OfficeIMO.Security 3.0.0

OfficeIMO.Security

OfficeIMO.Security is the shared cryptographic protocol owner for OfficeIMO. It provides neutral CMS/PKCS#7, S/MIME, RFC 3161, certificate-chain, and enveloped-data operations backed by Bouncy Castle.

It does not reference PDF, Email, Drawing, or another OfficeIMO format package. Format packages translate their own models to and from these neutral results.

dotnet add package OfficeIMO.Security

The package deliberately owns protocol orchestration, validation policy, bounded parsing, and stable result models. It does not invent cryptographic primitives, manage certificate stores, select recipients, or silently use network revocation services. Applications remain responsible for key custody and trust policy.

CMS signing and verification

using OfficeIMO.Security;

byte[] signature = CmsSignedDataSigner.SignDetached(content, signingCertificate);
CmsVerificationResult result = CmsSignedDataVerifier.VerifyDetached(signature, content);

foreach (CmsSignerVerificationResult signer in result.Signers) {
    Console.WriteLine($"{signer.Subject}: {signer.SignatureStatus}, {signer.CertificateValidation.ChainStatus}");
}

Signing uses the platform RSA handle and does not export the private key. Verification supports RSA and ECDSA signers, keeps mathematical signature, message digest, certificate trust, revocation, and timestamp outcomes separate, and never enables network revocation implicitly.

EnvelopedData

byte[] envelope = CmsEnvelopedDataService.Encrypt(content, new[] { recipientCertificate });
CmsDecryptionResult decrypted = CmsEnvelopedDataService.Decrypt(envelope, recipientWithPrivateKey);

Recipient selection is exact and caller-owned. The current Bouncy Castle key-transport adapter requires an exportable RSA private key for envelope decryption; a non-exportable key produces the stable EnvelopePrivateKeyNotExportable finding instead of silently falling back or exporting key material elsewhere.

Rfc3161TimestampVerifier validates timestamp signatures, TSA certificate profiles, message imprints, caller trust policy, and revocation as a separate neutral operation. TSA chain validation defaults to the token generation time; callers can override that instant through CertificateValidationOptions.VerificationTime.

Dependency footprint

• External: BouncyCastle.Cryptography 2.x.
• OfficeIMO: None. PDF and Email depend on Security; Security never depends on a format package.