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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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const std = @import("std");
const chilkat = @import("chilkat");
pub fn main(init: std.process.Init) !void {
const alloc = init.arena.allocator();
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.
const pdf = try chilkat.Pdf.init();
defer pdf.deinit();
// Load a PDF that has cryptographic signatures to be validated
pdf.loadFile("qa_data/pdf/sign_testing_1/helloSigned2.pdf") catch {
std.debug.print("{s}\n", .{try pdf.getLastErrorText(alloc)});
return;
};
// Each time we verify a signature, information about the signature is written into
// sigInfo (replacing whatever sigInfo previously contained).
const sig_info = try chilkat.JsonObject.init();
defer sig_info.deinit();
sig_info.setEmitCompact(false);
// Iterate over each signature and validate each.
const num_signatures = pdf.getNumSignatures();
var validated: bool = false;
var i: i32 = 0;
while (i < num_signatures) {
validated = if (pdf.verifySignature(i, sig_info)) true else |_| false;
std.debug.print("Signature {d} validated: {}\n", .{ i, validated });
std.debug.print("{s}\n", .{try sig_info.emit(alloc)});
i = i + 1;
}
std.debug.print("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.
const json = try chilkat.JsonObject.init();
defer json.deinit();
// 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
const unauth_attr_timestamp_token_tst_info_gen_time = try chilkat.DtObj.init();
defer unauth_attr_timestamp_token_tst_info_gen_time.deinit();
const signing_time = try chilkat.DtObj.init();
defer signing_time.deinit();
const auth_attr_signing_time_utctime = try chilkat.DtObj.init();
defer auth_attr_signing_time_utctime.deinit();
var int_val: i32 = 0;
var str_val: [:0]const u8 = "";
var issuer_cn: [:0]const u8 = "";
var serial: [:0]const u8 = "";
var cert_serial_number: [:0]const u8 = "";
var cert_issuer_cn: [:0]const u8 = "";
var cert_digest_alg_oid: [:0]const u8 = "";
var cert_digest_alg_name: [:0]const u8 = "";
var content_type: [:0]const u8 = "";
var message_digest: [:0]const u8 = "";
var signing_alg_oid: [:0]const u8 = "";
var signing_alg_name: [:0]const u8 = "";
var auth_attr1_2_840_113583_1_1_8_der: [:0]const u8 = "";
var auth_attr_content_type_name: [:0]const u8 = "";
var auth_attr_content_type_oid: [:0]const u8 = "";
var auth_attr_message_digest_name: [:0]const u8 = "";
var auth_attr_message_digest_digest: [:0]const u8 = "";
var unauth_attr_timestamp_token_name: [:0]const u8 = "";
var unauth_attr_timestamp_token_der: [:0]const u8 = "";
var unauth_attr_timestamp_token_timestamp_signature_verified: bool = false;
var unauth_attr_timestamp_token_tst_info_tsa_policy_id: [:0]const u8 = "";
var unauth_attr_timestamp_token_tst_info_message_imprint_hash_alg: [:0]const u8 = "";
var unauth_attr_timestamp_token_tst_info_message_imprint_digest: [:0]const u8 = "";
var unauth_attr_timestamp_token_tst_info_message_imprint_digest_matches: bool = false;
var unauth_attr_timestamp_token_tst_info_serial_number: [:0]const u8 = "";
var j: i32 = 0;
var count_j: i32 = 0;
var auth_attr_signing_time_name: [:0]const u8 = "";
var auth_attr_signing_certificate_name: [:0]const u8 = "";
var auth_attr_signing_certificate_der: [:0]const u8 = "";
validated = json.boolOf("validated");
_ = try json.stringOf(alloc, "signatureDictionary./Contents");
_ = try json.stringOf(alloc, "signatureDictionary./Filter");
_ = try json.stringOf(alloc, "signatureDictionary./M");
_ = try json.stringOf(alloc, "signatureDictionary./Name");
_ = try json.stringOf(alloc, "signatureDictionary./Prop_Build./App./Name");
_ = json.intOf("signatureDictionary./Prop_Build./App./R");
_ = try json.stringOf(alloc, "signatureDictionary./Prop_Build./App./REx");
_ = json.boolOf("signatureDictionary./Prop_Build./App./TrustedMode");
_ = try json.stringOf(alloc, "signatureDictionary./Prop_Build./Filter./Date");
_ = try json.stringOf(alloc, "signatureDictionary./Prop_Build./Filter./Name");
_ = json.intOf("signatureDictionary./Prop_Build./Filter./R");
_ = json.intOf("signatureDictionary./Prop_Build./Filter./V");
_ = try json.stringOf(alloc, "signatureDictionary./Prop_Build./PubSec./Date");
_ = json.boolOf("signatureDictionary./Prop_Build./PubSec./NonEFontNoWarn");
_ = json.intOf("signatureDictionary./Prop_Build./PubSec./R");
_ = try json.stringOf(alloc, "signatureDictionary./SubFilter");
_ = try json.stringOf(alloc, "signatureDictionary./Type");
i = 0;
var count_i: i32 = json.sizeOfArray("signatureDictionary./ByteRange");
while (i < count_i) {
json.setI(i);
int_val = json.intOf("signatureDictionary./ByteRange[i]");
i = i + 1;
}
i = 0;
count_i = json.sizeOfArray("signatureDictionary./Prop_Build./App./OS");
while (i < count_i) {
json.setI(i);
str_val = try json.stringOf(alloc, "signatureDictionary./Prop_Build./App./OS[i]");
i = i + 1;
}
i = 0;
count_i = json.sizeOfArray("pkcs7.verify.certs");
