A KMIP server stores and controls
Managed Objects like symmetric and asymmetric keys, certificates, and user defined objects. Clients then use the protocol for accessing these objects subject to a security model that is implemented by the servers. Operations are provided to create, locate, use, retrieve and update managed objects. Each
managed object comprises an immutable
Value like a key-block containing a cryptographic-key. These objects also have mutable
Attributes which can be used for storing metadata about their keys. Some attributes are derived directly from the Value, like the cryptographic-algorithm and key-length. Other attributes are defined in the specification for the management of objects like the Application-Specific Identifier which is usually derived from tape-identification data. Additional identifiers can be defined by the server or client per application need. Each object is identified by a unique and immutable object-identifier generated by the server and is used for getting object-values. Managed-objects may also be given a number of mutable yet globally unique
Name attribute which can be used for Locating objects.
Objects The types of managed-objects being managed by KMIP include: • Symmetric-Keys used for algorithms like AES. • Public and Private Keys used for asymmetric-algorithms like
RSA, DSA and ECDH. Separate objects are used for storing the public and private key, thus a user may have permission to access one but not the other. Related objects usually contain Link attributes containing the other object's unique identifier. • Certificates and PGP Keys. • Split Keys, with each split being a distinct object that can be managed independently from the other splits. • Secret Data, such as passwords. • Opaque Data for client and server defined extensions. • Certificate Signing Requests.
Operations The operations provided by KMIP include: • Create: creating a new managed object such as a symmetric key, and return the identifier. • Create Key Pair: creating two objects that represent asymmetric keys. • Get: retrieving an object's value given its unique identifier. The returned value may be wrapped (encrypted) with another key that is on the server for additional security. • Register: storing an externally generated key value. • Add Attributes, Get Attributes, Modify Attributes and Set Attribute: These can be used to manipulate mutable attributes of a managed object. • Locate: retrieving a list of objects based on a predicates. • Re-Key, Re-Key-Key-Pair: creating a new key that can replace an existing key. There are also attributes that can be used to have the server automatically rotate keys after a given period or number of uses. The Name is moved to the new key and is normally used to retrieve a key for protection operations such as encrypt and sign. The old key can also be retrieved using the Unique Identifier for process operations such as decryption and signature verification. • (Re-)Certify - certifies a certificate. • Split and Join N of M keys. • Encrypt, Decrypt, MAC etc.: Cryptographic operations performed on the key management server. A key itself can be marked being not-Extractable, in which case its value never leaves the server. • Export, Import: Move keys to and from other KMIP servers. • Activate, Deactivate etc.: Operations to implement the
NIST key life cycle. • Encapsulate, Decapsulate: Post
Quantum algorithm support.
Key life cycle Each key has a cryptographic state defined by the
National Institute of Standards and Technology (NIST). Keys are created in an Initial state, and must be Activated before they can be used. Keys may then be Deactivated and eventually Destroyed. A key may also be marked being Compromised. Operations are provided for manipulating Key-state in conformance with the NIST life-cycle guidelines. A Key-state may be interrogated using the State attribute or the attributes that record dates of each transformation such as Activation Date. Dates can be specified into the future thus keys automatically become unavailable for specified operations when they expire.
Message structure KMIP is a
stateless protocol in which messages are sent from a client to a server and then the client normally awaits on a reply. Each request may contain many operations thus enables the protocol to efficiently handle large numbers of keys. There are also advanced features for processing requests asynchronously. The KMIP protocol specifies several different types of encodings. The main one is a
type–length–value encoding of messages, called
TTLV (Tag, Type, Length, Value). Nested TTLV structures allow for encoding of complex, multi-operation messages in a single
binary message. There are also well defined
XML and
JSON encodings of the protocol for environments where binary is not appropriate. All of these protocols are expected to be transmitted using
TLS protocol in order to ensure integrity and security. However, it is also possible to register and retrieve keys that are wrapped (encrypted) using another key on the server, which provides an additional level of security.
System management KMIP provides standardized mechanisms to manage a KMIP server by suitably authorized administrative clients using System Objects. User objects can be created and authorized to perform specific operations on specific managed objects. Both Managed Objects and Users can be assigned to groups, and those groups can form a hierarchy which facilitates efficient management of complex operating environments. KMIP also provides a provisioning system that facilitates providing end points with credentials using simple one-time passwords. Default values of attributes can be provided, so that simple clients need not specify cryptographic and other parameters. For example, an administrative user might specify that all "SecretAgent" keys should be 192 bit
AES keys with
CBC block chaining. A client then only needs to specify that they wish to create a "SecretAgent" key to have those defaults provided. It is also possible to enforce constraints on key parameters that implement security policy.
KMIP profiles KMIP also defines a set of
profiles, which are subsets of the KMIP specification showing common usage for a particular context. A particular KMIP implementation is said to be
conformant to a profile when it fulfills all the requirements set forth in a profile specification document.
OASIS has put forth various profiles describing the requirements for compliance towards storage arrays and tape libraries, but any organization can create a profile.
Relationship to PKCS#11 PKCS#11 is a
C API used to control a
hardware security module. PKCS#11 provides cryptographic operations to encrypt and decrypt, as well as operations for simple key management. There is considerable amount of overlap between the PKCS#11 API and the KMIP protocol. The two standards were originally developed independently. PKCS#11 was created by
RSA Security, but the standard is now also governed by an
OASIS technical committee. It is the stated objective of both the PKCS#11 and KMIP committees to align the standards where practical. For example, the PKCS#11 Sensitive and Extractable attributes have been added to KMIP version 1.4. Many individuals are on the technical committees of both KMIP and PKCS#11. KMIP 2.0 also provides a standardized mechanism to transport PKCS#11 messages from clients to servers. This can be used to target different PKCS#11 implementations without the need to recompile the programs that use it. == KMIP implementations ==