cosmian_kms_interfaces 5.23.0

//! `HsmStore` — a single adapter that implements both `ObjectsStore` and `CryptoOracle`
//! for Hardware Security Module backends.  It consolidates what was previously two separate
//! types (`HsmStore` and `HsmCryptoOracle`) that always wrapped the same `Arc<dyn HSM>`.

use std::{collections::HashSet, sync::Arc};

use KmipKeyMaterial::TransparentRSAPublicKey;
use async_trait::async_trait;
use cosmian_kmip::{
    SafeBigInt,
    kmip_0::kmip_types::{CryptographicUsageMask, State},
    kmip_2_1::{
        extra::tagging::{SYSTEM_TAG_PRIVATE_KEY, SYSTEM_TAG_PUBLIC_KEY, SYSTEM_TAG_SYMMETRIC_KEY},
        kmip_attributes::Attributes,
        kmip_data_structures::{KeyBlock, KeyMaterial as KmipKeyMaterial, KeyValue},
        kmip_objects::{Object, ObjectType, PrivateKey, PublicKey, SymmetricKey},
        kmip_types::{CryptographicAlgorithm, KeyFormatType},
    },
};
use cosmian_logger::{debug, error, trace, warn};
use num_bigint_dig::{BigInt, Sign};
use zeroize::Zeroizing;

use crate::{
    AtomicOperation, CryptoAlgorithm, CryptoOracle, HSM, HsmKeyAlgorithm, HsmKeypairAlgorithm,
    HsmObject, HsmObjectFilter, InterfaceError, InterfaceResult, KeyMaterial, KeyType,
    ObjectWithMetadata, ObjectsStore, SigningAlgorithm,
    crypto_oracle::{EncryptedContent, KeyMetadata},
};

/// A single adapter that wraps an `Arc<dyn HSM>` and implements both [`ObjectsStore`] and
/// [`CryptoOracle`].  Callers can [`Clone`] the backend cheaply (only the inner `Arc` is
/// cloned) to register it in both the object-store and crypto-oracle maps.
#[derive(Clone)]
pub struct HsmStore {
    hsm: Arc<dyn HSM + Send + Sync>,
    hsm_admin: Vec<String>,
    vendor_id: String,
    /// UID routing prefix, e.g. `"hsm"`, `"hsm1"`, `"hsm2"`.
    prefix: String,
}

impl HsmStore {
    pub fn new(
        hsm: Arc<dyn HSM + Send + Sync>,
        hsm_admin: &[String],
        vendor_id: &str,
        prefix: &str,
    ) -> Self {
        Self {
            hsm,
            hsm_admin: hsm_admin.to_owned(),
            vendor_id: vendor_id.to_owned(),
            prefix: prefix.to_owned(),
        }
    }

    /// Returns `true` if `user` is an HSM admin.
    /// Wildcard `"*"` grants access to every user.
    fn is_admin(&self, user: &str) -> bool {
        self.hsm_admin.iter().any(|a| a == "*" || a == user)
    }

    /// Returns the name to use as the owner of HSM objects.
    /// Picks the first non-wildcard admin, falling back to `"admin"`.
    fn owner_name(&self) -> &str {
        self.hsm_admin
            .iter()
            .find(|a| a.as_str() != "*")
            .map_or("admin", String::as_str)
    }
}

// ──────────────────────────────────────────────────────────────────────────────
// ObjectsStore implementation
// ──────────────────────────────────────────────────────────────────────────────

#[async_trait(?Send)]
impl ObjectsStore for HsmStore {
    // Only single keys are created using this call,
    // keypair creation goes through the atomic operations
    /// Create a key on the HSM
    /// `tags` are not available on HSMs
    async fn create(
        &self,
        uid: Option<String>,
        owner: &str,
        object: &Object,
        attributes: &Attributes,
        _tags: &HashSet<String>,
    ) -> InterfaceResult<String> {
        if !self.is_admin(owner) {
            return Err(InterfaceError::Unauthorized(
                "Only the HSM Admin can create HSM objects".to_owned(),
            ));
        }
        // try converting the rest of the uid into a slot_id
        let uid = uid.as_ref().ok_or_else(|| {
            InterfaceError::InvalidRequest(
                format!("An HSM create request must have a uid in the form of 'hsm::<slot_id>::<key_id>'. Got {uid:?}"
            ))
        })?;
        let (slot_id, key_id) = parse_uid_with_prefix(uid, &self.prefix)?;
        if object.object_type() != ObjectType::SymmetricKey {
            return Err(InterfaceError::InvalidRequest(
                "Only symmetric keys can be created on the HSM in this server".to_owned(),
            ));
        }
        let algorithm = attributes.cryptographic_algorithm.as_ref().ok_or_else(|| {
            InterfaceError::InvalidRequest(
                "Create: HSM keys must have a cryptographic algorithm specified".to_owned(),
            )
        })?;
        if *algorithm != CryptographicAlgorithm::AES {
            return Err(InterfaceError::InvalidRequest(
                "Only AES symmetric keys can be created on the HSM in this server".to_owned(),
            ));
        }
        let key_length = attributes.cryptographic_length.as_ref().ok_or_else(|| {
            InterfaceError::InvalidRequest(
                "Symmetric key must have a cryptographic length specified".to_owned(),
            )
        })?;
        self.hsm
            .create_key(
                slot_id,
                key_id.as_bytes(),
                HsmKeyAlgorithm::AES,
                usize::try_from(*key_length).map_err(|e| {
                    InterfaceError::InvalidRequest(format!("Invalid key length: {e}"))
                })?,
                attributes.sensitive.unwrap_or(false),
            )
            .await?;
        debug!("Created HSM AES Key of length {key_length} with id {uid}",);
        Ok(uid.to_owned())
    }

