diff --git a/Knot.files b/Knot.files
index 0948839ab7bfb3499a69a21b77e6c7e22eeb8fa0..9262374c3519241cfea1540655121ebee3c90e7d 100644
--- a/Knot.files
+++ b/Knot.files
@@ -252,8 +252,6 @@ src/libknot/tsig.h
 src/libknot/tsig.c
 src/libknot/tsig-op.c
 src/libknot/tsig-op.h
-src/libknot/util/conv.c
-src/libknot/util/conv.h
 src/tests/libknot/libknot/tsig_tests.h
 src/tests/libknot/libknot/tsig_tests.c
 src/knot/zone/semantic-check.c
@@ -261,3 +259,5 @@ src/knot/zone/semantic-check.h
 src/tests/xfr_tests.h
 src/tests/xfr_tests.c
 doc/knot.texi
+src/common/base64.c
+src/common/base64.h
diff --git a/src/Makefile.am b/src/Makefile.am
index 92e8847b0df089d4ded16c58fe8806bc3026a02a..6a288d4dc69747c66b75e7b9d7b2c1d68e529bb4 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -157,8 +157,6 @@ libknot_la_SOURCES =				\
 	libknot/util/debug.c			\
 	libknot/util/debug.h			\
 	libknot/util/utils.h			\
-	libknot/util/conv.h			\
-	libknot/util/conv.c			\
 	libknot/util/descriptor.c		\
 	libknot/util/tolower.h			\
 	libknot/util/tolower.c			\
@@ -223,6 +221,8 @@ libknots_la_SOURCES =				\
 	common/mempattern.c			\
 	common/lists.c				\
 	common/base32.c				\
+	common/base64.c				\
+	common/base64.h				\
 	common/lists.h				\
 	common/heap.h				\
 	common/heap.c				\
diff --git a/src/common/base64.c b/src/common/base64.c
new file mode 100644
index 0000000000000000000000000000000000000000..f1f601c24b476f51d6dfeeece3de378598ba819e
--- /dev/null
+++ b/src/common/base64.c
@@ -0,0 +1,574 @@
+/* base64.c -- Encode binary data using printable characters.
+   Copyright (C) 1999-2001, 2004-2006, 2009-2012 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as published by
+   the Free Software Foundation; either version 2.1, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program; if not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Simon Josefsson.  Partially adapted from GNU MailUtils
+ * (mailbox/filter_trans.c, as of 2004-11-28).  Improved by review
+ * from Paul Eggert, Bruno Haible, and Stepan Kasal.
+ *
+ * See also RFC 4648 <http://www.ietf.org/rfc/rfc4648.txt>.
+ *
+ * Be careful with error checking.  Here is how you would typically
+ * use these functions:
+ *
+ * bool ok = base64_decode_alloc (in, inlen, &out, &outlen);
+ * if (!ok)
+ *   FAIL: input was not valid base64
+ * if (out == NULL)
+ *   FAIL: memory allocation error
+ * OK: data in OUT/OUTLEN
+ *
+ * size_t outlen = base64_encode_alloc (in, inlen, &out);
+ * if (out == NULL && outlen == 0 && inlen != 0)
+ *   FAIL: input too long
+ * if (out == NULL)
+ *   FAIL: memory allocation error
+ * OK: data in OUT/OUTLEN.
+ *
+ */
+
+#include <config.h>
+
+/* Get prototype. */
+#include "base64.h"
+
+/* Get malloc. */
+#include <stdlib.h>
+
+/* Get UCHAR_MAX. */
+#include <limits.h>
+
+#include <string.h>
+
+/* C89 compliant way to cast 'char' to 'unsigned char'. */
+static inline unsigned char
+to_uchar (char ch)
+{
+  return ch;
+}
+
+/* Base64 encode IN array of size INLEN into OUT array of size OUTLEN.
