Function verify_rsa_sha256

nodedb/src/control/security/jwt.rs:273–296

Verify RSA-SHA256 (RS256) signature using a DER-encoded public key. Supports both PKCS#1 (RSAPublicKey) and PKCS#8 (SubjectPublicKeyInfo) formats.

(public_key_der: &[u8], message: &[u8], signature: &[u8])

///
/// Supports both PKCS#1 (RSAPublicKey) and PKCS#8 (SubjectPublicKeyInfo) formats.
fn verify_rsa_sha256(public_key_der: &[u8], message: &[u8], signature: &[u8]) -> bool {
    use rsa::Pkcs1v15Sign;

    // Try PKCS#8 first, then PKCS#1.
    let rsa_key = if let Ok(key) =
        <rsa::RsaPublicKey as rsa::pkcs8::DecodePublicKey>::from_public_key_der(public_key_der)
    {
        key
    } else if let Ok(key) =
        <rsa::RsaPublicKey as rsa::pkcs1::DecodeRsaPublicKey>::from_pkcs1_der(public_key_der)
    {
        key
    } else {
        return false;
    };

    // Hash the message with SHA-256.
    use sha2::Digest;
    let digest = sha2::Sha256::digest(message);

    // Verify PKCS#1 v1.5 signature.
    let scheme = Pkcs1v15Sign::new::<sha2::Sha256>();
    rsa_key.verify(scheme, &digest, signature).is_ok()
}

/// Load an RSA public key from a PEM file (for JwtConfig initialization).
///