessageImprintDigestMatches = CkJsonObject_BoolOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".tstInfo.messageImprint.digestMatches");
unauthAttrTimestampTokenTstInfoSerialNumber = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".tstInfo.serialNumber");
CkJsonObject_DtOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".tstInfo.genTime",FALSE,unauthAttrTimestampTokenTstInfoGenTime);
j = 0;
count_j = CkJsonObject_SizeOfArray(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.digestAlgorithms");
while (j < count_j) {
CkJsonObject_putJ(json,j);
strVal = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.digestAlgorithms[j]");
j = j + 1;
}
j = 0;
count_j = CkJsonObject_SizeOfArray(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo");
while (j < count_j) {
CkJsonObject_putJ(json,j);
certSerialNumber = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].cert.serialNumber");
certIssuerCN = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].cert.issuerCN");
certDigestAlgOid = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].cert.digestAlgOid");
certDigestAlgName = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].cert.digestAlgName");
contentType = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].contentType");
CkJsonObject_DtOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].signingTime",FALSE,signingTime);
messageDigest = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].messageDigest");
signingAlgOid = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].signingAlgOid");
signingAlgName = CkJsonObject_stringOf(json,"pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].signingAlgName");
authAttrContentTypeName = CkJsonObject_stringOf(json,"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 = CkJsonObject_stringOf(json,"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 = CkJsonObject_stringOf(json,"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");
CkJsonObject_DtOf(json,"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 = CkJsonObject_stringOf(json,"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 = CkJsonObject_stringOf(json,"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 = CkJsonObject_stringOf(json,"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 = CkJsonObject_stringOf(json,"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 = CkJsonObject_SizeOfArray(json,"pkcs7.verify.pkcs7.verify.certs");
while (i < count_i) {
CkJsonObject_putI(json,i);
issuerCN = CkJsonObject_stringOf(json,"pkcs7.verify.pkcs7.verify.certs[i].issuerCN");
serial = CkJsonObject_stringOf(json,"pkcs7.verify.pkcs7.verify.certs[i].serial");
i = i + 1;
}
CkPdf_Dispose(pdf);
CkJsonObject_Dispose(sigInfo);
CkJsonObject_Dispose(json);
CkDtObj_Dispose(unauthAttrTimestampTokenTstInfoGenTime);
CkDtObj_Dispose(signingTime);
CkDtObj_Dispose(authAttrSigningTimeUtctime);
}