All Questions
Tagged with cryptography c
639 questions
0
votes
1
answer
75
views
RSA signature verification failing for smartcards
I am trying to sign a byte string using the c_sign function from pkcs and I am trying to verify it using RSA.verify() function in ASP.net, but for some reason its failing.
I am using 2048 bit RSA keys ...
1
vote
0
answers
48
views
Difference between the BN_mod_mul_reciprocal and BN_mod_mul_montgomery function groups in OpenSSL
The OpenSSL C library has two different sets of functions for performing modular multiplication quickly: BN_mod_mul_reciprocal and BN_mod_mul_montgomery. What are the differences between using either ...
- 21
0
votes
0
answers
84
views
How to import an ECDSA to the kernel crypto API: crypto_akcipher_set_pub_key always returns error?
I'm working on a kernel module which uses asymmetric cipher of kernel crypto api, kernel version 6.5.0. I generate asymmetric key pairs by openssl, convert them into DER format and import it into the ...
- 31
1
vote
0
answers
56
views
How can i implement a triple aes encryption to make dpa attack last a little longer on my case study? [closed]
I am trying to implement tmr methodology for my AES operation and i want to do it with the same key and the same plaintext slightly changed randomly for the last two plaintexts. I also added a voter ...
- 11
3
votes
0
answers
55
views
Make OpenSSL use pointers from input buffer for holding cms structure instead of allocating memory
An embedded device with limited memory is already using OpenSSL for communication.
I am implementing a CMS signature verification wrapper library using OpenSSL that should work for the device.
We ...
- 33
0
votes
0
answers
110
views
i am getting "undefined reference" error while i am going to defination it is there in arduino ide
I'm trying to generate keys for encoding and decoding using the Kyber API in an Arduino project, but I'm encountering a compilation error. My code includes the api.h header and attempts to call ...
0
votes
1
answer
154
views
Replicating hkdf2 key derivation in C
I am trying to create a derived key from my shared secret and shared key. I have done this before, in Java and Python, where it is a fairly straight forward process, however, it seems that in C this ...
2
votes
1
answer
182
views
Aligning Key Sizes Between OpenSSL and liboqs-go for Signature Verification in Go
I am developing a cryptographic application in Go, aiming to utilize keys generated by both OpenSSL and liboqs-go for signing and verifying purposes. I'm using the Dilithium2 algorithm through both ...
- 31
0
votes
1
answer
422
views
How to Generate Dilithium Keys with `liboqs-go` and Convert Them to PEM Format for OpenSSL
I am trying to using the liboqs-go library to generate cryptographic keys with post-quantum algorithms and need to use these keys with OpenSSL to generate CSRs and certificates. However, I'm facing ...
- 11
1
vote
0
answers
92
views
MbedTls: Does mbedtls_gcm_auth_decrypt output have the same length as input after decryption? Why/Does it need an extra 8 trailing bytes during?
MBedTls AES-GCM-In-Place-Decryption: Does mbedtls_gcm_auth_decrypt output-buffer have the same length as the input-buffer after encryption? Why does it/Does it really need an extra 8 trailing bytes ...
- 41
0
votes
0
answers
130
views
VS Code -- openssl/aes.h: No such file or directory gcc [Ln 4, Col 10]
I am trying to implement a time attack. Briefly there are these steps
a) Timing Measurement ( <time.h> to measure time )
b) Cryptographic Operations (For AES encryption, i am using OpenSSL)
c) ...
2
votes
1
answer
196
views
SHA256 Endianness problems
For a project, I wanted to implement SHA256 in C from scratch. However, the specification here mixes things up with little and big endianness and makes things unclear. I've coded the entire hashing ...
- 288
2
votes
1
answer
173
views
Mbed TLS: in-place en-/decryption for OAEP doesn't seem to work
RSA encryption/decryption works in Mbed TLS when using separate buffers where plainText, cipherText, and decryptedText (i.e. the content of plainText and decryptedText) are the same.
However, it does ...
- 41
0
votes
1
answer
307
views
RSA between C# and C's BCrypt [duplicate]
I am trying to use RSA 2048 to have encryption between my C# and C programs. To accomplish this, I am imbedding the private key inside my C program and imbedding the public key inside the C# program. ...
- 150
1
vote
0
answers
187
views
Converting C# RSA private key into a form BCrypt can understand
I need help using BCrypt to communicate between my C# app and my C app. Specifically, I need to imbed the private key inside my C application and then imbed the public key inside my C# app since my C# ...
- 150
2
votes
0
answers
116
views
RSASSA-PSS signature verification fails dues to padding with mbedtls but succeeds in Python
I am trying to verify signatures like this using mbedtls in C-Ansi but it fails even though that the same signature is verified in Python.
The code is being ran in the i.MX RT1170 CM7 using the crypto ...
- 29
2
votes
0
answers
266
views
Deterministic CTR_DRBG in OpenSSL
I'm using the OpenSSL EVP API in C to call the CTR_DRBG implementation and I'm having some trouble getting the output to be deterministic.
