# All Questions

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### Can anyone help me decipher this quickly? [closed]

7rN<V+A?ofCB I know its format is Xxxx Xxxx Please? I can't figure it out.
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### Why is the tweak length 64bit in BPS FPE algorithm?

In the algorithm for BPS Format Preserving Encryption Is this tweak always the same length (64bit)? Why did they choose the length 64bit for the tweak?
28 views

### Paillier cryptosystem, small integers and range of values

First, this a different take on my previous question: Pailler encryption of small integers to 32-bit integers I have to encode small integers (range 0-50) using the Paillier cryptosystem. Those ...
11 views

### OpenSSL CFB Modes [migrated]

I'm trying to understand OpenSSL notation - what is the difference between, for example: AES-256-CFB and ...
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### How is the server authenticated in ssh? [migrated]

The server does not know any secrets that can be used to authenticate itself. Also, what good is a fingerprint if it is based on the public key if it is basically the hash of some known public key. ...
24 views

### Challenge - What does this mean? [closed]

To keep it relatively simple this approach uses no foreign encryption key. A clue is that primes play a part. The paragraph immediately below this is source text. When pushed through an encryption ...
64 views

### generate RSA public key having public modulus and exponent [on hold]

i want to generate an RSA public public key file using openssl (or other tools) having public modulus and exponent, so i can use it later to encrypt files i have this: ...
35 views

### PKCS#7 message content

I am using a vendor library that signs a text producing a PKCS#7 message. I'm not sure of the content of this message. Does a pkcs#7 message have to contain the signed message, the certificate, the ...
97 views

### Is there a way to encrypt an integer within an arbitrary range?

I need an algorithm that can take an integer, an arbitrary range, a key of 16/24/32 bytes, and an initialization vector of 16 bytes(ideally), and return an integer in the same range. My latest attempt ...
54 views

### Need some understanding on RSA public key exponent

I am new in cryptography domain and try to build some understanding on RSA key pair generation. My doubt is on RSA public key exponent value . Can exponent be any value (prime or non prime numbers)? ...
94 views

### How can a Encrypt-And-MAC scheme be insecure if the encryption is CCA secure?

I was presented with this seemingly paradoxical information, and am hoping someone can explain what I'm missing here. I have an encrypt-and-mac scheme here.If I want to transmit message m to Bob, I'd ...
27 views

### What are the number of output bits of the internal function F used in BPS algorithm?

In the BPS specification document it says We denote by f the number of output bits of the internal function F What is this if the internal function is AES? Would it be the block size (e.g. 128)? ...
45 views

### TLS_PSK and perfect forward secrecy

My question is about how difficult is for someone having compromised the PSK and sniff all (DT)LS handshake, (so getting the NONCE), to get the encryption keys? I understand : getting the pre-master ...
38 views

### Do ECDH and ECDSA combined solution provide an authenticated protocol exchange solution in MCU environment?

I'm working on a project in MCU (micro controller) environment with GPRS connection to exchange data securely with the cloud. The encryption algorithm has been selected to use AES. I did some search ...
30 views

### Encryption Algorithms in Verilog code

Can we implement Encryption Algorithms like RC4,AES and DES in Verilog? if no what are the limitations?
28 views

### what is the algorithm this site thetoptens<dot>com, for Specified unique user [closed]

I found this site that have a nice algorithm for Specified unique user, Trust me, This algorithm not working with cookies, or just IP or fingerprint of browser you can test it. ON this site you ...
76 views

### How to pronounce SHA1 and SHA2?

I'm not a native English speaker. So I want to know how to pronounce SHA1 and SHA2 like a native English speaker. Should they be pronounced as [Shar(p) One] and [Shar(p) Two]? Thanks in advance.
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### undersanding a free- coordinates version of Segre’s Lemma of Tangents [closed]

Reading we found this version of the Segre's Lemma of tangents, and we don't understand it. I will put an * follow by a number in the section we don't understand so you can see what are we thinking. ...
17 views

