Implement as a vector of function pointers.

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@1997 ec53bebd-3082-4978-b11e-865c3cabbd6b

lib/krb5/encrypt.c

@@ -3,71 +3,131 @@
 
 RCSID("$Id$");
 
-krb5_error_code
+struct encryption_type {
-krb5_des_cbc_encrypt (krb5_context context,
+    int type;
-		      void *ptr,
+    size_t blocksize;
-		      size_t len,
+    size_t confoundersize;
-		      int etype,
+    size_t checksumsize;
-		      krb5_keyblock *keyblock,
+    void (*encrypt)(void *, size_t, const krb5_keyblock *, int);
-		      krb5_data *result)
+    void (*checksum)(void *, size_t, void *);
+};
+
+static void
+NULL_checksum(void *p, size_t len, void *result)
+{
+}
+
+static void
+MD5_checksum(void *p, size_t len, void *result)
+{
+    struct md5 m;
+    md5init(&m);
+    md5_update(&m, p, len);
+    md5_finito(&m, result);
+}
+
+static void
+SHA1_checksum(void *p, size_t len, void *result)
+{
+    struct sha m;
+    sha_init(&m);
+    sha_update(&m, p, len);
+    sha_finito(&m, result);
+}
+
+static void
+CRC_checksum(void *p, size_t len, void *result)
+{
+    u_int32_t crc;
+    unsigned char *r = result;
+    crc_init_table ();
+    crc = crc_update (p, len, 0);
+    r[0] = crc & 0xff;
+    r[1] = (crc >> 8)  & 0xff;
+    r[2] = (crc >> 16) & 0xff;
+    r[3] = (crc >> 24) & 0xff;
+}
+
+static void
+NULL_encrypt(void *p, size_t len, const krb5_keyblock *keyblock, int encrypt)
+{
+}
+
+static void
+DES_encrypt(void *p, size_t len, 
+		const krb5_keyblock *keyblock, int encrypt)
 {
-    u_char *p;
-    size_t sz;
     des_cblock key;
     des_key_schedule schedule;
+    memcpy(&key, keyblock->keyvalue.data, sizeof(key));
+    des_set_key(&key, schedule);
+    des_cbc_encrypt(p, p, len, schedule, &key, encrypt);
+}
 
-    switch(etype){
+static void
-    case ETYPE_DES_CBC_MD5:
+DES3_encrypt(void *p, size_t len, const krb5_keyblock *keyblock, int encrypt)
-	sz = 16;
+{
-	break;
-    case ETYPE_DES_CBC_CRC:
-	sz = 4;
-	break;
-    default:
-	return KRB5_PROG_ETYPE_NOSUPP;
-    }
     
-    sz += len + 8;
+}
-    sz = (sz + 7) & ~7; /* pad to 8 bytes */
+
-    p = calloc (1, sz);
+static struct encryption_type em [] = {
+    { ETYPE_DES_CBC_CRC, 8, 8, 4, DES_encrypt, CRC_checksum },
+    { ETYPE_DES_CBC_MD5, 8, 8, 16, DES_encrypt, MD5_checksum },
+    { ETYPE_NULL, 1, 0, 0, NULL_encrypt, NULL_checksum },
+};
+
+static int num_etypes = sizeof(em) / sizeof(em[0]);
+
+static krb5_error_code
+krb5_do_encrypt(krb5_context context,
+		 void *ptr, 
+		 size_t len,
+		 struct encryption_type *et,
+		 krb5_keyblock *keyblock,
+		 krb5_data *result)
+{
+    size_t size;
+    size_t sz;
+    unsigned char *p;
+    size = len + et->confoundersize + et->checksumsize;
+    sz = (size + et->blocksize - 1) & ~ (et->blocksize - 1);
+    p = calloc(1, sz);
     if (p == NULL)
 	return ENOMEM;
-    des_new_random_key((des_cblock*)p);
+    des_rand_data(p, et->confoundersize);
-#if 0
+    memcpy(p + et->confoundersize + et->checksumsize, ptr, len);
-    des_rand_data ((des_cblock*)p, 8);
+    (*et->checksum)(p, size, p + et->confoundersize);
-#endif
+    (*et->encrypt)(p, sz, keyblock, 1);
-    memcpy (p + 12, ptr, len);
-    switch(etype){
-    case ETYPE_DES_CBC_MD5:
-	{
-	    struct md5 m;
-	    md5init(&m);
-	    md5_update(&m, p, sz);
-	    md5_finito(&m, p + 8);
-	    break;
-	}
-    case ETYPE_DES_CBC_CRC:
-	{
-	    u_int32_t crc;
-	    crc_init_table ();
-	    crc = crc_update (p, sz, 0);
-	    p[8]  = crc & 0xff;
-	    p[9]  = (crc >> 8)  & 0xff;
-	    p[10] = (crc >> 16) & 0xff;
-	    p[11] = (crc >> 24) & 0xff;
-	    break;
-	}
-    }
-  
-    memcpy (&key, keyblock->keyvalue.data, sizeof(key));
-    des_set_key (&key, schedule);
-    des_cbc_encrypt ((des_cblock *)p, (des_cblock *)p, sz, 
-		     schedule, &key, DES_ENCRYPT);
-
     result->data = p;
     result->length = sz;
     return 0;
-    
+}
+
+static krb5_error_code
+krb5_do_decrypt(krb5_context context,
+		void *ptr,
+		size_t len,
+		struct encryption_type *et,
+		const krb5_keyblock *keyblock,
+		krb5_data *result)
+{
+    unsigned char *his_checksum;
+    unsigned char *p = ptr;
+    size_t length = 0; /* magic! */
+    (*et->encrypt)(ptr, len, keyblock, 0);
+    his_checksum = malloc(et->checksumsize);
+    memcpy(his_checksum, ptr + et->confoundersize, et->checksumsize);
+    memset(ptr + et->confoundersize, 0, et->checksumsize);
+
+    (*et->checksum)(p, length, p + et->confoundersize);
+    if (memcmp(p + et->confoundersize, his_checksum, et->checksumsize))
+	return KRB5KRB_AP_ERR_BAD_INTEGRITY;
+    result->data = malloc(length);
+    if(result->data == NULL)
+	return ENOMEM;
+    result->length = length;
+    memcpy(result->data, p + et->confoundersize, et->checksumsize);
+    return 0;
 }
 
 krb5_error_code
@@ -78,11 +138,9 @@ krb5_encrypt (krb5_context context,
 	      krb5_keyblock *keyblock,
 	      krb5_data *result)
 {
-    switch(etype){
+    struct encryption_type *e;
-    case ETYPE_DES_CBC_MD5:
+    for(e = em; e < em + num_etypes; e++)
-    case ETYPE_DES_CBC_CRC:
+	if(etype == e->type)
-	return krb5_des_cbc_encrypt(context, ptr, len, etype, 
+	    return krb5_do_encrypt(context, ptr, len, e, keyblock, result);
-				    keyblock, result);
-    }
     return KRB5_PROG_ETYPE_NOSUPP;
 }