Meeting – October 8, 2014 | Hashes



Originally posted on University of Florida Student Infosec Team:

Hi SITers!

This week’s presentation will introduce the science behind hashes such as SHA2/MD5 and how they are commonly used on Linux systems. Additionally, this presentation will introduce the hashmap datastructure and how it is implemented in the C programming language. We will discuss how a poor implementation can result in a vulnerability.

Make sure to bring your laptop with the VMs that we installed at the beginning of the semester! If you did not get a chance to download them, find an officer and we’ll give you them.
[Be Social!]
IRC: #ufsit on Freenode
[Time and Location]
Wednesday 7:00pm – 9:00pm
CSE E309

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Brace yourself… cool-old-term is coming!


Just wow. Too bad its not arch.

Originally posted on Swordfish's Labs:

Since when I played Fallout III for the first time I have always wanted my terminal to look like those old jittery CRT screens that you loved in the game. Sadly there was nothing like that on Linux… Till I decided to make one myself!

In the last six months I dedicated some of my spare time to create a terminal emulator which had to look that way, but also had to be customizable and reasonably lightweight. Now the project is near completion I want to share with everyone the result!

The application is written using QtQuick 5.2 and uses as engine the Konsole QML port made by Canonical (

If you are a graphical designer and you want to help the project feel free to contact me. I’m quite bad with gimp and I would be really glad if someone created a couple of frames and a good icon…

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The cost of artificially pumping a low volume altcoin: pumping the alt markets by yourself with the BTC/LTC “pump machine” strategy


For this article we regard ALL prices in crypto-crypto units, and unless otherwise noted, denominated in units of BTC. Therefore bitcoin costs 1, LTC (today) costs ~.009 BTC/LTC, etc…

I have noticed there is a way to burn bitcoin in order to raise the price of an altcoin, assuming low volume, and assuming there is a secondary market, such as LTC, on which the coin is trading. I call it the pump machine. It goes as follows:

Method of spending BTC to temporarily pump the bitcoin price of a low volume coin, which will be denoted SHT:

1) Suppose you only have 1 BTC

2) Buy as much SHT as you can with 1 BTC

Problem seeing this image? Try

It doesn’t matter what coin SHT represents in this example, but I choose DRK because I will soon describe trading coins which reach price parity with LTC, and why that can be very good.

3) Go to the LTC/SHT market and sell all the SHT for LTC. Now you have a bunch of litecoins.

Casually sell the SHT for LTC.

4) Go back to the BTC markets – this time, the BTC/LTC trading floor. Take the LTC and sell it for BTC. You’ll now have a bit less than 1 BTC (most likely).

Get bitcoin back…

5) Now that you hold BTC (perhaps a bit less than 1) go back and pump SHT! Buy .9887 BTC worth of SHT, rinse and repeat.  If the markets are dull enough, you can make it seem, for a while, like more bitcoin than you could possibly spend on SHT is buying the SHT up.  In the end you’ll pay for this deception, but in the short term, it’s a pump machine.

6) Continue the cycle. Watch your bitcoin stash go melt away slowly as you literally pay to pump the price. It’s a bit like a carnot engine.


Consider donating to keep ad free.  13xdMqkaVKkHKT3ZZx5ikAvQUEkzqpDkDb

Coming soon: the advantage of trading an alt which has reached price parity with LTC. Complete with math.


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Posted in Bitcoin, Electronics and Engineering, Physics and Mathematics, Stuff

It may be time to buy some LTC again. Here’s why. The golden rules for altcoin trading.

Problem with image? See it on imgur here

Litecoin price in BTC on the btc-e exchange, for as long as can remember. We are at about all time lows.

This blog post is a glorified (with some images and minor changes) copy pasta of my post on /r/cryptomarkets.

LTC – how low can it go? It might be time to take a shot with LTC for a potential bitcoin profit.

Problem with image?  Go to

Past performance is no indication of future…oh whatever. Let’s get some LTC. 1) it’s old 2) its inflation rate is very slow 3) it’s not bitcoin 4) historically speaking, this is an OK price.  5) LTC enjoys special status in the cryptocurrency world as a secondary market, and should always be watched out of the corner of one’s greedy eye.

I have done this with LTC a few times – the best of which was last November. Priced in BTC, it is now near parity with DRK and below .01 … which isn’t far from the price I think I paid for a bunch of LTC right before the boom in November, when I started writing about trading in /r/cryptomarkets with “the golden rules for alt trading.”

