Keyword密码C语言源代码.doc

/KEYWORD.H头文件#ifndef _KEYWORD_H_#define _KEYWORD_H_typedef struct tagKeywordTablechar p;char c;KeywordTable;void cst_keyword_table (char *key);void prnt_keyword_table ();int keyword_encrypt (char *plain_txt, char *cipher_txt);int keyword_decrypt (char *cipher_txt, char *plain_txt);#endif/KEYWORD.C源文件#include keyword.h#include #include #include KeywordTable keyword_table26;void cst_keyword_table (char *in_key)int i = 0, j, k;int char_count = 0, left_ch_index = 0;char ch, left_chs26 = 0, key26 = 0;int key_len;strcpy (key, in_key);key_len = strlen (key);while (1)if (keyi = )for (j = i; j key_len - 1; +j)keyj = keyj + 1;key_len-;if (i = key_len)break;i+;for (i = 0; i 1)for (k = j; k key_len -1; +k)keyk = keyk + 1;key_len-;elsej+;elsej+;if (j = key_len)break;if (char_count = 0)left_chsleft_ch_index+ = ch;for (i = 0; i left_ch_index; +i)keykey_len+ = left_chsi;for (i = 0; i 26; +i)keyword_tablei.p = a + i;keyword_tablei.c = keyi;void prnt_keyword_table ()int i;printf (Plain:t);for (i = 0; i 26; +i)printf (%c , keyword_tablei.p);printf (nCipher:t);for (i = 0; i 26; +i)printf (%c , keyword_tablei.c);puts(n);int keyword_encrypt (char *plain_txt, char *cipher_txt)int length = strlen (plain_txt);int i;for (i = 0; i = a & plain_txti = A & plain_txti = Z)cipher_txti = keyword_tableplain_txti - A.c - 32;elsecipher_txti = plain_txti;cipher_txtlength = 0;return length;int keyword_decrypt (char *cipher_txt, char *plain_txt)int length = strlen (cipher_txt);int i, j;for (i = 0; i = a & cipher_txti = z)for (j = 0; j = A & cipher_txti = Z)for (j = 0; j 26; +j)if (keyword_tablej.c = cipher_txti + 32)plain_txti = keyword_tablej.p - 32;break;elseplain_txti = cipher_txti;plain_txtlength = 0;return length;/MAIN.C文件#include #include #include #include keyword.hint main ()char plain_txt1000, cipher_txt1000;char key26 = 0;printf (Please input your key (string): );scanf (%s, key);cst_keyword_table (key);printf (Keyword Table:n);prnt_keyword_table ();printf (Please input plain text: );scanf (%s, plain_txt);keyword_encrypt (plain_txt, cipher_txt);printf (Cipher is : %sn, cipher_tx