+   If OUTLEN is less than BASE64_LENGTH(INLEN), write as many bytes as
+   possible.  If OUTLEN is larger than BASE64_LENGTH(INLEN), also zero
+   terminate the output buffer. */
+void
+base64_encode (const char *restrict in, size_t inlen,
+               char *restrict out, size_t outlen)
+{
+  static const char b64str[64] =
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+  while (inlen && outlen)
+    {
+      *out++ = b64str[(to_uchar (in[0]) >> 2) & 0x3f];
+      if (!--outlen)
+        break;
+      *out++ = b64str[((to_uchar (in[0]) << 4)
+                       + (--inlen ? to_uchar (in[1]) >> 4 : 0))
+                      & 0x3f];
+      if (!--outlen)
+        break;
+      *out++ =
+        (inlen
+         ? b64str[((to_uchar (in[1]) << 2)
+                   + (--inlen ? to_uchar (in[2]) >> 6 : 0))
+                  & 0x3f]
+         : '=');
+      if (!--outlen)
+        break;
+      *out++ = inlen ? b64str[to_uchar (in[2]) & 0x3f] : '=';
+      if (!--outlen)
+        break;
+      if (inlen)
+        inlen--;
+      if (inlen)
+        in += 3;
+    }
+
+  if (outlen)
+    *out = '\0';
+}
+
+/* Allocate a buffer and store zero terminated base64 encoded data
+   from array IN of size INLEN, returning BASE64_LENGTH(INLEN), i.e.,
+   the length of the encoded data, excluding the terminating zero.  On
+   return, the OUT variable will hold a pointer to newly allocated
+   memory that must be deallocated by the caller.  If output string
+   length would overflow, 0 is returned and OUT is set to NULL.  If
+   memory allocation failed, OUT is set to NULL, and the return value
+   indicates length of the requested memory block, i.e.,
+   BASE64_LENGTH(inlen) + 1. */
+size_t
+base64_encode_alloc (const char *in, size_t inlen, char **out)
+{
+  size_t outlen = 1 + BASE64_LENGTH (inlen);
+
+  /* Check for overflow in outlen computation.
+   *
+   * If there is no overflow, outlen >= inlen.
+   *
+   * If the operation (inlen + 2) overflows then it yields at most +1, so
+   * outlen is 0.
+   *
+   * If the multiplication overflows, we lose at least half of the
+   * correct value, so the result is < ((inlen + 2) / 3) * 2, which is
+   * less than (inlen + 2) * 0.66667, which is less than inlen as soon as
+   * (inlen > 4).
+   */
+  if (inlen > outlen)
+    {
+      *out = NULL;
+      return 0;
+    }
+
+  *out = malloc (outlen);
+  if (!*out)
+    return outlen;
+
+  base64_encode (in, inlen, *out, outlen);
+
+  return outlen - 1;
+}
+
+/* With this approach this file works independent of the charset used
+   (think EBCDIC).  However, it does assume that the characters in the
+   Base64 alphabet (A-Za-z0-9+/) are encoded in 0..255.  POSIX
+   1003.1-2001 require that char and unsigned char are 8-bit
+   quantities, though, taking care of that problem.  But this may be a
+   potential problem on non-POSIX C99 platforms.
+
+   IBM C V6 for AIX mishandles "#define B64(x) ...'x'...", so use "_"
+   as the formal parameter rather than "x".  */
+#define B64(_)                                  \
+  ((_) == 'A' ? 0                               \
+   : (_) == 'B' ? 1                             \
+   : (_) == 'C' ? 2                             \
+   : (_) == 'D' ? 3                             \
+   : (_) == 'E' ? 4                             \
+   : (_) == 'F' ? 5                             \
+   : (_) == 'G' ? 6                             \
+   : (_) == 'H' ? 7                             \
+   : (_) == 'I' ? 8                             \
+   : (_) == 'J' ? 9                             \
+   : (_) == 'K' ? 10                            \
+   : (_) == 'L' ? 11                            \
+   : (_) == 'M' ? 12                            \
+   : (_) == 'N' ? 13                            \
+   : (_) == 'O' ? 14                            \
+   : (_) == 'P' ? 15                            \
+   : (_) == 'Q' ? 16                            \
+   : (_) == 'R' ? 17                            \
+   : (_) == 'S' ? 18                            \
+   : (_) == 'T' ? 19                            \
+   : (_) == 'U' ? 20                            \
+   : (_) == 'V' ? 21                            \
+   : (_) == 'W' ? 22                            \
+   : (_) == 'X' ? 23                            \
+   : (_) == 'Y' ? 24                            \
+   : (_) == 'Z' ? 25                            \
+   : (_) == 'a' ? 26                            \
+   : (_) == 'b' ? 27                            \
+   : (_) == 'c' ? 28                            \
+   : (_) == 'd' ? 29                            \
+   : (_) == 'e' ? 30                            \
