Hardware Security Module
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Hardware Security Module (often abbreviated to HSM) is type of secure cryptoprocessor targeted at managing digital keys for server applications. They are physical devices that traditionally come in the form of a plug-in card or an external security device that can be attached directly to the server or general purpose computer.
The goals of an HSM are the: (a) secure generation, (b) secure storage, (c) and use of cryptographic and sensitive data material. HSMs provide both logical and physical protection of these materials from non-authorized use and potential adversaries. In short, they protect high-value cryptographic keys.
The cryptographic material handled by most HSMs are asymmetric key pairs (and certificates) used in public-key cryptography. Some HSMs can also handle symmetric keys and other arbitrary data.
Many HSM systems have means to securely backup the keys they handle either in a wrapped form via the computer's operating system or externally using a smartcard or some other security token. HSMs should never allow for secrets exportation in plaintext form, even when migrating between HSMs or performing backup operations.
Some HSM systems are also hardware cryptographic accelerators. They usually cannot beat the performance of a software-only solutions for symmetric key operations. However, with performances ranges from 1 to 7,000 1024-bit RSA signs/second, HSM's can provide significant CPU offload for asymmetric key operations.
A few of the HSMs available in the market have the ability to execute specially developed execution modules within the HSM's secure enclosure. Such ability is useful, for example, in cases where special algorithms or business logic has to be executed in a secured and controlled environment. The execution modules can be developed in native C language, in .NET, Java or other programming languages. While providing the benefit securing application-specific code, these execution engines confuse the status of an HSM's FIPS or Common Criteria validation status.
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[edit] Tamper Protection
The tamper evidence, resistance, and response – Tamper Protection – are the key and major differences HSMs have from usual server computers acting as cryptographic accelerators.
Whereas there are some standards covering security requirements for cryptographic modules, the most widely accepted (both as customers’ choice and government requests) is the NIST FIPS 140-2.
[edit] HSM software APIs
Below is a list of popular cryptography APIs that can be used with hardware modules from different vendors.
- PKCS#11 – RSA's API, designed to be platform independent, defining a generic interface to HSMs. Also known as 'cryptoki'
- OpenSSL – OpenSSL Engine API
- JCE/JCA – Java's Cryptography API
- Microsoft CAPI – Microsoft's API as used by IIS, CA and others, also available in .NET.
[edit] HSM main uses
HSMs can be employed in any application that uses digital keys. Typically the keys must be of high-value - meaning there would be a sigificant, negative impact to the owner of the key if it were compromized. The list of applications are endless, but some of the primay uses include:
[edit] PKI environment (CA HSMs)
On the PKI environment, the HSMs are usually used by all Certification Authorities (CAs) and Registration Authorities (RAs) to generate, store, and handle key pairs. In this scenario, there are some fundamental features a device must have, namely:
- Logical and physical high level protection
- Multi-part user authorization (Blakely-Shamir k/m) schema
- Full audit and log traces
- Secure key backup
In the PKI environment, the device performance is much less important in both online and offline operations as Registration Authority procedures represent the performance bottleneck of the Infrastructure.
[edit] Card payment system HSMs (bank HSMs)
Limited-feature HSMs are used in card processing systems. These systems are usually less complex than CA HSMs and normally do not feature a standard API. These devices can be grouped in two main classes:
OEM or integrated modules for automated teller machines and POS terminals:
- to encrypt the PIN entered when using the card.
- to load keys into protected memory.
Authorisation and personalisation modules may be used to:
- check an on-line PIN by comparing with an encrypted PIN block.
- In conjunction with an ATM controller, verify credit/debit card transactions by checking card security codes or by performing host processing component of an EMV based transaction
- support a crypto-API with a smart card (such as an EMV).
- re-encrypt a PIN block to send it to another authorisation host.
- support a protocol of POS ATM network management.
- support de-facto standards of host-host key|data exchange API.
- generate and print a "PIN mailer".
- generate data for a magnetic stripe card (PVV, CVV).
- generate a card keyset and support the personalisation process for smart cards.
The major organization that produces and maintains standards for HSMs on banking market is the Payment Card Industry Security Standards Council.
[edit] SSL connectivity
There are applications where performance is a bottleneck but security must not be forgotten. These applications usually are presented as secure Web services served through HTTPS (SSL/TLS). In this environment SSL Acceleration HSMs are employed. Typical performance numbers for these applications range from 50 to 1,000 1024-bit RSA signs/second, although some devices can reach numbers as high as +7,000 operations per second.
[edit] See also
[edit] External links
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