--- layout: "docs" page_title: "PKCS11 - Seals - Configuration" sidebar_current: "docs-configuration-seal-pkcs11" description: |- The PKCS11 seal configures Vault to use an HSM with PKCS11 as the seal wrapping mechanism. --- # `pkcs11` Seal The PKCS11 seal configures Vault to use an HSM with PKCS11 as the seal wrapping mechanism. Vault Enterprise's HSM PKCS11 support is activated by one of the following: * The presence of a `seal "pkcs11"` block in Vault's configuration file * The presence of the environment variable `VAULT_HSM_LIB` set to the library's path as well as `VAULT_HSM_TYPE` set to `pkcs11`. If enabling via environment variable, all other required values (i.e. `VAULT_HSM_SLOT`) must be also supplied. **IMPORTANT**: Having Vault generate its own key is the easiest way to get up and running, but for security, Vault marks the key as non-exportable. If your HSM key backup strategy requires the key to be exportable, you should generate the key yourself. The list of creation attributes that Vault uses to generate the key are listed at the end of this document. ## Requirements The following software packages are required for Vault Enterprise HSM: - PKCS#11 compatible HSM integration library. Vault targets version 2.2 or higher of PKCS#11. Depending on any given HSM, some functions (such as key generation) may have to be performed manually. - The [GNU libltdl library](https://www.gnu.org/software/libtool/manual/html_node/Using-libltdl.html) — ensure that it is installed for the correct architecture of your servers ## `pkcs11` Example This example shows configuring HSM PKCS11 seal through the Vault configuration file by providing all the required values: ```hcl seal "pkcs11" { lib = "/usr/vault/lib/libCryptoki2_64.so" slot = "0" pin = "AAAA-BBBB-CCCC-DDDD" key_label = "vault-hsm-key" hmac_key_label = "vault-hsm-hmac-key" } ``` ## `pkcs11` Parameters These parameters apply to the `seal` stanza in the Vault configuration file: - `lib` `(string: )`: The path to the PKCS#11 library shared object file. May also be specified by the `VAULT_HSM_LIB` environment variable. **Note:** Depending on your HSM, this may be either a binary or a dynamic library, and its use may require other libraries depending on which system the Vault binary is currently running on (e.g.: a Linux system may require other libraries to interpret Windows .dll files). - `slot` `(string: )`: The slot number to use, specified as a string (e.g. `"0"`). May also be specified by the `VAULT_HSM_SLOT` environment variable. - `token_label` `(string: )`: The slot token label to use. May also be specified by the `VAULT_HSM_TOKEN_LABEL` environment variable. - `pin` `(string: )`: The PIN for login. May also be specified by the `VAULT_HSM_PIN` environment variable. _If set via the environment variable, Vault will obfuscate the environment variable after reading it, and it will need to be re-set if Vault is restarted._ - `key_label` `(string: )`: The label of the key to use. If the key does not exist and generation is enabled, this is the label that will be given to the generated key. May also be specified by the `VAULT_HSM_KEY_LABEL` environment variable. - `default_key_label` `(string: "")`: This is the default key label for decryption operations. Prior to 0.10.1, key labels were not stored with the ciphertext. Seal entries now track the label used in encryption operations. The default value for this field is the `key_label`. If `key_label` is rotated and this value is not set, decryption may fail. May also be specified by the `VAULT_HSM_DEFAULT_KEY_LABEL` environment variable. This value