Questions tagged [encryption]

Encryption is the process of transforming plaintext using a cipher into ciphertext to make it unreadable to anyone except those possessing the key. Decryption is the process of transforming that ciphertext back into plaintext, using the key.

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Homomorphic encryption - addition for more than two parties

I have just found out about the homomorphic encryption and I was wondering how is it possible to perform an addition for more than two parties? More concretely, I want to have several parties $P_i$, ...
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Elliptical Curve Cryptography benchmark test

I have built web app that implement Elliptical Curve Cryptography. During testing using data set that i chose on my own, it already run well.. But, for now, i want to test it in some benchmark test, ...
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Any algorithm with a pair of master keys and multiple pairs of subkey for a secure key escrow?

Note: This question looks like my other question — Any algorithm with a master key for decrypting private key encrypted messages? — which is perfectly answered by @real-or-random, but this one is ...
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Custom encryption scheme for SSL

Suppose that messages transmitted over SSL are modified as follows: the message is splitted in blocks, $B_1, ..., B_m$ (each with at most $2^{14}$ bytes) for each block $B_i$ we do: ...
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Negligible probability of failure in correctness definition (predicate based encryption)

I would like to understand why some definitions of correctness allow a negligible failure probability. i.e. the probability that decryption reverses encryption is 1 minus a negligibly small amount. I ...
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Are there any proof of work style encryption algorithms? i.e. an encryption algorithm which takes a lot of work to encrypt, but is easy to decrypt

I'm wondering whether or not there is an encryption algorithm, or at least the possibility of one, which takes a lot of work to encrypt, yet can be decrypted very easily? I have come across this ...
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Question on recovering a key in the algorithm

Let $E$ be a block cipher that has block size and key size both equal to 64 bits. Let $E'$ be a block cipher that has 64-bit block size and is defined as follows: For a 128 bits key $K \mathbin\Vert ...
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Is there any cipher standard based on SHA-3, where it is not used as part of RFC2104?

I'm thinking about using a cipher, which uses AES CTR+SHA-3. My basic idea is this: IV|AES-CTR(PLAINTEXT_SIZE|PLAINTEXT|SHA-3(KEY|PLAINTEXT_SIZE|PLAINTEXT)) So, ...
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146 views

AES-192 bit fixed matrix values in mixed column step

In advanced encryption standard,in mixed column step,how those fixed matrix values came? The values are (02 03 01 01), will these values will be the same for 192 ...
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Why in the Rao-Nam private key version of McEliece scheme, P matrix is multiplied after adding error vector?

The private key version of McEliece known as Rao-Nam scheme, the encryption is done as c = (mSG + e)P. What is the need for applying permutation matrix on the error vector?
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Does multiple encryption cycles (using the same password for each iteration) offer any security?

Does running a plaintext through AES multiple times with the same password offers any security benefit akin to triple DES? Note that I'm assuming “same password for each iteration”.
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How does the Chop Chop attack effect TKIP?

I know that chop chop attack is because of WEP's insecure checksum mechanism that is CRC32. As TKIP uses MIC along with CRC32 which just makes an attacker to wait for 60 sec upon two mismatch MIC ...
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177 views

Polynomially many iterations of one way permutation

I have seen that the existence of weak OWFs implies the existence of strong OWFs. It comes from repeating the weak OWF polynomially many times on different random inputs. However, I have a different ...
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Leaked bits from other cryptosystems

We know discrete logarithm leaks last bit and factoring is easy if half the bits of factors are known. Are there similar trivia associated with SVP based schemes, NTRU scheme, McEliece scheme etc.?
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Why is simulation-based security for functional encryption impossible in the standard model?

Boneh et al.(Functional Encryption Definitions and Challenges) present that simulation-based security for functional encryption is impossible in the standard model. I can not understand this. In ...
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146 views

What's the advantage of branching program? Why we use branching program to compute the encrypted data?

