Intel EP80579 User Manual

Intel

®

 EP80579 Software for Security Applications on Intel

®

 QuickAssist Technology

PG

August 2009

26

Order Number: 320183-004US

“Galois/Counter Mode (GCM) is a block cipher mode of operation that uses universal 

hashing over a binary Galois field to provide authenticated encryption.” This is an 

excerpt from the GCM specification which can be accessed at: 

The Cryptographic API module provides TLS and SSL key generation operation along 

with a Mask Generation Function (MGF).

TLS/SSL Generation: For both algorithms functions are provided for the generation of 

the Master-Secret and Key Materials. These are optimized accelerations for use in SSL/

TLS key negotiation and generation applications.

MGF: Takes a seed of specified length and produces a generated mask, which is 

pseudorandom, of the specified size.

This section gives a brief overview of Public Key algorithms and standards relevant for 

EP80579 security software. The following is a list of Public key algorithms/standards:

• Diffie-Hellman (DH) Key Exchange – PKCS #3 v1.4
• RSA Cryptography Standard – PKCS #1 v2.1 and ANSI X9.31
• Digital Signature Algorithm (DSA) – FIPS-186-2
• GCD, Miller-Rabin, Lucas and Fermat primality testing (ANSI X9.80)

DH is used to create a “shared secret”, from which symmetric key information may be 

derived. This Key can be used to encrypt subsequent communications using a 

symmetric key cipher. 

The protocol has two system parameters p and g. They are both public and may be 

used by all the users in a system. Parameter p is a prime number and parameter g 

(usually called a generator) is an integer less than p, with the following property: for 

every number n between 1 and p-1 inclusive, there is a power k of g such that n = g

k

 

mod p.

The underlying mathematical principle is the identity: (g

a

 mod p)

b

 mod p = (g

b

 mod p)

a

 

mod p. DH cryptographic strength is derived from the fact that logarithms are difficult 

to do in a MODP group. A set of standard DH (MODP) groups are defined in RFC-2409 

and RFC-3526. Modulus sizes range from 768 to 4096 bits.

There are two modes of Diffie-Hellman:

• Normal Diffie-Hellman: DH parameters are contained within a certificate, signed 

by a certificate authority (CA).

• Ephemeral Diffie-Hellman: DH parameters are created “on the fly” by the 

negotiating parties. These parameters are then signed using a DSS or RSA 

certificate, which is itself signed by a CA.