forked from wolfSSL/wolfssl
Merge pull request #6512 from SparkiDev/math_enc_mem_exptmod
Math, Encrypted Memory: mod exp fix
This commit is contained in:
David Garske
GitHub
@ -5104,6 +5104,51 @@ int sp_copy(const sp_int* a, sp_int* r)
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}
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#endif
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#if ((defined(WOLFSSL_SP_MATH_ALL) && ((!defined(WOLFSSL_RSA_VERIFY_ONLY) && \
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!defined(WOLFSSL_RSA_PUBLIC_ONLY)) || !defined(NO_DH))) || \
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defined(OPENSSL_ALL)) && defined(WC_PROTECT_ENCRYPTED_MEM)
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/* Copy 2 numbers into two results based on y. Copy a fixed number of digits.
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*
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* Constant time implementation.
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* When y is 0, r1 = a2 and r2 = a1.
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* When y is 1, r1 = a1 and r2 = a2.
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*
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* @param [in] a1 First number to copy.
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* @param [in] a2 Second number to copy.
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* @param [out] r1 First result number to copy into.
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* @param [out] r2 Second result number to copy into.
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* @param [in] y Indicates which number goes into which result number.
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* @param [in] used Number of digits to copy.
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*/
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static void _sp_copy_2_ct(const sp_int* a1, const sp_int* a2, sp_int* r1,
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sp_int* r2, int y, unsigned int used)
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{
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unsigned int i;
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/* Copy data - constant time. */
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for (i = 0; i < used; i++) {
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r1->dp[i] = (a1->dp[i] & ((sp_digit)wc_off_on_addr[y ])) +
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(a2->dp[i] & ((sp_digit)wc_off_on_addr[y^1]));
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r2->dp[i] = (a1->dp[i] & ((sp_digit)wc_off_on_addr[y^1])) +
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(a2->dp[i] & ((sp_digit)wc_off_on_addr[y ]));
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}
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/* Copy used. */
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r1->used = (a1->used & ((int)wc_off_on_addr[y ])) +
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(a2->used & ((int)wc_off_on_addr[y^1]));
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r2->used = (a1->used & ((int)wc_off_on_addr[y^1])) +
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(a2->used & ((int)wc_off_on_addr[y ]));
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#ifdef WOLFSSL_SP_INT_NEGATIVE
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/* Copy sign. */
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r1->sign = (a1->sign & ((int)wc_off_on_addr[y ])) +
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(a2->sign & ((int)wc_off_on_addr[y^1]));
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r2->sign = (a1->sign & ((int)wc_off_on_addr[y^1])) +
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(a2->sign & ((int)wc_off_on_addr[y ]));
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#endif
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}
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#endif
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#if defined(WOLFSSL_SP_MATH_ALL) || (defined(HAVE_ECC) && defined(FP_ECC))
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/* Initializes r and copies in value from a.
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*
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@ -12483,6 +12528,9 @@ int sp_invmod_mont_ct(const sp_int* a, const sp_int* m, sp_int* r,
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#if (defined(WOLFSSL_SP_MATH_ALL) && !defined(WOLFSSL_RSA_VERIFY_ONLY) && \
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!defined(WOLFSSL_RSA_PUBLIC_ONLY)) || !defined(NO_DH) || \
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defined(OPENSSL_ALL)
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#ifndef WC_PROTECT_ENCRYPTED_MEM
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/* Internal. Exponentiates b to the power of e modulo m into r: r = b ^ e mod m
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* Process the exponent one bit at a time.
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* Is constant time and can be cache attack resistant.
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@ -12614,6 +12662,105 @@ static int _sp_exptmod_ex(const sp_int* b, const sp_int* e, int bits,
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FREE_SP_INT_ARRAY(t, NULL);
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return err;
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}
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#else
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/* Internal. Exponentiates b to the power of e modulo m into r: r = b ^ e mod m
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* Process the exponent one bit at a time with base in Montgomery form.
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* Is constant time and cache attack resistant.
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*
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* Based on work by Marc Joye, Sung-Ming Yen, "The Montgomery Powering Ladder",
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* Cryptographic Hardware and Embedded Systems, CHES 2002
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*
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* Algorithm:
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* b: base, e: exponent, m: modulus, r: result, bits: #bits to use
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* 1. t[1] = b mod m.
