Zig

Get an S/MIME Signing Time

Demonstrates the Chilkat Mime.GetSignatureSigningTimeStr method, which returns the CMS signingTime attribute for the signer at a zero-based index, as an RFC 822-style date string in GMT. The only argument is the signer index.

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 is the timestamp the signer asserted at signing — useful for "when was this signed" audit trails and for evaluating whether the signing certificate was valid at that moment. Because it is a signed attribute, it is tamper-evident. Guard the call with HasSignatureSigningTime, since the attribute is optional. Note it is the signer's claim, not a trusted third-party timestamp.

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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();

    const mime = try chilkat.Mime.init();
    defer mime.deinit();
    mime.loadMimeFile("qa_data/signed.eml") catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    // After verifying, get the CMS signingTime for each signer that has one, as an RFC 822 date string
    // in GMT.  The only argument is the zero-based signer index.
    mime.verify() catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    const n = mime.getNumSignerCerts();
    var i: i32 = 0;
    i = 0;
    while (i < n) : (i += 1) {
        // Only signers that included a signing time have one to retrieve.
        if (mime.hasSignatureSigningTime(i)) {
            const signing_time = mime.getSignatureSigningTimeStr(alloc, i) catch {
                std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
                return;
            };

            std.debug.print("Signer {d} signing time: {s}\n", .{ i, signing_time });
        }
    }
}