add radix_to_bin()

src/headers/tomcrypt_math.h

@@ -30,6 +30,8 @@
    #define LTC_MILLER_RABIN_REPS    35
 #endif
 
+int radix_to_bin(const void *in, int radix, void *out, size_t* len);
+
 /** math descriptor */
 typedef struct {
    /** Name of the math provider */

src/math/radix_to_bin.c

@@ -0,0 +1,55 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+#include "tomcrypt.h"
+
+/**
+   @file radix_to_bin.c
+   Convert an MPI from a specific radix to binary data.
+   Steffen Jaeckel
+*/
+
+/**
+   Convert an MPI from a specific radix to binary data
+
+   @param in    The input
+   @param radix The radix of the input
+   @param out   The output buffer
+   @param len   [in/out] The length of the output buffer
+
+   @return CRYPT_OK on success.
+*/
+int radix_to_bin(const void *in, int radix, void *out, size_t* len)
+{
+   size_t l;
+   void* mpi;
+   int err;
+
+   LTC_ARGCHK(in  != NULL);
+   LTC_ARGCHK(len != NULL);
+
+   if ((err = mp_init(&mpi)) != CRYPT_OK) return err;
+   if ((err = mp_read_radix(mpi, in, radix)) != CRYPT_OK) goto LBL_ERR;
+
+   if ((l = mp_unsigned_bin_size(mpi)) > *len) {
+      *len = l;
+      err = CRYPT_BUFFER_OVERFLOW;
+      goto LBL_ERR;
+   }
+   *len = l;
+
+   if ((err = mp_to_unsigned_bin(mpi, out)) != CRYPT_OK) goto LBL_ERR;
+
+LBL_ERR:
+   mp_clear(mpi);
+   return err;
+}
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */