Zig Requires Chilkat v11.0.0+

Generate a CSR with keyUsage, extKeyUsage, and other Extensions

See more CSR Examples

Demonstrates how to generate a CSR containing a 1.2.840.113549.1.9.14 extensionRequest with the following extensions:

• 1.3.6.1.4.1.311.20.2 enrollCerttypeExtension
• 2.5.29.15 keyUsage
• 2.5.29.37 extKeyUsage
• 2.5.29.14 subjectKeyIdentifier

Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

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

    // This example will generate a secp256r1 ECDSA key for the CSR.
    const ecc = try chilkat.Ecc.init();
    defer ecc.deinit();
    const prng = try chilkat.Prng.init();
    defer prng.deinit();
    const priv_key = try chilkat.PrivateKey.init();
    defer priv_key.deinit();
    ecc.genKey("secp256r1", prng, priv_key) catch {
        std.debug.print("Failed to generate a new ECDSA private key.\n", .{});
        return;
    };

    const csr = try chilkat.Csr.init();
    defer csr.deinit();

    // Add common CSR fields:
    csr.setCommonName("mysubdomain.mydomain.com");
    csr.setCountry("GB");
    csr.setState("Yorks");
    csr.setLocality("York");
    csr.setCompany("Internet Widgits Pty Ltd");
    csr.setEmailAddress("support@mydomain.com");

    // Add the following 1.2.840.113549.1.9.14 extensionRequest
    // Note: The easiest way to know the content and format of the XML to be added is to examine
    // a pre-existing CSR with the same desired extensionRequest.  You can use Chilkat to
    // get the extensionRequest from an existing CSR.

    // Here is a sample extension request:

    // <?xml version="1.0" encoding="utf-8"?>
    // <set>
    //     <sequence>
    //         <sequence>
    //             <oid>1.3.6.1.4.1.311.20.2</oid>
    //             <asnOctets>
    //                 <universal tag="30" constructed="0">AEUAbgBkAEUAbgB0AGkAdAB5AEMAbABpAGUAbgB0AEEAdQB0AGgAQwBlAHIAdABpAGYAaQBjAGEAdABl
    // AF8AQwBTAFIAUABhAHMAcwB0AGgAcgBvAHUAZwBoAC8AVgAx</universal>
    //             </asnOctets>
    //         </sequence>
    //         <sequence>
    //             <oid>2.5.29.15</oid>
    //             <bool>1</bool>
    //             <asnOctets>
    //                 <bits n="3">A0</bits>
    //             </asnOctets>
    //         </sequence>
    //         <sequence>
    //             <oid>2.5.29.37</oid>
    //             <asnOctets>
    //                 <sequence>
    //                     <oid>1.3.6.1.5.5.7.3.3</oid>
    //                 </sequence>
    //             </asnOctets>
    //         </sequence>
    //         <sequence>
    //             <oid>2.5.29.14</oid>
    //             <asnOctets>
    //                 <octets>MCzBMQAViXBz8IDt8LsgmJxJ4Xg=</octets>
    //             </asnOctets>
    //         </sequence>
    //     </sequence>
    // </set>

    // Use this online tool to generate code from sample XML:
    // Generate Code to Create XML

    // A few notes:
    // The string "AEUAbgBkAEUAbgB0AGkAdAB5AEMAbABpAGUAbgB0AEEAdQB0AGgAQwBlAHIAdABpAGYAaQBjAGEAdABlAF8AQwBTAFIAUABhAHMAcwB0AGgAcgBvAHUAZwBoAC8AVgAx"
    // is the base64 encoding of the utf-16be byte representation of the string "EndEntityClientAuthCertificate_CSRPassthrough/V1"

    const s = "EndEntityClientAuthCertificate_CSRPassthrough/V1";
    const bd_temp = try chilkat.BinData.init();
    defer bd_temp.deinit();
    bd_temp.appendString(s, "utf-16be") catch {};
    const s_base64_utf16be = try bd_temp.getEncoded(alloc, "base64");
    // The string should be "AEUA....."
    std.debug.print("{s}\n", .{s_base64_utf16be});

    // Here's the code to generate the above extension request.

    const xml = try chilkat.Xml.init();
    defer xml.deinit();
    xml.setTag("set");
    xml.updateChildContent("sequence|sequence|oid", "1.3.6.1.4.1.311.20.2");
    xml.updateAttrAt("sequence|sequence|asnOctets|universal", true, "tag", "30") catch {};
    xml.updateAttrAt("sequence|sequence|asnOctets|universal", true, "constructed", "0") catch {};
    xml.updateChildContent("sequence|sequence|asnOctets|universal", s_base64_utf16be);
    xml.updateChildContent("sequence|sequence[1]|oid", "2.5.29.15");
    xml.updateChildContent("sequence|sequence[1]|bool", "1");
    xml.updateAttrAt("sequence|sequence[1]|asnOctets|bits", true, "n", "3") catch {};
    // A0 is hex for decimal 160.
    xml.updateChildContent("sequence|sequence[1]|asnOctets|bits", "A0");
    xml.updateChildContent("sequence|sequence[2]|oid", "2.5.29.37");
    xml.updateChildContent("sequence|sequence[2]|asnOctets|sequence|oid", "1.3.6.1.5.5.7.3.3");

    // This is the subjectKeyIdentifier extension.
    // The string "MCzBMQAViXBz8IDt8LsgmJxJ4Xg=" is base64 that decodes to 20 bytes, which is a SHA1 hash.
    // This is simply a hash of the DER of the public key.

    const pub_key = try chilkat.PublicKey.init();
    defer pub_key.deinit();
    priv_key.toPublicKey(pub_key) catch {};
    const bd_pub_key_der = try chilkat.BinData.init();
    defer bd_pub_key_der.deinit();
    bd_pub_key_der.appendEncoded(try pub_key.getEncoded(alloc, true, "base64"), "base64") catch {};
    const ski = try bd_pub_key_der.getHash(alloc, "sha1", "base64");

    xml.updateChildContent("sequence|sequence[3]|oid", "2.5.29.14");
    xml.updateChildContent("sequence|sequence[3]|asnOctets|octets", ski);

    // Add the extension request to the CSR
    csr.setExtensionRequest(xml) catch {};

    // Generate the CSR with the extension request
    const csr_pem = csr.genCsrPem(alloc, priv_key) catch {
        std.debug.print("{s}\n", .{try csr.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("{s}\n", .{csr_pem});
}