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* 2. t[0] = 1
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* 3. For i in (bits-1)...0
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* 3.1. y = e[i]
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* 3.2. t[2] = t[0] * t[1]
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* 3.3. t[3] = t[y] ^ 2
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* 3.4. t[y] = t[3], t[y^1] = t[2]
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* 4. r = t[0]
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*
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* @param [in] b SP integer that is the base.
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* @param [in] e SP integer that is the exponent.
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* @param [in] bits Number of bits in exponent to use. May be greater than
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* count of bits in e.
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* @param [in] m SP integer that is the modulus.
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* @param [out] r SP integer to hold result.
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*
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* @return MP_OKAY on success.
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* @return MP_MEM when dynamic memory allocation fails.
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*/
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static int _sp_exptmod_ex(const sp_int* b, const sp_int* e, int bits,
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const sp_int* m, sp_int* r)
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{
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int err = MP_OKAY;
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int done = 0;
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DECL_SP_INT_ARRAY(t, m->used * 2 + 1, 4);
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/* Allocate temporaries. */
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ALLOC_SP_INT_ARRAY(t, m->used * 2 + 1, 4, err, NULL);
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if (err == MP_OKAY) {
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/* Initialize temporaries. */
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_sp_init_size(t[0], m->used * 2 + 1);
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_sp_init_size(t[1], m->used * 2 + 1);
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_sp_init_size(t[2], m->used * 2 + 1);
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_sp_init_size(t[3], m->used * 2 + 1);
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/* 1. Ensure base is less than modulus. */
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if (_sp_cmp_abs(b, m) != MP_LT) {
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err = sp_mod(b, m, t[1]);
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/* Handle base == modulus. */
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if ((err == MP_OKAY) && sp_iszero(t[1])) {
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_sp_set(r, 0);
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done = 1;
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}
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}
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else {
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/* Copy base into working variable. */
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err = sp_copy(b, t[1]);
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}
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}
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if ((!done) && (err == MP_OKAY)) {
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int i;
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/* 2. t[0] = 1 */
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_sp_set(t[0], 1);
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/* 3. For i in (bits-1)...0 */
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for (i = bits - 1; (err == MP_OKAY) && (i >= 0); i--) {
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/* 3.1. y = e[i] */
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int y = (e->dp[i >> SP_WORD_SHIFT] >> (i & SP_WORD_MASK)) & 1;
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/* 3.2. t[2] = t[0] * t[1] */
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err = sp_mulmod(t[0], t[1], m, t[2]);
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/* 3.3. t[3] = t[y] ^ 2 */
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if (err == MP_OKAY) {
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_sp_copy((sp_int*)(((size_t)t[0] & sp_off_on_addr[y^1]) +
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((size_t)t[1] & sp_off_on_addr[y ])),
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t[3]);
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err = sp_sqrmod(t[3], m, t[3]);
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}
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/* 3.4. t[y] = t[3], t[y^1] = t[2] */
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if (err == MP_OKAY) {
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_sp_copy_2_ct(t[2], t[3], t[0], t[1], y, m->used);
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}
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}
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}
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if ((!done) && (err == MP_OKAY)) {
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/* 4. r = t[0] */
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err = sp_copy(t[0], r);
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}
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FREE_SP_INT_ARRAY(t, NULL);
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return err;
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}
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#endif /* WC_PROTECT_ENCRYPTED_MEM */
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#endif
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#if (defined(WOLFSSL_SP_MATH_ALL) && ((!defined(WOLFSSL_RSA_VERIFY_ONLY) && \
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@ -12621,6 +12768,9 @@ static int _sp_exptmod_ex(const sp_int* b, const sp_int* e, int bits,
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defined(OPENSSL_ALL)
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#ifndef WC_NO_HARDEN
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#if !defined(WC_NO_CACHE_RESISTANT)
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#ifndef WC_PROTECT_ENCRYPTED_MEM
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/* Internal. Exponentiates b to the power of e modulo m into r: r = b ^ e mod m
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* Process the exponent one bit at a time with base in Montgomery form.
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* Is constant time and cache attack resistant.
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@ -12759,6 +12909,130 @@ static int _sp_exptmod_mont_ex(const sp_int* b, const sp_int* e, int bits,
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FREE_SP_INT_ARRAY(t, NULL);
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return err;
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}
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#else
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/* Internal. Exponentiates b to the power of e modulo m into r: r = b ^ e mod m
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* Process the exponent one bit at a time with base in Montgomery form.