One thing that makes LTC different from other scrypt alts is its very slow ditribution – it’s just as slow as bitcoin. To me, that makes it still attractive as a swing trade, because big investors are probably thinking about it. What do y’all think?

BTW, just looked. I decided to buy lots off LTC last year at .008, and it’s not far from this mark. I wrote the golden rules to this sub from a 5-star hotel (I don’t stay in those) thanks to that trade. Good times…

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Posted in Bitcoin, Electronics and Engineering, Physics and Mathematics, Stuff

Sexism in computer science? We will find out.

Please take this short poll:

Which do you prefer?

A) while loops
B) baking cookies

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Hexadecimal word games. Not fail = foresee!

If you write “fail” as 0x0FA11, not fail becomes 0xF05EE..or “foresee!”

It’s fun to try and write words in hex, like “deadbeef” of “cafebabe.” If we allow ourselves certain 1337 notations for letters, we can write even more words as Hexadecimal integers like “5ca1ab1e.” Pretty cool!

What is not scalable? Well that’s computable … not 0x5ca1ab1e is 0xa35e54e1. This isn’t a word.

But as I demonstrated above, much fun can be had by taking binary operations on these integers. Not fail is foresee. Can you find any others?



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Posted in Electronics and Engineering, Physics and Mathematics, Stuff

A precise analysis of an L-network for impedance matching below 3 MHz. The desire for “an ideal” characterization of the circuit parameter space for utility in fabrication by hand. The reduction to a pure mathematics problem.


This is a full description of a situation often encountered by scientists in the process of fabrication of the NMR probe. The analysis requires some tedious complex algebra, a bit of circuit theory, and enforces a matching condition. I tried to write this so that one may infer the cirucit theory from context. If there is a problem, just ask.

We will examine the impedance of this reactive L network

Goals of this challenege:

Characterize the parameter space of the variables Cm, Ct, ω, L, r and produce some useful set of tables for lab, in which the relationship between Cm and Ct is known for a given ω L and r. Furthermore to ponder the level of greed allowed. Which parameters limit others? Compare this with what the laboratory reality is.


One must always strive for impedance matching conditions to be satisfied, which for us means 50 ohms real. So we must


Im_Z = 0

Re_Z = R := 50 ohms


These requirements are nasty if you allow the impedance of the coil to have a small (but very physical and influential) real part r

Z_coil = j ω L + r

So the total impedance is

Z_tot = -j / (Cm ω) + Z_coil || Z_Ct = Re_Z + j Im_Z = R + j 0 = 50


* Z_m is the impedance of the matching cap only
* Z_t is the impedance of the tuning cap only
* the notation A || B means “A parallel B” and A || B = ( 1/A + 1/B)^(-1)

Since Z_coil has a real and an imaginary part, the expression for total impedance is a headache.

So I did it by hand, and with mathematica, and iteratively found what I consider decently short code with reasonably concise expressions. Here we go.



Clone the mathematica stuff here


git clone


In which there is a file where I do in fact show the real and imaginary parts of Z_tot are:

real part (which we denote Re_Z…please note the sloppyness. Here w is ω)

Re_Z = r/((r^2 +
L^2 w^2) (r^2/(r^2 +
L^2 w^2)^2 + (T w - (L w)/(r^2 + L^2 w^2))^2))

and imaginary part (Im_Z)

ImZ = (-(1/(M w)) - (T w)/(r^2/(r^2 +
L^2 w^2)^2 + (T w - (L w)/(r^2 +
L^2 w^2))^2) + (L w)/((r^2 +
L^2 w^2) (r^2/(r^2 +
L^2 w^2)^2 + (T w - (L w)/(r^2 + L^2 w^2))^2)))

where we eliminated the need for subscripts but denoting Cm := M and Ct := T.

How do we make useful data from these equations? To answer this, we must first assess what the experimenter can really control.

* coils are hard to wind and have prescibed results. In general, the parameter r is less than 1 ohm, but its actual value is not constant through frequency sadly. It must be treated as such.

* A typical coil inductance L satisfied 1.0 uH < L 30 uH. Intermediate values such as 8 uH tend to be the most difficult to fabricate. A coil inductance of 8uH I find would be useful for lower frequencies, below 3MHz, which are currently causing me problems. It is here the equations become extremely sensitive.