Configuration and all input arguments are fixed (entropy, ...
0
votes
0
answers
193
views
MbedTls: Writing public-key in DER-format (mbedtls_pk_write_pubkey_der) works, but writing same key in PEM (mbedtls_pk_write_pubkey_pem) fails?
I'm trying to write out a public key created using MbedTls in a c-programm. This works when using the function to write out DER-keys as it returns the number of bytes written (91) and the key in ...
- 41
1
vote
1
answer
119
views
What's wrong with the following implementation of MD5?
I'm trying to implement a MD5 hash function in C. I've read the RFC, and done the following, and am trying to figure out what's wrong in here. I know that I should probably be using a library like ...
- 126
1
vote
1
answer
84
views
Cryptography in C
You have intercepted a poorly evolved terrorist cell that uses Caesar's method as a cipher. Messages are always in English. What they do is replace each letter with another letter by moving the ...
- 33
0
votes
0
answers
24
views
XOR Hex and ASCII [duplicate]
I have a 16 bit key (e.g., abcd) that represents hex values, and a 16 bit input (e.g., 0123) that I read in and stored in a character array. How would I XOR these together in C? I'm pretty stuck on ...
- 33
1
vote
1
answer
199
views
Internal handling of IV in AES_GCM_256, for multiple encryption calls on same plaintext
I am trying to understand the working of OpenSSL's EVP_EncryptUpdate function, specifically why does it return different cipher-text for same plaintext, key and IV (initially provided), over multiple ...
- 13
0
votes
1
answer
141
views
crypto_secretbox_easy appends several '[NUL]' characters to the end of text
I have created two functions 'encryptf', and 'decrytpf' (named with 'f' to avoid naming conflict with pre-existing libsodium functions. These functions are pretty self explanatory, they encrypt, and ...
- 71
0
votes
1
answer
114
views
I have written the code of affine cipher in C. It correctly encrypts/decrypts the uppercase letters but incorrectly encrypts/decrypts lowercase letter
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
# define MAX_LENGTH 100
int GCD(int a, int b) {
if(b == 0) {
return a;
}
GCD(b, a%b);
}
struct Pair{
...
- 1
1
vote
0
answers
55
views
Trying to use OQS-OpenSSL_1_1_1 in Golang
I'm use open-quantum-safe/openssl to create certificates and key pairs , now i want to use this library(https://github.com/open-quantum-safe/openssl) to create certs & keys using golang so i can ...
- 31
0
votes
1
answer
150
views
CryptDecrypt function fails with NTE_BAD_DATA in C
Im trying to decrypt a .png file but for some reson CryptDecrypt returns Bad Data error.
I'm new to C and Cryptography so it would be awesome if someone could tell me why is it happaning and how to ...
2
votes
0
answers
58
views
LibTomcrypt Invalid input packet while decrypting
Im trying to create an API from C to Lua for lua can use ecc_encrypt and decrypt from libtomcrypt, for it have the function encrypt that encrypt the mensage given by blocks and when im trying do ...
- 31
1
vote
1
answer
97
views
Problem with the out put of the ecc_decryption_key using libtomcrypt in C
I Have the following simple code.
Im just initializing the parameters, calling a make_key function, encrypting the data and trying to decrypted the data
#define LTM_DESC
#include <tomcrypt.h>
...
- 31
1
vote
1
answer
151
views
Use "/dev/urandom" with GMP library to generate a very big random number
I'm using Debian Bookworm and GMP library version 60201.
I need to generate a random number with GMP library but I have 2 requirements, if possible, of course!
1 - Generate a number between 0 and a ...
- 31
1
vote
1
answer
213
views
tpm2.LoadExternal() throws error code 0x16 : unsupported symmetric algorithm or key size, or not appropriate for instance Error
I have a DPE application and I am doing client.Sign of a message. This function returns a signature, a certificate from which we can get public key and other few things.
I have extracted the public ...
- 21
0
votes
0
answers
90
views
Macro Defined Functions - Compiling Error
I am trying to compile and create executable for the dilithium2 algorithm which is a Quantum Cryptography Project. I am getting into trouble with using macro defined functions in my compiling process. ...
1
vote
1
answer
66
views
gnutls_cipher_encrypt2 returns "The request is invalid."
I'm messing around with GnuTLS and I want to write a C program which encrypts/decrypts a file using the GnuTLS functions.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#...
- 43
0
votes
1
answer
410
views
Setting EVP_PKEY_RSA_PSS key type to EVP_PKEY* object leads to segmentation fault in C
I have a C code which creates a public key from exponent and modulus of a JWK data. Leave about JWK data here.
here the generated public key is in EVP_PKEY* format and its type is "EVP_PKEY_RSA&...
- 21
0
votes
0
answers
205
views
JWT token verification fails in C
I am trying to verify JWT token which has PS384 algorithm in its header. I am trying using this library. This provides some sample applications also including RS256 algorithm.
and it is mentioned that ...