is ignored in new installations. - `hmac_key_label` `(string: )`: The label of the key to use for HMACing. This needs to be a suitable type. If Vault tries to create this it will attempt to use CKK_GENERIC_SECRET_KEY. If the key does not exist and generation is enabled, this is the label that will be given to the generated key. May also be specified by the `VAULT_HSM_HMAC_KEY_LABEL` environment variable. - `default_key_label` `(string: "")`: This is the default HMAC key label for signing operations. Prior to 0.10.1, HMAC key labels were not stored with the signature. Seal entries now track the label used in signing operations. The default value for this field is the `hmac_key_label`. If `hmac_key_label` is rotated and this value is not set, signature verification may fail. May also be specified by the `VAULT_HSM_HMAC_DEFAULT_KEY_LABEL` environment variable. This value is ignored in new installations. - `mechanism` `(string: )`: The encryption/decryption mechanism to use, specified as a decimal or hexadecimal (prefixed by `0x`) string. May also be specified by the `VAULT_HSM_MECHANISM` environment variable. Currently supported mechanisms (in order of precedence): - `0x1085` `CKM_AES_CBC_PAD` (HMAC mechanism required) - `0x1082` `CKM_AES_CBC` (HMAC mechanism required) - `0x1087` `CKM_AES_GCM` - `0x0009` `CKM_RSA_PKCS_OAEP` - `0x0001` `CKM_RSA_PKCS` - `hmac_mechanism` `(string: "0x0251")`: The encryption/decryption mechanism to use, specified as a decimal or hexadecimal (prefixed by `0x`) string. Currently only `0x0251` (corresponding to `CKM_SHA256_HMAC` from the specification) is supported. May also be specified by the `VAULT_HSM_HMAC_MECHANISM` environment variable. This value is only required for specific mechanisms. - `generate_key` `(string: "false")`: If no existing key with the label specified by `key_label` can be found at Vault initialization time, instructs Vault to generate a key. This is a boolean expressed as a string (e.g. `"true"`). May also be specified by the `VAULT_HSM_GENERATE_KEY` environment variable. Vault may not be able to successfully generate keys in all circumstances, such as if proprietary vendor extensions are required to create keys of a suitable type. - `regenerate_key` `(string: "false")`: Force generation of a new key even if one with the given `key_label` and `hmac_key_label` already exists. _**This will render previous data unrecoverable**_ and is meant for testing scenarios. This is a boolean expressed as a string (e.g. `"true"`). May also be specified by the `VAULT_HSM_REGENERATE_KEY` environment variable. ### Mechanism Specific Flags - `rsa_encrypt_local` `(string: "false")`: For HSMs that do not support encryption for RSA keys, perform encryption locally. Available for mechanisms `CKM_RSA_PKCS_OAEP` and `CKM_RSA_PKCS`. May also be specified by the `VAULT_HSM_RSA_ENCRYPT_LOCAL` environment variable. - `rsa_oaep_hash` `(string: "sha256")`: Specifiy the hash algorithm to use for RSA with OAEP padding. Valid values are sha1, sha224, sha256, sha384, and sha512. Available for mechanism `CKM_RSA_PKCS_OAEP`. May also be specified by the `VAULT_HSM_RSA_OAEP_HASH` environment variable. ~> **Note:** Although the configuration file allows you to pass in `VAULT_HSM_PIN` as part of the seal's parameters, it is *strongly* recommended to set this value via environment variables. ## `pkcs11` Environment Variables Alternatively, the HSM seal can be activated by providing the following environment variables: ```text VAULT_HSM_LIB VAULT_HSM_TYPE VAULT_HSM_SLOT VAULT_HSM_TOKEN_LABEL VAULT_HSM_PIN VAULT_HSM_KEY_LABEL