Fixed seckey export (wrong length, missing 16bit checksum)

dist/src/lib/create.c

@@ -450,6 +450,8 @@ write_seckey_body(const pgp_seckey_t *key,
             (void) fprintf(stderr, "\nturning encryption on...\n");
         }
         pgp_push_enc_crypt(output, &crypted);
+    }else{
+        pgp_push_sum16_writer(output);
     }
 
 	switch (key->pubkey.alg) {
@@ -475,12 +477,18 @@ write_seckey_body(const pgp_seckey_t *key,
 		return 0;
 	}
 
-	if (!pgp_write(output, key->checkhash, PGP_CHECKHASH_SIZE)) {
-		return 0;
-	}
 
 	if (key->s2k_usage != PGP_S2KU_NONE) {
+        
+        if (!pgp_write(output, key->checkhash, PGP_CHECKHASH_SIZE)) {
+            return 0;
+        }
         pgp_writer_pop(output);
+    }else{
+        uint16_t checksum = pgp_pop_sum16_writer(output);
+        if (!pgp_write_scalar(output, checksum, 2)) {
+            return 0;
+        }
     }
 
 	return 1;
@@ -757,7 +765,7 @@ pgp_write_struct_seckey_ptag(const pgp_seckey_t *key,
 	/* Ref: RFC4880 Section 5.5.3 */
 
 	/* pubkey, excluding MPIs */
-	length += 1 + 4 + 1 + 1;
+	length += 1 + 4 + 1;
 
 	/* s2k usage */
 	length += 1;

dist/src/lib/writer.c

@@ -1406,6 +1406,60 @@ pgp_push_checksum_writer(pgp_output_t *output, pgp_seckey_t *seckey)
 
 /**************************************************************************/
 
+typedef struct {
+    uint16_t  sum;
+} sum16_t;
+
+static unsigned
+sum16_writer(const uint8_t *src,
+                     const unsigned len,
+                     pgp_error_t **errors,
+                     pgp_writer_t *writer)
+{
+    sum16_t	*arg;
+    unsigned	 ret = 1;
+    int		 n;
+    
+    arg = pgp_writer_get_arg(writer);
+ 
+    for (n = 0; n < len; ++n) {
+        arg->sum = (arg->sum + src[n]) & 0xffff;
+    }
+    
+    /* write to next stacked writer */
+    ret = stacked_write(writer, src, len, errors);
+    /* tidy up and return */
+    return ret;
+}
+
+void
+pgp_push_sum16_writer(pgp_output_t *output)
+{
+    sum16_t *sum;
+
+    if ((sum = calloc(1, sizeof(*sum))) == NULL) {
+        (void) fprintf(stderr,
+                       "pgp_push_sum16_writer: bad alloc\n");
+    } else {
+        pgp_writer_push(output, sum16_writer,
+                        NULL, NULL, sum);
+    }
+}
+
+uint16_t
+pgp_pop_sum16_writer(pgp_output_t *output)
+{
+    uint16_t	 sum;
+    sum16_t		*arg;
+    arg = pgp_writer_get_arg(&output->writer);
+    sum = arg->sum;
+    pgp_writer_pop(output);
+    free(arg);
+    return sum;
+}
+
+/**************************************************************************/
+
 #define MAX_PARTIAL_DATA_LENGTH 1073741824
 
 typedef struct {

dist/src/lib/writer.h

@@ -116,4 +116,8 @@ unsigned pgp_writer_info_finalise(pgp_error_t **, pgp_writer_t *);
 
 void pgp_push_stream_enc_se_ip(pgp_output_t *, const pgp_key_t *, const char *);
 
+void pgp_push_sum16_writer(pgp_output_t *output);
+
+uint16_t pgp_pop_sum16_writer(pgp_output_t *output);
+
 #endif /* WRITER_H_ */