- 21
0
votes
0
answers
134
views
STM32F7 problem with FreeRTOS and Cryptographic Library
Im using STM32F723 and using the Cryptographic Library (https://wiki.stmicroelectronics.cn/stm32mcu/wiki/Security:Getting_started_with_the_Cryptographic_Library).
When testing basic cmox_aead_encrypt ...
- 23
0
votes
1
answer
264
views
RSA Signature generated by X-Cube Crypto Library (Embedded C) and Python script are not matching even though we used same key for both methods
My application to generate SHA256 hash value for the "xx_xx.hex " file and then generate RSA signature for hash . SHA256 value generated by X-Cube-CRYPTOLIB and python script both are same. ...
- 13
0
votes
1
answer
117
views
RSA Decryption in C: Can't get the correct message
Good night, guys. I am struggling for a week with an exercise of programming in C. It was basically:
"Imagine you know my public RSA key which has the modulus n = 16076635963 and the public ...
- 65
0
votes
1
answer
194
views
How to fetch supported public-key algorithms from OpenSSL 3.0?
Currently I use EVP_PKEY_meth_get_count(), EVP_PKEY_meth_get0 and suchlike calls to fetch list of supported public-key algorithms. However, OpenSSL 3.0 deprecates their usage. Which API should be used ...
- 14.1k
2
votes
0
answers
84
views
How to get the VB6 PRNG to generate a byte output from a specific seed, and how to replicate in C?
Long time reader and lurker, first time poster.
I'm hoping to get some help regarding an old problem that has eluded me. I'm trying to figure out how the VB6 PRNG was used to generate a byte output ...
- 29
1
vote
0
answers
66
views
What is the easiest way to create a secured network client in Linux (C) without any external libraries?
As i said, i want to create a secured network connection (TSL/QUIC/...) in C for Linux. Is there a easy way to create that directly based on the linux standard libraries without OpenSSL or other ...
- 451
0
votes
0
answers
58
views
When inserting lkm rootkit the kernel crashes
I am writing an lkm rootkit for ubuntu 5.19.0-35-generic 20.04 tls server, found here. I have a program that updates the hex string of a big int, and whenever I run it the entire kernel crashes.
int ...
user21382175
1
vote
0
answers
156
views
GMP library usage cause memory exhaustion
I am using GMP library for large number of calculation. I have checked through valgrind that there is no memory leaks in program for small numbers of calculations. But when I try to calculate large ...
- 31
0
votes
0
answers
76
views
How would I do big math whilst operating withing the kernel?
I am making a client for a server that operates in kernel-space and am attempting to write my own protocol for encryption, mostly due to the fact that it seems fun but also because no user-space ...
user21382175
2
votes
1
answer
4k
views
What does OPENSSL_NO_DEPRECATED_3_0 mean?
For example, consider this snippet:
# ifndef OPENSSL_NO_DEPRECATED_3_0
OSSL_DEPRECATEDIN_3_0 size_t HMAC_size(const HMAC_CTX *e);
OSSL_DEPRECATEDIN_3_0 HMAC_CTX *HMAC_CTX_new(void);
...
- 125
1
vote
2
answers
2k
views
mbedTLS ECDSA verification fails
I am porting one ECC ECDSA verify library to mbedTLS to benefit from large pool of crypto functions and I'm at a point where after 2 nights, I'm not able to verify the signature. It works well with ...
- 7,431
-3
votes
1
answer
106
views
Access Violation only with large values, but working with small ones [closed]
I am working on a C method to find the inverse of a number mod n, and it works perfectly fine when for example I call this method with 6.0 and 65537.0, it gives me the correct result, even when ...
1
vote
1
answer
160
views
OpenWall BCrypt: Example of Hashing Input using crypt_r and explanation of inputs and best practice
I am struggling with finding examples for OpenWall's bcrypt implementation that use crypt_gensalt_rn and crypt_r that also explain in depth exactly what is happening in terms of input, settings etc ...
- 204
0
votes
1
answer
521
views
OpenSSl 3 not verifying (using) tag using chacha20 poly1305
i just started learning openssl,
when i use chacha20_poly1305() to encrypt and mac some text, it does not work
What am i doing wrong, how does this work
int main( )
{
unsigned char key[] = "...
- 1
2
votes
1
answer
99
views
Why do I have inconsistent evaluation of cipher and corresponding plain message using RSA algorithm?
Rationale
To simulate the RSA algorithm in C using a robust command-line application written in C.
Here is my problem:
Taking values of e=7, p=3 and q=11 works fine when encrypting and decrypting.
...
- 153
0
votes
0
answers
231
views
WolfSSL Settings.h File shows some error during the project building. it shows Unresolved inclution: "stm32f4xx"
I am still studing about the WolfSSL Library. I'm usng Nucleo-STM32L476RG to run the programm.After generating the code,i try to build the code and then it shows error in settings.h file. The error ...