### Sign & Encrypt vs. Encrypt & Sign - What does gpg do? [migrated]

I've already read the discussion Should we sign-then-encrypt, or encrypt-then-sign? and the paper Defective Sign & Encrypt in S/MIME, PKCS#7, MOSS, PEM, PGP, and XML. My question has to do with ...
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### Storing sensitive information for a short time, how should I encrypt it or do I even need too? [migrated]

So I will be accepting some sensitive information via a html form, I will be using PHP to store the information. All this has been set up, tested etc. The form works in 4 "steps", each step is its own ...
49 views

### Secure “table-look-up” operation

I am thinking about this problem: The server has a two-column table $T=\{c_1,c_2\}$. A user has a query $q$ that is sent to server. The server find an item $x$ in the first column satisfying $x=q$ ...
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### How to find out encryption algorithm with a known key? [closed]

how to find out the original text encrypted text: TSCyyWynRp5fE8IOluJP17/nLRE7zh0eqrrp+0FGWK6QRE8nZ3PnJfTK3i5 CPUaGZIqY+Sfy1JiEM2GXn4ZIgvkX4fIColUtzeNhlfk= ...
87 views

### Define “cryptographer”

I often encounter the phrase "I am not a cryptographer". Is there a generally accepted definition for who is a cryptographer? What qualifications would be expected? For instance, should that person ...
67 views

### Is reverse NTRU still secure?

I'm currently prototyping something with the NTRU encryption scheme but I wish to use it in "reverse" -- distribute private keys so anyone can decrypt, but keep the public keys secret and thus only ...
26 views

### ECDSA cryptography [closed]

i am trying to get EC_key public key out of X509 certificate to validate the signature X509_get_pubkey returns EVP_key . My intention here is to generate a ECDSA signature with an private key and ...
66 views

### If I compute the SHA-1 of all possible 40 digits hexadecimal strings, will I get all possible sha1 hashes? [duplicate]

Wikipedia says sha1 produces a 160-bit (20-byte) hash value. So if I compute the SHA-1 of all possible SHA-1 values, which as far as I understand is at current time impossible both to calculate and ...
32 views

### research on Encryption for master [closed]

I'm tring to choose an way for an Encryption mothod for my research? So,I want to choose one-layer encryption or multilayer encryption,and I want it to be easy to applicable. when I search about it, ...
47 views

### Is this scheme to derive multiple keys secure?

I need a cryptographic scheme to generate a deterministic chain of private keys that look random to outside observer but can always be reconstructed from a single root key, also: Neither private ...
37 views

### Why is (gy, gx) signed in STS (station-to-station)?

My question relates to the station-to-station protocol as described in https://en.wikipedia.org/wiki/Station-to-Station_protocol [1] and http://cacr.uwaterloo.ca/hac/ [2] p 519. ...
37 views

### Digital signatures using a partially public key

I'm thinking to sign a message using a key that is made up of a publicly shared key and a privately shared key. The operation for mixing the two keys could be concatenation, if it suffices. To ...
27 views

### Blowfish and DES small block size and maximum message size

Would the following affect the maximum message size limititaion of Blowfish and DES due their small 64 bit block size? Let's take Blowfish for example. You take a 256 bit Blowfish key, quickly ...
38 views

### Is there a standard format for compact 56-bit DES keys?

DES keys are traditionally stored as 8-byte blobs, with only the high 7 bits of each byte being meaningful to the algorithm; the low bit of each byte is set so that the population count of the byte is ...
41 views

### Help defining a shift cipher mathematically

For an assignment question, I am trying to prove formally that double encryption with two keys by the shift-cipher encryption function results in a shift cipher as well. If the Shift-cipher encryption ...
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### Veracrypt Hash Algorithms Missing [migrated]

I was going to encrypt my system drive with Veracrypt 1.14 and when choosing the Hash Alghorithm, I noticed there were only these two available despite cipher chosen: SHA-256 RIPMED-160 So ...