    async fn retrieve(&self, uid: &str) -> InterfaceResult<Option<ObjectWithMetadata>> {
        // try converting the rest of the UID into a slot_id and key id
        let (slot_id, key_id) = parse_uid_with_prefix(uid, &self.prefix)?;
        match self.hsm.export(slot_id, key_id.as_bytes()).await {
            Ok(Some(hsm_object)) => {
                let owm =
                    to_object_with_metadata(&hsm_object, uid, self.owner_name(), &self.vendor_id)?;
                Ok(Some(owm))
            }
            Ok(None) => Ok(None),
            Err(e) => {
                // The key cannot be exported — this may be because it is
                // non-extractable (sensitive flag in PKCS#11) or because
                // the PKCS#11 find-by-id/label re-lookup failed after initial
                // discovery. In either case, fall back to a metadata-only stub
                // so that attribute-only KMIP operations (GetAttributes, Locate
                // enrichment) succeed without accessing the key material.
                // Fixes: https://github.com/Cosmian/kms/issues/933
                debug!(
                    "HSM key {uid} export failed ({e}); falling back to metadata-only stub for \
                     attribute operations"
                );
                let meta = self
                    .hsm
                    .get_key_metadata(slot_id, key_id.as_bytes())
                    .await?;
                let Some(meta) = meta else {
                    return Ok(None);
                };
                let attrs = build_sensitive_stub_attributes(&meta);
                let object = build_sensitive_stub_object(&meta);
                Ok(Some(ObjectWithMetadata::new(
                    uid.to_owned(),
                    object,
                    self.owner_name().to_owned(),
                    State::Active,
                    attrs,
                )))
            }
        }
    }

    async fn retrieve_tags(&self, _uid: &str) -> InterfaceResult<HashSet<String>> {
        // Not supported for HSMs
        Ok(HashSet::new())
    }

    async fn update_object(
        &self,
        uid: &str,
        _object: &Object,
        _attributes: &Attributes,
        _tags: Option<&HashSet<String>>,
    ) -> InterfaceResult<()> {
        // HSM PKCS#11 slots have no generic KMIP attribute storage: attributes
        // such as Name cannot be persisted to the HSM. We return Ok so that
        // KMIP attribute-only operations (ModifyAttribute, SetAttribute) succeed
        // without error.  Operations that require key material (encrypt, decrypt,
        // wrap, unwrap) always go through the HSM crypto oracle and are unaffected.
        // See: https://github.com/Cosmian/kms/issues/933
        warn!(
            "ModifyAttribute/SetAttribute on HSM key {uid}: attribute update accepted but not \
             persisted to PKCS#11 slot (HSM does not support KMIP attribute storage)"
        );
        Ok(())
    }

    async fn update_state(&self, _uid: &str, _state: State) -> InterfaceResult<()> {
        // not supported for HSMs
        Err(InterfaceError::InvalidRequest(
            "Update state is not supported for HSMs".to_owned(),
        ))
    }

    async fn delete(&self, uid: &str) -> InterfaceResult<()> {
        let (slot_id, key_id) = parse_uid_with_prefix(uid, &self.prefix)?;
        self.hsm.delete(slot_id, key_id.as_bytes()).await?;
        Ok(())
    }

    async fn atomic(
        &self,
        user: &str,
        operations: &[AtomicOperation],
    ) -> InterfaceResult<Vec<String>> {
        if let Some((uid, _object, attributes, _tags)) = is_rsa_keypair_creation(operations) {
            debug!("Creating RSA keypair with uid: {uid}");
            if !self.is_admin(user) {
                return Err(InterfaceError::Unauthorized(
                    "Only the HSM Admin can create HSM keypairs".to_owned(),
                ));
            }
            let (slot_id, sk_id) = parse_uid_with_prefix(&uid, &self.prefix)?;
            let pk_id = sk_id.clone() + SYSTEM_TAG_PUBLIC_KEY;
            self.hsm
                .create_keypair(
                    slot_id,
                    sk_id.as_bytes(),
                    pk_id.as_bytes(),
                    HsmKeypairAlgorithm::RSA,
                    usize::try_from(attributes.cryptographic_length.unwrap_or(2048)).map_err(
                        |e| InterfaceError::InvalidRequest(format!("Invalid key length: {e}")),
                    )?,
                    attributes.sensitive.unwrap_or_default(),
                )
                .await?;
            return Ok(vec![
                format!("{}::{slot_id}::{sk_id}", self.prefix),
                format!("{}::{slot_id}::{pk_id}", self.prefix),
            ]);
        }

        // Handle attribute-only updates (e.g., Fresh flag persisted after export/get).
        // The HSM does not store KMIP metadata attributes, so delegate to update_object()
        // which already accepts gracefully without error.
        if operations
            .iter()
            .all(|op| matches!(op, AtomicOperation::UpdateObject(_)))
        {
            for op in operations {
                if let AtomicOperation::UpdateObject((uid, object, attrs, tags)) = op {
                    self.update_object(uid, object, attrs, tags.as_ref())
                        .await?;
                }
            }
            return Ok(vec![]);
        }