+   : (_) == 'f' ? 31                            \
+   : (_) == 'g' ? 32                            \
+   : (_) == 'h' ? 33                            \
+   : (_) == 'i' ? 34                            \
+   : (_) == 'j' ? 35                            \
+   : (_) == 'k' ? 36                            \
+   : (_) == 'l' ? 37                            \
+   : (_) == 'm' ? 38                            \
+   : (_) == 'n' ? 39                            \
+   : (_) == 'o' ? 40                            \
+   : (_) == 'p' ? 41                            \
+   : (_) == 'q' ? 42                            \
+   : (_) == 'r' ? 43                            \
+   : (_) == 's' ? 44                            \
+   : (_) == 't' ? 45                            \
+   : (_) == 'u' ? 46                            \
+   : (_) == 'v' ? 47                            \
+   : (_) == 'w' ? 48                            \
+   : (_) == 'x' ? 49                            \
+   : (_) == 'y' ? 50                            \
+   : (_) == 'z' ? 51                            \
+   : (_) == '0' ? 52                            \
+   : (_) == '1' ? 53                            \
+   : (_) == '2' ? 54                            \
+   : (_) == '3' ? 55                            \
+   : (_) == '4' ? 56                            \
+   : (_) == '5' ? 57                            \
+   : (_) == '6' ? 58                            \
+   : (_) == '7' ? 59                            \
+   : (_) == '8' ? 60                            \
+   : (_) == '9' ? 61                            \
+   : (_) == '+' ? 62                            \
+   : (_) == '/' ? 63                            \
+   : -1)
+
+static const signed char b64[0x100] = {
+  B64 (0), B64 (1), B64 (2), B64 (3),
+  B64 (4), B64 (5), B64 (6), B64 (7),
+  B64 (8), B64 (9), B64 (10), B64 (11),
+  B64 (12), B64 (13), B64 (14), B64 (15),
+  B64 (16), B64 (17), B64 (18), B64 (19),
+  B64 (20), B64 (21), B64 (22), B64 (23),
+  B64 (24), B64 (25), B64 (26), B64 (27),
+  B64 (28), B64 (29), B64 (30), B64 (31),
+  B64 (32), B64 (33), B64 (34), B64 (35),
+  B64 (36), B64 (37), B64 (38), B64 (39),
+  B64 (40), B64 (41), B64 (42), B64 (43),
+  B64 (44), B64 (45), B64 (46), B64 (47),
+  B64 (48), B64 (49), B64 (50), B64 (51),
+  B64 (52), B64 (53), B64 (54), B64 (55),
+  B64 (56), B64 (57), B64 (58), B64 (59),
+  B64 (60), B64 (61), B64 (62), B64 (63),
+  B64 (64), B64 (65), B64 (66), B64 (67),
+  B64 (68), B64 (69), B64 (70), B64 (71),
+  B64 (72), B64 (73), B64 (74), B64 (75),
+  B64 (76), B64 (77), B64 (78), B64 (79),
+  B64 (80), B64 (81), B64 (82), B64 (83),
+  B64 (84), B64 (85), B64 (86), B64 (87),
+  B64 (88), B64 (89), B64 (90), B64 (91),
+  B64 (92), B64 (93), B64 (94), B64 (95),
+  B64 (96), B64 (97), B64 (98), B64 (99),
+  B64 (100), B64 (101), B64 (102), B64 (103),
+  B64 (104), B64 (105), B64 (106), B64 (107),
+  B64 (108), B64 (109), B64 (110), B64 (111),
+  B64 (112), B64 (113), B64 (114), B64 (115),
+  B64 (116), B64 (117), B64 (118), B64 (119),
+  B64 (120), B64 (121), B64 (122), B64 (123),
+  B64 (124), B64 (125), B64 (126), B64 (127),
+  B64 (128), B64 (129), B64 (130), B64 (131),
+  B64 (132), B64 (133), B64 (134), B64 (135),
+  B64 (136), B64 (137), B64 (138), B64 (139),
+  B64 (140), B64 (141), B64 (142), B64 (143),
+  B64 (144), B64 (145), B64 (146), B64 (147),
+  B64 (148), B64 (149), B64 (150), B64 (151),
+  B64 (152), B64 (153), B64 (154), B64 (155),
+  B64 (156), B64 (157), B64 (158), B64 (159),
+  B64 (160), B64 (161), B64 (162), B64 (163),
+  B64 (164), B64 (165), B64 (166), B64 (167),
+  B64 (168), B64 (169), B64 (170), B64 (171),
+  B64 (172), B64 (173), B64 (174), B64 (175),
+  B64 (176), B64 (177), B64 (178), B64 (179),
+  B64 (180), B64 (181), B64 (182), B64 (183),
+  B64 (184), B64 (185), B64 (186), B64 (187),
+  B64 (188), B64 (189), B64 (190), B64 (191),
+  B64 (192), B64 (193), B64 (194), B64 (195),
+  B64 (196), B64 (197), B64 (198), B64 (199),
+  B64 (200), B64 (201), B64 (202), B64 (203),
+  B64 (204), B64 (205), B64 (206), B64 (207),
+  B64 (208), B64 (209), B64 (210), B64 (211),
+  B64 (212), B64 (213), B64 (214), B64 (215),
+  B64 (216), B64 (217), B64 (218), B64 (219),
+  B64 (220), B64 (221), B64 (222), B64 (223),
+  B64 (224), B64 (225), B64 (226), B64 (227),
+  B64 (228), B64 (229), B64 (230), B64 (231),
+  B64 (232), B64 (233), B64 (234), B64 (235),
+  B64 (236), B64 (237), B64 (238), B64 (239),
+  B64 (240), B64 (241), B64 (242), B64 (243),
+  B64 (244), B64 (245), B64 (246), B64 (247),
+  B64 (248), B64 (249), B64 (250), B64 (251),