Branching program is one type of NC1 circuit and can be used to compute encrypted data. So whether there exist other methods in the NC1 circuit to compute encrypted data. What's the advantage of ...
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273 views

Storing Ciphertext in Firebase - Key Choice and Storage

I am building an application where I want that data submitted by the user is stored encrypted in the database, such that only the user can access it. I started reading into cryptography and it looks ...
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101 views

Algorithms to securely derive symmetric keys

I need to derive symmetric keys between two communication endpoints on an embedded device with 800MHz ARM core. What algorithms are available to have this secure key derivation mechanism? I know ...
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Encryption in ABE

With reference to the image above, what is meant by Choose $d_r$ other points of the polynomial $q_r$ to define it completely
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229 views

Threshold encryption with threshold on encryption part

For a thought experiment I'm looking for a threshold encryption scheme where $k$ out of $n$ shares are needed to encrypt the data and everybody can decrypt the data. However, I only found schemes ...
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290 views

How well do ARX algorithms preform (in terms of diffusion)?

I have been researching ARX algorithms, but I would like to know how well does ARX (both single or multiple rounds of) provide diffusion compared to an s-box or an SP network. Also, are there any ...
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103 views

Generating irreversible unique id based on fingerprint template

I'm a student who follows software engineering. I'm looking for method to generating irreversible unique id based on fingerprint for a software competition. What kind of encryption method can we use? ...
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How to get the value of the subkeys in IDEA decryption?

So I saw this example of IDEA .. If the key is : 5a14 fb3e 021c 79e0 6081 46a0 117b ff03 The encryption subkeys are: http://imgur.com/a/bZGMF The decryption subkeys are: http://imgur.com/a/FnF2c ...
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how researchers extract encryption times when randomness is involved?

I have seen some research papers where they compare encryption/signature times on elliptic curves.But when i have implemented the algorithms and calculated encryption times but each time i get some ...
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zero knowledge messaging implementation

I understand that messages are encrypted using a symmetric algorithm such as AES, and the symmetric key is encrypted using an asymmetric algorithm such as RSA. In my particular implementation, the ...
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PGP - MIME, is it correct?

I see following x.509 certificate attached(or may be signed, not sure) with OpenPGP key. Is that s/MIME certificate attached with PGP? What that does? Can this be created with GnuPG or probably, how ...
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280 views

Thorp-Shuffle Coupling

My question is regarding the coupling of the Thorp-Shuffle, as described in Morris/Rogaway/Stegers, Thorp-Shuffle Encryption. On pages 7 to 9, they describe and implement a coupling. It's all fairly ...
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325 views

RSA-Encryption, How to find private key (d) knowing public key (n) (e) & knowing how big the cypher text is (88 digits)?

How do i crack given n as n = 4099430871402176635782717535427267202018459295862032363925221458393907152187479623765591 and e as ...
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103 views

Is it ever worse to add more rounds?

As my understanding goes, it is generally more secure to add more rounds to an algorithm (though it may increase processing time). Is there any exceptions to this rule? Theoretically - if your ...
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115 views

What do the inputs of `hash_df` look like?

I am making an implementation of hash_df (NIST documentation found in SP800-90A.pdf on page 67) I found “Does hash_df use binary or an ASCII hexadecimal ...
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How to secure DICOM images

I am working on securing DICOM medical images, and the proposed approach is to use selective image encryption based on a segmented Region Of Interest (ROI) and Region Of Background (ROB) of the DICOM ...
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Decryption and Hashing in random order of a file

I have a requirement where an encrypted file is read in random order of 32k chunks and decrypted and final content hash is computed. This hash should match the original content of file. I need this ...
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210 views

Test vectors for Piccolo algorithm?

I'm looking for Test Vectors to test my implementation of PICCOLO. I would like to test a different input from the usual where the key and the plaintext are either 000..000 or FFF...FFF. I wrote ...
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142 views

Can a number be encrypted, added to other numbers, and then the sum decrypted?

