Add a Detached Signature (Separate Key, Header Control)

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Demonstrates the Chilkat Mime.AddDetachedSignaturePk2 method, which creates a detached signature with a separately supplied certificate and private key, and a third argument controlling transfer of the existing message header fields to the new outer entity.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

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

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

    const mime = try chilkat.Mime.init();
    defer mime.deinit();
    mime.setBodyFromPlainText("This message will be signed.") catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    // Load the certificate and its private key separately.
    const cert = try chilkat.Cert.init();
    defer cert.deinit();
    cert.loadFromFile("qa_data/signer.cer") catch {
        std.debug.print("{s}\n", .{try cert.getLastErrorText(alloc)});
        return;
    };

    const priv_key = try chilkat.PrivateKey.init();
    defer priv_key.deinit();
    priv_key.loadPemFile("qa_data/signer_privkey.pem") catch {
        std.debug.print("{s}\n", .{try priv_key.getLastErrorText(alloc)});
        return;
    };

    // Create a detached signature with separately supplied cert and private key, where the 3rd
    // argument controls whether the existing message header fields are transferred to the new outer
    // multipart/signed entity.
    const transfer_header_fields = true;
    mime.addDetachedSignaturePk2(cert, priv_key, transfer_header_fields) catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    mime.saveMime("qa_output/signed.eml") catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("Detached signature added (headers transferred).\n", .{});
}