+  B64 (252), B64 (253), B64 (254), B64 (255)
+};
+
+#if UCHAR_MAX == 255
+# define uchar_in_range(c) true
+#else
+# define uchar_in_range(c) ((c) <= 255)
+#endif
+
+/* Return true if CH is a character from the Base64 alphabet, and
+   false otherwise.  Note that '=' is padding and not considered to be
+   part of the alphabet.  */
+bool
+isbase64 (char ch)
+{
+  return uchar_in_range (to_uchar (ch)) && 0 <= b64[to_uchar (ch)];
+}
+
+/* Initialize decode-context buffer, CTX.  */
+void
+base64_decode_ctx_init (struct base64_decode_context *ctx)
+{
+  ctx->i = 0;
+}
+
+/* If CTX->i is 0 or 4, there are four or more bytes in [*IN..IN_END), and
+   none of those four is a newline, then return *IN.  Otherwise, copy up to
+   4 - CTX->i non-newline bytes from that range into CTX->buf, starting at
+   index CTX->i and setting CTX->i to reflect the number of bytes copied,
+   and return CTX->buf.  In either case, advance *IN to point to the byte
+   after the last one processed, and set *N_NON_NEWLINE to the number of
+   verified non-newline bytes accessible through the returned pointer.  */
+static inline char *
+get_4 (struct base64_decode_context *ctx,
+       char const *restrict *in, char const *restrict in_end,
+       size_t *n_non_newline)
+{
+  if (ctx->i == 4)
+    ctx->i = 0;
+
+  if (ctx->i == 0)
+    {
+      char const *t = *in;
+      if (4 <= in_end - *in && memchr (t, '\n', 4) == NULL)
+        {
+          /* This is the common case: no newline.  */
+          *in += 4;
+          *n_non_newline = 4;
+          return (char *) t;
+        }
+    }
+
+  {
+    /* Copy non-newline bytes into BUF.  */
+    char const *p = *in;
+    while (p < in_end)
+      {
+        char c = *p++;
+        if (c != '\n')
+          {
+            ctx->buf[ctx->i++] = c;
+            if (ctx->i == 4)
+              break;
+          }
+      }
+
+    *in = p;
+    *n_non_newline = ctx->i;
+    return ctx->buf;
+  }
+}
+
+#define return_false                            \
+  do                                            \
+    {                                           \
+      *outp = out;                              \
+      return false;                             \
+    }                                           \
+  while (false)
+
+/* Decode up to four bytes of base64-encoded data, IN, of length INLEN
+   into the output buffer, *OUT, of size *OUTLEN bytes.  Return true if
+   decoding is successful, false otherwise.  If *OUTLEN is too small,
+   as many bytes as possible are written to *OUT.  On return, advance
+   *OUT to point to the byte after the last one written, and decrement
+   *OUTLEN to reflect the number of bytes remaining in *OUT.  */
+static inline bool
+decode_4 (char const *restrict in, size_t inlen,
+          char *restrict *outp, size_t *outleft)
+{
+  char *out = *outp;
+  if (inlen < 2)
+    return false;
+
+  if (!isbase64 (in[0]) || !isbase64 (in[1]))
+    return false;
+
+  if (*outleft)
+    {
+      *out++ = ((b64[to_uchar (in[0])] << 2)
+                | (b64[to_uchar (in[1])] >> 4));
+      --*outleft;
+    }
+
+  if (inlen == 2)
+    return_false;
+
+  if (in[2] == '=')
+    {
+      if (inlen != 4)
+        return_false;
+
+      if (in[3] != '=')
+        return_false;
+    }
+  else
+    {
+      if (!isbase64 (in[2]))
+        return_false;
+
+      if (*outleft)
+        {
+          *out++ = (((b64[to_uchar (in[1])] << 4) & 0xf0)
+                    | (b64[to_uchar (in[2])] >> 2));
+          --*outleft;
+        }
+
+      if (inlen == 3)
+        return_false;
+
+      if (in[3] == '=')
+        {
+          if (inlen != 4)
+            return_false;
+        }
+      else
+        {
+          if (!isbase64 (in[3]))
+            return_false;
+
+          if (*outleft)
+            {
+              *out++ = (((b64[to_uchar (in[2])] << 6) & 0xc0)
+                        | b64[to_uchar (in[3])]);
+              --*outleft;
+            }
+        }
+    }
+
+  *outp = out;
+  return true;
+}
+
+/* Decode base64-encoded input array IN of length INLEN to output array
+   OUT that can hold *OUTLEN bytes.  The input data may be interspersed
+   with newlines.  Return true if decoding was successful, i.e. if the
+   input was valid base64 data, false otherwise.  If *OUTLEN is too
+   small, as many bytes as possible will be written to OUT.  On return,
+   *OUTLEN holds the length of decoded bytes in OUT.  Note that as soon
+   as any non-alphabet, non-newline character is encountered, decoding
+   is stopped and false is returned.  If INLEN is zero, then process
+   only whatever data is stored in CTX.
