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New BN functions.

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Add new function BN_bn2binpad() which checks the length of the output
buffer and pads the result with zeroes if necessary.

New functions BN_bn2lebinpad() and BN_lebin2bn() which use little endian
format.

Reviewed-by: Rich Salz <rsalz@openssl.org>
This commit is contained in:
Dr. Stephen Henson
2016-02-01 00:02:05 +00:00
parent 19f7130beb
commit 85a4807f94
4 changed files with 117 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

94
crypto/bn/bn_lib.c
View File

@@ -575,18 +575,104 @@ BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
}
/* ignore negative */
int BN_bn2bin(const BIGNUM *a, unsigned char *to)
static int bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
{
int n, i;
int i;
BN_ULONG l;
bn_check_top(a);
n = i = BN_num_bytes(a);
i = BN_num_bytes(a);
if (tolen == -1)
tolen = i;
else if (tolen < i)
return -1;
/* Add leading zeroes if necessary */
if (tolen > i) {
memset(to, 0, tolen - i);
to += tolen - i;
}
while (i--) {
l = a->d[i / BN_BYTES];
*(to++) = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff;
}
return (n);
return tolen;
}
int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
{
if (tolen < 0)
return -1;
return bn2binpad(a, to, tolen);
}
int BN_bn2bin(const BIGNUM *a, unsigned char *to)
{
return bn2binpad(a, to, -1);
}
BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret)
{
unsigned int i, m;
unsigned int n;
BN_ULONG l;
BIGNUM *bn = NULL;
if (ret == NULL)
ret = bn = BN_new();
if (ret == NULL)
return (NULL);
bn_check_top(ret);
s += len - 1;
/* Skip trailing zeroes. */
for ( ; len > 0 && *s == 0; s--, len--)
continue;
n = len;
if (n == 0) {
ret->top = 0;
return ret;
}
i = ((n - 1) / BN_BYTES) + 1;
m = ((n - 1) % (BN_BYTES));
if (bn_wexpand(ret, (int)i) == NULL) {
BN_free(bn);
return NULL;
}
ret->top = i;
ret->neg = 0;
l = 0;
while (n--) {
l = (l << 8L) | *(s--);
if (m-- == 0) {
ret->d[--i] = l;
l = 0;
m = BN_BYTES - 1;
}
}
/*
* need to call this due to clear byte at top if avoiding having the top
* bit set (-ve number)
*/
bn_correct_top(ret);
return 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)
return -1;
/* Add trailing zeroes if necessary */
if (tolen > i)
memset(to + i, 0, tolen - i);
to += i - 1;
while (i--) {
l = a->d[i / BN_BYTES];
*(to--) = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff;
}
return tolen;
}
int BN_ucmp(const BIGNUM *a, const BIGNUM *b)

42
crypto/pem/pvkfmt.c
View File

@@ -93,23 +93,11 @@ static unsigned int read_ledword(const unsigned char **in)
static int read_lebn(const unsigned char **in, unsigned int nbyte, BIGNUM **r)
{
const unsigned char *p;
unsigned char *tmpbuf, *q;
unsigned int i;
p = *in + nbyte - 1;
tmpbuf = OPENSSL_malloc(nbyte);
if (tmpbuf == NULL)
return 0;
q = tmpbuf;
for (i = 0; i < nbyte; i++)
*q++ = *p--;
*r = BN_bin2bn(tmpbuf, nbyte, NULL);
OPENSSL_free(tmpbuf);
if (*r) {
*in += nbyte;
return 1;
} else
*r = BN_lebin2bn(*in, nbyte, NULL);
if (*r == NULL)
return 0;
*in += nbyte;
return 1;
}
/* Convert private key blob to EVP_PKEY: RSA and DSA keys supported */
@@ -417,26 +405,8 @@ static void write_ledword(unsigned char **out, unsigned int dw)
static void write_lebn(unsigned char **out, const BIGNUM *bn, int len)
{
int nb, i;
unsigned char *p = *out, *q, c;
nb = BN_num_bytes(bn);
BN_bn2bin(bn, p);
q = p + nb - 1;
/* In place byte order reversal */
for (i = 0; i < nb / 2; i++) {
c = *p;
*p++ = *q;
*q-- = c;
}
*out += nb;
/* Pad with zeroes if we have to */
if (len > 0) {
len -= nb;
if (len > 0) {
memset(*out, 0, len);
*out += len;
}
}
BN_bn2lebinpad(bn, *out, len);
*out += len;
}
static int check_bitlen_rsa(RSA *rsa, int ispub, unsigned int *magic);

20
doc/crypto/BN_bn2bin.pod
View File

@@ -2,16 +2,21 @@
=head1 NAME
BN_bn2bin, BN_bin2bn, BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn,
BN_print, BN_print_fp, BN_bn2mpi, BN_mpi2bn - format conversions
BN_bn2bin, BN_bin2bn, BN_bn2lebinpad, BN_lebin2bn, BN_bn2hex, BN_bn2dec,
BN_hex2bn, BN_dec2bn, BN_print, BN_print_fp, BN_bn2mpi,
BN_mpi2bn - format conversions
=head1 SYNOPSIS
#include <openssl/bn.h>
int BN_bn2bin(const BIGNUM *a, unsigned char *to);
int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen);
BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret);
int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen);
BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret);
char *BN_bn2hex(const BIGNUM *a);
char *BN_bn2dec(const BIGNUM *a);
int BN_hex2bn(BIGNUM **a, const char *str);
@@ -29,10 +34,18 @@ BN_bn2bin() converts the absolute value of B<a> into big-endian form
and stores it at B<to>. B<to> must point to BN_num_bytes(B<a>) bytes of
memory.
BN_bn2binpad() also converts the absolute value of B<a> into big-endian form
and stores it at B<to>. B<tolen> indicates the length of the output buffer
B<to>. The result is padded with zeroes if necessary. If B<tolen> is less than
BN_num_bytes(B<a>) an error is returned.
BN_bin2bn() converts the positive integer in big-endian form of length
B<len> at B<s> into a B<BIGNUM> and places it in B<ret>. If B<ret> is
NULL, a new B<BIGNUM> is created.
BN_bn2lebinpad() and BN_bin2lbn() are identical to BN_bn2binpad() and
BN_bin2bn() except the buffer is in little-endian format.
BN_bn2hex() and BN_bn2dec() return printable strings containing the
hexadecimal and decimal encoding of B<a> respectively. For negative
numbers, the string is prefaced with a leading '-'. The string must be
@@ -67,6 +80,9 @@ if B<ret> is NULL.
BN_bn2bin() returns the length of the big-endian number placed at B<to>.
BN_bin2bn() returns the B<BIGNUM>, NULL on error.
BN_bn2binpad() returns the number of bytes written or -1 if the supplied
buffer is too small.
BN_bn2hex() and BN_bn2dec() return a null-terminated string, or NULL
on error. BN_hex2bn() and BN_dec2bn() return the number's length in
hexadecimal or decimal digits, and 0 on error.

3
include/openssl/bn.h
View File

@@ -270,6 +270,9 @@ BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b);
void BN_swap(BIGNUM *a, BIGNUM *b);
BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret);
int BN_bn2bin(const BIGNUM *a, unsigned char *to);
int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen);
BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret);
int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen);
BIGNUM *BN_mpi2bn(const unsigned char *s, int len, BIGNUM *ret);
int BN_bn2mpi(const BIGNUM *a, unsigned char *to);
int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);