Task: Bacon cipher

C: #include <stdio.h>
#include <string.h>
#include <stdlib.h>


char *codes[] = {
    "AAAAA", "AAAAB", "AAABA", "AAABB", "AABAA",
    "AABAB", "AABBA", "AABBB", "ABAAA", "ABAAB",
    "ABABA", "ABABB", "ABBAA", "ABBAB", "ABBBA",
    "ABBBB", "BAAAA", "BAAAB", "BAABA", "BAABB",
    "BABAA", "BABAB", "BABBA", "BABBB", "BBAAA",
    "BBAAB", "BBBAA"
};

char *get_code(const char c) {
    if (c >= 97 && c <= 122) return codes[c - 97];
    return codes[26];
}

char get_char(const char *code) {
    int i;
    if (!strcmp(codes[26], code)) return ' ';
    for (i = 0; i < 26; ++i) {
        if (strcmp(codes[i], code) == 0) return 97 + i;
    }
    printf("\nCode \"%s\" is invalid\n", code);
    exit(1);
}

void str_tolower(char s[]) {
    int i;
    for (i = 0; i < strlen(s); ++i) s[i] = tolower(s[i]);
}

char *bacon_encode(char plain_text[], char message[]) {
    int i, count;
    int plen = strlen(plain_text), mlen = strlen(message);
    int elen = 5 * plen;
    char c;
    char *p, *et, *mt;
    et = malloc(elen + 1);  
    str_tolower(plain_text);
    for (i = 0, p = et; i < plen; ++i, p += 5) {
        c = plain_text[i];
        strncpy(p, get_code(c), 5);
    }
    *++p = '\0';

    
    str_tolower(message);
    mt = calloc(mlen + 1, 1);
    for (i = 0, count = 0; i < mlen; ++i) {
        c = message[i];
        if (c >= 'a' && c <= 'z') {
            if (et[count] == 'A')
                mt[i] = c;
            else
                mt[i] = c - 32;  
            if (++count == elen) break;
        }
        else mt[i] = c;
    }
    free(et);     
    return mt;
}

char *bacon_decode(char cipher_text[]) {
    int i, count, clen = strlen(cipher_text);
    int plen;
    char *p, *ct, *pt;
    char c, quintet[6];
    ct = calloc(clen + 1, 1);
    for (i = 0, count = 0; i < clen; ++i) {
        c = cipher_text[i];
        if (c >= 'a' && c <= 'z')
            ct[count++] = 'A';
        else if (c >= 'A' && c <= 'Z')
            ct[count++] = 'B';
    }

    plen = strlen(ct) / 5; 
    pt = malloc(plen + 1);
    for (i = 0, p = ct; i < plen; ++i, p += 5) {
        strncpy(quintet, p, 5);
        quintet[5] = '\0';
        pt[i] = get_char(quintet);
    }
    pt[plen] = '\0';
    free(ct);
    return pt;
} 

int main() {
    char plain_text[] = "the quick brown fox jumps over the lazy dog";
    char message[] = "bacon's cipher is a method of steganography created by francis bacon."
        "this task is to implement a program for encryption and decryption of "
        "plaintext using the simple alphabet of the baconian cipher or some "
        "other kind of representation of this alphabet (make anything signify anything). "
        "the baconian alphabet may optionally be extended to encode all lower "
        "case characters individually and/or adding a few punctuation characters "
        "such as the space.";
    char *cipher_text, *hidden_text;
    cipher_text = bacon_encode(plain_text, message);
    printf("Cipher text ->\n\n%s\n", cipher_text);
    hidden_text = bacon_decode(cipher_text);
    printf("\nHidden text ->\n\n%s\n", hidden_text);
    free(cipher_text);
    free(hidden_text);
    return 0;
}





Java: import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

public class BaconCipher {
    private static final Map<Character, String> codes;

    static {
        codes = new HashMap<>();
        codes.putAll(Map.of(
            'a', "AAAAA", 'b', "AAAAB", 'c', "AAABA", 'd', "AAABB", 'e', "AABAA",
            'f', "AABAB", 'g', "AABBA", 'h', "AABBB", 'i', "ABAAA", 'j', "ABAAB"
        ));
        codes.putAll(Map.of(
            'k', "ABABA", 'l', "ABABB", 'm', "ABBAA", 'n', "ABBAB", 'o', "ABBBA",
            'p', "ABBBB", 'q', "BAAAA", 'r', "BAAAB", 's', "BAABA", 't', "BAABB"
        ));
        codes.putAll(Map.of(
            'u', "BABAA", 'v', "BABAB", 'w', "BABBA", 'x', "BABBB", 'y', "BBAAA",
            'z', "BBAAB", ' ', "BBBAA" 
        ));
    }

    private static String encode(String plainText, String message) {
        String pt = plainText.toLowerCase();
        StringBuilder sb = new StringBuilder();
        for (char c : pt.toCharArray()) {
            if ('a' <= c && c <= 'z') sb.append(codes.get(c));
            else sb.append(codes.get(' '));
        }
        String et = sb.toString();
        String mg = message.toLowerCase();  
        sb.setLength(0);
        int count = 0;
        for (char c : mg.toCharArray()) {
            if ('a' <= c && c <= 'z') {
                if (et.charAt(count) == 'A') sb.append(c);
                else sb.append(((char) (c - 32))); 
                count++;
                if (count == et.length()) break;
            } else sb.append(c);
        }
        return sb.toString();
    }

    private static String decode(String message) {
        StringBuilder sb = new StringBuilder();
        for (char c : message.toCharArray()) {
            if ('a' <= c && c <= 'z') sb.append('A');
            if ('A' <= c && c <= 'Z') sb.append('B');
        }
        String et = sb.toString();
        sb.setLength(0);
        for (int i = 0; i < et.length(); i += 5) {
            String quintet = et.substring(i, i + 5);
            Character key = codes.entrySet().stream().filter(a -> Objects.equals(a.getValue(), quintet)).findFirst().map(Map.Entry::getKey).orElse(null);
            sb.append(key);
        }
        return sb.toString();
    }

    public static void main(String[] args) {
        String plainText = "the quick brown fox jumps over the lazy dog";
        String message = "bacon's cipher is a method of steganography created by francis bacon. " +
            "this task is to implement a program for encryption and decryption of " +
            "plaintext using the simple alphabet of the baconian cipher or some " +
            "other kind of representation of this alphabet (make anything signify anything). " +
            "the baconian alphabet may optionally be extended to encode all lower " +
            "case characters individually and/or adding a few punctuation characters " +
            "such as the space.";
        String cipherText = encode(plainText, message);
        System.out.printf("Cipher text ->\n\n%s\n", cipherText);
        String decodedText = decode(cipherText);
        System.out.printf("\nHidden text ->\n\n%s\n", decodedText);
    }
}