* The capacitance T and M can within reason, be expected to continuously vary between 0 < T,M < 1 nF and even more reasonably if the upper boundary is around 300 pF.

* the frequency is going to satisfy 1 MHz < f < 30 MHz; so ω = 6.28 f so we can say about, that
1 e7 < ω < 3e8

I have made many charts. Got any brilliant ideas?


A typical annoying situation in lab would be:

Drat. To reach the target frequency, we must either replace the capacitors with larger ones,
or exchange the coil with one of larger inductance. Which will take me less time?

I usually do not know in fact. I either make a intuitive guess, prepare some primitive tests, or try a bit of each.

The code in the github repo above will give you some parameter sliders. You can try plotting M, and T vs ω as L and that little tiny r are varied…I still must get to the bottom of these matters, such as, the qualitative effect of increasing r at fixed ω and L etc. How to encapsulate all such desirable relations in a single concise set of diagrams is what I truly seek, from the kind theorists of who may read this.


Final thoughts.

I have studied this problem up down left right…I wrote some interesting special cases down here, but I believe there is more to be known about these equations that could be of service to the designer.

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Posted in Electronics and Engineering, Physics and Mathematics, Stuff

Sad grep I – V

~$ sad grep poetry of the internet


# facebook | grep brains





# cat ./telecom| egrep (options|competit.?.?.?.?.?)


# dmesg






~$ ls


~$ pwd


~$ ls -laR | grep food





# cat ./reddit/r/bitcoin/* | grep criminals

Display all 169,236 possibilities? (y or n)




~$ ./github/ | grep working code







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Posted in Bitcoin, Electronics and Engineering, scamcoins, Stuff

When should I sell my Bitcoin Mining hardware? Bitcoin Mining Hardware Resale Value vs Projected Return


It’s interesting to look back at these “old” numbers from November 2013!


Originally posted on altoidnerd science:

If you have any questions about this process, you can contact me with the form below!  Happy mining. 

In general, the profit margin for miners becomes slimmer through time as the competition to break into bitcoin mining increases and the barriers to entry are higher than ever.  Customers have in general had poor experiences with ASIC manufacturers who have delivered the mining products late, making the hardware purchase a net loss for the investor.  The situation is not so grim for the miner, however, because the bitcoin price and price velocity are as high as they have ever been, and are not showing signs of flinching.

Despite the apparent victory for the miner when the price rises, it is a common misconception that a positive return of investment can be saved for a poor mining hardware purchase if the bitcoin price rises enough.  This is not actually true – well…

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Does a single electron moving at constant velocity generate electromagnetic waves?



Redditor /u/Mimshot gave the following example:

If an observer is near the path of a small, moving charged particle (unless there’s some special quantum effect I’d love you to tell me about if it exists) the observer will see the E field increase and then decrease and will see the B field ramp from baseline, then reverse direction, which is certainly wave-like. I’m not saying it radiates photons, but I’m wondering if “no, it must be accelerating” is a complete answer.

Is there some quantum effect I’m missing?



I “know” immediately there is no radiation in this case, because the theory of relativity tells us we can use a frame of reference in which the particle is stationary. Hence, as a rule, only accelerating particles radiate and thus give rise to traveling waves. Nevertheless, this question did get me to think about what the fields would be like in such a situation. A passing electron would seem to have some time dependent magnetic fields because the “ramp” explanation above, but it cannot be the case since we should know, just “because”, only accelerating charges radiate.

After some thought I came up with the following proof that the magnetic field is static in this case.

Start here

J(r,t) = ρ(r,t)v(r,t) = e δ(r – r’,t)v(r – r’)

v has no time dependence.

The current I is ∫ J d2 x’

I = ∫ d2 x’ e δ(r – r’,t)v(r – r’) = e v = a constant

To find B we use ampere’s law for some closed loop

∫ B dx = μ I = constant

If you’re concerned about the ∂E/∂t term lets look at the full maxwell equation

 x B = μ J + μ ε ∂E/∂t

Applying the operation ∫ d2 x to both sides gives

∫ B dx = μ I + μ ε ∂/∂t ( ∫ d2 x E )

The RHS of the above equation is simpified using gauss law, the integral gives the charge enclosed by a surface

∫ d2 x E = q/ε


∫ B dx = μ I + μ ε ∂/∂t ( q/ε )

but ∂/∂t ( q ) = 0

so that term doesn’t change things.

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