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* Is constant time and cache attack resistant.
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*
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* Based on work by Marc Joye, Sung-Ming Yen, "The Montgomery Powering Ladder",
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* Cryptographic Hardware and Embedded Systems, CHES 2002
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*
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* Algorithm:
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* b: base, e: exponent, m: modulus, r: result, bits: #bits to use
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* 1. t[1] = b mod m.
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* 2. t[0] = ToMont(1)
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* 3. t[1] = ToMont(t[1])
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* 4. For i in (bits-1)...0
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* 4.1. y = e[i]
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* 4.2. t[2] = t[0] * t[1]
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* 4.3. t[3] = t[y] ^ 2
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* 4.4. t[y] = t[3], t[y^1] = t[2]
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* 5. t[0] = FromMont(t[0])
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* 6. r = t[0]
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*
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* @param [in] b SP integer that is the base.
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* @param [in] e SP integer that is the exponent.
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* @param [in] bits Number of bits in exponent to use. May be greater than
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* count of bits in e.
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* @param [in] m SP integer that is the modulus.
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* @param [out] r SP integer to hold result.
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*
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* @return MP_OKAY on success.
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* @return MP_MEM when dynamic memory allocation fails.
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*/
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static int _sp_exptmod_mont_ex(const sp_int* b, const sp_int* e, int bits,
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const sp_int* m, sp_int* r)
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{
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int err = MP_OKAY;
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int done = 0;
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DECL_SP_INT_ARRAY(t, m->used * 2 + 1, 4);
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/* Allocate temporaries. */
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ALLOC_SP_INT_ARRAY(t, m->used * 2 + 1, 4, err, NULL);
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if (err == MP_OKAY) {
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/* Initialize temporaries. */
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_sp_init_size(t[0], m->used * 2 + 1);
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_sp_init_size(t[1], m->used * 2 + 1);
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_sp_init_size(t[2], m->used * 2 + 1);
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_sp_init_size(t[3], m->used * 2 + 1);
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/* 1. Ensure base is less than modulus. */
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if (_sp_cmp_abs(b, m) != MP_LT) {
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err = sp_mod(b, m, t[1]);
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/* Handle base == modulus. */
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if ((err == MP_OKAY) && sp_iszero(t[1])) {
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_sp_set(r, 0);
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done = 1;
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}
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}
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else {
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/* Copy base into working variable. */
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err = sp_copy(b, t[1]);
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}
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}
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if ((!done) && (err == MP_OKAY)) {
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int i;
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sp_int_digit mp;
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/* Calculate Montgomery multiplier for reduction. */
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_sp_mont_setup(m, &mp);
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/* 2. t[0] = ToMont(1)
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* Calculate 1 in Montgomery form.
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*/
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err = sp_mont_norm(t[0], m);
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if (err == MP_OKAY) {
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/* 3. t[1] = ToMont(t[1])
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* Convert base to Montgomery form.
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*/
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err = sp_mulmod(t[1], t[0], m, t[1]);
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}
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/* 4. For i in (bits-1)...0 */
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for (i = bits - 1; (err == MP_OKAY) && (i >= 0); i--) {
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/* 4.1. y = e[i] */
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int y = (e->dp[i >> SP_WORD_SHIFT] >> (i & SP_WORD_MASK)) & 1;
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/* 4.2. t[2] = t[0] * t[1] */
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err = sp_mul(t[0], t[1], t[2]);
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if (err == MP_OKAY) {
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err = _sp_mont_red(t[2], m, mp);
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}
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/* 4.3. t[3] = t[y] ^ 2 */
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if (err == MP_OKAY) {
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_sp_copy((sp_int*)(((size_t)t[0] & sp_off_on_addr[y^1]) +
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((size_t)t[1] & sp_off_on_addr[y ])),
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t[3]);
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err = sp_sqr(t[3], t[3]);
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}
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if (err == MP_OKAY) {
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err = _sp_mont_red(t[3], m, mp);
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}
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/* 4.4. t[y] = t[3], t[y^1] = t[2] */
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if (err == MP_OKAY) {
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_sp_copy_2_ct(t[2], t[3], t[0], t[1], y, m->used);
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}
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}
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if (err == MP_OKAY) {
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/* 5. t[0] = FromMont(t[0]) */
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err = _sp_mont_red(t[0], m, mp);
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/* Reduction implementation returns number to range: 0..m-1. */
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}
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}
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if ((!done) && (err == MP_OKAY)) {
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/* 6. r = t[0] */
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err = sp_copy(t[0], r);
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}
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FREE_SP_INT_ARRAY(t, NULL);
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return err;
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}
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#endif /* WC_PROTECT_ENCRYPTED_MEM */
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#else
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#ifdef SP_ALLOC
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@ -1977,6 +1977,8 @@ int fp_exptmod_nb(exptModNb_t* nb, fp_int* G, fp_int* X, fp_int* P, fp_int* Y)
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#endif /* WC_RSA_NONBLOCK */
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#ifndef WC_PROTECT_ENCRYPTED_MEM
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/* timing resistant montgomery ladder based exptmod
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Based on work by Marc Joye, Sung-Ming Yen, "The Montgomery Powering Ladder",
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Cryptographic Hardware and Embedded Systems, CHES 2002
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@ -2159,6 +2161,171 @@ static int _fp_exptmod_ct(fp_int * G, fp_int * X, int digits, fp_int * P,
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return err;
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}
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#else
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/* Copy from a1 and a2 into r1 and r2 based on y in constant time.