I imagine there is a class of algorithms for this, but I don't know the name to google for more info. To describe the desired behavior: ...
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Use of elapsed execution time as a variable input

Given that, with a significant number of decimals, it may be difficult to predict elapsed execution time of a piece of code, despite having knowledge of exact hardware and software specifications; is ...
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Digital Dead Drops or guaranteed significant uncertainty of identity over TCP/IP for a large set of users

Client is part of a Set members. Every distinct object in members has in common, that they do want to communicate to the Server without the Server or other objects of members knowing the origin of ...
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How to calculate how many trials I need to guess the plain text if a simple P-Box is used to make the cipher text

If I have 64 bit as input for a straight box that use a transposition process to encipher the plain text and the given 64 bits contains 60 bits as (1s), then how many trial I should do?
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Why the light contrast of a set $\mathcal{E}$ of VCRG produced by an encryption scheme for a binary image B is defined as follows

In the paper “Image encryption by multiple random grids”, Shyong Jian Shyu, 42(7):1582-1596,· July 2009, the light contrast of a set $\mathcal{E}$ of VCRG produced by an encryption scheme for a binary ...
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What are the most appropriate PKI based cryptographic protocols for peer to peer communicaton?

I've been trying to find out which is the most appropriate PKI based cryptographic protocol for peer to peer communication. I do understand that they vary with respect to the peer to peer architecture ...
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60 views

Algorithm to rotate values in a predefined manner

I will start with an example. Some beacon like estimote Beacons use something called secure ID. The ID transmitted by the beacon change every 10 minutes autonomously without contacting the server. ...
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How to use OpenSSL command line utility to encrypt data with encrypted key from public key?

I may not be asking the right question. I am fairly new to data encryption. I am currently being sent encrypted data that's stored as follows: [ [keysize] [key encrypted with public key] [ivsize] [...
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526 views

Format Preserving Encryption FF1 Samples

NIST published methods for Format-Preserving Encryption and there is a link in the document giving examples for FF1 methods. I am confused by the value of R given in the examples. $R$ is the output ...
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How to encrypt an image with logistic chaotic map?

I need to encrypt color images, using logistic chaotic map. Could you please recommend an algorithm for this? All the articles that I've found on the Internet are completely unclear.
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If you receive a message with a digital signature, how do you know what verification key to use and the verification algorithm?

Really, I'm asking how do you know who sent it? My confusion has arisen from the following scenario... Problems with Signing-then-encrypting. If Alice digitally signed some data and then encrypted ...
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66 views

Can error correcting codes be used to guess this plaintext?

I pick a finite set of messages, perhaps the set of integers $M = \lbrace n \in \mathbf{Z} \, : \, 0 \leq n\lt10 \rbrace$, which you are then allowed to encode in any way you want (some form of error ...
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Encryption & decryption of integers using modular multiplicative inverse and extended euclidean algorithm

I'm looking for a neat algorithm, which is capable of encrypting an integer to another integer and decrypting it again AND is secure. When I was in university, my professor showed me an awesome way ...
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Is it possible to create a detection oracle for all block cipher modes? — ciphertext-only cryptanalysis

I have made an ECB/CBC detection oracle, and am now trying to make a detection oracle that can differentiate between CBC/CFB/OFB/CTR/etc. I can already tell ECB apart from the others due to this ...
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251 views

Confidentiality then Integrity with different keys

Can anyone describe how we can do what is said in the below sentence which is in Mark Stamp crypto slides (PPTX) on slide number 101 : Can do a little better - about 1.5 “encryptions” The whole ...
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130 views

Example of FHEI scheme?

I am reading this paper Toward Secure Multikeyword Top-k Retrieval over Encrypted Cloud Data. I am trying to work out an example of the FHEI (Fully homomorphic Encryption over Integers) scheme ...
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PBC library: group of composite order for pairing operation

How to generate composite order group using PBC library? With PBC library, element_init_G1(g,pairing) statement creates element $g$ for group of prime order. I want ...

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