mp_export: Addition of buffer size and written bytes

bn_deprecated.c

@@ -313,4 +313,18 @@ mp_err mp_toradix(const mp_int *a, char *str, int radix)
    return mp_to_radix(a, str, SIZE_MAX, radix);
 }
 #endif
+#ifdef BN_MP_IMPORT_C
+mp_err mp_import(mp_int *rop, size_t count, int order, size_t size, int endian, size_t nails,
+                 const void *op)
+{
+   return mp_unpack(rop, count, order, size, endian, nails, op);
+}
+#endif
+#ifdef BN_MP_EXPORT_C
+mp_err mp_export(void *rop, size_t *countp, int order, size_t size,
+                 int endian, size_t nails, const mp_int *op)
+{
+   return mp_pack(rop, countp, order, size, endian, nails, op, SIZE_MAX);
+}
+#endif
 #endif

bn_mp_export.c → bn_mp_pack.c

@@ -1,49 +1,60 @@
 #include "tommath_private.h"
-#ifdef BN_MP_EXPORT_C
+#ifdef BN_MP_PACK_C
 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
 /* SPDX-License-Identifier: Unlicense */
 
+
+
 /* based on gmp's mpz_export.
  * see http://gmplib.org/manual/Integer-Import-and-Export.html
  */
-mp_err mp_export(void *rop, size_t *countp, int order, size_t size,
-                 int endian, size_t nails, const mp_int *op)
+mp_err mp_pack(void *rop, size_t *countp, mp_order order, size_t size,
+               mp_endian endian, size_t nails, const mp_int *op,
+               size_t maxsize)
 {
    mp_err err;
-   size_t odd_nails, nail_bytes, i, j, bits, count;
+   size_t odd_nails, nail_bytes, i, j, count, written;
    unsigned char odd_nail_mask;
 
    mp_int t;
 
+   if (rop == NULL) {
+      return MP_MEM;
+   }
+
+   if (maxsize == 0u) {
+      return MP_VAL;
+   }
+
    if ((err = mp_init_copy(&t, op)) != MP_OKAY) {
       return err;
    }
 
-   if (endian == 0) {
-      union {
-         unsigned int i;
-         char c[4];
-      } lint;
-      lint.i = 0x01020304;
-
-      endian = (lint.c[0] == '\x04') ? -1 : 1;
+   if (endian == MP_NATIVE_ENDIAN) {
+      MP_GET_ENDIANNESS(endian);
    }
 
    odd_nails = (nails % 8u);
    odd_nail_mask = 0xff;
-   for (i = 0; i < odd_nails; ++i) {
+   for (i = 0u; i < odd_nails; ++i) {
       odd_nail_mask ^= (unsigned char)(1u << (7u - i));
    }
    nail_bytes = nails / 8u;
 
-   bits = (size_t)mp_count_bits(&t);
-   count = (bits / ((size * 8u) - nails)) + (((bits % ((size * 8u) - nails)) != 0u) ? 1u : 0u);
+   count = mp_pack_count(&t, nails, size);
 
-   for (i = 0; i < count; ++i) {
-      for (j = 0; j < size; ++j) {
+   written = 0u;
+   for (i = 0u; i < count; ++i) {
+      for (j = 0u; j < size; ++j) {
          unsigned char *byte = (unsigned char *)rop +
-                               (((order == -1) ? i : ((count - 1u) - i)) * size) +
-                               ((endian == -1) ? j : ((size - 1u) - j));
+                               (((order == MP_LSB_FIRST) ? i : ((count - 1u) - i)) * size) +
+                               ((endian == MP_LITTLE_ENDIAN) ? j : ((size - 1u) - j));
+         if (maxsize == 0u) {
+            err = MP_VAL;
+            break;
+         }
+         maxsize--;
+         written++;
 
          if (j >= (size - nail_bytes)) {
             *byte = 0;
@@ -55,11 +66,12 @@ mp_err mp_export(void *rop, size_t *countp, int order, size_t size,
          if ((err = mp_div_2d(&t, (j == ((size - nail_bytes) - 1u)) ? (int)(8u - odd_nails) : 8, &t, NULL)) != MP_OKAY) {
             goto LBL_ERR;
          }
+
       }
    }
 
    if (countp != NULL) {
-      *countp = count;
+      *countp = written;
    }
    err = MP_OKAY;
 
