diff options
Diffstat (limited to 'rc4.h')
| -rw-r--r-- | rc4.h | 68 |
1 files changed, 51 insertions, 17 deletions
@@ -13,43 +13,77 @@ #include "string-tick.h" /** - * Takes a password from user input and returns it (max 32 chars) - * @return password + * Returns a password string taken from user input with a maximum of 32 characters. The user's input + * should not be echoed in the terminal, so ncurses noecho() function should be used. + * @return the password taken from input */ char* rc4_getPassword(void); /** - * Performs key exchange - * @param keySchedule - * @param key password + * Precondition: keySchedule is an int array of size 256 and key is a valid string + * Postcondition: keySchedule values have been initialized by the RC4 key-scheduling algorithm. + * Performs the RC4 key exchange with keylength 256. Pseudocode example: + * for i from 0 to 255 + * S[i] := i + * endfor + * j := 0 + * for i from 0 to 255 + * j := (j + S[i] + key[i mod keylength]) mod 256 + swap values of S[i] and S[j] + * endfor + * + * @param keySchedule int array of size keylength + * @param key user given password */ void rc4_key_exchange(int keySchedule[KEY_SCHEDULE_LENGTH], char* key); /** - * Performs pseudo-random generation algorithm - * @param keySchedule + * Precondition: keySchedule is an int array of size 256 already initialized by the RC4 key-scheduling algorithm + * Performs the RC4 pseudo-random generation algorithm with keylength 256. Returns a string of length len with output + * frm this algorithm. Pseudocode example: + * i := 0 + * j := 0 + * while GeneratingOutput: + * i := (i + 1) mod 256 + * j := (j + S[i]) mod 256 + * swap values of S[i] and S[j] + * K := S[(S[i] + S[j]) mod 256] + * output K + * endwhile + * + * @param keySchedule int array of size keylength (already initialized) * @param len size of portfolio in bytes - * @return string that can be XOR'ed with message to be en/decoded + * @return string of size len that can be XOR'ed with message to be en/decoded */ char* rc4_prga(int keySchedule[KEY_SCHEDULE_LENGTH], size_t len); /** - * XOR's the string created by prga by the portfolio to encrypt or decrypt it - * @param output string to be XOR'ed - * @param message portoflio string - * @param len length of portfolio in bytes + * Precondition: output is a string containing the output of the RC4 pseudo-random generation algorithm. pString + * is a String object containing the portfolio. + * XOR's the each index of output by each index of the char* in pString and stores that in the index of output + * @param output string + * @param message portoflio String */ void rc4_execute(char* output, String* pString); /** - * Returns an either encrypted or decrypted string of the input - * @param input the string to encrypt or decrypt - * @param input_len the length of the string - * @param password the password to encrypt or decrypt with - * @return encrypted or decrypted string + * Returns an encoded string given a String object and password used to encode it. + * @param pString The String to encode. + * @param password the key used to encode + * @return encoded string */ char* rc4_encode_string(String* pString, char* password); +/** + * Given input input_pString, returns an encrypted or decrypted version of it. If trying to encrypt a non-JSON + * formatted input_pString, abort. Similarly, if trying to decrypt a JSON-formatted input_pString, abort. password may + * be a string or NULL. If NULL, get a password from the user if encrypting, ask for the password again to confirm + * inputs are the same. If decrypting and the decrypted String is not JSON formatted, abort (wrong password). + * @param input_pString the String to encrypt/decrypt + * @param password the key or NULL + * @param option ENCRYPT or DECRYPT + * @return encrypted or decrypted String + */ String* rc4_get_crypted_string(String* input_pString, char* password, int option); #endif
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