+
+   Initially, CTX must have been initialized via base64_decode_ctx_init.
+   Subsequent calls to this function must reuse whatever state is recorded
+   in that buffer.  It is necessary for when a quadruple of base64 input
+   bytes spans two input buffers.
+
+   If CTX is NULL then newlines are treated as garbage and the input
+   buffer is processed as a unit.  */
+
+bool
+base64_decode_ctx (struct base64_decode_context *ctx,
+                   const char *restrict in, size_t inlen,
+                   char *restrict out, size_t *outlen)
+{
+  size_t outleft = *outlen;
+  bool ignore_newlines = ctx != NULL;
+  bool flush_ctx = false;
+  unsigned int ctx_i = 0;
+
+  if (ignore_newlines)
+    {
+      ctx_i = ctx->i;
+      flush_ctx = inlen == 0;
+    }
+
+
+  while (true)
+    {
+      size_t outleft_save = outleft;
+      if (ctx_i == 0 && !flush_ctx)
+        {
+          while (true)
+            {
+              /* Save a copy of outleft, in case we need to re-parse this
+                 block of four bytes.  */
+              outleft_save = outleft;
+              if (!decode_4 (in, inlen, &out, &outleft))
+                break;
+
+              in += 4;
+              inlen -= 4;
+            }
+        }
+
+      if (inlen == 0 && !flush_ctx)
+        break;
+
+      /* Handle the common case of 72-byte wrapped lines.
+         This also handles any other multiple-of-4-byte wrapping.  */
+      if (inlen && *in == '\n' && ignore_newlines)
+        {
+          ++in;
+          --inlen;
+          continue;
+        }
+
+      /* Restore OUT and OUTLEFT.  */
+      out -= outleft_save - outleft;
+      outleft = outleft_save;
+
+      {
+        char const *in_end = in + inlen;
+        char const *non_nl;
+
+        if (ignore_newlines)
+          non_nl = get_4 (ctx, &in, in_end, &inlen);
+        else
+          non_nl = in;  /* Might have nl in this case. */
+
+        /* If the input is empty or consists solely of newlines (0 non-newlines),
+           then we're done.  Likewise if there are fewer than 4 bytes when not
+           flushing context and not treating newlines as garbage.  */
+        if (inlen == 0 || (inlen < 4 && !flush_ctx && ignore_newlines))
+          {
+            inlen = 0;
+            break;
+          }
+        if (!decode_4 (non_nl, inlen, &out, &outleft))
+          break;
+
+        inlen = in_end - in;
+      }
+    }
+
+  *outlen -= outleft;
+  
+  return inlen == 0;
+}
+
+/* Allocate an output buffer in *OUT, and decode the base64 encoded
+   data stored in IN of size INLEN to the *OUT buffer.  On return, the
+   size of the decoded data is stored in *OUTLEN.  OUTLEN may be NULL,
+   if the caller is not interested in the decoded length.  *OUT may be
+   NULL to indicate an out of memory error, in which case *OUTLEN
+   contains the size of the memory block needed.  The function returns
+   true on successful decoding and memory allocation errors.  (Use the
+   *OUT and *OUTLEN parameters to differentiate between successful
+   decoding and memory error.)  The function returns false if the
+   input was invalid, in which case *OUT is NULL and *OUTLEN is
+   undefined. */
+bool
+base64_decode_alloc_ctx (struct base64_decode_context *ctx,
+                         const char *in, size_t inlen, char **out,
+                         size_t *outlen)
+{
+  /* This may allocate a few bytes too many, depending on input,
+     but it's not worth the extra CPU time to compute the exact size.
+     The exact size is 3 * (inlen + (ctx ? ctx->i : 0)) / 4, minus 1 if the
+     input ends with "=" and minus another 1 if the input ends with "==".
+     Dividing before multiplying avoids the possibility of overflow.  */
+  size_t needlen = 3 * (inlen / 4) + 3;
+
+  *out = malloc (needlen);
+  if (!*out)
+    return true;
+
+  if (!base64_decode_ctx (ctx, in, inlen, *out, &needlen))
+    {
+      free (*out);
+      *out = NULL;
+      return false;
+    }
+
+  if (outlen)
+    *outlen = needlen;
+
+  return true;
+}
diff --git a/src/common/base64.h b/src/common/base64.h
new file mode 100644
index 0000000000000000000000000000000000000000..aa0b6960779c534f8c856a9e1a96d4a42683f837
--- /dev/null
+++ b/src/common/base64.h
@@ -0,0 +1,60 @@
+/* base64.h -- Encode binary data using printable characters.
