Commit 85a4807f authored by Dr. Stephen Henson's avatar Dr. Stephen Henson
Browse files

New BN functions. 



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: default avatarRich Salz <rsalz@openssl.org>
parent 19f7130b

crypto/bn/bn_lib.c

+90 −4
Original line number Diff line number Diff line
@@ -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)

crypto/pem/pvkfmt.c

+6 −36
Original line number Diff line number Diff line
@@ -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)

    *r = BN_lebin2bn(*in, nbyte, NULL);

    if (*r == 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

        return 0;

}



/* Convert private key blob to EVP_PKEY: RSA and DSA keys supported */
@@ -417,27 +405,9 @@ 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);

    BN_bn2lebinpad(bn, *out, len);

    *out += len;

}

    }

}



static int check_bitlen_rsa(RSA *rsa, int ispub, unsigned int *magic);

static int check_bitlen_dsa(DSA *dsa, int ispub, unsigned int *magic);

doc/crypto/BN_bn2bin.pod

+18 −2
Original line number Diff line number Diff line
@@ -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.

include/openssl/bn.h

+3 −0
Original line number Diff line number Diff line
@@ -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);