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0

Is this based on some existing scheme. if so what? I can't be sure at all how hard your scheme would be to break from your description. As a rule of thumb rolling your own code rather than using existing libraries is generally discouraged since your odds of making mistakes are high. Trying to invent your own algorithm is much worse and is almost ...


6

Well, for one, the description of your scheme is not a scheme description. This is just a collection of vague intents. The description of a cryptographic scheme must be such that by reading the description alone, I could write an independent implementation that interoperates with yours. A good description looks like this. Or that. Also, in your description, ...


2

Generally, the best two rules governing encryption scheme creation when seeking reliable security and not just "folklore security" are: Rule 1: Usually you do not need to run your own crypto Rule 2: If you need to run your own crypto, immediately refer to rule 1. If at last, for some reasons, you so need to run own crypto that it overwhelms the two above ...


1

Diti is almost right about the historical context, but the real historical reason is in the part he/she omitted. For quite some time, gpg used DSA keys by default, which can only be used for signing, and then had to attach an elGamal subkey (which can be used for encryption only) to get a fully functional key. For RSA, that isn't necessary, but it was kept ...


9

SNI is there for virtual hosting (several servers, with distinct names, on the same IP address). When a SSL client connects to a SSL server, it wants to know whether it is talking to the right server. To do that, it looks for the name of the intended server in the certificate. Every evil hacker can buy a certificate for his own server (called ...


6

The fact that you are communicating to some server obviously cannot be hidden from IP. The packets have to leave your machine, enter the network, be routed to the destination, and be delivered. It's not a secret that you're contacting a server that delivers pages from https://www.fred.com. However, the URL does not contain the IP. Instead, it contains ...


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The hostname is included in the initial SSL handshake to support servers which have multiple host names (with different certificates) on the same IP address (SNI: Server Name Indication). This is similar to the Host-header in plain HTTP requests. The name is included in the first message from the client (ClientHello), that is before any identification and ...


1

You generally don't want to encrypt passwords as that opens the door to them being stolen. Instead you want to hash them, a one-way operation is mathematically impossible (or at least very hard) to reverse. This means that stealing password hashes will never lead to stealing passwords. PHP has a great set of functions for this: password_hash and ...


-1

In this public-key encryption (or assymetrical encription), to encrypt something, you do the following: Take your message to be transmited (as a number) : let's say it's 5. Calculate 3 ^ 5 (3 raised to the "secret") = 243 Calculate the modulus of it, divided by another number: let's say 143. So, 243 / 143 = 100. There you go. Your encrypted secret is ...


21

Your question is a little like this (with apologies to Tom Stoppard): "why can I stir the jam into my rice pudding, but not stir it out again?" Some mathematical operations are as easy to do backwards as forwards. For instance you can add 100 to a number as easily as subtracting 100. However, some are more difficult to reverse. For instance, if I take x and ...


1

In your interpretation of the message, you're performing a step that a computer wouldn't: you're assuming the output of the base64 decoding process is ASCII-encoded hexadecimal and converting it to binary before performing the disassembly process. The first few bytes of the message are (note: there's a newline before the 5 571266161278423 with hex values ...


0

I don't know of any bootloader that will allow you to change the selected OS based on password entered alone, I would say you would need to customise a bootloader to achieve this. This link may be of interest to you also: veracrypt As may this previous Answer


3

Max, the best tool ever created for thinking about cryptography is the Rubik's cube. If you presume a world where solving them is an unsolved problem, there are direct analogs for DiffieHellmanKeyExchange, RSA signing, RSA encryption, etc. You can play tricks with writing down moves and performing them on cubes and exchanging them; and the group theory ...


3

To answer a different part of your question: No, even if the message was encrypted using the public key, real asymmetric encryption systems will not let the attacker easily try their list of possibilities and look for a match with the ciphertext. This exact concern is why asymmetric encryption is always done using a probabilistic encryption scheme, in which ...


58

There are one-way functions in computer science (not mathematically proven, but you will be rich and famous if you prove otherwise). These functions are easy to solve one way but hard to reverse e.g. it is easy for you to compute 569 * 757 * 911 = 392397763 in a minute or two on a piece of paper. On the other if I gave you 392397763 and asked you to find the ...


2

What you need to do is read up on Public-Key Cryptography. The short answer is it is based on an algorithm that allows one key to encrypt and the other key to do the decryption, which is why you cannot work backwards. That is a simplified explanation of what is happening, if you want to get to the heart of the issue you can look at sources such as the ...


