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Decrypt MIME using RSAES-OAEP with SHA256 and AES-128 content encryption

See more MIME Examples

Demonstrates how to decrypt MIME what was encrypted with RSAES-OAEP with SHA256 and AES-128 content encryption.

In actuality, we don't really need to know in advance the various algorithms used to encrypt the MIME. When decrypting, the information about the algorithms required are embedded in the PCKS7 message itself, and this tells a decryptor what it should use.

Note: This example requires Chilkat v9.5.0.67 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 requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // We begin with this encrypted MIME:

    // Content-Type: application/x-pkcs7-mime; name="smime.p7m"; smime-type="enveloped-data"
    // someHeader1: Some value 1
    // someHeader2: Some value 2
    // Content-Disposition: attachment; filename="smime.p7m"
    // Content-Transfer-Encoding: base64
    //
    // MIIDvAYJKoZIhvcNAQcDoIIDrTCCA6kCAQAxggGgMIIBnAIBADB1MGgxCzAJBgNVBAYTAlVTMQsw
    // CQYDVQQIDAJJTDEQMA4GA1UEBwwHV2hlYXRvbjEhMB8GA1UECgwYSW50ZXJuZXQgV2lkZ2l0cyBQ
    // dHkgTHRkMRcwFQYDVQQDDA5DaGlsa2F0V2lkZ2V0cwIJAMRwugDmvniwMBwGCSqGSIb3DQEBBzAP
    // oA0wCwYJYIZIAWUDBAIBBIIBAFaUL1ga1bOrdqYKcMm+FHUacBvzfBxk0fnPA0AMBdN8BvTWT3CN
    // YuqBhjOGyq0FpYD9pVZybUuFMCVsVyIW2O62HnsOK58YaPEUUcdH2sI+yjqX9UAn0P0nVDSsVdeK
    // W8x9kMfZg+3UP+y1q+lu7VRJO3f2C9oLQpTkc4VW4n7UOcUI0waykLCjCTL8lFDb7/J3GeuMKyhH
    // 5riNz50kpbzqn7m2Ks9yA+QmcTdXclclGFr2vwEUFzSdT2pxh/vaUrogCxkYWbQ2eV7vZg6O4kV0
    // aqHBqySkPTAzHKiHH8K8GVdlTuJ8350CpICa4T8w7/Ht5I7dyOPPKy4C+rVtrvcwggH+BgkqhkiG
    // 9w0BBwEwHQYJYIZIAWUDBAECBBDTC2WNBN+z2I47/4Feu9YqgIIB0MZvl3nC/q/Wzil6HtfQTr12
    // Q5moHY+ORzAa1P9XvX2ZUFhW530mV395mQw/A4o4ekmX9eRPEZquYzZPLT8hNeZIuNdhpcSQUmad
    // rKnKkR0wKJ3jJ3LhOIohVBQSYs8kVDZKq6lJBIznlsurFelZoNEhyRschhteDZx5rb7fCe8c2+/O
    // DHxaqaHCAzm/Bd7kcg6FFfuTZy3tu0PgP5IsXN4OFA3kkvwjAs4XsVS8jdIcmDNBkYieE8WmJOIm
    // Mz7mh/CHWLgWfGKa0Dkb9RcbFgLwYNT3GzuXFw9XPbKkEZjEAtJajWbN6P0WQl96YYd9qZxUpGxZ
    // zjTHEYzViUdUXolfpLufttrRXyxN1RFWhNFMFbv66xYqklMSgpdM/Mbk+EuvX6eXayDPvDBpfYMw
    // NoRAzv1Ony2c0ez9rBemJICicxAzpuvHbRxdjYs63Dnv+TYgpBK12AxWWpPIjXvw0WQKgTC3Tg8s
    // EnuGhpENqso/clJBEBSn4+2WhYtYbdI5sVme67lvqQl1Xxy3r18SWaQbyDOwgYi1E+54lMDOxMy0
    // y0FPHk5pP45DnXWj+XORPp5LhuZr5mf62YOXSSUwR5P0cXy4Rc+pN5lhRQPCf5z2