+   Copyright (C) 2004-2006, 2009-2012 Free Software Foundation, Inc.
+   Written by Simon Josefsson.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as published by
+   the Free Software Foundation; either version 2.1, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program; if not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef BASE64_H
+# define BASE64_H
+
+/* Get size_t. */
+# include <stddef.h>
+
+/* Get bool. */
+# include <stdbool.h>
+
+/* This uses that the expression (n+(k-1))/k means the smallest
+   integer >= n/k, i.e., the ceiling of n/k.  */
+# define BASE64_LENGTH(inlen) ((((inlen) + 2) / 3) * 4)
+
+struct base64_decode_context
+{
+  unsigned int i;
+  char buf[4];
+};
+
+extern bool isbase64 (char ch);
+
+extern void base64_encode (const char *restrict in, size_t inlen,
+                           char *restrict out, size_t outlen);
+
+extern size_t base64_encode_alloc (const char *in, size_t inlen, char **out);
+
+extern void base64_decode_ctx_init (struct base64_decode_context *ctx);
+
+extern bool base64_decode_ctx (struct base64_decode_context *ctx,
+                               const char *restrict in, size_t inlen,
+                               char *restrict out, size_t *outlen);
+
+extern bool base64_decode_alloc_ctx (struct base64_decode_context *ctx,
+                                     const char *in, size_t inlen,
+                                     char **out, size_t *outlen);
+
+#define base64_decode(in, inlen, out, outlen) \
+        base64_decode_ctx (NULL, in, inlen, out, outlen)
+
+#define base64_decode_alloc(in, inlen, out, outlen) \
+        base64_decode_alloc_ctx (NULL, in, inlen, out, outlen)
+
+#endif /* BASE64_H */
diff --git a/src/libknot/tsig-op.c b/src/libknot/tsig-op.c
index 62fb1f39283887118b8e29eea3c3240a8f55997d..b49e81ef43d9b9ce6f76cf79779367cebf33fcbb 100644
--- a/src/libknot/tsig-op.c
+++ b/src/libknot/tsig-op.c
@@ -21,10 +21,10 @@
 #include <time.h>
 
 #include "common.h"
+#include "common/base64.h"
 #include "tsig.h"
 #include "tsig-op.h"
 #include "util/wire.h"
-#include "libknot/util/conv.h"
 #include "util/error.h"
 #include "util/debug.h"
 #include "consts.h"
@@ -32,7 +32,9 @@
 
 const int KNOT_TSIG_MAX_DIGEST_SIZE = 64;    // size of HMAC-SHA512 digest
 const uint16_t KNOT_TSIG_FUDGE_DEFAULT = 300;  // default Fudge value
-
+enum b64_const {
+	B64BUFSIZE = 65535
+};
 
 static int knot_tsig_check_algorithm(const knot_rrset_t *tsig_rr)
 {
@@ -104,14 +106,21 @@ static int knot_tsig_compute_digest(const uint8_t *wire, size_t wire_len,
 
 	/* Decode key from Base64. */
 	char decoded_key[B64BUFSIZE];
-
-	int decoded_key_size = b64_pton(key->secret, (uint8_t *)decoded_key,
-					B64BUFSIZE);
+	
+	size_t decoded_key_size = B64BUFSIZE;
+	int ret = base64_decode(key->secret, strlen(key->secret),
+	                        decoded_key,
+	                        &decoded_key_size);
+	if (ret != 1) {
+		dbg_tsig("TSIG: New decode function failed! (%d)\n", ret);
+		return KNOT_ERROR;
+	}
+	
 	if (decoded_key_size < 0) {
 		dbg_tsig("TSIG: Could not decode Base64\n");
 		return KNOT_ERROR;
 	}
-
+	
 	dbg_tsig_detail("TSIG: decoded key size: %d\n", decoded_key_size);
 	dbg_tsig_detail("TSIG: decoded key: '%*s'\n", decoded_key_size, decoded_key);
 
diff --git a/src/libknot/util/conv.c b/src/libknot/util/conv.c
deleted file mode 100644
index 6626ddd509ed1ec2ae0798404396f9e7d44de503..0000000000000000000000000000000000000000
--- a/src/libknot/util/conv.c
+++ /dev/null
@@ -1,325 +0,0 @@
-/*
- * Copyright (c) 2001-2011, NLnet Labs. All rights reserved.
- *
- * This software is open source.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * Redistributions of source code must retain the above copyright notice,
- * this list of conditions and the following disclaimer.