VAULT_HSM_DEFAULT_KEY_LABEL VAULT_HSM_HMAC_KEY_LABEL VAULT_HSM_HMAC_DEFAULT_KEY_LABEL VAULT_HSM_MECHANISM VAULT_HSM_HMAC_MECHANISM VAULT_HSM_GENERATE_KEY VAULT_HSM_REGENERATE_KEY VAULT_HSM_RSA_ENCRYPT_LOCAL VAULT_HSM_RSA_OAEP_HASH ``` ## Vault Key Generation Attributes If Vault generates the HSM key for you, the following is the list of attributes it uses. These identifiers correspond to official PKCS#11 identifiers. ### AES Key * `CKA_CLASS`: `CKO_SECRET_KEY` (It's a secret key) * `CKA_KEY_TYPE`: `CKK_AES` (Key type is AES) * `CKA_VALUE_LEN`: `32` (Key size is 256 bits) * `CKA_LABEL`: Set to the key label set in Vault's configuration * `CKA_ID`: Set to a random 32-bit unsigned integer * `CKA_PRIVATE`: `true` (Key is private to this slot/token) * `CKA_TOKEN`: `true` (Key persists to the slot/token rather than being for one session only) * `CKA_SENSITIVE`: `true` (Key is a sensitive value) * `CKA_ENCRYPT`: `true` (Key can be used for encryption) * `CKA_DECRYPT`: `true` (Key can be used for decryption) * `CKA_WRAP`: `true` (Key can be used for wrapping) * `CKA_UNWRAP`: `true` (Key can be used for unwrapping) * `CKA_EXTRACTABLE`: `false` (Key cannot be exported) ### RSA Key _Public Key_ * `CKA_CLASS`: `CKO_PUBLIC_KEY` (It's a public key) * `CKA_KEY_TYPE`: `CKK_RSA` (Key type is RSA) * `CKA_LABEL`: Set to the key label set in Vault's configuration * `CKA_ID`: Set to a random 32-bit unsigned integer * `CKA_ENCRYPT`: `true` (Key can be used for encryption) * `CKA_WRAP`: `true` (Key can be used for wrapping) * `CKA_MODULUS_BITS`: `2048` (Key size is 2048 bits) * `CKA_PUBLIC_EXPONENT`: `0x10001` (Public exponent of 65537) * `CKA_TOKEN`: `true` (Key persists to the slot/token rather than being for one session only) _Private Key_ * `CKA_CLASS`: `CKO_PRIVATE_KEY` (It's a private key) * `CKA_KEY_TYPE`: `CKK_RSA` (Key type is RSA) * `CKA_LABEL`: Set to the key label set in Vault's configuration * `CKA_ID`: Set to a random 32-bit unsigned integer * `CKA_DECRYPT`: `true` (Key can be used for decryption) * `CKA_UNWRAP`: `true` (Key can be used for unwrapping) * `CKA_TOKEN`: `true` (Key persists to the slot/token rather than being for one session only) * `CKA_EXTRACTABLE`: `false` (Key cannot be exported) ### HMAC Key * `CKA_CLASS`: `CKO_SECRET_KEY` (It's a secret key) * `CKA_KEY_TYPE`: `CKK_GENERIC_SECRET_KEY` (Key type is a generic secret key) * `CKA_VALUE_LEN`: `32` (Key size is 256 bits) * `CKA_LABEL`: Set to the HMAC key label set in Vault's configuration * `CKA_ID`: Set to a random 32-bit unsigned integer * `CKA_PRIVATE`: `true` (Key is private to this slot/token) * `CKA_TOKEN`: `true` (Key persists to the slot/token rather than being for one session only) * `CKA_SENSITIVE`: `true` (Key is a sensitive value) * `CKA_SIGN`: `true` (Key can be used for signing) * `CKA_VERIFY`: `true` (Key can be used for verifying) * `CKA_EXTRACTABLE`: `false` (Key cannot be exported) ## Key Rotation This seal supports rotating keys by using different key labels to track key versions. To rotate the key value, generate a new key in a different key label in the HSM and update Vault's configuration with the new key label value. Restart your vault instance to pick up the new key label and all new encryption operations will use the updated key label. Old keys must not be disabled or deleted and are used to decrypt older data. **NOTE**: Prior to version 0.10.1, key information was not tracked with the ciphertext. If rotation is desired for data that was seal wrapped prior to this version must also set `default_key_label` and `hmac_default_key_label` to allow for decryption of older values.