https://github.com/adam-mcdaniel/rsa
An RSA🔐 implementation in C, using arbitrarily large integers
https://github.com/adam-mcdaniel/rsa
c cybersecurity decryption encryption header-only library rsa-cryptography
Last synced: about 1 year ago
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An RSA🔐 implementation in C, using arbitrarily large integers
- Host: GitHub
- URL: https://github.com/adam-mcdaniel/rsa
- Owner: adam-mcdaniel
- License: mit
- Created: 2024-04-10T01:42:16.000Z (about 2 years ago)
- Default Branch: main
- Last Pushed: 2024-04-23T21:11:51.000Z (about 2 years ago)
- Last Synced: 2025-04-01T10:01:44.296Z (about 1 year ago)
- Topics: c, cybersecurity, decryption, encryption, header-only, library, rsa-cryptography
- Language: C
- Homepage: https://adam-mcdaniel.net
- Size: 1010 KB
- Stars: 9
- Watchers: 2
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# rsa
This repository implements the RSA algorithm in C, with arbitarily large integers. The implementation uses [a custom bigint library](https://github.com/adam-mcdaniel/bigint) to handle large key sizes.
The library is header-only, and can be included in any C project.
It has support for generating keys and encrypting/decrypting messages.
## Usage
To use the library, first include it in your C file.
```c
#include "rsa.h"
```
Then, generate a public/private key pair using the `generate_key_pair` function.
```c
int main() {
bigint p1 = bigint_from_string("61");
bigint p2 = bigint_from_string("53");
bigint n, t, e, d;
generate_key_pair(p1, p2, &n, &t, &e, &d);
printf("Public key: ");
bigint_print(e);
printf("\nPrivate key: ");
bigint_print(d);
return 0;
}
```
Then, use the `encrypt_text` and `decrypt_text` functions to encrypt and decrypt messages.
```c
int main() {
bigint p1 = bigint_from_string("61");
bigint p2 = bigint_from_string("53");
bigint n, t, e, d;
generate_key_pair(p1, p2, &n, &t, &e, &d);
printf("Public key: ");
bigint_print(e);
printf("\nPrivate key: ");
bigint_print(d);
char message[] = "Hello, world!";
bigint *encrypted = encrypt_text(message, e, n);
char *decrypted = decrypt_text(encrypted, strlen(message), d, n);
printf("\nEncrypted: ");
for (int i = 0; i < strlen(message); i++) {
bigint_print(encrypted[i]);
printf(" ");
}
printf("\nDecrypted: %s\n", decrypted);
return 0;
}
```
## Building
To build your program with the RSA library, simply add it to your include path, [along with the bigint header file](https://github.com/adam-mcdaniel/bigint), and link against the C standard library.
```bash
gcc -I path/to/rsa -I path/to/bigint main.c -o main
```
### CMake
To build with CMake, you can use a `CMakeLists.txt` file like the following:
```cmake
cmake_minimum_required(VERSION 3.0)
# Create a new project
project(HelloWorld)
# Add an executable
add_executable(HelloWorld main.c)
include_directories(path/to/rsa)
include_directories(path/to/bigint)
```
Alternatively, you can use `FetchContent` to download the RSA and Bigint repositories and include them in your project.
```cmake
# Import the library from the git repo
include(FetchContent)
FetchContent_Declare(
rsa
GIT_REPOSITORY https://github.com/adam-mcdaniel/rsa
GIT_TAG main
)
FetchContent_MakeAvailable(rsa)
# Include the header only library
include_directories(${rsa_SOURCE_DIR})
# Do the same for the bigint project
FetchContent_Declare(
bigint
GIT_REPOSITORY https://github.com/adam-mcdaniel/bigint
GIT_TAG main
)
FetchContent_MakeAvailable(bigint)
# Include the header only library
include_directories(${bigint_SOURCE_DIR})
```
## License
This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.