- *
- * Redistributions in binary form must reproduce the above copyright notice,
- * this list of conditions and the following disclaimer in the documentation
- * and/or other materials provided with the distribution.
- *
- * Neither the name of the NLNET LABS nor the names of its contributors may
- * be used to endorse or promote products derived from this software without
- * specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
- * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <stdlib.h>
-#include <stdint.h>
-#include <ctype.h>
-#include "conv.h"
-
-#define	B64BUFSIZE	65535	/*!< Buffer size for b64 conversion. */
-
-
-static const char Base64[] =
-	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
-static const char Pad64 = '=';
-
-static int b64rmap_initialized = 0;
-static uint8_t b64rmap[256];
-
-static const uint8_t b64rmap_special = 0xf0;
-static const uint8_t b64rmap_end = 0xfd;
-static const uint8_t b64rmap_space = 0xfe;
-static const uint8_t b64rmap_invalid = 0xff;
-
-/**
- * Initializing the reverse map is not thread safe.
- * Which is fine for NSD. For now...
- **/
-static void b64_initialize_rmap()
-{
-	int i;
-	char ch;
-
-	/* Null: end of string, stop parsing */
-	b64rmap[0] = b64rmap_end;
-
-	for (i = 1; i < 256; ++i) {
-		ch = (char)i;
-		/* Whitespaces */
-		if (isspace(ch)) {
-			b64rmap[i] = b64rmap_space;
-		}
-		/* Padding: stop parsing */
-		else if (ch == Pad64) {
-			b64rmap[i] = b64rmap_end;
-		}
-		/* Non-base64 char */
-		else {
-			b64rmap[i] = b64rmap_invalid;
-		}
-	}
-
-	/* Fill reverse mapping for base64 chars */
-	for (i = 0; Base64[i] != '\0'; ++i) {
-		b64rmap[(uint8_t)Base64[i]] = i;
-	}
-
-	b64rmap_initialized = 1;
-}
-
-static int b64_pton_do(char const *src, uint8_t *target, size_t targsize)
-{
-	int tarindex, state, ch;
-	uint8_t ofs;
-
-	state = 0;
-	tarindex = 0;
-
-	while (1) {
-		ch = *src++;
-		ofs = b64rmap[ch];
-
-		if (ofs >= b64rmap_special) {
-			/* Ignore whitespaces */
-			if (ofs == b64rmap_space) {
-				continue;
-			}
-			/* End of base64 characters */
-			if (ofs == b64rmap_end) {
-				break;
-			}
-			/* A non-base64 character. */
-			return (-1);
-		}
-
-		switch (state) {
-		case 0:
-			if ((size_t)tarindex >= targsize) {
-				return (-1);
-			}
-			target[tarindex] = ofs << 2;
-			state = 1;
-			break;
-		case 1:
-			if ((size_t)tarindex + 1 >= targsize) {
-				return (-1);
-			}
-			target[tarindex]   |=  ofs >> 4;
-			target[tarindex+1]  = (ofs & 0x0f)
-					      << 4 ;
-			tarindex++;
-			state = 2;
-			break;
-		case 2:
-			if ((size_t)tarindex + 1 >= targsize) {
-				return (-1);
-			}
-			target[tarindex]   |=  ofs >> 2;
-			target[tarindex+1]  = (ofs & 0x03)
-					      << 6;
-			tarindex++;
-			state = 3;
-			break;
-		case 3:
-			if ((size_t)tarindex >= targsize) {
-				return (-1);
-			}
-			target[tarindex] |= ofs;
-			tarindex++;
-			state = 0;
-			break;
-		default:
-			abort();
-		}
-	}
-
-	/*
-	 * We are done decoding Base-64 chars.  Let's see if we ended
-	 * on a byte boundary, and/or with erroneous trailing characters.
-	 */
-
-	if (ch == Pad64) {		/* We got a pad char. */
-		ch = *src++;		/* Skip it, get next. */
-		switch (state) {
-		case 0:		/* Invalid = in first position */
-		case 1:		/* Invalid = in second position */
-			return (-1);
-
-		case 2:		/* Valid, means one byte of info */
-			/* Skip any number of spaces. */
-			for ((void)NULL; ch != '\0'; ch = *src++)
-				if (b64rmap[ch] != b64rmap_space) {
-					break;
-				}
-			/* Make sure there is another trailing = sign. */
-			if (ch != Pad64) {
-				return (-1);
-			}
-			ch = *src++;		/* Skip the = */
-			/* Fall through to "single trailing =" case. */
-			/* FALLTHROUGH */
-
-		case 3:		/* Valid, means two bytes of info */
-			/*
-			 * We know this char is an =.  Is there anything but
-			 * whitespace after it?