    const sb = try chilkat.StringBuilder.init();
    defer sb.deinit();
    const b_crlf = true;
    sb.appendLine("Content-Type: application/x-pkcs7-mime; name=\"smime.p7m\"; smime-type=\"enveloped-data\"", b_crlf) catch {};
    sb.appendLine("someHeader1: Some value 1", b_crlf) catch {};
    sb.appendLine("someHeader2: Some value 2", b_crlf) catch {};
    sb.appendLine("Content-Disposition: attachment; filename=\"smime.p7m\"", b_crlf) catch {};
    sb.appendLine("Content-Transfer-Encoding: base64", b_crlf) catch {};
    sb.appendLine("", b_crlf) catch {};
    sb.appendLine("MIIDvAYJKoZIhvcNAQcDoIIDrTCCA6kCAQAxggGgMIIBnAIBADB1MGgxCzAJBgNVBAYTAlVTMQsw", b_crlf) catch {};
    sb.appendLine("CQYDVQQIDAJJTDEQMA4GA1UEBwwHV2hlYXRvbjEhMB8GA1UECgwYSW50ZXJuZXQgV2lkZ2l0cyBQ", b_crlf) catch {};
    sb.appendLine("dHkgTHRkMRcwFQYDVQQDDA5DaGlsa2F0V2lkZ2V0cwIJAMRwugDmvniwMBwGCSqGSIb3DQEBBzAP", b_crlf) catch {};
    sb.appendLine("oA0wCwYJYIZIAWUDBAIBBIIBAFaUL1ga1bOrdqYKcMm+FHUacBvzfBxk0fnPA0AMBdN8BvTWT3CN", b_crlf) catch {};
    sb.appendLine("YuqBhjOGyq0FpYD9pVZybUuFMCVsVyIW2O62HnsOK58YaPEUUcdH2sI+yjqX9UAn0P0nVDSsVdeK", b_crlf) catch {};
    sb.appendLine("W8x9kMfZg+3UP+y1q+lu7VRJO3f2C9oLQpTkc4VW4n7UOcUI0waykLCjCTL8lFDb7/J3GeuMKyhH", b_crlf) catch {};
    sb.appendLine("5riNz50kpbzqn7m2Ks9yA+QmcTdXclclGFr2vwEUFzSdT2pxh/vaUrogCxkYWbQ2eV7vZg6O4kV0", b_crlf) catch {};
    sb.appendLine("aqHBqySkPTAzHKiHH8K8GVdlTuJ8350CpICa4T8w7/Ht5I7dyOPPKy4C+rVtrvcwggH+BgkqhkiG", b_crlf) catch {};
    sb.appendLine("9w0BBwEwHQYJYIZIAWUDBAECBBDTC2WNBN+z2I47/4Feu9YqgIIB0MZvl3nC/q/Wzil6HtfQTr12", b_crlf) catch {};
    sb.appendLine("Q5moHY+ORzAa1P9XvX2ZUFhW530mV395mQw/A4o4ekmX9eRPEZquYzZPLT8hNeZIuNdhpcSQUmad", b_crlf) catch {};
    sb.appendLine("rKnKkR0wKJ3jJ3LhOIohVBQSYs8kVDZKq6lJBIznlsurFelZoNEhyRschhteDZx5rb7fCe8c2+/O", b_crlf) catch {};
    sb.appendLine("DHxaqaHCAzm/Bd7kcg6FFfuTZy3tu0PgP5IsXN4OFA3kkvwjAs4XsVS8jdIcmDNBkYieE8WmJOIm", b_crlf) catch {};
    sb.appendLine("Mz7mh/CHWLgWfGKa0Dkb9RcbFgLwYNT3GzuXFw9XPbKkEZjEAtJajWbN6P0WQl96YYd9qZxUpGxZ", b_crlf) catch {};
    sb.appendLine("zjTHEYzViUdUXolfpLufttrRXyxN1RFWhNFMFbv66xYqklMSgpdM/Mbk+EuvX6eXayDPvDBpfYMw", b_crlf) catch {};
    sb.appendLine("NoRAzv1Ony2c0ez9rBemJICicxAzpuvHbRxdjYs63Dnv+TYgpBK12AxWWpPIjXvw0WQKgTC3Tg8s", b_crlf) catch {};
    sb.appendLine("EnuGhpENqso/clJBEBSn4+2WhYtYbdI5sVme67lvqQl1Xxy3r18SWaQbyDOwgYi1E+54lMDOxMy0", b_crlf) catch {};
    sb.appendLine("y0FPHk5pP45DnXWj+XORPp5LhuZr5mf62YOXSSUwR5P0cXy4Rc+pN5lhRQPCf5z2", b_crlf) catch {};

    // Load the encrypted MIME into the MIME object.
    const mime = try chilkat.Mime.init();
    defer mime.deinit();
    mime.loadMimeSb(sb) catch {};

    // Provide the required cert + private key from a PFX (.pfx/.p12) file.
    mime.addPfxSourceFile("qa_data/rsaes-oaep/cert_plus_privatekey.pfx", "PFX_PASSWORD") catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    // Decrypt.
    mime.decrypt() catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    // Examine the decrypted MIME.
    std.debug.print("{s}\n", .{try mime.getMime(alloc)});
    std.debug.print("Decrypt test 1 succeeded.\n", .{});

    // -----------------------------------------------------------
    // Now let's decrypt another way..
    // We have the same cert and private key in PEM files..

    const cert = try chilkat.Cert.init();
    defer cert.deinit();
    try cert.loadFromFile("qa_data/rsaes-oaep/cert.pem");

    const priv_key = try chilkat.PrivateKey.init();
    defer priv_key.deinit();
    try priv_key.loadPemFile("qa_data/rsaes-oaep/privatekey.pem");

    // Decrypt using the cert + private key
    const mime2 = try chilkat.Mime.init();
    defer mime2.deinit();
    mime2.loadMimeSb(sb) catch {};

    mime2.decrypt2(cert, priv_key) catch {
        std.debug.print("{s}\n", .{try mime2.getLastErrorText(alloc)});
        return;
    };

    // Examine the decrypted MIME.
    std.debug.print("{s}\n", .{try mime2.getMime(alloc)});
    std.debug.print("Decrypt test 2 succeeded.\n", .{});
}