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Save a Private Key as a Traditional DER File

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Demonstrates the Chilkat PrivateKey.SavePkcs1File method, which saves the key using the traditional/preferred unencrypted DER representation. The only argument is the destination path.

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.

Background: This writes the older, algorithm-specific DER structure — useful for compatibility with tools that predate or do not accept PKCS #8. For new work, PKCS #8 (SavePkcs8File) is more interoperable. The output is unencrypted, so protect the file accordingly.

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

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

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

    // Save using the traditional/preferred unencrypted DER representation.
    priv_key.savePkcs1File("qa_output/private_pkcs1.der") catch {
        std.debug.print("{s}\n", .{try priv_key.getLastErrorText(alloc)});
        return;
    };

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