	MCSoft Security Solutions

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ActiveX

MCMAC

Algorithms

MCSoft MCMAC ActiveX DLL

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Generation of Message Authentication Codes (MAC) with MCMAC

With the MCMAC ActiveX DLL it is possible to generate Message Authentication Codes for arbitrary files and Strings . These can then be used for different purposes. A possibility is for example the signature of E-Mail messages, where changes in the content or in the attachments can be easily detected. The messages are securely protected on the way to the receiver.

A list and a description of the implemented codes can be found in the following table.

Algorithm	Signature length [Bit]	Mode	Security
Rijndael	128-256	CBCMAC, CCMMAC, COAMAC	High, very high
RC6**	128	CBCMAC, CCMMAC, COAMAC	High
Serpent	128	CBCMAC, CCMMAC, COAMAC	High
Twofish	128	CBCMAC, CCMMAC, COAMAC	High
MD5	128	HMAC	Moderate
SHA1	160	HMAC	High
SHA224	224	HMAC	Very high
SHA256	256	HMAC	Very high
SHA384	384	HMAC	Very high
SHA512	512	HMAC	Very high

** look at the product comparsion table

Table 1: Message Authentication Codes implemented in the MCMAC ActiveX DLL

A Message Authentication code, defines a procedure for the generation of symmetric digital signatures for files and strings. The used algorithms are one-way functions and produce from a message of arbitrary length a "finger print" in form of a code of defined length. Through the finger prints it is possible to recognize changes which were made to the messages. At this point it is important to mention that a secret key is added to the finger print.
In contrast to asymmetric digital signatures, MACs are computed and verified with the same key, so that these can only be verified by the intended receiver.

Integrity of data

The purpose of a MAC is to authenticate both the source of a message and its integrity without the use of any additional mechanisms. The integrity of the data becomes secured by the Message Authentication Code (MAC). Before the message is sent over an insecure channel a code, which is computed with a Hash function, is attached to the message. The hash value is protected by a secret key and one can verify the hash value only with the same key. After the receipt of the message the integrity must be verified. The receiver computes the MAC on the received message using the same key and MAC function as it was used by the sender, and compares the result computed with the received MAC. If the two values match, the message has been correctly received. Then the receiver can be sure that the message is the original one.