[PATCH] gcry_mpi_sub_ui: fix subtracting from negative value
Jussi Kivilinna
jussi.kivilinna at iki.fi
Tue Nov 30 21:23:45 CET 2021
* mpi/mpi-add.c (_gcry_mpi_sub_ui): Set output sign bit when 'u'
is negative.
* tests/mpitests.c (test_add): Additional tests for mpi_add_ui; Check
test output and fail if output does not match expected.
(test_sub): Additional tests for mpi_sub_ui; Check test output and fail
if output does not match expected.
(test_mul): Additional tests for mpi_mul_ui; Check test output and fail
if output does not match expected.
--
Signed-off-by: Jussi Kivilinna <jussi.kivilinna at iki.fi>
---
mpi/mpi-add.c | 1 +
tests/mpitests.c | 119 ++++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 113 insertions(+), 7 deletions(-)
diff --git a/mpi/mpi-add.c b/mpi/mpi-add.c
index 53f476e0..38dd352f 100644
--- a/mpi/mpi-add.c
+++ b/mpi/mpi-add.c
@@ -191,6 +191,7 @@ _gcry_mpi_sub_ui(gcry_mpi_t w, gcry_mpi_t u, unsigned long v )
cy = _gcry_mpih_add_1(wp, up, usize, v);
wp[usize] = cy;
wsize = usize + cy;
+ wsign = 1;
}
else { /* The signs are different. Need exact comparison to determine
* which operand to subtract from which. */
diff --git a/tests/mpitests.c b/tests/mpitests.c
index 96e01551..48ea18b2 100644
--- a/tests/mpitests.c
+++ b/tests/mpitests.c
@@ -378,7 +378,8 @@ test_add (void)
gcry_mpi_t two;
gcry_mpi_t ff;
gcry_mpi_t result;
- unsigned char* pc;
+ gcry_mpi_t minusfive;
+ char *pc;
gcry_mpi_scan(&one, GCRYMPI_FMT_USG, ones, sizeof(ones), NULL);
gcry_mpi_scan(&two, GCRYMPI_FMT_USG, twos, sizeof(twos), NULL);
@@ -386,21 +387,47 @@ test_add (void)
result = gcry_mpi_new(0);
gcry_mpi_add(result, one, two);
- gcry_mpi_aprint(GCRYMPI_FMT_HEX, &pc, NULL, result);
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
if (debug)
gcry_log_debug ("Result of one plus two:\n%s\n", pc);
+ if (strcmp (pc, "030303030303030303030303030303030303030303030303"
+ "030303030303030303030303030303030303030303030303") != 0)
+ fail ("mpi_add failed at line %d", __LINE__);
gcry_free(pc);
gcry_mpi_add(result, ff, one);
- gcry_mpi_aprint(GCRYMPI_FMT_HEX, &pc, NULL, result);
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
if (debug)
gcry_log_debug ("Result of ff plus one:\n%s\n", pc);
+ if (strcmp (pc, "010101010101010101010101010101010101010101010101"
+ "01010101010101010101010101010101010101010101010100") != 0)
+ fail ("mpi_add failed at line %d", __LINE__);
+ gcry_free(pc);
+
+ gcry_mpi_scan(&minusfive, GCRYMPI_FMT_HEX, "-5", 0, NULL);
+ gcry_mpi_add_ui (result, minusfive, 2);
+
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+ if (debug)
+ gcry_log_debug ("Result of minus five plus two:\n%s\n", pc);
+ if (strcmp (pc, "-03") != 0)
+ fail ("mpi_add_ui failed at line %d", __LINE__);
+ gcry_free(pc);
+
+ gcry_mpi_add_ui (result, result, 3);
+
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+ if (debug)
+ gcry_log_debug ("Result of minus three plus three:\n%s\n", pc);
+ if (strcmp (pc, "00") != 0)
+ fail ("mpi_add_ui failed at line %d", __LINE__);
gcry_free(pc);
gcry_mpi_release(one);
gcry_mpi_release(two);
gcry_mpi_release(ff);
gcry_mpi_release(result);
+ gcry_mpi_release(minusfive);
return 1;
}
@@ -408,24 +435,76 @@ test_add (void)
static int
test_sub (void)
{
+ gcry_mpi_t zero;
gcry_mpi_t one;
gcry_mpi_t two;
+ gcry_mpi_t five;
gcry_mpi_t result;
- unsigned char* pc;
+ gcry_mpi_t minusfive;
+ char *pc;
gcry_mpi_scan(&one, GCRYMPI_FMT_USG, ones, sizeof(ones), NULL);
gcry_mpi_scan(&two, GCRYMPI_FMT_USG, twos, sizeof(twos), NULL);