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* When y is 1, r1 = a1 and r2 = a2.
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* When y is 0, r1 = a2 and r2 = a1.
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* Always copy size digits as that is the maximum size for a1 and a2.
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*/
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static void fp_copy_2_ct(fp_int* a1, fp_int* a2, fp_int* r1, fp_int* r2, int y,
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int size)
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{
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int i;
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/* Copy data - constant time. */
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for (i = 0; i < size; i++) {
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r1->dp[i] = (a1->dp[i] & ((fp_digit)wc_off_on_addr[y ])) +
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(a2->dp[i] & ((fp_digit)wc_off_on_addr[y^1]));
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r2->dp[i] = (a1->dp[i] & ((fp_digit)wc_off_on_addr[y^1])) +
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(a2->dp[i] & ((fp_digit)wc_off_on_addr[y ]));
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}
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/* Copy used. */
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r1->used = (a1->used & ((int)wc_off_on_addr[y ])) +
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(a2->used & ((int)wc_off_on_addr[y^1]));
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r2->used = (a1->used & ((int)wc_off_on_addr[y^1])) +
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(a2->used & ((int)wc_off_on_addr[y ]));
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/* Copy sign. */
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r1->sign = (a1->sign & ((int)wc_off_on_addr[y ])) +
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(a2->sign & ((int)wc_off_on_addr[y^1]));
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r2->sign = (a1->sign & ((int)wc_off_on_addr[y^1])) +
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(a2->sign & ((int)wc_off_on_addr[y ]));
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}
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/* timing resistant montgomery ladder based exptmod
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Based on work by Marc Joye, Sung-Ming Yen, "The Montgomery Powering Ladder",
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Cryptographic Hardware and Embedded Systems, CHES 2002
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*/
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static int _fp_exptmod_ct(fp_int * G, fp_int * X, int digits, fp_int * P,
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fp_int * Y)
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{
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#ifndef WOLFSSL_SMALL_STACK
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fp_int R[4]; /* need a temp for cache resistance */
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#else
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fp_int *R;
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#endif
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fp_digit buf, mp;
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int err, bitcnt, digidx, y;
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/* now setup montgomery */
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if ((err = fp_montgomery_setup (P, &mp)) != FP_OKAY) {
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return err;
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}
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#ifdef WOLFSSL_SMALL_STACK
|
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R = (fp_int*)XMALLOC(sizeof(fp_int) * 4, NULL, DYNAMIC_TYPE_BIGINT);
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if (R == NULL)
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return FP_MEM;
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#endif
