Posted on 01 October 2010.
Posted on 01 October 2010.
Is it really secure?
How safe is Excel encryption. Is Excel encryption really secure?
This article describes the strength of Excel encryption. Excel encryption is achieved by setting a "password to open". The security level in Excel 2002 and 2003 depends on strength of encryption algorithm and strength of password.
Strength of encryption algorithm
In Excel 95, 97 and 2000 the encryption method contains vulnerabilities. This means that the document can be decrypted within 10 seconds without knowing the password. There are password crackers that even offer online services to do this.
In Excel 2002 and 2003, the default encryption method is "97/2000 compatible", which means that the same insecure encryption method is used.
Fortunately there is a solution. To achieve good encryption, one has to select a strong encryption method. This is done by clicking the "Advanced" button next to the "Password to open" field. A list of available Crypto Service Providers (CSP's) appears.
Choose encryption type with strong encryption capacity in Excel
Here select a CSP with at least 128 bits RC4, like the "Microsoft Enhanced Cryptographic Provider v1.0". 128 bits encryption is considered strong encryption. RC4 is widely used, for example by Online Banking Systems and in PDF encryption.
Strength of password
If the encryption method is strong, the only way for a cracker to break the document security is by trying to find the password. It's important to know the difference between weak and strong passwords.
Password crackers are automated tools dedicated to finding passwords. Usually the steps are:
1. password guessing
2. dictionary attack (trying all words from a dictionary list, e.g. list of names)
How much time is needed to crack a password by brute-force?
If the password cannot be guessed and is not found in a dictionary, the cracker has to try a brute-force attack. When brute-forcing, the time to crack the password depends on the amount of possible passwords that the cracker has to try. The amount of possible passwords increases with password length and with increasing diversity of characters being used (complexity).
Let's take the scenario of a cracker trying 15 million passwords per second. This is currently the maximum speed being claimed by password cracker vendors. You need a pretty fast computer to achieve this. The following table shows the computed time to crack a password with 15 million tries per second. Notice the incredible increase in time to try all possible combinations when password length and complexity increase.
length: 4, complexity: a-z ==> less than 1 second
length: 4, complexity: a-zA-Z0-9 + symbols ==> 4.8 seconds
length: 5, complexity: a-zA-Z ==> 25 seconds
length: 6, complexity: a-zA-Z0-9 ==> 1 hour
length: 6, complexity: a-zA-Z0-9 + symbols ==> 11 hours
length: 7, complexity: a-zA-Z0-9 + symbols ==> 6 weeks
length: 8, complexity: a-zA-Z0-9 ==> 5 months
length: 8, complexity: a-zA-Z0-9 + symbols ==> 10 years
length: 9, complexity: a-zA-Z0-9 + symbols ==> 1000 years
length: 10, complexity: a-zA-Z0-9 ==> 1700 years
length: 10, complexity: a-zA-Z0-9 + symbols ==> 91800 years
What we see is that:
To be on the safe side, we recommend a minimum password length of 10 characters.
Note: the crack times mentioned in the table are needed to try all the possible passwords. There is a great chance that the cracker only needs 50% of this time. Also bear in mind that a cracker can always have a lucky shot at his first try and crack the password immediately. The chance is very small, but theoretically it is possible.
Is Excel encryption really secure?
Yes, encryption in Excel 2002 and 2003 is really secure if you select
As always, we are here to help so if you have any queries please do not hesitate to contact us on 0871 2300417 or by emailing firstname.lastname@example.org.
Netcom Technologies - www.netcom-it-services.co.uk
Posted on 28 September 2010.
What does your desk say about you?
If you are sitting at your desk now, take a look around and ask yourself: "What is this desk saying about me?"
For example, what messages does a photo of your mum send to your co-workers, or a low-maintenance cactus, or the tons of boxes and files below your desk?
Ask a psychologist and, unsurprisingly, they’ll tell you that just like the clothes we choose to wear or the meal we take at lunch, our desk is often perceived as an extension of our personalities. Nothing ground-breaking there – but certainly worth bearing in mind.
Recent studies have revealed that desks can be useful to managers attempting to understand and motivate their staff. Vice versa, if you are interested in the way you are perceived at work – and perhaps you are thinking of modifying that perception – a desktop makeover is a great place to start.
When considering the state of your desk and what signals it sends about you, keep in mind the following stereotypes:
The motivated workspace. Strategically placing work targets, charts, graphs and deadlines in plain view of passers-by is likely to make them think you are ambitious and goal orientated.
Family, friends and pets. Lost that human touch? Littering your space with pictures of these will give the impression that you are a “people person”, motivated by the relationships around you.
Hedonist’s shrine. Adventure calendars, holiday postcards and lively screen savers: sprinkling these around says, “I like a good time.” You could well be perceived as the “work to live” type as opposed to the “live to work”.
