The Security Lexicon

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MAC

MD2, MD4, MD5

are hash functions developed by Rivest. The result is 128-bit long. MD2 is adapted to 8-bit machines, whereas the two others are dedicated to 32-bit machines. MD4 is already broken.

Masquerade

is a hack where the hacker uses the system in the name of an authorized person (impersonation)

MediaGuard

is a Conditional Access system developed by Canal + Technologies.

Message Authentication Code

is a one-way hash computed from a message and some secret data. Its purpose is to detect alteration of the message.

Message Recovery

is one property of some digital signature schemes (such as ISO9796 RSA signature). In such protocol, the message can be re-constructed from the signature without any extra information.

Middle person attack

Attack when two persons exchange public values to generate a secret (for instance DIFFIE HELLMAN Key Agreement Protocol). The opponent, Carol, intercepts the public value of Alice. She sends her public value to Bob. She intercepts the public value of Bob. Then she sends her public value to Alice. Carol can then decrypt any message and send her own encrypted messages with the other keys to the expected target.
Solutions, such as Authenticated Diffie Hellman Key agreement, by appending a signature are perfect countermeasures against this attack.

MISTY

is a block cipher developed by MITSUBISHI. Its key-length is 128 bit. It is secure against differential cryptanalysis and linear cryptanalysis.

MLS

stands for Multilevel system

Mod chip

is the name of chipsets delivered by crackers to break a protection system. It often replaces an existing chip on the motherboard or needs to be soldered as piggyback. Thus, it requires some skills to implement. The main targets are game consoles. Six months after its release, there were already mod chips available for the XBox.

MONDEX

is a micropayment scheme based on the use of a smart card. MONDEX supports any currencies. A MONDEX card is interoperable worldwide.

Multilevel security system

see Bell Lapadula