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/*
* Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdio.h>
#include "internal/cryptlib.h"
#include "internal/numbers.h"
#include <limits.h>
#include <openssl/asn1.h>
#include <openssl/bn.h>
#include "asn1_local.h"
ASN1_INTEGER *ASN1_INTEGER_dup(const ASN1_INTEGER *x)
{
return ASN1_STRING_dup(x);
}
int ASN1_INTEGER_cmp(const ASN1_INTEGER *x, const ASN1_INTEGER *y)
{
int neg, ret;
/* Compare signs */
neg = x->type & V_ASN1_NEG;
if (neg != (y->type & V_ASN1_NEG)) {
if (neg)
return -1;
else
return 1;
}
ret = ASN1_STRING_cmp(x, y);
if (neg)
return -ret;
else
return ret;
}
/*-
* This converts a big endian buffer and sign into its content encoding.
* This is used for INTEGER and ENUMERATED types.
* The internal representation is an ASN1_STRING whose data is a big endian
* representation of the value, ignoring the sign. The sign is determined by
* the type: if type & V_ASN1_NEG is true it is negative, otherwise positive.
*
* Positive integers are no problem: they are almost the same as the DER
* encoding, except if the first byte is >= 0x80 we need to add a zero pad.
*
* Negative integers are a bit trickier...
* The DER representation of negative integers is in 2s complement form.
* The internal form is converted by complementing each octet and finally
* adding one to the result. This can be done less messily with a little trick.
* If the internal form has trailing zeroes then they will become FF by the
* complement and 0 by the add one (due to carry) so just copy as many trailing
* zeros to the destination as there are in the source. The carry will add one
* to the last none zero octet: so complement this octet and add one and finally
* complement any left over until you get to the start of the string.
*
* Padding is a little trickier too. If the first bytes is > 0x80 then we pad
* with 0xff. However if the first byte is 0x80 and one of the following bytes
* is non-zero we pad with 0xff. The reason for this distinction is that 0x80
* followed by optional zeros isn't padded.
*/
/*
* If |pad| is zero, the operation is effectively reduced to memcpy,
* and if |pad| is 0xff, then it performs two's complement, ~dst + 1.
* Note that in latter case sequence of zeros yields itself, and so
* does 0x80 followed by any number of zeros. These properties are
* used elsewhere below...
*/
static void twos_complement(unsigned char *dst, const unsigned char *src,
size_t len, unsigned char pad)
{
unsigned int carry = pad & 1;
/* Begin at the end of the encoding */
dst += len;
src += len;
/* two's complement value: ~value + 1 */
while (len-- != 0) {
*(--dst) = (unsigned char)(carry += *(--src) ^ pad);
carry >>= 8;
}
}
static size_t i2c_ibuf(const unsigned char *b, size_t blen, int neg,
unsigned char **pp)
{
unsigned int pad = 0;
size_t ret, i;
unsigned char *p, pb = 0;
if (b != NULL && blen) {
ret = blen;
i = b[0];
if (!neg && (i > 127)) {
pad = 1;
pb = 0;
} else if (neg) {
pb = 0xFF;
if (i > 128) {
pad = 1;
} else if (i == 128) {
/*
* Special case [of minimal negative for given length]:
* if any other bytes non zero we pad, otherwise we don't.
*/
for (pad = 0, i = 1; i < blen; i++)
pad |= b[i];
pb = pad != 0 ? 0xffU : 0;
pad = pb & 1;
}
}
ret += pad;
} else {
ret = 1;
blen = 0; /* reduce '(b == NULL || blen == 0)' to '(blen == 0)' */
}
if (pp == NULL || (p = *pp) == NULL)
return ret;
/*
* This magically handles all corner cases, such as '(b == NULL ||
* blen == 0)', non-negative value, "negative" zero, 0x80 followed
* by any number of zeros...
*/
*p = pb;
p += pad; /* yes, p[0] can be written twice, but it's little
* price to pay for eliminated branches */
twos_complement(p, b, blen, pb);
*pp += ret;
return ret;
}
/*
* convert content octets into a big endian buffer. Returns the length
* of buffer or 0 on error: for malformed INTEGER. If output buffer is
* NULL just return length.
*/
static size_t c2i_ibuf(unsigned char *b, int *pneg,
const unsigned char *p, size_t plen)
{
int neg, pad;
/* Zero content length is illegal */
if (plen == 0) {
ASN1err(ASN1_F_C2I_IBUF, ASN1_R_ILLEGAL_ZERO_CONTENT);
return 0;
}
neg = p[0] & 0x80;
if (pneg)
*pneg = neg;
/* Handle common case where length is 1 octet separately */
if (plen == 1) {
if (b != NULL) {
if (neg)
b[0] = (p[0] ^ 0xFF) + 1;
else
b[0] = p[0];
}
return 1;
}
pad = 0;
if (p[0] == 0) {
pad = 1;
} else if (p[0] == 0xFF) {
size_t i;
/*
* Special case [of "one less minimal negative" for given length]:
* if any other bytes non zero it was padded, otherwise not.
*/
for (pad = 0, i = 1; i < plen; i++)
pad |= p[i];
pad = pad != 0 ? 1 : 0;
}
/* reject illegal padding: first two octets MSB can't match */
if (pad && (neg == (p[1] & 0x80))) {
ASN1err(ASN1_F_C2I_IBUF, ASN1_R_ILLEGAL_PADDING);
return 0;
}
/* skip over pad */
p += pad;
plen -= pad;
if (b != NULL)
twos_complement(b, p, plen, neg ? 0xffU : 0);
return plen;
}
int i2c_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **pp)
{
return i2c_ibuf(a->data, a->length, a->type & V_ASN1_NEG, pp);
}
/* Convert big endian buffer into uint64_t, return 0 on error */
static int asn1_get_uint64(uint64_t *pr, const unsigned char *b, size_t blen)
{
size_t i;
uint64_t r;
if (blen > sizeof(*pr)) {
ASN1err(ASN1_F_ASN1_GET_UINT64, ASN1_R_TOO_LARGE);
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