@@ -68,4 +80,5 @@ mp_err mp_export(void *rop, size_t *countp, int order, size_t size,
    return err;
 }
 
+
 #endif

bn_mp_pack_count.c

@@ -0,0 +1,13 @@
+#include "tommath_private.h"
+#ifdef BN_MP_PACK_COUNT_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
+
+
+size_t mp_pack_count(mp_int *a, size_t nails, size_t size)
+{
+   size_t bits = (size_t)mp_count_bits(a);
+   return ((bits / ((size * 8u) - nails)) + (((bits % ((size * 8u) - nails)) != 0u) ? 1u : 0u));
+}
+
+#endif

bn_mp_import.c → bn_mp_unpack.c

@@ -1,28 +1,23 @@
 #include "tommath_private.h"
-#ifdef BN_MP_IMPORT_C
+#ifdef BN_MP_UNPACK_C
 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
 /* SPDX-License-Identifier: Unlicense */
 
+
 /* based on gmp's mpz_import.
  * see http://gmplib.org/manual/Integer-Import-and-Export.html
  */
-mp_err mp_import(mp_int *rop, size_t count, int order, size_t size,
-                 int endian, size_t nails, const void *op)
+mp_err mp_unpack(mp_int *rop, size_t count, mp_order order, size_t size,
+                 mp_endian endian, size_t nails, const void *op)
 {
    mp_err err;
    size_t odd_nails, nail_bytes, i, j;
    unsigned char odd_nail_mask;
 
    mp_zero(rop);
 
-   if (endian == 0) {
-      union {
-         unsigned int i;
-         char c[4];
-      } lint;
-      lint.i = 0x01020304;
-
-      endian = (lint.c[0] == '\x04') ? -1 : 1;
+   if (endian == MP_NATIVE_ENDIAN) {
+      MP_GET_ENDIANNESS(endian);
    }
 
    odd_nails = (nails % 8u);
@@ -35,8 +30,8 @@ mp_err mp_import(mp_int *rop, size_t count, int order, size_t size,
    for (i = 0; i < count; ++i) {
       for (j = 0; j < (size - nail_bytes); ++j) {
          unsigned char byte = *((const unsigned char *)op +
-                                (((order == 1) ? i : ((count - 1u) - i)) * size) +
-                                ((endian == 1) ? (j + nail_bytes) : (((size - 1u) - j) - nail_bytes)));
+                                (((order == MP_MSB_FIRST) ? i : ((count - 1u) - i)) * size) +
+                                ((endian == MP_BIG_ENDIAN) ? (j + nail_bytes) : (((size - 1u) - j) - nail_bytes)));
 
          if ((err = mp_mul_2d(rop, (j == 0u) ? (int)(8u - odd_nails) : 8, rop)) != MP_OKAY) {
             return err;
@@ -52,4 +47,5 @@ mp_err mp_import(mp_int *rop, size_t count, int order, size_t size,
    return MP_OKAY;
 }
 
+
 #endif

demo/test.c

@@ -2345,6 +2345,53 @@ static int test_mp_read_write_sbin(void)
    return EXIT_FAILURE;
 }
 
