Its been a while……

November 1, 2012

Wow, I didn’t realise its been that long since I blogged.

With Work and Study there’s little time for anything else.

Couple of things I’ve been doing since the last post

1. Started a new job as a Security Consultant

2. Started to lean Linux, with Back-Track Linux of all things !

3. Started playing with Raspberry Pi’s. I now have 3 (XBMC media player, Lapdock and i’m building a small robot using a Gertboard)

4. Learning to Solder……

5. Studying 2 MSc Modules – Computer Security and Smart Cards, Tokens & Applications. Passed Information Security, Cryptography, Network Security & Information Crime so far.

6. Bought shares in a Brewery (Go Brewdog 🙂 )

Must try to post more regularly, if just for my own sanity…..

A Christmas Story

December 28, 2010

I spent great evening at the Bloomsbury theater watching ” 9 lessons and Carols for Godless People”on Sunday. This is a Christmas show with a difference, Its organized by Robin Ince as an Atheists Christmas celebration.

Its not Anti-Christian, but more of  a Celebration of The Universe, Science and Humanity. Its also an opportunity to see a huge number of acts for very little money !

The acts were (In no order, I had been in a few pubs before the show):

Robin Ince

Josie Long

Simon Singh

Baba Brinkman

Mitch Benn

Jim Bob

Isy Suttie

Chris Addison

Ben Goldacre

Martin White & The Mystery Fax Machine Orchestra

Gavin Osborn

Jo Neary

Marcus Du Sautoy

Matt Parker

Helen Arney

David Armand

Richard Wiseman

Not bad for £25 !

Merry Xmas

I don’t really want to comment on this, but the  simple quote

“I didn’t understand quite how bad things had become in this country until I saw armed cops being deployed against schoolchildren in the middle of Whitehall.”

says it all.

And from the Guardian

“police mounted on horses charged at about 1,000 students”

“17 people were treated for injuries in London. Of them, 13 needed hospital treatment”

“some parents arrived at the police cordon pleading for their children to be released”

El Gamal explained

May 19, 2010

This is a work in progress. I need to check as there is an Error in the Decryption ! I will edit when I get time to fix the issue.

El-Gamal (Simplified)

Key generation

Alice has a prime number (p) Special Number (g) and a random number for her private key (a)

  • (p) is the key so needs to be long (1024\2048)
  • (g) must be a primitive element modulo (p)
  • (a) must be bigger than 1 and smaller than p-1

The algorithm is A = ga mod p

Alice’s public key is A

Alice’s private key is a.

The system-wide parameters are p & g

Simplified key generation Example

p = 23

g = 11

a = 6

Therefore, A = ga (mod p)

Therefore 9 = 116 (mod 23)

Alice’s public key is 9 (A), and her private key is 6 (a).

The public key is known to everyone and the parameters p & g are known to everyone

Simplified Encryption Example

The example message Bob sends is 10 (M)

Bob generate a random number 3 (k).

Compute C1 and C2 where C1=gk mod p and C2=MAk mod p

Bob sends (C1,C2) to the Alice, this contains the message and value k.

Therefore if C1=gk mod p and C2=MAk mod p

Then C1=113 mod 23 and C2=10*93 mod 23

C1=20, C2= 22

The cipher text is (20, 22)

Simplified Decryption Example

Alice receives (20,22)

The calculation is C2 / C1a=(gk)a mod p

where 206 = (113)6 mod 23. Both calculate as 16

(This is where the final calculation goes, when I figure it out !)

Lifelock –

May 19, 2010

Lifelock is a company that guarantees to protect you from Identity theft, for only $10 dollars a month.

They are so cofident that they can protect your ID, that their advertisements include the Social Security Number of their CEO (From

Pretty good so far. Until you find out his identity has been stolen 13 times since 2007.

If the CEO of an identity protection company can’t even keep his own identity secure, would you trust them…….

RSA explained

May 5, 2010

I’ve been struggling to learn the mathematics behind RSA encryption. This is my “aid Memoir” I’m trying to memories.

Key Creation

• Choose primes p and q
Pick two prime numbers, e.g. 7 & 17
• Calculate the Modulus N, where N=pq
Multiply the two prime numbers to create N (7×17)=119
• Choose an e, where 1 < e <(p-1)(q-1) and GCD(e, (p-1)(q-1)) = 1
Pick a prime number e that is less than (p-1)*(q-1). (6*16)=96 and where the Greatest common devisor (GCD) of all three (e, p-1, q-1) is 1 (i.e. no other common devisors)
In This case, we pick 37.
• Public key is (N, e)
Public key are the two numbers N & e. (119,37)
• Compute d, where d = e^-1 mod (p-1)(q-1)
e^-1 mod (p-1)(q-1)
37^-1 mod 6×16
37^-1 mod 96
37*13=1 (Mod 96)
• Private key is d
The Private key is 13

p=7, q=17
N= 119
e = 37
d = 13

Public Key is (119,37)
Private Key is (13)


We will use the cleartext “14” for this example

Encryption uses the algorithm C ^ e = E ( mod N )
This is Cleartext to the power of The Prime number from the Public Key = answer (Mod N (the multiplication of the original two prime numbers)

14^37= “Huge Number” (Mod 119) =63 (By my calculator)

The Encrypted text (E) is “63”


Decryption uses the algorithm E ^ d = C ( mod N)

63^13 =C (mod 119)
63^13 = 14 (Mod 119)
63^13 = “Huge Number” (Mod 119) = 14


April 15, 2010

Just a short list of places I’ve eaten at recently.

Mimosa(Cardiff) – Review here

TAS(London) – Really good Turkish Restaurant. Makes me embarrassed I’ve ever been to a kebab takeaway !

Galileos Locanda(London) – Fair Italian, The Carpaccio was tasteless but the swordfish linguine was excellent (as was the lasagna so I’m informed)

Mezzaluna(Bath) – fantastic Italian restaurant with delicious food, very friendly management and the best olives I’ve ever tasted !

Green Park Brasserie(Bath) – Slightly posh and more of a wine bar than a restaurant. Fantastic steaks. We ate a bit early as a cool jazz quartet turned up as we were finishing our desert and we had to leave to finish our pub crawl !

Brasserie Gerard(Bath) – A bit french in its approach (slightly arrogant !) but pleasant. We had the chateaubriand which was great for a huge fillet steak although the béarnaise sauce was a bit sour.

Springs Cafe(Bath) – This is the (very good) cafe at the thermae spa. The ceasar salad was excellent but as everyone is in cotton bathrobes and slippers it can feel like being in a cult !