result = gcry_mpi_new(0);
gcry_mpi_sub(result, two, one);
- gcry_mpi_aprint(GCRYMPI_FMT_HEX, &pc, NULL, result);
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
if (debug)
gcry_log_debug ("Result of two minus one:\n%s\n", pc);
+ if (strcmp (pc, "010101010101010101010101010101010101010101010101"
+ "010101010101010101010101010101010101010101010101") != 0)
+ fail ("mpi_sub failed at line %d", __LINE__);
+ gcry_free(pc);
+
+ zero = gcry_mpi_new(0);
+ five = gcry_mpi_new(0);
+ minusfive = gcry_mpi_new(0);
+ gcry_mpi_set_ui (zero, 0);
+ gcry_mpi_set_ui (one, 1);
+ gcry_mpi_set_ui (two, 2);
+ gcry_mpi_set_ui (five, 5);
+ gcry_mpi_sub (minusfive, zero, five);
+
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, minusfive);
+ if (debug)
+ gcry_log_debug ("Result of zero minus five:\n%s\n", pc);
+ if (strcmp (pc, "-05") != 0)
+ fail ("mpi_sub failed at line %d", __LINE__);
+ gcry_free(pc);
+
+ gcry_mpi_sub_ui (result, five, 2);
+
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+ if (debug)
+ gcry_log_debug ("Result of five minus two:\n%s\n", pc);
+ if (strcmp (pc, "03") != 0)
+ fail ("mpi_sub_ui failed at line %d", __LINE__);
+ gcry_free(pc);
+
+ gcry_mpi_sub_ui (result, one, 10);
+
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+ if (debug)
+ gcry_log_debug ("Result of one minus ten:\n%s\n", pc);
+ if (strcmp (pc, "-09") != 0)
+ fail ("mpi_sub_ui failed at line %d", __LINE__);
+ gcry_free(pc);
+
+ gcry_mpi_sub_ui (result, minusfive, 2);
+
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+ if (debug)
+ gcry_log_debug ("Result of minus five minus two:\n%s\n", pc);
+ if (strcmp (pc, "-07") != 0)
+ fail ("mpi_sub_ui failed at line %d", __LINE__);
gcry_free(pc);
gcry_mpi_release(one);
gcry_mpi_release(two);
gcry_mpi_release(result);
+ gcry_mpi_release(zero);
+ gcry_mpi_release(five);
+ gcry_mpi_release(minusfive);
return 1;
}
@@ -436,21 +515,47 @@ test_mul (void)
gcry_mpi_t two;
gcry_mpi_t three;
gcry_mpi_t result;
- unsigned char* pc;
+ gcry_mpi_t minusfive;
+ char *pc;
gcry_mpi_scan(&two, GCRYMPI_FMT_USG, twos, sizeof(twos), NULL);
gcry_mpi_scan(&three, GCRYMPI_FMT_USG, threes, sizeof(threes), NULL);
result = gcry_mpi_new(0);
gcry_mpi_mul(result, two, three);
- gcry_mpi_aprint(GCRYMPI_FMT_HEX, &pc, NULL, result);
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
if (debug)
gcry_log_debug ("Result of two mul three:\n%s\n", pc);
+ if (strcmp (pc, "060C12181E242A30363C42484E545A60666C72787E848A90"
+ "969CA2A8AEB4BAC0C6CCD2D8DEE4EAF0F6FD03090F151B21"
+ "1B150F0902FCF6F0EAE4DED8D2CCC6C0BAB4AEA8A29C9690"
+ "8A847E78726C66605A544E48423C36302A241E18120C06") != 0)
+ fail ("mpi_mul failed at line %d", __LINE__);
+ gcry_free(pc);
+
+ gcry_mpi_scan(&minusfive, GCRYMPI_FMT_HEX, "-5", 0, NULL);
+ gcry_mpi_mul_ui (result, minusfive, 3);
+
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+ if (debug)
+ gcry_log_debug ("Result of minus five mul three:\n%s\n", pc);
+ if (strcmp (pc, "-0F") != 0)
+ fail ("mpi_mul_ui failed at line %d", __LINE__);
+ gcry_free(pc);
+
+ gcry_mpi_mul_ui (result, result, 0);
+
+ gcry_mpi_aprint(GCRYMPI_FMT_HEX, (unsigned char **)&pc, NULL, result);
+ if (debug)
+ gcry_log_debug ("Result of minus fifteen mul zero:\n%s\n", pc);
+ if (strcmp (pc, "00") != 0)
+ fail ("mpi_mul_ui failed at line %d", __LINE__);
gcry_free(pc);
gcry_mpi_release(two);
gcry_mpi_release(three);
gcry_mpi_release(result);
+ gcry_mpi_release(minusfive);
return 1;
}
--
2.32.0
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