Using salsa20 to obfuscate strings, reference: https://stackoverflow.com/a/59929628/37020

salsa20_obfuscator.c

// Relies on https://github.com/alexwebr/salsa20
// To compile and run: place it in a directory with salsa20.c and salsa20.h and run:
//   %  cc salsa20_obfuscator.c salsa20.c && ./a.out
// Then write strings in stdin. For example:
//   % $ echo "Cancel" | ./a.out
//   'Cancel' -> [0x89, 0x88, 0x6a, 0xd1, 0x12, 0xc1]

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "salsa20.h"

// hard-coded 128-bit key, can be anything
uint8_t k[32] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };

// hard-coded nonce, can be anything
uint8_t n[8] = { 101, 102, 103, 104, 105, 106, 107, 108 };

int main() {
    char *line = NULL;
    size_t linecap = 0;
    ssize_t linelen;

    uint8_t encryption_buffer[1024];

    while ((linelen = getline(&line, &linecap, stdin)) > 0) {
        // strip trailing newline
        if (line[linelen-1] == '\n') {
            line[linelen-1] = '\0';
            linelen--;
        }

        if (linelen == 0) {
            continue;
        }

        if (linelen > sizeof(encryption_buffer)) {
            printf("Skipping long word (len=%ld) '%s'\n", linelen, line);
            continue;
        }

        memcpy(encryption_buffer, line, linelen);

        s20_crypt(k, S20_KEYLEN_128, n, 0, encryption_buffer, linelen);
        printf("'%s' -> [0x%x", line, encryption_buffer[0]);
        for (size_t i=1; i < linelen; i++) {
            printf(", 0x%x", encryption_buffer[i]);
        }
        printf("]\n");
    }
    if (line != NULL) {
        free(line);
    }
    return 0;
}