+static int test_mp_pack_unpack(void)
+{
+   mp_int a, b;
+   int err;
+   size_t countp, size, bits, bytes;
+   unsigned char *buf = NULL;
+
+   mp_order order = MP_LSB_FIRST;
+   mp_endian endianess = MP_NATIVE_ENDIAN;
+
+   if ((err = mp_init_multi(&a, &b, NULL)) != MP_OKAY)                       goto LTM_ERR;
+   if ((err = mp_rand(&a, 15)) != MP_OKAY)                                   goto LTM_ERR;
+
+   bits = (size_t)mp_count_bits(&a);
+   bytes = (size_t)(((bits + 1u) + (size_t)(CHAR_BIT - 1)) / (size_t)CHAR_BIT);
+   size = bytes * mp_pack_count(&a, 0, 1);
+
+   buf = MP_MALLOC(size);
+   if (buf == NULL) {
+      fprintf(stderr, "test_pack_unpack failed to allocate %zu bytes\n",
+              sizeof(*buf) * size);
+      goto LTM_ERR;
+   }
+
+   if ((err = mp_pack((void *)buf, &countp, order, 1,
+                      endianess, 0, &a, size)) != MP_OKAY)                   goto LTM_ERR;
+   printf("size = %zu, countp = %zu, countp * byte_size = %zu\n",
+          size, countp, countp * bits);
+   if ((err = mp_unpack(&b, countp, order, 1,
+                        endianess, 0, (const void *)buf)) != MP_OKAY)        goto LTM_ERR;
+
+   if (mp_cmp(&a, &b) != MP_EQ) {
+      fprintf(stderr, "pack/unpack cycle failed\n");
+      goto LTM_ERR;
+   }
+
+   MP_FREE(buf, size);
+   mp_clear_multi(&a, &b, NULL);
+   return EXIT_SUCCESS;
+LTM_ERR:
+   if (buf != NULL) {
+      MP_FREE(buf, size);
+   }
+   mp_clear_multi(&a, &b, NULL);
+   return EXIT_FAILURE;
+}
+
 static int unit_tests(int argc, char **argv)
 {
    static const struct {
@@ -2364,6 +2411,7 @@ static int unit_tests(int argc, char **argv)
       T1(mp_decr, MP_DECR),
       T1(mp_div_3, MP_DIV_3),
       T1(mp_dr_reduce, MP_DR_REDUCE),
+      T2(mp_pack_unpack,MP_PACK, MP_UNPACK),
       T2(mp_fread_fwrite, MP_FREAD, MP_FWRITE),
       T1(mp_get_u32, MP_GET_I32),
       T1(mp_get_u64, MP_GET_I64),

doc/bn.tex

@@ -2176,12 +2176,38 @@ \section{Binary Conversions}
 byte depending on the sign.  If the sign is zpos (e.g. not negative) the prefix is zero, otherwise the prefix
 is non--zero.
 
-The two functions \texttt{mp\_import} and \texttt{mp\_export} implement the corresponding GMP functions as described at \url{http://gmplib.org/manual/Integer-Import-and-Export.html}.
-\index{mp\_import} \index{mp\_export}
+The two functions \texttt{mp\_unpack} (get your gifts out of the box, import binary data) and \texttt{mp\_pack} (put your gifts into the box, export binary data) implement the similarly working GMP functions as described at \url{http://gmplib.org/manual/Integer-Import-and-Export.html} with the exception that \texttt{mp\_pack} will not allocate memory if \texttt{rop} is \texttt{NULL}.
+\index{mp\_unpack} \index{mp\_pack}
 \begin{alltt}
-int mp_import(mp_int *rop, size_t count, int order, size_t size, int endian, size_t nails, const void *op);
-int mp_export(void *rop, size_t *countp, int order, size_t size, int endian, size_t nails, const mp_int *op);
+int mp_unpack(mp_int *rop, size_t count, mp_order order, size_t size,
+             mp_endian endian, size_t nails, const void *op, size_t maxsize);
+int mp_pack(void *rop, size_t *countp, mp_order order, size_t size,
+             mp_endian endian, size_t nails, const mp_int *op);
 \end{alltt}
+The function \texttt{mp\_pack} has the additional variable \texttt{maxsize} which must hold the size of the buffer \texttt{rop} in bytes. Use
+\begin{alltt}
+/* Parameters "nails" and "size" are the same as in mp_pack */
+size_t mp_pack_size(mp_int *a, size_t nails, size_t size);
+\end{alltt}
+To get the size in bytes necessary to be put in \texttt{maxsize}).
+
+To enhance the readability of your code, the following enums have been wrought for your convenience.
+\begin{alltt}
+#ifdef MP_USE_ENUMS
+typedef enum {
+   MP_LSB_FIRST = -1,
+   MP_MSB_FIRST =  1
+} mp_order;
+typedef enum {
+   MP_LITTLE_ENDIAN  = -1,
+   MP_NATIVE_ENDIAN  =  0,
+   MP_BIG_ENDIAN     =  1
+} mp_endian;
+\end{alltt}
+Also available as preprocessor macros.
+
+
+
 
