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-rw-r--r--common/zb32.c120
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+/* zb32.c - z-base-32 functions
+ * Copyright (C) 2014 Werner Koch
+ *
+ * This file is part of GnuPG.
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of either
+ *
+ * - the GNU Lesser General Public License as published by the Free
+ * Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * or
+ *
+ * - the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * or both in parallel, as here.
+ *
+ * This file 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+
+#include "util.h"
+#include "zb32.h"
+
+/* Zooko's base32 variant. See RFC-6189 and
+ http://philzimmermann.com/docs/human-oriented-base-32-encoding.txt
+ Caller must xfree the returned string. Returns NULL and sets ERRNO
+ on error. To avoid integer overflow DATALEN is limited to 2^16
+ bytes. Note, that DATABITS is measured in bits!. */
+char *
+zb32_encode (const void *data, unsigned int databits)
+{
+ static char const zb32asc[32] = {'y','b','n','d','r','f','g','8',
+ 'e','j','k','m','c','p','q','x',
+ 'o','t','1','u','w','i','s','z',
+ 'a','3','4','5','h','7','6','9' };
+ const unsigned char *s;
+ char *output, *d;
+ size_t datalen;
+
+ datalen = (databits + 7) / 8;
+ if (datalen > (1 << 16))
+ {
+ errno = EINVAL;
+ return NULL;
+ }
+
+ d = output = xtrymalloc (8 * (datalen / 5)
+ + 2 * (datalen % 5)
+ - ((datalen%5)>2)
+ + 1);
+ if (!output)
+ return NULL;
+
+ /* I use straightforward code. The compiler should be able to do a
+ better job on optimization than me and it is easier to read. */
+ for (s = data; datalen >= 5; s += 5, datalen -= 5)
+ {
+ *d++ = zb32asc[((s[0] ) >> 3) ];
+ *d++ = zb32asc[((s[0] & 7) << 2) | (s[1] >> 6) ];
+ *d++ = zb32asc[((s[1] & 63) >> 1) ];
+ *d++ = zb32asc[((s[1] & 1) << 4) | (s[2] >> 4) ];
+ *d++ = zb32asc[((s[2] & 15) << 1) | (s[3] >> 7) ];
+ *d++ = zb32asc[((s[3] & 127) >> 2) ];
+ *d++ = zb32asc[((s[3] & 3) << 3) | (s[4] >> 5) ];
+ *d++ = zb32asc[((s[4] & 31) ) ];
+ }
+
+ switch (datalen)
+ {
+ case 4:
+ *d++ = zb32asc[((s[0] ) >> 3) ];
+ *d++ = zb32asc[((s[0] & 7) << 2) | (s[1] >> 6) ];
+ *d++ = zb32asc[((s[1] & 63) >> 1) ];
+ *d++ = zb32asc[((s[1] & 1) << 4) | (s[2] >> 4) ];
+ *d++ = zb32asc[((s[2] & 15) << 1) | (s[3] >> 7) ];
+ *d++ = zb32asc[((s[3] & 127) >> 2) ];
+ *d++ = zb32asc[((s[3] & 3) << 3) ];
+ break;
+ case 3:
+ *d++ = zb32asc[((s[0] ) >> 3) ];
+ *d++ = zb32asc[((s[0] & 7) << 2) | (s[1] >> 6) ];
+ *d++ = zb32asc[((s[1] & 63) >> 1) ];
+ *d++ = zb32asc[((s[1] & 1) << 4) | (s[2] >> 4) ];
+ *d++ = zb32asc[((s[2] & 15) << 1) ];
+ break;
+ case 2:
+ *d++ = zb32asc[((s[0] ) >> 3) ];
+ *d++ = zb32asc[((s[0] & 7) << 2) | (s[1] >> 6) ];
+ *d++ = zb32asc[((s[1] & 63) >> 1) ];
+ *d++ = zb32asc[((s[1] & 1) << 4) ];
+ break;
+ case 1:
+ *d++ = zb32asc[((s[0] ) >> 3) ];
+ *d++ = zb32asc[((s[0] & 7) << 2) ];
+ break;
+ default:
+ break;
+ }
+ *d = 0;
+
+ /* Need to strip some bytes if not a multiple of 40. */
+ output[(databits + 5 - 1) / 5] = 0;
+ return output;
+}