        Err(InterfaceError::InvalidRequest(
            "HSM atomic operations only support RSA keypair creations for now".to_owned(),
        ))
    }

    async fn is_object_owned_by(&self, _uid: &str, owner: &str) -> InterfaceResult<bool> {
        let is_admin = self.is_admin(owner);
        debug!("Is {owner} an HSM admin? {}", is_admin);
        Ok(is_admin)
    }

    async fn list_uids_for_tags(
        &self,
        _tags: &HashSet<String>,
    ) -> InterfaceResult<HashSet<String>> {
        // Not Tags on the HSM
        Ok(HashSet::new())
    }

    async fn find(
        &self,
        researched_attributes: Option<&Attributes>,
        state: Option<State>,
        user: &str,
        user_must_be_owner: bool,
        vendor_id: &str,
    ) -> InterfaceResult<Vec<(String, State, Attributes)>> {
        let slot_ids = self.hsm.get_available_slot_list().await?;
        let mut uids = Vec::new();
        // When the caller requires ownership (e.g. /access/owned), non-admin
        // users should not see HSM keys — only HSM admins "own" HSM keys.
        if user_must_be_owner && !self.is_admin(user) {
            debug!(
                "User '{}' is not an HSM admin; skipping HSM keys for ownership query",
                user
            );
            return Ok(uids);
        }
        let mut search_attributes = researched_attributes.cloned().unwrap_or_else(|| {
            debug!("No researched_attributes provided. Defaulting to empty filter attributes");
            Attributes::default()
        });
        match check_basic_compatibility(vendor_id, &search_attributes, state) {
            Ok(()) => {}
            Err(e) => {
                debug!("{e}");
                return Ok(uids);
            }
        }
        let object_filter = match HsmObjectFilter::try_from(&search_attributes) {
            Ok(object_filter) => object_filter,
            Err(e) => {
                debug!("HSM find: incompatible filter, skipping HSM search: {e}");
                return Ok(uids);
            }
        };
        let key_size_filter = search_attributes.get_cryptographic_length();
        let key_id_filter = match search_attributes.unique_identifier {
            Some(unique_identifier) => {
                let Some(str) = unique_identifier.as_str() else {
                    return Ok(uids);
                };
                Some(str.to_owned())
            }
            None => None,
        };

        for slot_id in slot_ids {
            let found = self
                .hsm
                .find(slot_id, object_filter.clone())
                .await
                .unwrap_or(vec![]);
            for object_id in found {
                trace!("Getting metadata for: {:02X?}", object_id);
                let object_meta = self
                    .hsm
                    .get_key_metadata(slot_id, &object_id)
                    .await
                    .unwrap_or_default();
                if let Some(expected_key_size) = key_size_filter {
                    if let Some(ref meta) = object_meta {
                        if meta.key_length_in_bits != expected_key_size {
                            continue;
                        }
                    } else {
                        continue;
                    }
                }
                let object_string = match str::from_utf8(&object_id) {
                    Ok(object_string) => object_string,
                    Err(err) => {
                        error!("Failed to decode object_id {}", err);
                        continue;
                    }
                };
                let uid = format!("{}::{slot_id}::{object_string}", self.prefix);
                trace!("Found: {uid}");
                if let Some(ref wanted_id) = key_id_filter {
                    if !uid.eq(wanted_id) {
                        continue;
                    }
                }
                // Populate basic attributes from HSM metadata so callers
                // (Locate, /access/owned) can display key info without a
                // separate GetAttributes round-trip.
                let attrs = build_find_attributes(&object_meta, &object_filter);
                uids.push((uid, State::Active, attrs));
            }
        }

        Ok(uids)
    }
}

// ──────────────────────────────────────────────────────────────────────────────
// CryptoOracle implementation
// ──────────────────────────────────────────────────────────────────────────────

#[async_trait]
impl CryptoOracle for HsmStore {
    async fn encrypt(
        &self,
        uid: &str,
        data: &[u8],
        cryptographic_algorithm: Option<CryptoAlgorithm>,
        authenticated_encryption_additional_data: Option<&[u8]>,
    ) -> InterfaceResult<EncryptedContent> {
        if authenticated_encryption_additional_data.is_some() {
            return Err(InterfaceError::InvalidRequest(
                "Additional authenticated data are not supported on HSMs for now".to_owned(),
            ));
        }
        let (mut slot_id, mut key_id) = parse_uid_with_prefix(uid, &self.prefix)?;
        let supported_algorithms = self.hsm.get_supported_algorithms(slot_id).await?;
        let cryptographic_algorithm = if let Some(ca) = cryptographic_algorithm {
            ca
        } else {
            debug!("Using default algorithm to encrypt");
            match self.hsm.get_key_type(slot_id, key_id.as_bytes()).await? {
                None => {
                    return Err(InterfaceError::InvalidRequest(format!(
                        "The key type of key: {uid}, cannot be determined"
                    )));
                }
                Some(key_type) => match key_type {
                    KeyType::AesKey => CryptoAlgorithm::get_aes_algorithm(&supported_algorithms)?,
                    KeyType::RsaPublicKey => {
                        CryptoAlgorithm::get_rsa_algorithm(&supported_algorithms)?
                    }
                    KeyType::RsaPrivateKey => {
                        // try fetching the corresponding public key
                        let pk_uid = format!("{uid}_pk");
                        debug!(
                            "encrypt: an RSA private key {uid} was specified. Trying to use \
                             public key {pk_uid} for encryption"
                        );
                        (slot_id, key_id) = parse_uid_with_prefix(&pk_uid, &self.prefix)?;
                        self.hsm
                            .get_key_type(slot_id, key_id.as_bytes())
                            .await?
                            .ok_or_else(|| {
                                InterfaceError::InvalidRequest(format!(
                                    "The key {uid} is a private key, but no public key {pk_uid} \
                                     is available"
                                ))
                            })?;
                        CryptoAlgorithm::get_rsa_algorithm(&supported_algorithms)?
                    }
                },
            }
        };
        self.hsm
            .encrypt(slot_id, key_id.as_bytes(), cryptographic_algorithm, data)
            .await
    }