 \chapter{Algebraic Functions}
 \section{Extended Euclidean Algorithm}

libtommath_VS2008.vcproj

@@ -428,10 +428,6 @@
 			RelativePath="bn_mp_exch.c"
 			>
 		</File>
-		<File
-			RelativePath="bn_mp_export.c"
-			>
-		</File>
 		<File
 			RelativePath="bn_mp_expt_u32.c"
 			>
@@ -508,10 +504,6 @@
 			RelativePath="bn_mp_ilogb.c"
 			>
 		</File>
-		<File
-			RelativePath="bn_mp_import.c"
-			>
-		</File>
 		<File
 			RelativePath="bn_mp_incr.c"
 			>
@@ -648,6 +640,14 @@
 			RelativePath="bn_mp_or.c"
 			>
 		</File>
+		<File
+			RelativePath="bn_mp_pack.c"
+			>
+		</File>
+		<File
+			RelativePath="bn_mp_pack_count.c"
+			>
+		</File>
 		<File
 			RelativePath="bn_mp_prime_fermat.c"
 			>
@@ -832,6 +832,10 @@
 			RelativePath="bn_mp_ubin_size.c"
 			>
 		</File>
+		<File
+			RelativePath="bn_mp_unpack.c"
+			>
+		</File>
 		<File
 			RelativePath="bn_mp_xor.c"
 			>

