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photo, a photo by bostonlinuxandunix on Flickr.

BLU Meeting: Whole Disk Encryption

This month's meeting is a series of "lightning talks" by several speakers.

First off was Jerry Feldman's presentation, which lasted about 15 minutes.
Jerry's talk was about general issues common to all whole-disk encryption
software.

Next up was Ned Harvey, from 7:15pm to 7:58pm, who compared a number of
disk encryption suites:

1. TrueCrypt
2. Microsoft'd BitLocker
3. Apple's OSX Encrypted DMG, SparseImage and SparseBundle
   
4. Apple's FileVault 1 and FileVault 2
5. EncFS, Boxceyptor, Encfs4win, CryptKeeper
   

Some of Ned's discussion:

• how hardware AES crypto chips improve performance
• biometrics and TPM
• need to save TPM's 40-char key -- needed e.g. when motherboard gets replaced, to activate new TPM hardware on the new motherboard
• impact on backup/restore
• using crypto with DropBox to share with coworkers

next up was Bill Ricker, from 8:01pm to 8:29pm, discussing a new paper on a weakness in RSA public key generation

"Ron was wrong, Whis is right" (Arjen K. Lenstra and James P. Hughes)

New research: There's no need to panic over factorable keys--just mind your Ps and Qs

Impure Math

(an old classic I ran across on USENET in 1983)

Once upon a time (1/T), pretty Polly Nomial was strolling

across a field of vectors when she came to the boundary of a

singularly large matrix. Now Polly was convergent, and her mother had

made it an absolute condition that she never enter such an array

without her brackets on. Polly, however, who had changed variables

that morning and was feeling particularly badly behaved, ignored this

condition and made her way in amongst the complex elements.

Rows and columns closed in on her from all sides. Tangents

approached her surface. She became tensor and tensor. Quite

suddenly, two branches of a hyperbola touched her at a single point.

She oscillated violently, lost all sense of directrix, and went

completely divergent. As she reached a turning point, she tripped

over a square root that was protruding from the Erf, and plunged

headlong down a steep gradient. When she rounded off once more, she

found herself inverted, apparently alone, in a non-Euclidean space.

She was being watched, however. That smooth operator, Curly Pi, was

lurking inner product. As his eyes devoured her curvilinear

coordinates, a singular expression crossed his face. He wondered, was

she convergent? He decided to integrate improperly at once.

Hearing a common fraction behind her, polly rotated and saw

Curly Pi approaching with his power series extrapolated. She could

see at once by his degenerative conic and his dissipative terms that

he was bent on no good.

"Arcsinh", she gasped.

"Ho, ho", he said. "What a symmetric little asymptote you

have. I can see that your angles have lots of secs."

"Oh, sir", she protested, "keep away from me. I haven't got

my brackets on."

"Calm yourself, my dear", said our suave operator. "Your

fears are purely imaginary."

I, I, she thought, perhaps he's not normal but homologous.

"What order are you?" the brute demanded.

"Seventeen", replied Polly.

Curly leered. "I suppose you've never been operated on?"

"Of course not", Polly replied quite properly, "I'm absolutely

convergent."

"Come, come", said Curly. "Let's off to a decimal place I

know and I'll take you to the limit."

"Never", gasped Polly.

"Abscissa", he swore, using the vilest oath he knew. His

patience was gone. Coshing her over the coefficient with a log until

she was powerless Curly removed her discontinuities. He stared at her

significant places and began smoothing her points of inflection.

Poor, poor Polly. The algorithmic method was now her only hope. She

felt his hand tending to her asymptotic limit. Her convergence would

soon be gone forever.

There was no mercy, for Curly was a Heavyside operator.

Curly's radius squared itself. Polly's loci quivered. He integrated

by parts. He integrated by partial fractions. After he cofactored,

he performed Runge-Kutta on her. The complex beast even went all the

way around and did a contour integration. What an indignity - to be

multiply connected on her first integration. Curly went on operating

until he had satisfied her hypothesis, then he exponentiated and

became completely orthogonal.

When Polly got home that night, her mother noticed that she

was no longer piece-wise continuous, but had been truncated in several

places and it was to late to differentiate now. As the months went

by, Polly's denominator increased monotonically. Finally, she went to

L'Hospital and generated a small but pathological function that left

surds all over the place and drove Polly to deviation.

The moral of our sad story is this:

"If you want to keep your expressions convergent, never allow them a

single degree of freedom."

-the end

-Aunty Derivative