    async fn decrypt(
        &self,
        uid: &str,
        data: &[u8],
        cryptographic_algorithm: Option<CryptoAlgorithm>,
        authenticated_encryption_additional_data: Option<&[u8]>,
    ) -> InterfaceResult<Zeroizing<Vec<u8>>> {
        if authenticated_encryption_additional_data.is_some() {
            return Err(InterfaceError::InvalidRequest(
                "Additional authenticated data are not supported on HSMs for now".to_owned(),
            ));
        }
        let (slot_id, key_id) = parse_uid_with_prefix(uid, &self.prefix)?;
        let supported_algorithms = self.hsm.get_supported_algorithms(slot_id).await?;
        let cryptographic_algorithm = if let Some(ca) = cryptographic_algorithm {
            ca
        } else {
            debug!("Using default algorithm to decrypt");
            match self.hsm.get_key_type(slot_id, key_id.as_bytes()).await? {
                None => {
                    return Err(InterfaceError::InvalidRequest(
                        "The key {}type is not known".to_owned(),
                    ));
                }
                Some(key_type) => match key_type {
                    KeyType::AesKey => CryptoAlgorithm::get_aes_algorithm(&supported_algorithms)?,
                    KeyType::RsaPrivateKey => {
                        CryptoAlgorithm::get_rsa_algorithm(&supported_algorithms)?
                    }
                    KeyType::RsaPublicKey => {
                        return Err(InterfaceError::Default(
                            "An RSA public key cannot be used to decrypt".to_owned(),
                        ));
                    }
                },
            }
        };
        self.hsm
            .decrypt(slot_id, key_id.as_bytes(), cryptographic_algorithm, data)
            .await
    }

    async fn get_key_type(&self, uid: &str) -> InterfaceResult<Option<KeyType>> {
        let (slot_id, key_id) = parse_uid_with_prefix(uid, &self.prefix)?;
        self.hsm.get_key_type(slot_id, key_id.as_bytes()).await
    }

    async fn get_key_metadata(&self, uid: &str) -> InterfaceResult<Option<KeyMetadata>> {
        let (slot_id, key_id) = parse_uid_with_prefix(uid, &self.prefix)?;
        self.hsm.get_key_metadata(slot_id, key_id.as_bytes()).await
    }

    async fn sign(
        &self,
        uid: &str,
        data: &[u8],
        cryptographic_parameters: Option<
            &cosmian_kmip::kmip_2_1::kmip_types::CryptographicParameters,
        >,
    ) -> InterfaceResult<Vec<u8>> {
        let (slot_id, key_id) = parse_uid_with_prefix(uid, &self.prefix)?;
        let key_type = self.hsm.get_key_type(slot_id, key_id.as_bytes()).await?;
        match key_type {
            Some(KeyType::RsaPrivateKey) => {}
            Some(other) => {
                return Err(InterfaceError::InvalidRequest(format!(
                    "Sign: key {uid} is a {other:?}, expected an RSA private key"
                )));
            }
            None => {
                return Err(InterfaceError::InvalidRequest(format!(
                    "Sign: key {uid} not found on the HSM"
                )));
            }
        }
        let algorithm = SigningAlgorithm::from_kmip(cryptographic_parameters)?;
        debug!("sign: using algorithm {algorithm:?} for key {uid}");
        self.hsm
            .sign(slot_id, key_id.as_bytes(), algorithm, data)
            .await
    }

    async fn signature_verify(
        &self,
        uid: &str,
        _data: &[u8],
        _signature: &[u8],
        _cryptographic_parameters: Option<
            &cosmian_kmip::kmip_2_1::kmip_types::CryptographicParameters,
        >,
    ) -> InterfaceResult<bool> {
        Err(InterfaceError::NotSupported(format!(
            "SignatureVerify via HSM is not yet implemented for key: {uid}"
        )))
    }

    async fn mac(
        &self,
        uid: &str,
        _data: &[u8],
        _cryptographic_parameters: Option<
            &cosmian_kmip::kmip_2_1::kmip_types::CryptographicParameters,
        >,
    ) -> InterfaceResult<Vec<u8>> {
        Err(InterfaceError::NotSupported(format!(
            "MAC via HSM is not yet implemented for key: {uid}"
        )))
    }

    async fn mac_verify(
        &self,
        uid: &str,
        _data: &[u8],
        _mac_data: &[u8],
        _cryptographic_parameters: Option<
            &cosmian_kmip::kmip_2_1::kmip_types::CryptographicParameters,
        >,
    ) -> InterfaceResult<bool> {
        Err(InterfaceError::NotSupported(format!(
            "MACVerify via HSM is not yet implemented for key: {uid}"
        )))
    }
}