Fashion hub. Need to say: style over substance? Or rather, style with substance? A few well-placed fashionable gadgets or accessories can raise your style stocks. Be careful though: like beauty, what is fashionable changes between beholders.
The naked desk. Often thought to be the workspace of more introverted types. Other introvert signs are building a wall of office files to hide behind or facing your desk in a position where you avoid eye contact. However, with the rise in desktop interpretations perhaps the bare desk is just a clever workplace poker face.
A talking point. Football team memorabilia, pictures of you hugging your favourite band or a model of your dream car – build a beacon like this to invite workplace comments.People who are happy to reveal their interests are usually seen as extroverted – which can be great, depending on your job.
Controlled environment. Need to show your manager that you are better organised this year? The tidy desktop just might help you take a step in the right direction. Workers with an ordered space are usually thought to be conscientious and punctual … but then appearances can be deceptive!
Chaos theory. Looking to appear capable of high-risk multi-tasking? Consider spreading your stationery across your desk at random, throw in a few half-empty coffee cups, and style a few rough piles of documents. The messy desk can be associated with the flexible multi-tasker able to switch between jobs quickly and without stress. On the other hand, you could just appear disorganised and unreliable...
The next time you walk across the office, take some time to analyse your colleagues’ and manager’s desktops. You might find a new friend, or realise how your desk needs to look to make your boss smile.
Posted on 31 December 1969.
CTRL and A Selects all in the current document.
CTRL and B Bold text.
CTRL and C Copies the item or text to the Clipboard and can be pasted using CTRL and V.
CTRL and D Displays the Font dialogue box.
CTRL and E Centre Alignment.
CTRL and F Displays the Find dialog box, to search the current document.
CTRL and G Displays the Go to dialog box, to go to a specific location in the current document.
CTRL and H Displays the Replace dialogue box.
CTRL and I Italic text.
CTRL and J Full Justification.
CTRL and K Create Hyperlink
CTRL and L Left Alignment
CTRL and M Tab
CTRL and N Creates a new document.
CTRL and O Displays the Open File dialogue box.
CTRL and P Displays the Print dialog box.
CTRL and R Right Alignment.
CTRL and S Displays the Save dialog box.
CTRL and U Underline text
CTRL and V Pastes the copied item or text from the Clipboard into the current position in the document.
CTRL and X Cuts the item or text selected to the Clipboard.
CTRL and Y Redo the last undone action.
CTRL and Z Undoes the last action.
CTRL and ENTER Insert Page Break.
CTRL and F2 Show Print preview.
CTRL and F4 Closes the active document window.
CTRL and F6 Opens the next document window.
F1 key Get help or use the Office assistant.
SHIFT and F1 Key Context sensitive help.
F2 Key Move text or image.
SHIFT and F2 Key Copy Text.
F3 Key Insert an autotext entry.
SHIFT and F3 Key Change the case of the selected text.
F4 Key Perform last action again.
SHIFT and F4 Key Perform a Find or Go to action again.
F5 Key Displays the Go to dialogue box, from here you can also Find and Replace.
SHIFT and F5 Key Move to a previous revision.
F6 Key Go to the next frame or pane.
SHIFT and F6 Key Go to the previous frame or pane.
F7 Key Launch the Spell checker.
SHIFT and F7 Key Launch the Thesaurus.
F8 Key Extend the current selection.
SHIFT and F8 Key Shrink the current selection.
F9 Key Update the selected fields.
SHIFT and F9 Key Switch between a field code and its result.
F10 Key Activate the menu bar.
SHIFT and F10 Key Display a Shortcut Menu. Same as right clicking.
F11 Key Go to the next field.
SHIFT and F11 Key Go to the previous field.
F12 Key Save file As, equivalent to tools menu.
SHIFT and F12 Key Save document, equivalent to tools menu.
As always, if you have any business IT support needs or need any help or advice please feel free to give us a call on 0871 2300417 or email email@example.com.
Posted on 09 August 2010.
Digital cameras usually default to taking high resolution images. This is okay for storing your home photo’s but for business purposes the large images produced quickly fill unnecessary space on server storage and email mailboxes. Its always good netiquette to reduce the size of images before sending them over email or storing them on your company’s server. Even though you may be able to send large images, the recipients mail system may not be allowed to accept large images. The failsafe option is to set your digital camera to set lower resolution images. If this isn’t possible your free to use our guide to reduce your image sizes.
How to resize photos and pictures before sending through email?
Posted on 31 December 1969.
Netcom specialise in IT managed support services and this comprehensive approach means we handle everything from the supply and support of PCs and servers to broadband and multisite branch office connectivity, telephone systems, hosted email and much more. Whatever your business, whatever your needs, Netcom takes the headache out of IT.