Uniform BN_bn2binpad() and BN_bn2lebinpad() implementations
@@ -458,8 +458,11 @@ BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
return ret;
}
+typedef enum {big, little} endianess_t;
+
/* ignore negative */
-static int bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
+static
+int bn2binpad(const BIGNUM *a, unsigned char *to, int tolen, endianess_t endianess)
{
int n;
size_t i, lasti, j, atop, mask;
@@ -491,10 +494,17 @@ static int bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
lasti = atop - 1;
atop = a->top * BN_BYTES;
- for (i = 0, j = 0, to += tolen; j < (size_t)tolen; j++) {
+ if (endianess == big)
+ to += tolen; /* start from the end of the buffer */
+ for (i = 0, j = 0; j < (size_t)tolen; j++) {
+ unsigned char val;
l = a->d[i / BN_BYTES];
mask = 0 - ((j - atop) >> (8 * sizeof(i) - 1));
- *--to = (unsigned char)(l >> (8 * (i % BN_BYTES)) & mask);
+ val = (unsigned char)(l >> (8 * (i % BN_BYTES)) & mask);
+ if (endianess == big)
+ *--to = val;
+ else
+ *to++ = val;
i += (i - lasti) >> (8 * sizeof(i) - 1); /* stay on last limb */
}
@@ -505,12 +515,12 @@ int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
{
if (tolen < 0)
return -1;
- return bn2binpad(a, to, tolen);
+ return bn2binpad(a, to, tolen, big);
}
int BN_bn2bin(const BIGNUM *a, unsigned char *to)
{
- return bn2binpad(a, to, -1);
+ return bn2binpad(a, to, -1, big);
}
BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret)
@@ -562,22 +572,9 @@ BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret)
int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen)
{
- int i;
- BN_ULONG l;
- bn_check_top(a);
- i = BN_num_bytes(a);
- if (tolen < i)
+ if (tolen < 0)
return -1;
- /* Add trailing zeroes if necessary */
- if (tolen > i)
- memset(to + i, 0, tolen - i);
- to += i;
- while (i--) {
- l = a->d[i / BN_BYTES];
- to--;
- *to = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff;
- }
- return tolen;
+ return bn2binpad(a, to, tolen, little);
}
BIGNUM *BN_native2bn(const unsigned char *s, int len, BIGNUM *ret)