// ──────────────────────────────────────────────────────────────────────────────
// Private helpers
// ──────────────────────────────────────────────────────────────────────────────

/// Build a metadata-only `Attributes` struct for a non-extractable (sensitive) HSM key.
///
/// Used when `hsm.export()` fails with a sensitive-key error. The stub allows
/// attribute-only KMIP operations (`ModifyAttribute`, `GetAttributes`) to succeed
/// without accessing the key material.
/// See: <https://github.com/Cosmian/kms/issues/933>
fn build_sensitive_stub_attributes(meta: &KeyMetadata) -> Attributes {
    let (algorithm, obj_type, usage_mask, key_format_type) = match meta.key_type {
        KeyType::AesKey => (
            CryptographicAlgorithm::AES,
            ObjectType::SymmetricKey,
            CryptographicUsageMask::Encrypt
                | CryptographicUsageMask::Decrypt
                | CryptographicUsageMask::WrapKey
                | CryptographicUsageMask::UnwrapKey
                | CryptographicUsageMask::KeyAgreement,
            KeyFormatType::Raw,
        ),
        KeyType::RsaPrivateKey => (
            CryptographicAlgorithm::RSA,
            ObjectType::PrivateKey,
            CryptographicUsageMask::Decrypt
                | CryptographicUsageMask::UnwrapKey
                | CryptographicUsageMask::Sign,
            KeyFormatType::PKCS1,
        ),
        KeyType::RsaPublicKey => (
            CryptographicAlgorithm::RSA,
            ObjectType::PublicKey,
            CryptographicUsageMask::Encrypt
                | CryptographicUsageMask::WrapKey
                | CryptographicUsageMask::Verify,
            KeyFormatType::PKCS1,
        ),
    };
    Attributes {
        cryptographic_algorithm: Some(algorithm),
        cryptographic_length: Some(i32::try_from(meta.key_length_in_bits).unwrap_or_default()),
        object_type: Some(obj_type),
        cryptographic_usage_mask: Some(usage_mask),
        key_format_type: Some(key_format_type),
        sensitive: Some(true),
        ..Attributes::default()
    }
}

/// Build a stub KMIP `Object` for a non-extractable (sensitive) HSM key.
///
/// The `key_value` is intentionally empty because the key bytes cannot be
/// exported from the HSM. This stub is only used for attribute-only operations.
/// See: <https://github.com/Cosmian/kms/issues/933>
fn build_sensitive_stub_object(meta: &KeyMetadata) -> Object {
    let length = i32::try_from(meta.key_length_in_bits).unwrap_or_default();
    match meta.key_type {
        KeyType::AesKey => {
            let attributes = Attributes {
                cryptographic_algorithm: Some(CryptographicAlgorithm::AES),
                cryptographic_length: Some(length),
                object_type: Some(ObjectType::SymmetricKey),
                sensitive: Some(true),
                ..Attributes::default()
            };
            Object::SymmetricKey(SymmetricKey {
                key_block: KeyBlock {
                    key_format_type: KeyFormatType::TransparentSymmetricKey,
                    key_compression_type: None,
                    key_value: Some(KeyValue::Structure {
                        key_material: KmipKeyMaterial::TransparentSymmetricKey {
                            key: zeroize::Zeroizing::new(vec![]),
                        },
                        attributes: Some(attributes),
                    }),
                    cryptographic_algorithm: Some(CryptographicAlgorithm::AES),
                    cryptographic_length: Some(length),
                    key_wrapping_data: None,
                },
            })
        }
        // For RSA sensitive keys (unusual but possible), build a minimal SymmetricKey-shaped
        // stub so callers can still perform attribute-only operations.  The object_type in
        // the attributes is set correctly (PrivateKey / PublicKey).
        KeyType::RsaPrivateKey | KeyType::RsaPublicKey => {
            let obj_type = if meta.key_type == KeyType::RsaPrivateKey {
                ObjectType::PrivateKey
            } else {
                ObjectType::PublicKey
            };
            let attributes = Attributes {
                cryptographic_algorithm: Some(CryptographicAlgorithm::RSA),
                cryptographic_length: Some(length),
                object_type: Some(obj_type),
                sensitive: Some(true),
                ..Attributes::default()
            };
            // Return a SymmetricKey wrapper — the key material is empty and the
            // sensitive flag signals callers not to attempt material access.
            Object::SymmetricKey(SymmetricKey {
                key_block: KeyBlock {
                    key_format_type: KeyFormatType::TransparentSymmetricKey,
                    key_compression_type: None,
                    key_value: Some(KeyValue::Structure {
                        key_material: KmipKeyMaterial::TransparentSymmetricKey {
                            key: zeroize::Zeroizing::new(vec![]),
                        },
                        attributes: Some(attributes),
                    }),
                    cryptographic_algorithm: Some(CryptographicAlgorithm::RSA),
                    cryptographic_length: Some(length),
                    key_wrapping_data: None,
                },
            })
        }
    }
}