makefile

@@ -30,30 +30,31 @@ OBJECTS=bn_cutoffs.o bn_deprecated.o bn_mp_2expt.o bn_mp_abs.o bn_mp_add.o bn_mp
 bn_mp_and.o bn_mp_clamp.o bn_mp_clear.o bn_mp_clear_multi.o bn_mp_cmp.o bn_mp_cmp_d.o bn_mp_cmp_mag.o \
 bn_mp_cnt_lsb.o bn_mp_complement.o bn_mp_copy.o bn_mp_count_bits.o bn_mp_decr.o bn_mp_div.o bn_mp_div_2.o \
 bn_mp_div_2d.o bn_mp_div_3.o bn_mp_div_d.o bn_mp_dr_is_modulus.o bn_mp_dr_reduce.o bn_mp_dr_setup.o \
-bn_mp_error_to_string.o bn_mp_exch.o bn_mp_export.o bn_mp_expt_u32.o bn_mp_exptmod.o bn_mp_exteuclid.o \
-bn_mp_fread.o bn_mp_from_sbin.o bn_mp_from_ubin.o bn_mp_fwrite.o bn_mp_gcd.o bn_mp_get_double.o \
-bn_mp_get_i32.o bn_mp_get_i64.o bn_mp_get_l.o bn_mp_get_ll.o bn_mp_get_mag_u32.o bn_mp_get_mag_u64.o \
-bn_mp_get_mag_ul.o bn_mp_get_mag_ull.o bn_mp_grow.o bn_mp_ilogb.o bn_mp_import.o bn_mp_incr.o bn_mp_init.o \
-bn_mp_init_copy.o bn_mp_init_i32.o bn_mp_init_i64.o bn_mp_init_l.o bn_mp_init_ll.o bn_mp_init_multi.o \
-bn_mp_init_set.o bn_mp_init_size.o bn_mp_init_u32.o bn_mp_init_u64.o bn_mp_init_ul.o bn_mp_init_ull.o \
-bn_mp_invmod.o bn_mp_is_square.o bn_mp_iseven.o bn_mp_isodd.o bn_mp_kronecker.o bn_mp_lcm.o bn_mp_lshd.o \
-bn_mp_mod.o bn_mp_mod_2d.o bn_mp_mod_d.o bn_mp_montgomery_calc_normalization.o bn_mp_montgomery_reduce.o \
+bn_mp_error_to_string.o bn_mp_exch.o bn_mp_expt_u32.o bn_mp_exptmod.o bn_mp_exteuclid.o bn_mp_fread.o \
+bn_mp_from_sbin.o bn_mp_from_ubin.o bn_mp_fwrite.o bn_mp_gcd.o bn_mp_get_double.o bn_mp_get_i32.o \
+bn_mp_get_i64.o bn_mp_get_l.o bn_mp_get_ll.o bn_mp_get_mag_u32.o bn_mp_get_mag_u64.o bn_mp_get_mag_ul.o \
+bn_mp_get_mag_ull.o bn_mp_grow.o bn_mp_ilogb.o bn_mp_incr.o bn_mp_init.o bn_mp_init_copy.o \
+bn_mp_init_i32.o bn_mp_init_i64.o bn_mp_init_l.o bn_mp_init_ll.o bn_mp_init_multi.o bn_mp_init_set.o \
+bn_mp_init_size.o bn_mp_init_u32.o bn_mp_init_u64.o bn_mp_init_ul.o bn_mp_init_ull.o bn_mp_invmod.o \
+bn_mp_is_square.o bn_mp_iseven.o bn_mp_isodd.o bn_mp_kronecker.o bn_mp_lcm.o bn_mp_lshd.o bn_mp_mod.o \
+bn_mp_mod_2d.o bn_mp_mod_d.o bn_mp_montgomery_calc_normalization.o bn_mp_montgomery_reduce.o \
 bn_mp_montgomery_setup.o bn_mp_mul.o bn_mp_mul_2.o bn_mp_mul_2d.o bn_mp_mul_d.o bn_mp_mulmod.o bn_mp_neg.o \
-bn_mp_or.o bn_mp_prime_fermat.o bn_mp_prime_frobenius_underwood.o bn_mp_prime_is_prime.o \
-bn_mp_prime_miller_rabin.o bn_mp_prime_next_prime.o bn_mp_prime_rabin_miller_trials.o \
-bn_mp_prime_rand.o bn_mp_prime_strong_lucas_selfridge.o bn_mp_radix_size.o bn_mp_radix_smap.o \
-bn_mp_rand.o bn_mp_read_radix.o bn_mp_reduce.o bn_mp_reduce_2k.o bn_mp_reduce_2k_l.o \