33

Juggling is easy: you just throw the balls at the right time, so that you have a free hand when they fall. With one ball or two balls, this is trivial. With three, it is easy enough. With more balls, it (surprisingly) becomes harder. Even substantially harder. In all generality, "reversing" encryption done using an n-bit key is like juggling with 2n balls. ...


-3

Well, you've kind of stated what a public key is for. A person generates a key pair - the public and private keys. If a file is encrypted with the private key, only the corresponding public key will decrypt that file. This has the rather pleasing additional benefit of guaranteeing the sender/encryptor of the file. Unless the private key is stolen ofc.


2

It is difficult for someone to tell you if a particular resource is adequately protected as it depends on the value of the files stored on the server as well as many other factors. I am assuming that you are using WPA/WPA2-PSK, which is what most small businesses usually use. Every employee connects to the wireless network using the same password. The risk ...


41

No, SSL uses a symmetric key so an attacker is unable to decrypt the message he has just captured. However, SSL is vulnerable to a traffic analysis attack. E.g. If you have 2 messages of very different lengths like "Execute order 66" "This is a very very very very very very very very very very very very very very very very very very very very long ...


4

As the other answered, it is generally not possible. However, there is always the possibility of having some information leaking depending on how the message is structured: an observer could read the encrypted message flow between party and obtain some of the meaning of these messages based on size or flow.


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No. See How does SSL/TLS work?: basically, every time you transfer data, it's encrypted with a symmetric key generated for that particular transaction. The public key is only used to verify the server's identity, so even if the attacker knows it, they can't tell what message you sent simply by looking at the ciphertext.


6

Well in the case of SSL, it would not be possible because of the way SSL works. The message would not be encrypted with the public key. Instead, the public key would be used to share information between the two persons in order to agree on a symmetric session key. This key will then be used to encrypt the "order", so you can't replicate this on your own ...


1

As this seems to be homework, I'll try not to just give you the answer, but to give you some questions and thoughts which should help you. Also, here are some links which should be interesting: Modern Cryptography Overview Padding Symmetric vs Public key crypto Cost of Crypto a)The communications require a key exchange not supported by block ciphers. ...


1

I'm unfamiliar with the details of the systems you specify but understand email encryption in general. Once a message is encrypted, the system cannot re-encrypt it with a stronger algorithm without user intervention as the system can't decrypt the email to re-encrypt it. So you're email is frozen in time in terms of the encryption that was used. Even if the ...


0

Sounds like a very cool project. It seems that you have rediscovered the very problem that Kerberos was designed to solve. Looking at your example, why would you not just use PKI both ways? Or can you not control the certificates at both ends? You could look at SSL session initialization to see how you could transfer a confidential message under the gaze ...


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You are making two assumptions here, that would need justification: NSA / "other agencies" invest in supercomputers. They do ? How exactly would you know that ? Did you read it on the Source of All Truths, i.e. "the Internet" ? NSA's unique goal in life is to break TLS sessions. Considering that the NSA has been created in 1952, while SSL was first ...


2

Super computers have a lot more use than just 'breaking' Cryptography. the NSA could be using super computers for anything from Big Data Analysis to Breaking a specific Encryption.


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There are many likely reasons. 99% of popular web sites support TLS 1.0, but only 58% support TLS 1.2 (SSL Pulse, 4/5/15) The existence of strong encryption does not imply the use of strong encryption The use of strong encryption does not imply the correct use of strong encryption The NSA is arguably interested in many, many things aside from TLS web ...


1

With an Arduino, you are limited in many ways. One of the ways you are limited is in your entropy (the random bits) which you need for ANY encryption system. You could add entropy randomness using the analogue pins of your Arduino, van Heusden has a example here. He has also quite some interesting articles about entropy and how it affects security. A ...


1

You can never know for certain if your cryptosystem is still safe. But there are few classical ways of going about this. If you are the one whose cryptosystem may be broken: Use your cryptosystem to send false information and see if the enemy responds to the false information. If they do, they've read your message. Note that that indicates that your ...


1

I agree that most Europeans will see their IBAN as private data and want them to be encrypted. But there is another compelling reason to encrypt and sign the IBANs: A man-in-the middle attacker may maliciously alter them to receive the money you want to pay off. So you should protect any IBAN against this threat.


5

There are encryption techniques like the One Time Pad that are provably non-compromisable when employed properly (but the one-time pad as single encryption technology has other problem like the possibility to change the encrypted message unnoticed). Otherwise, it is often good enough to know that there are no publically known breaks to the encryption ...


