MIME S/MIME Signing Algorithm Properties

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Demonstrates the properties that control S/MIME signing: SigningAlg (the RSA signature scheme, PKCS1-V1_5 or RSASSA-PSS), SigningHashAlg (the message-digest algorithm), Micalg and Protocol (the micalg and protocol parameters of a multipart/signed Content-Type), and UseXPkcs7 (whether historical x-pkcs7 media-type names are used). The properties are configured before creating a detached signature.

let mime = chilkat::Mime::new();
if mime.set_body_from_plain_text("This message will be signed.").is_err() {
    println!("{}", mime.last_error_text());
    return;
}

// SigningAlg is the RSA signature scheme.  The default is PKCS1-V1_5; set RSASSA-PSS (or pss) for
// RSASSA-PSS.
mime.set_signing_alg("PKCS1-V1_5");

// SigningHashAlg is the message-digest algorithm.  The default is sha256.
mime.set_signing_hash_alg("sha256");

// Micalg and Protocol are the micalg and protocol parameters written into a multipart/signed
// Content-Type header field.  They are normally set automatically, but can be controlled here.
mime.set_micalg("sha-256");
mime.set_protocol("application/pkcs7-signature");

// UseXPkcs7 controls whether newly created S/MIME media types use the historical x-pkcs7 names.
mime.set_use_x_pkcs7(false);

// Load a signing certificate (with private key access) from a PFX.  The PFX password should come
// from a secure source rather than being hard-coded.
let pfx_password = "myPfxPassword".to_string();
let cert = chilkat::Cert::new();
if cert.load_pfx_file("qa_data/signer.pfx", &pfx_password).is_err() {
    println!("{}", cert.last_error_text());
    return;
}

// Create the detached signature using the algorithms configured above.
if mime.add_detached_signature(&cert).is_err() {
    println!("{}", mime.last_error_text());
    return;
}

println!("Signed with SigningAlg={} SigningHashAlg={}", mime.signing_alg(), mime.signing_hash_alg());