-bn_mp_reduce_2k_setup.o bn_mp_reduce_2k_setup_l.o bn_mp_reduce_is_2k.o bn_mp_reduce_is_2k_l.o \
-bn_mp_reduce_setup.o bn_mp_root_u32.o bn_mp_rshd.o bn_mp_sbin_size.o bn_mp_set.o bn_mp_set_double.o \
-bn_mp_set_i32.o bn_mp_set_i64.o bn_mp_set_l.o bn_mp_set_ll.o bn_mp_set_u32.o bn_mp_set_u64.o \
-bn_mp_set_ul.o bn_mp_set_ull.o bn_mp_shrink.o bn_mp_signed_rsh.o bn_mp_sqr.o bn_mp_sqrmod.o bn_mp_sqrt.o \
-bn_mp_sqrtmod_prime.o bn_mp_sub.o bn_mp_sub_d.o bn_mp_submod.o bn_mp_to_radix.o bn_mp_to_sbin.o \
-bn_mp_to_ubin.o bn_mp_ubin_size.o bn_mp_xor.o bn_mp_zero.o bn_prime_tab.o bn_s_mp_add.o \
-bn_s_mp_balance_mul.o bn_s_mp_exptmod.o bn_s_mp_exptmod_fast.o bn_s_mp_get_bit.o bn_s_mp_invmod_fast.o \
-bn_s_mp_invmod_slow.o bn_s_mp_karatsuba_mul.o bn_s_mp_karatsuba_sqr.o bn_s_mp_montgomery_reduce_fast.o \
-bn_s_mp_mul_digs.o bn_s_mp_mul_digs_fast.o bn_s_mp_mul_high_digs.o bn_s_mp_mul_high_digs_fast.o \
-bn_s_mp_prime_is_divisible.o bn_s_mp_rand_jenkins.o bn_s_mp_rand_platform.o bn_s_mp_reverse.o \
-bn_s_mp_sqr.o bn_s_mp_sqr_fast.o bn_s_mp_sub.o bn_s_mp_toom_mul.o bn_s_mp_toom_sqr.o
+bn_mp_or.o bn_mp_pack.o bn_mp_pack_count.o bn_mp_prime_fermat.o bn_mp_prime_frobenius_underwood.o \
+bn_mp_prime_is_prime.o bn_mp_prime_miller_rabin.o bn_mp_prime_next_prime.o \
+bn_mp_prime_rabin_miller_trials.o bn_mp_prime_rand.o bn_mp_prime_strong_lucas_selfridge.o \
+bn_mp_radix_size.o bn_mp_radix_smap.o bn_mp_rand.o bn_mp_read_radix.o bn_mp_reduce.o bn_mp_reduce_2k.o \
+bn_mp_reduce_2k_l.o bn_mp_reduce_2k_setup.o bn_mp_reduce_2k_setup_l.o bn_mp_reduce_is_2k.o \
+bn_mp_reduce_is_2k_l.o bn_mp_reduce_setup.o bn_mp_root_u32.o bn_mp_rshd.o bn_mp_sbin_size.o bn_mp_set.o \
+bn_mp_set_double.o bn_mp_set_i32.o bn_mp_set_i64.o bn_mp_set_l.o bn_mp_set_ll.o bn_mp_set_u32.o \
+bn_mp_set_u64.o bn_mp_set_ul.o bn_mp_set_ull.o bn_mp_shrink.o bn_mp_signed_rsh.o bn_mp_sqr.o \
+bn_mp_sqrmod.o bn_mp_sqrt.o bn_mp_sqrtmod_prime.o bn_mp_sub.o bn_mp_sub_d.o bn_mp_submod.o \
+bn_mp_to_radix.o bn_mp_to_sbin.o bn_mp_to_ubin.o bn_mp_ubin_size.o bn_mp_unpack.o bn_mp_xor.o bn_mp_zero.o \
+bn_prime_tab.o bn_s_mp_add.o bn_s_mp_balance_mul.o bn_s_mp_exptmod.o bn_s_mp_exptmod_fast.o \
+bn_s_mp_get_bit.o bn_s_mp_invmod_fast.o bn_s_mp_invmod_slow.o bn_s_mp_karatsuba_mul.o \
+bn_s_mp_karatsuba_sqr.o bn_s_mp_montgomery_reduce_fast.o bn_s_mp_mul_digs.o bn_s_mp_mul_digs_fast.o \
+bn_s_mp_mul_high_digs.o bn_s_mp_mul_high_digs_fast.o bn_s_mp_prime_is_divisible.o \
+bn_s_mp_rand_jenkins.o bn_s_mp_rand_platform.o bn_s_mp_reverse.o bn_s_mp_sqr.o bn_s_mp_sqr_fast.o \
+bn_s_mp_sub.o bn_s_mp_toom_mul.o bn_s_mp_toom_sqr.o
 
 #END_INS