-			 */
-			for ((void)NULL; ch != '\0'; ch = *src++)
-				if (b64rmap[ch] != b64rmap_space) {
-					return (-1);
-				}
-
-			/*
-			 * Now make sure for cases 2 and 3 that the "extra"
-			 * bits that slopped past the last full byte were
-			 * zeros.  If we don't check them, they become a
-			 * subliminal channel.
-			 */
-			if (target[tarindex] != 0) {
-				return (-1);
-			}
-		}
-	} else {
-		/*
-		 * We ended by seeing the end of the string.  Make sure we
-		 * have no partial bytes lying around.
-		 */
-		if (state != 0) {
-			return (-1);
-		}
-	}
-
-	return (tarindex);
-}
-
-
-static int b64_pton_len(char const *src)
-{
-	int tarindex, state, ch;
-	uint8_t ofs;
-
-	state = 0;
-	tarindex = 0;
-
-	while (1) {
-		ch = *src++;
-		ofs = b64rmap[ch];
-
-		if (ofs >= b64rmap_special) {
-			/* Ignore whitespaces */
-			if (ofs == b64rmap_space) {
-				continue;
-			}
-			/* End of base64 characters */
-			if (ofs == b64rmap_end) {
-				break;
-			}
-			/* A non-base64 character. */
-			return (-1);
-		}
-
-		switch (state) {
-		case 0:
-			state = 1;
-			break;
-		case 1:
-			tarindex++;
-			state = 2;
-			break;
-		case 2:
-			tarindex++;
-			state = 3;
-			break;
-		case 3:
-			tarindex++;
-			state = 0;
-			break;
-		default:
-			abort();
-		}
-	}
-
-	/*
-	 * We are done decoding Base-64 chars.  Let's see if we ended
-	 * on a byte boundary, and/or with erroneous trailing characters.
-	 */
-
-	if (ch == Pad64) {		/* We got a pad char. */
-		ch = *src++;		/* Skip it, get next. */
-		switch (state) {
-		case 0:		/* Invalid = in first position */
-		case 1:		/* Invalid = in second position */
-			return (-1);
-
-		case 2:		/* Valid, means one byte of info */
-			/* Skip any number of spaces. */
-			for ((void)NULL; ch != '\0'; ch = *src++)
-				if (b64rmap[ch] != b64rmap_space) {
-					break;
-				}
-			/* Make sure there is another trailing = sign. */
-			if (ch != Pad64) {
-				return (-1);
-			}
-			ch = *src++;		/* Skip the = */
-			/* Fall through to "single trailing =" case. */
-			/* FALLTHROUGH */
-
-		case 3:		/* Valid, means two bytes of info */
-			/*
-			 * We know this char is an =.  Is there anything but
-			 * whitespace after it?
-			 */
-			for ((void)NULL; ch != '\0'; ch = *src++)
-				if (b64rmap[ch] != b64rmap_space) {
-					return (-1);
-				}
-
-		}
-	} else {
-		/*
-		 * We ended by seeing the end of the string.  Make sure we
-		 * have no partial bytes lying around.
-		 */
-		if (state != 0) {
-			return (-1);
-		}
-	}
-
-	return (tarindex);
-}
-
-int b64_pton(char const *src, uint8_t *target, size_t targsize)
-{
-	if (!b64rmap_initialized) {
-		b64_initialize_rmap();
-	}
-
-	if (target) {
-		return b64_pton_do(src, target, targsize);
-	} else {
-		return b64_pton_len(src);
-	}
-}
-
-#define	B64BUFSIZE	65535	/*!< Buffer size for b64 conversion. */
diff --git a/src/libknot/util/conv.h b/src/libknot/util/conv.h
deleted file mode 100644
index d1e6daea7d7f4eef467571d05d4f17c7c9c8ca59..0000000000000000000000000000000000000000
--- a/src/libknot/util/conv.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * Copyright (c) 2001-2011, NLnet Labs. All rights reserved.
- *
- * This software is open source.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * Redistributions of source code must retain the above copyright notice,
- * this list of conditions and the following disclaimer.
- *
- * Redistributions in binary form must reproduce the above copyright notice,
- * this list of conditions and the following disclaimer in the documentation
- * and/or other materials provided with the distribution.
- *
- * Neither the name of the NLNET LABS nor the names of its contributors may
- * be used to endorse or promote products derived from this software without
- * specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
- * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-#ifndef _KNOT_CONV_H_
-#define _KNOT_CONV_H_
-
-#define	B64BUFSIZE	65535	/*!< Buffer size for b64 conversion. */
-
-/*!
- * \brief Base64 presentation to wire conversion.
- */
-int b64_pton(char const *src, uint8_t *target, size_t targsize);
-
-#endif // _KNOT_CONV_H_