fn build_find_attributes(meta: &Option<KeyMetadata>, filter: &HsmObjectFilter) -> Attributes {
    let mut attrs = Attributes::default();
    if let Some(m) = meta {
        attrs.cryptographic_length = Some(i32::try_from(m.key_length_in_bits).unwrap_or_default());
        match m.key_type {
            KeyType::AesKey => {
                attrs.cryptographic_algorithm = Some(CryptographicAlgorithm::AES);
                attrs.object_type = Some(ObjectType::SymmetricKey);
                attrs.key_format_type = Some(KeyFormatType::Raw);
            }
            KeyType::RsaPrivateKey => {
                attrs.cryptographic_algorithm = Some(CryptographicAlgorithm::RSA);
                attrs.object_type = Some(ObjectType::PrivateKey);
                attrs.key_format_type = Some(KeyFormatType::PKCS1);
            }
            KeyType::RsaPublicKey => {
                attrs.cryptographic_algorithm = Some(CryptographicAlgorithm::RSA);
                attrs.object_type = Some(ObjectType::PublicKey);
                attrs.key_format_type = Some(KeyFormatType::PKCS1);
            }
        }
    } else {
        // No metadata available — infer from the filter
        match filter {
            HsmObjectFilter::AesKey => {
                attrs.cryptographic_algorithm = Some(CryptographicAlgorithm::AES);
                attrs.object_type = Some(ObjectType::SymmetricKey);
                attrs.key_format_type = Some(KeyFormatType::Raw);
            }
            HsmObjectFilter::RsaKey => {
                attrs.cryptographic_algorithm = Some(CryptographicAlgorithm::RSA);
            }
            HsmObjectFilter::RsaPrivateKey => {
                attrs.cryptographic_algorithm = Some(CryptographicAlgorithm::RSA);
                attrs.object_type = Some(ObjectType::PrivateKey);
                attrs.key_format_type = Some(KeyFormatType::PKCS1);
            }
            HsmObjectFilter::RsaPublicKey => {
                attrs.cryptographic_algorithm = Some(CryptographicAlgorithm::RSA);
                attrs.object_type = Some(ObjectType::PublicKey);
                attrs.key_format_type = Some(KeyFormatType::PKCS1);
            }
            HsmObjectFilter::Any => {}
        }
    }
    attrs
}

fn check_basic_compatibility(
    vendor_id: &str,
    researched_attributes: &Attributes,
    state: Option<State>,
) -> InterfaceResult<()> {
    // HSM keys are always active.
    if let Some(s) = state {
        if s != State::Active {
            return Err(InterfaceError::Default(format!(
                "Unsupported state for HSMs: expected Active, got {s:?}"
            )));
        }
    }

    if researched_attributes.link.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: link".to_owned(),
        ));
    }

    if !researched_attributes.get_tags(vendor_id).is_empty() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: tags".to_owned(),
        ));
    }

    if researched_attributes.object_group.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: object_group".to_owned(),
        ));
    }

    if researched_attributes.object_group_member.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: object_group_member".to_owned(),
        ));
    }

    if researched_attributes.comment.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: comment".to_owned(),
        ));
    }

    if researched_attributes.contact_information.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: contact_information".to_owned(),
        ));
    }

    if let Some(critical) = researched_attributes.critical {
        if critical {
            return Err(InterfaceError::Default(
                "Unsupported attribute for HSMs: critical = true".to_owned(),
            ));
        }
    }

    if researched_attributes.description.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: description".to_owned(),
        ));
    }

    if researched_attributes.digest.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: digest".to_owned(),
        ));
    }

    if researched_attributes.short_unique_identifier.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: short_unique_identifier".to_owned(),
        ));
    }

    if researched_attributes.cryptographic_usage_mask.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: cryptographic_usage_mask".to_owned(),
        ));
    }

    if researched_attributes.x_509_certificate_identifier.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: x_509_certificate_identifier".to_owned(),
        ));
    }

    if researched_attributes.x_509_certificate_issuer.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: x_509_certificate_issuer".to_owned(),
        ));
    }

    if researched_attributes.x_509_certificate_subject.is_some() {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: x_509_certificate_subject".to_owned(),
        ));
    }

    // HSM keys do not have KMIP Name attributes.  If the caller filters by Name,
    // no HSM key can ever match — return empty rather than ignoring the filter
    // and leaking unrelated internal keys (e.g. the server KEK). (issue #935)
    if researched_attributes
        .name
        .as_ref()
        .is_some_and(|names| !names.is_empty())
    {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: name".to_owned(),
        ));
    }

    // HSM keys do not carry ApplicationSpecificInformation; filter should return empty.
    if researched_attributes
        .application_specific_information
        .is_some()
    {
        return Err(InterfaceError::Default(
            "Unsupported attribute for HSMs: application_specific_information".to_owned(),
        ));
    }

    Ok(())
}

/// The creation of RSA key pairs is done via 2 atomic operations,
/// one to create the private key and one to generate the public key.
/// All the information we need is contained in the atomic operation
/// to create the private key, so we recover it here
///
/// # Returns
/// - the UID of the private key
/// - the object of the private key
/// - the attributes of the private key
fn is_rsa_keypair_creation(
    operations: &[AtomicOperation],
) -> Option<(String, Object, Attributes, HashSet<String>)> {
    operations
        .iter()
        .filter_map(|op| match op {
            AtomicOperation::Create((uid, object, attributes, tags)) => {
                if object.object_type() != ObjectType::PrivateKey {
                    return None;
                }
                if !attributes
                    .cryptographic_algorithm
                    .as_ref()
                    .is_some_and(|algorithm| *algorithm == CryptographicAlgorithm::RSA)
                {
                    return None;
                }
                Some((
                    uid.clone(),
                    object.clone(),
                    attributes.clone(),
                    tags.clone(),
                ))
            }
            _ => None,
        })
        .collect::<Vec<_>>()
        .first()
        .cloned()
}