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fp_init(&R[0]);
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fp_init(&R[1]);
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fp_init(&R[2]);
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fp_init(&R[3]);
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/* now we need R mod m */
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err = fp_montgomery_calc_normalization (&R[0], P);
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if (err != FP_OKAY) {
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#ifdef WOLFSSL_SMALL_STACK
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XFREE(R, NULL, DYNAMIC_TYPE_BIGINT);
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#endif
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return err;
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}
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/* now set R[0][1] to G * R mod m */
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if (fp_cmp_mag(P, G) != FP_GT) {
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/* G > P so we reduce it first */
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err = fp_mod(G, P, &R[1]);
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if (err != FP_OKAY) {
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#ifdef WOLFSSL_SMALL_STACK
|
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XFREE(R, NULL, DYNAMIC_TYPE_BIGINT);
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#endif
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return err;
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}
|
||||
} else {
|
||||
fp_copy(G, &R[1]);
|
||||
}
|
||||
err = fp_mulmod (&R[1], &R[0], P, &R[1]);
|
||||
if (err != FP_OKAY) {
|
||||
#ifdef WOLFSSL_SMALL_STACK
|
||||
XFREE(R, NULL, DYNAMIC_TYPE_BIGINT);
|
||||
#endif
|
||||
return err;
|
||||
}
|
||||
|
||||
/* for j = t-1 downto 0 do
|
||||
r_!k = R0*R1; r_k = r_k^2
|
||||
*/
|
||||
|
||||
/* set initial mode and bit cnt */
|
||||
bitcnt = 1;
|
||||
buf = 0;
|
||||
digidx = digits - 1;
|
||||
|
||||
for (;;) {
|
||||
/* grab next digit as required */
|
||||
if (--bitcnt == 0) {
|
||||
/* if digidx == -1 we are out of digits so break */
|
||||
if (digidx == -1) {
|
||||
break;
|
||||
}
|
||||
/* read next digit and reset bitcnt */
|
||||
buf = X->dp[digidx--];
|
||||
bitcnt = (int)DIGIT_BIT;
|
||||
}
|
||||
|
||||
/* grab the next msb from the exponent */
|
||||
y = (int)(buf >> (DIGIT_BIT - 1)) & 1;
|
||||
buf <<= (fp_digit)1;
|
||||
|
||||
/* do ops */
|
||||
err = fp_mul(&R[0], &R[1], &R[2]);
|
||||
if (err != FP_OKAY) {
|
||||
#ifdef WOLFSSL_SMALL_STACK
|
||||
XFREE(R, NULL, DYNAMIC_TYPE_BIGINT);
|
||||
#endif
|
||||
return err;
|
||||
}
|
||||
err = fp_montgomery_reduce(&R[2], P, mp);
|
||||
if (err != FP_OKAY) {
|
||||
#ifdef WOLFSSL_SMALL_STACK
|
||||
XFREE(R, NULL, DYNAMIC_TYPE_BIGINT);
|
||||
#endif
|
||||
return err;
|
||||
}
|
||||
|
||||
/* instead of using R[y] for sqr, which leaks key bit to cache monitor,
|
||||
* use R[3] as temp, make sure address calc is constant, keep
|
||||
* &R[0] and &R[1] in cache */
|
||||
fp_copy((fp_int*) ( ((wc_ptr_t)&R[0] & wc_off_on_addr[y^1]) +
|
||||
((wc_ptr_t)&R[1] & wc_off_on_addr[y]) ),
|
||||
&R[3]);
|
||||
err = fp_sqr(&R[3], &R[3]);
|
||||
if (err != FP_OKAY) {
|
||||
#ifdef WOLFSSL_SMALL_STACK
|
||||
XFREE(R, NULL, DYNAMIC_TYPE_BIGINT);
|
||||
#endif
|
||||
return err;
|
||||
}
|
||||
err = fp_montgomery_reduce(&R[3], P, mp);
|
||||
if (err != FP_OKAY) {
|
||||
#ifdef WOLFSSL_SMALL_STACK
|
||||
XFREE(R, NULL, DYNAMIC_TYPE_BIGINT);
|
||||
#endif
|
||||
return err;
|
||||
}
|
||||
fp_copy_2_ct(&R[2], &R[3], &R[0], &R[1], y, P->used);
|
||||
}
|
||||
|
||||
err = fp_montgomery_reduce(&R[0], P, mp);
|
||||
fp_copy(&R[0], Y);
|
||||
#ifdef WOLFSSL_SMALL_STACK
|
||||
XFREE(R, NULL, DYNAMIC_TYPE_BIGINT);
|
||||
#endif
|
||||
return err;
|
||||
}
|
||||
|
||||
#endif /* WC_PROTECT_ENCRYPTED_MEM */
|
||||
|
||||
#endif /* TFM_TIMING_RESISTANT */
|
||||
|
||||
/* y = g**x (mod b)
|
||||
|
||||
Reference in New Issue
Block a user