initial commit

libpcp/pad.h

@@ -0,0 +1,76 @@
+#ifndef _HAVE_PCP_ZPADDING
+#define _HAVE_PCP_ZPADDING
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdlib.h>
+#include <limits.h>
+
+#include "mem.h"
+
+#ifdef DEBUG
+#define ZPADCHAR 48
+#else
+#define ZPADCHAR 0
+#endif
+
+// prepends a binary stream with a number of
+// \0's as required by the secret_box and
+// secret_box_open functions of libsodium.
+//
+// parameters:
+//
+// padded:    destination array (ref)
+// unpadded:  source array without padding
+// padlen:    length of padding
+// unpadlen:  length of source array
+//
+// turns "efa5" into "00000000efa5" with padlen 8
+//
+// if DEBUG is set, destination will be padded with
+// the character '0', NOT the integer 0.
+//
+// allocates memory for padded and it is up to the
+// user to free it after use.
+//
+// sample call:
+//
+// char unpadded[] = {0xef, 0xa5};
+// unsigned char *padded;
+// pcp_pad_prepend(&padded, unpadded, 8, 2);
+//
+// the result, padded, would be 10 bytes long, 8
+// bytes for the leading zeros and 2 for the content
+// of the original unpadded.
+void pcp_pad_prepend(unsigned char **padded, unsigned char *unpadded,
+		 size_t padlen, size_t unpadlen);
+
+// removes zero's of a binary stream, which is
+// the reverse of pcp_pad_prepend().
+//
+// parameters:
+// 
+// unpadded:   destination array (ref), with padding removed
+// padded:     source array with padding
+// padlen:     length of padding
+// unpadlen:   length of source array
+//
+// turns "00000000efa5" into "efa5" with padlen 8
+//
+// allocates memory for unpadded and it is up to the
+// user to free it after use.
+//
+// sample call:
+//
+// char padded[] = {0x0, 0x0, 0x0, 0x0, 0xef, 0xa5};
+// unsigned char *unpadded;
+// pcp_pad_remove(unpadded, padded, 4, 2);
+//
+// the result, unpadded would be 2 bytes long containing
+// only the 2 bytes we want to have with zeros removed.
+void pcp_pad_remove(unsigned char **unpadded, unsigned char *padded,
+		size_t padlen, size_t unpadlen);
+
+
+#endif // _HAVE_PCP_ZPADDING