Key Management Interoperability Protocol

The types of managed objects that are managed by KMIP include:

• Symmetric Keys used for algorithms such as AES.
• Public and Private Keys used for asymmetric algorithms such as RSA and ECDH. Separate objects are used to store the public and private key, so that a user may have permission to access one but not the other. Related objects usually contain Link attributes that contain 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.

The operations provided by KMIP include:

• Create, which creates a new managed object such as a symmetric key, and return the identifier.
• Create Key Pair, which creates which creates two objects that represent asymmetric keys.
• Get, which retrieves 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, which stores 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, which retrieves a list of objects based on a predicates.
• Re-Key, which creates 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 which certifies a certificate.
• Split and Join n of m keys.
• Encrypt, Decrypt, MAC etc. Cryptographic operations performed on the key management server. The key itself could be marked as not Extractable in which case its value never leaves the server.
• Export and Import keys to other KMIP servers.
• Operations to implement the NIST key life cycle.

Each key has a cryptographic state as defined by the National Institute of Standards and Technology (NIST). Keys are created in an Initial state, but must be Activated before they can be used. They may then be Deactivated and eventually Destroyed. The key may also be marked as Compromised.

Operations are provided that manipulate the state in conformance with the NIST life cycle guidelines. The state of a key 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 so that keys automatically become unavailable for specified operations as they expire.

KMIP is a stateless protocol in which messages are sent from a client to a server and then the client normally waits for a reply. Each request may contain many operations which enables the protocol to efficiently handle large numbers of keys. There are also advanced features to process 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. A very compact CBOR encoding is also provided for applications that require it.

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 and additional level of security.

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 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[1] and tape libraries,[2] but any organization can create a profile.

PKCS#11 is an 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 are being added to KMIP version 1.4. Many of the same people are on the technical committees of both KMIP and PKCS#11.

KMIP 2.0 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.

The KMIP standard is defined using a formal specification document, testcases, and profiles put forth by the OASIS KMIP technical committee. These documents are publicly available on the OASIS website.

Interop booths at the 2015 RSA conference. Each vendor interoperates with each other vendor.

Vendors demonstrate interoperability during a process organized by the OASIS KMIP technical committee in the months before each RSA security conference. These demonstrations are informally known as interops. KMIP interops have been held every year since 2010. The following chart shows the number of individual tests performed by each client and server vendor combination since 2012.

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  Individual interoperability tests performed by each server/client vendor combination since 2012
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  Results of 2017 OASIS KMIP interoperability testing