1

Here are some flaws I can think of: SMS spoofing is trivial (e.g. at work I use an online SMS sending service which lets me set any arbitrary alphanumeric sequence as the sending number), meaning the only security that the whitelisting step is providing is that the attacker must know which numbers are on the whitelist. In a typical scenario such ...


3

No, not really. You can't switch because ECC and RSA are totally different algorithms that use totally different keys. The best you can do is generate a new ECC subkey which will be signed by your old RSA master key, then you can use that subkey for signing and/or encryption.


0

There is the hardware based RDRAND instruction on IvyBridge Intel processors. If that is availabe (ie chip has instuction and does not have the RDRAND hardware bug cover-up) then I think Linux does automatically use it. Meaning you should get very large amounts of true random numbers very fast.


9

Entropy is required in the following sense: if a PRNG has only n bits of entropy, then this means that it has (conceptually) only 2n possible internal states, and thus could be broken through brutal enumeration of these 2n states, provided that n is low enough for such a brute force attack to be feasible. Then things become complex, because the "entropy ...


0

Nice project but as usual you really should not reinvent the wheel. Writing such protocols for production use is a bad idea in almost every case. I recommend reading Bruce Schneier's Cryptography Engineering book. It is not a light read but would definitely clear out all your questions. First of all I think burning keys into executables is a terrible idea. ...


0

Fundamental to the question, is if the endpoint is not secured, keys, whatever they may be can be obtained, which is why for endpoint secure transactions, the terminal itself is under the aegis of the proprietor - eg. atms, cash points, etc.


1

You can't have a private key hard coded in software that is distributed. The two options I see are: Have each client generate a unique key-pair that they use for communicating with the server. Bob would send his public key to the server when he initially connects. The server will then encrypt messages to Bob with his public key. The first communication ...


3

You don't know. You technically don't even know whether the password is stored at all, let alone whether it's stored hashed. Them being able to email you the password immediately after you tell it to them says nothing of storage.


2

TL;DR: For GnuPG 1.0 and 2.0, default is Cast5, for GnuPG 2.1 it is AES-128. Recipient's Preferences Per default, GnuPG will read the recipient's algorithm preferences and take the first algorithm in that list it supports (in other words, it takes the most-preferred supported algorithm the recipient asks for). Safe Algorithms If no preferences are given ...


1

It is possible for a module to be FIPS 140 Validated and include non-validated features like ECIES. You can see multiple instances of this in various validation documents: Blackberry Validated FIPS 140-1 and FIPS 140-2 Cryptographic Modules (2013) (includes BSAFE) The trick is that to use those modules in a FIPS-compliant way, you need to only use the ...


-3

Shiva Kumar U know One thing ........ Data Transmits from source to destination those steps are ok. But arranging different. In Encryption have change the data into hash code values.


2

Bitlocker uses AES in CBC mode, Truecrypt and others use AES/Twofish/Serpent/cascades in XTS mode (Wikipedia: Block cipher mode of operation). CBC mode is less secure in that it allows single bit manipulation, for example switching a specific bit of data when attacker can gain physical access to the machine then return it to you. This can open backdoor ...


1

I initially shared the same goal when I began considering encrypting my PC. Unfortunately, after hours and hours of research, all I learned was that VeraCrypt does not currently support encrypting Linux system drives. Ref: https://veracrypt.codeplex.com/wikipage?title=Supported%20Systems%20for%20System%20Encryption I was also not able to find an ...


0

The other answers already explain the security of GSM and the technologies involved against technical attacks. However, there are a number of other attacks which bypass the technical protections. The German Wikipedia article on transaction authentication numbers (which are often sent by SMS) lists some attacks: stealing or stealthily access the victim's ...


1

Am I correct in assuming that even though all the data from the last point above can potentially be read by someone else, the fact that the private key is required to recover the symmetric key means this is secure? Depends on your definition of secure. If you want to ensure confidentiality and integrity, and you go with CBC as you suggest in the ...


0

The real question is whether you're using a signing/authentication GPG subkey as your SSH key, or an encryption one. The former is fine, the latter is not: an RSA key must never be used to both encrypt and sign! (Authentication uses digital signatures.)


2

The basic design you propose is secure. Of course, the security of any working system also depends on the implementation. However, using public key crypto for backups has little benefit compared to symmetric crypto. The usual arrangement for backups is to have a symmetric key. You store this in two places: your working machine, and in a secure, safe, ...



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