--- /dev/null
+/* CC0 license (public domain) - see LICENSE file for details */
+#include <ccan/str/hex/hex.h>
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static bool char_to_hex(unsigned char *val, char c)
+{
+ if (c >= '0' && c <= '9') {
+ *val = c - '0';
+ return true;
+ }
+ if (c >= 'a' && c <= 'f') {
+ *val = c - 'a' + 10;
+ return true;
+ }
+ if (c >= 'A' && c <= 'F') {
+ *val = c - 'A' + 10;
+ return true;
+ }
+ return false;
+}
+
+bool hex_decode(const char *str, size_t slen, void *buf, size_t bufsize)
+{
+ unsigned char v1, v2;
+ unsigned char *p = buf;
+
+ while (slen > 1) {
+ if (!char_to_hex(&v1, str[0]) || !char_to_hex(&v2, str[1]))
+ return false;
+ if (!bufsize)
+ return false;
+ *(p++) = (v1 << 4) | v2;
+ str += 2;
+ slen -= 2;
+ bufsize--;
+ }
+ return slen == 0 && bufsize == 0;
+}
+
+static char hexchar(unsigned int val)
+{
+ if (val < 10)
+ return '0' + val;
+ if (val < 16)
+ return 'a' + val - 10;
+ abort();
+}
+
+bool hex_encode(const void *buf, size_t bufsize, char *dest, size_t destsize)
+{
+ size_t used = 0;
+
+ if (destsize < 1)
+ return false;
+
+ while (used < bufsize) {
+ unsigned int c = ((const unsigned char *)buf)[used];
+ if (destsize < 3)
+ return false;
+ *(dest++) = hexchar(c >> 4);
+ *(dest++) = hexchar(c & 0xF);
+ used++;
+ destsize -= 2;
+ }
+ *dest = '\0';
+
+ return used + 1;
+}