while (i < count_i) {
json.setI(i);
issuer_cn = try json.stringOf(alloc, "pkcs7.verify.certs[i].issuerCN");
serial = try json.stringOf(alloc, "pkcs7.verify.certs[i].serial");
i = i + 1;
}
i = 0;
count_i = json.sizeOfArray("pkcs7.verify.digestAlgorithms");
while (i < count_i) {
json.setI(i);
str_val = try json.stringOf(alloc, "pkcs7.verify.digestAlgorithms[i]");
i = i + 1;
}
i = 0;
count_i = json.sizeOfArray("pkcs7.verify.signerInfo");
while (i < count_i) {
json.setI(i);
cert_serial_number = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].cert.serialNumber");
cert_issuer_cn = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].cert.issuerCN");
cert_digest_alg_oid = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].cert.digestAlgOid");
cert_digest_alg_name = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].cert.digestAlgName");
content_type = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].contentType");
message_digest = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].messageDigest");
signing_alg_oid = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].signingAlgOid");
signing_alg_name = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].signingAlgName");
auth_attr1_2_840_113583_1_1_8_der = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113583.1.1.8\".der");
auth_attr_content_type_name = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.3\".name");
auth_attr_content_type_oid = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.3\".oid");
auth_attr_message_digest_name = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.4\".name");
auth_attr_message_digest_digest = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.4\".digest");
unauth_attr_timestamp_token_name = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".name");
unauth_attr_timestamp_token_der = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".der");
unauth_attr_timestamp_token_timestamp_signature_verified = json.boolOf("pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".timestampSignatureVerified");
unauth_attr_timestamp_token_tst_info_tsa_policy_id = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".tstInfo.tsaPolicyId");
unauth_attr_timestamp_token_tst_info_message_imprint_hash_alg = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".tstInfo.messageImprint.hashAlg");
unauth_attr_timestamp_token_tst_info_message_imprint_digest = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".tstInfo.messageImprint.digest");
unauth_attr_timestamp_token_tst_info_message_imprint_digest_matches = json.boolOf("pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".tstInfo.messageImprint.digestMatches");
unauth_attr_timestamp_token_tst_info_serial_number = try json.stringOf(alloc, "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, unauth_attr_timestamp_token_tst_info_gen_time) catch {};
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.setJ(j);
str_val = try json.stringOf(alloc, "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.setJ(j);
cert_serial_number = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].cert.serialNumber");
cert_issuer_cn = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].cert.issuerCN");
cert_digest_alg_oid = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].cert.digestAlgOid");
cert_digest_alg_name = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].cert.digestAlgName");
content_type = try json.stringOf(alloc, "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, signing_time) catch {};
message_digest = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].messageDigest");
signing_alg_oid = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].signingAlgOid");
signing_alg_name = try json.stringOf(alloc, "pkcs7.verify.signerInfo[i].unauthAttr.\"1.2.840.113549.1.9.16.2.14\".verify.signerInfo[j].signingAlgName");
auth_attr_content_type_name = try json.stringOf(alloc, "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");
auth_attr_content_type_oid = try json.stringOf(alloc, "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");
auth_attr_signing_time_name = try json.stringOf(alloc, "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, auth_attr_signing_time_utctime) catch {};
auth_attr_signing_certificate_name = try json.stringOf(alloc, "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");
auth_attr_signing_certificate_der = try json.stringOf(alloc, "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");
auth_attr_message_digest_name = try json.stringOf(alloc, "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");
auth_attr_message_digest_digest = try json.stringOf(alloc, "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.setI(i);
issuer_cn = try json.stringOf(alloc, "pkcs7.verify.pkcs7.verify.certs[i].issuerCN");
serial = try json.stringOf(alloc, "pkcs7.verify.pkcs7.verify.certs[i].serial");
i = i + 1;
}
}