/// Parse the `uid` into a `(slot_id, key_id)` pair, stripping the given prefix.
fn parse_uid_with_prefix(uid: &str, prefix: &str) -> Result<(usize, String), InterfaceError> {
    let rest = uid
        .strip_prefix(&format!("{prefix}::"))
        .ok_or_else(|| {
            InterfaceError::InvalidRequest(format!(
                "An HSM request must have a uid in the form of '{prefix}::<slot_id>::<key_id>', got: {uid}"
            ))
        })?;
    let (slot_id, key_id) = rest.split_once("::").ok_or_else(|| {
        InterfaceError::InvalidRequest(format!(
            "An HSM request must have a uid in the form of '{prefix}::<slot_id>::<key_id>', got: {uid}"
        ))
    })?;
    let slot_id = slot_id.parse::<usize>().map_err(|e| {
        InterfaceError::InvalidRequest(format!("The slot_id must be a valid unsigned integer: {e}"))
    })?;
    Ok((slot_id, key_id.to_owned()))
}

fn to_object_with_metadata(
    hsm_object: &HsmObject,
    uid: &str,
    user: &str,
    vendor_id: &str,
) -> InterfaceResult<ObjectWithMetadata> {
    match hsm_object.key_material() {
        KeyMaterial::AesKey(bytes) => {
            let length: i32 = 8 * i32::try_from(bytes.len())
                .map_err(|e| InterfaceError::InvalidRequest(format!("Invalid key length: {e}")))?;
            let mut attributes = Attributes {
                cryptographic_algorithm: Some(CryptographicAlgorithm::AES),
                cryptographic_length: Some(length),
                object_type: Some(ObjectType::SymmetricKey),
                // TODO: query these flags from the HSM
                cryptographic_usage_mask: Some(
                    CryptographicUsageMask::Encrypt
                        | CryptographicUsageMask::Decrypt
                        | CryptographicUsageMask::WrapKey
                        | CryptographicUsageMask::UnwrapKey
                        | CryptographicUsageMask::KeyAgreement,
                ),
                ..Attributes::default()
            };
            let mut tags: HashSet<String> =
                serde_json::from_str(hsm_object.id()).unwrap_or_else(|_| HashSet::new());
            tags.insert(SYSTEM_TAG_SYMMETRIC_KEY.to_owned());
            attributes
                .set_tags(vendor_id, tags)
                .map_err(|e| InterfaceError::InvalidRequest(format!("Invalid tags: {e}")))?;
            let kmip_key_material = KmipKeyMaterial::TransparentSymmetricKey { key: bytes.clone() };
            let object = Object::SymmetricKey(SymmetricKey {
                key_block: KeyBlock {
                    key_format_type: KeyFormatType::TransparentSymmetricKey,
                    key_compression_type: None,
                    key_value: Some(KeyValue::Structure {
                        key_material: kmip_key_material,
                        attributes: Some(attributes.clone()),
                    }),
                    cryptographic_algorithm: Some(CryptographicAlgorithm::AES),
                    cryptographic_length: Some(
                        8 * i32::try_from(bytes.len()).map_err(|e| {
                            InterfaceError::InvalidRequest(format!("Invalid key length: {e}"))
                        })?,
                    ),
                    key_wrapping_data: None,
                },
            });
            Ok(ObjectWithMetadata::new(
                uid.to_owned(),
                object,
                user.to_owned(),
                State::Active,
                attributes,
            ))
        }
        KeyMaterial::RsaPrivateKey(km) => {
            let mut attributes = Attributes {
                cryptographic_algorithm: Some(CryptographicAlgorithm::RSA),
                cryptographic_length: Some(
                    8 * i32::try_from(km.modulus.len()).map_err(|e| {
                        InterfaceError::InvalidRequest(format!("Invalid key length: {e}"))
                    })?,
                ),
                object_type: Some(ObjectType::PrivateKey),
                // TODO: query these flags from the HSM
                cryptographic_usage_mask: Some(
                    CryptographicUsageMask::Decrypt
                        | CryptographicUsageMask::UnwrapKey
                        | CryptographicUsageMask::Sign,
                ),
                ..Attributes::default()
            };
            let mut tags: HashSet<String> =
                serde_json::from_str(hsm_object.id()).unwrap_or_else(|_| HashSet::new());
            tags.insert(SYSTEM_TAG_PRIVATE_KEY.to_owned());
            attributes
                .set_tags(vendor_id, tags)
                .map_err(|e| InterfaceError::InvalidRequest(format!("Invalid tags: {e}")))?;
            let kmip_key_material = KmipKeyMaterial::TransparentRSAPrivateKey {
                modulus: Box::new(BigInt::from_bytes_be(Sign::Plus, km.modulus.as_slice())),
                private_exponent: Some(Box::new(SafeBigInt::from_bytes_be(
                    km.private_exponent.as_slice(),
                ))),
                public_exponent: Some(Box::new(BigInt::from_bytes_be(
                    Sign::Plus,
                    km.public_exponent.as_slice(),
                ))),
                p: Some(Box::new(SafeBigInt::from_bytes_be(km.prime_1.as_slice()))),
                q: Some(Box::new(SafeBigInt::from_bytes_be(km.prime_2.as_slice()))),
                prime_exponent_p: Some(Box::new(SafeBigInt::from_bytes_be(
                    km.exponent_1.as_slice(),
                ))),
                prime_exponent_q: Some(Box::new(SafeBigInt::from_bytes_be(
                    km.exponent_2.as_slice(),
                ))),
                c_r_t_coefficient: Some(Box::new(SafeBigInt::from_bytes_be(
                    km.coefficient.as_slice(),
                ))),
            };
            let object = Object::PrivateKey(PrivateKey {
                key_block: KeyBlock {
                    key_format_type: KeyFormatType::TransparentRSAPrivateKey,
                    key_compression_type: None,
                    key_value: Some(KeyValue::Structure {
                        key_material: kmip_key_material,
                        attributes: Some(attributes.clone()),
                    }),
                    cryptographic_algorithm: Some(CryptographicAlgorithm::RSA),
                    cryptographic_length: Some(
                        8 * i32::try_from(km.modulus.len()).map_err(|e| {
                            InterfaceError::InvalidRequest(format!("Invalid key length: {e}"))
                        })?,
                    ),
                    key_wrapping_data: None,
                },
            });
            Ok(ObjectWithMetadata::new(
                uid.to_owned(),
                object,
                user.to_owned(),
                State::Active,
                attributes,
            ))
        }
        KeyMaterial::RsaPublicKey(km) => {
            let mut attributes = Attributes {
                cryptographic_algorithm: Some(CryptographicAlgorithm::RSA),
                cryptographic_length: Some(
                    i32::try_from(km.modulus.len()).map_err(|e| {
                        InterfaceError::InvalidRequest(format!("Invalid key length: {e}"))
                    })? * 8,
                ),
                object_type: Some(ObjectType::PublicKey),
                // TODO: query these flags from the HSM
                cryptographic_usage_mask: Some(
                    CryptographicUsageMask::Encrypt
                        | CryptographicUsageMask::WrapKey
                        | CryptographicUsageMask::Verify,
                ),
                ..Attributes::default()
            };
            let mut tags: HashSet<String> =
                serde_json::from_str(hsm_object.id()).unwrap_or_else(|_| HashSet::new());
            tags.insert(SYSTEM_TAG_PUBLIC_KEY.to_owned());
            attributes
                .set_tags(vendor_id, tags)
                .map_err(|e| InterfaceError::InvalidRequest(format!("Invalid tags: {e}")))?;
            let kmip_key_material = TransparentRSAPublicKey {
                modulus: Box::new(BigInt::from_bytes_be(Sign::Plus, km.modulus.as_slice())),
                public_exponent: Box::new(BigInt::from_bytes_be(
                    Sign::Plus,
                    km.public_exponent.as_slice(),
                )),
            };
            let object = Object::PublicKey(PublicKey {
                key_block: KeyBlock {
                    key_format_type: KeyFormatType::TransparentRSAPublicKey,
                    key_compression_type: None,
                    key_value: Some(KeyValue::Structure {
                        key_material: kmip_key_material,
                        attributes: Some(attributes.clone()),
                    }),
                    cryptographic_algorithm: Some(CryptographicAlgorithm::RSA),
                    cryptographic_length: Some(
                        i32::try_from(km.modulus.len()).map_err(|e| {
                            InterfaceError::InvalidRequest(format!("Invalid key length: {e}"))
                        })? * 8,
                    ),
                    key_wrapping_data: None,
                },
            });
            Ok(ObjectWithMetadata::new(
                uid.to_owned(),
                object,
                user.to_owned(),
                State::Active,
                attributes,
            ))
        }
    }
}

#[cfg(test)]
mod tests {
    use cosmian_kmip::kmip_2_1::{
        kmip_attributes::Attributes,
        kmip_types::{Name, NameType},
    };

    use super::check_basic_compatibility;
    use crate::InterfaceError;

    /// Locate with a Name filter must not match any HSM key (issue #935):
    /// HSM keys have no KMIP Name, so the filter should yield empty results
    /// rather than silently ignoring the Name and leaking internal keys.
    #[test]
    fn test_name_filter_rejected_for_hsm() {
        let attrs = Attributes {
            name: Some(vec![Name {
                name_value: "test-duplicate".to_owned(),
                name_type: NameType::UninterpretedTextString,
            }]),
            ..Default::default()
        };

        let result = check_basic_compatibility("cosmian", &attrs, None);
        assert!(
            matches!(result, Err(InterfaceError::Default(ref msg)) if msg.contains("name")),
            "Expected name attribute to be rejected for HSM, got: {result:?}"
        );
    }

    /// Locate with no Name filter should be compatible (basic `SymmetricKey` search).
    #[test]
    fn test_no_name_filter_compatible() {
        use cosmian_kmip::kmip_2_1::kmip_objects::ObjectType;
        let attrs = Attributes {
            object_type: Some(ObjectType::SymmetricKey),
            ..Default::default()
        };

        let result = check_basic_compatibility("cosmian", &attrs, None);
        assert!(
            result.is_ok(),
            "Expected ObjectType-only filter to be compatible with HSM, got: {result:?}"
        );
    }
}