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boringssl/third_party/sike/isogeny.c
Kris Kwiatkowski eb43eca5a8 Add support for SIKE/p503 post-quantum KEM 
Based on Microsoft's implementation available on github:
Source: https://github.com/Microsoft/PQCrypto-SIDH
Commit: 77044b76181eb61c744ac8eb7ddc7a8fe72f6919

Following changes has been applied

* In intel assembly, use MOV instead of MOVQ:
  Intel instruction reference in the Intel Software Developer's Manual
  volume 2A, the MOVQ has 4 forms. None of them mentions moving
  literal to GPR, hence "movq $rax, 0x0" is wrong. Instead, on 64bit
  system, MOV can be used.

* Some variables were wrongly zero-initialized (as per C99 spec)

* Move constant values to .RODATA segment, as keeping them in .TEXT
  segment is not compatible with XOM.

* Fixes issue in arm64 code related to the fact that compiler doesn't
  reserve enough space for the linker to relocate address of a global
  variable when used by 'ldr' instructions. Solution is to use 'adrp'
  followed by 'add' instruction. Relocations for 'adrp' and 'add'
  instructions is generated by prefixing the label with :pg_hi21:
  and :lo12: respectively.

* Enable MULX and ADX. Code from MS doesn't support PIC. MULX can't
  reference global variable directly. Instead RIP-relative addressing
  can be used. This improves performance around 10%-13% on SkyLake

* Check if CPU supports BMI2 and ADOX instruction at runtime. On AMD64
  optimized implementation of montgomery multiplication and reduction
  have 2 implementations - faster one takes advantage of BMI2
  instruction set introduced in Haswell and ADOX introduced in
  Broadwell. Thanks to OPENSSL_ia32cap_P it can be decided at runtime
  which implementation to choose. As CPU configuration is static by
  nature, branch predictor will be correct most of the time and hence
  this check very often has no cost.

* Reuse some utilities from boringssl instead of reimplementing them.
  This includes things like:
  * definition of a limb size (use crypto_word_t instead of digit_t)
  * use functions for checking in constant time if value is 0 and/or
    less then
  * #define's used for conditional compilation

* Use SSE2 for conditional swap on vector registers. Improves
  performance a little bit.

* Fix f2elm_t definition. Code imported from MSR defines f2elm_t type as
  a array of arrays. This decays to a pointer to an array (when passing
  as an argument). In C, one can't assign const pointer to an array with
  non-const pointer to an array. Seems it violates 6.7.3/8 from C99
  (same for C11). This problem occures in GCC 6, only when -pedantic
  flag is specified and it occures always in GCC 4.9 (debian jessie).

* Fix definition of eval_3_isog. Second argument in eval_3_isog mustn't be
  const. Similar reason as above.

* Use HMAC-SHA256 instead of cSHAKE-256 to avoid upstreaming cSHAKE
  and SHA3 code.

* Add speed and unit tests for SIKE.

Change-Id: I22f0bb1f9edff314a35cd74b48e8c4962568e330
2019-04-12 11:26:23 -07:00

261 lines
16 KiB
C
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/********************************************************************************************
* SIDH: an efficient supersingular isogeny cryptography library
*
* Abstract: elliptic curve and isogeny functions
*********************************************************************************************/
#include "utils.h"
#include "isogeny.h"
#include "fpx.h"
static void xDBL(const point_proj_t P, point_proj_t Q, const f2elm_t A24plus, const f2elm_t C24)
{ // Doubling of a Montgomery point in projective coordinates (X:Z).
// Input: projective Montgomery x-coordinates P = (X1:Z1), where x1=X1/Z1 and Montgomery curve constants A+2C and 4C.
// Output: projective Montgomery x-coordinates Q = 2*P = (X2:Z2).
f2elm_t t0, t1;
sike_fp2sub(P->X, P->Z, t0); // t0 = X1-Z1
sike_fp2add(P->X, P->Z, t1); // t1 = X1+Z1
sike_fp2sqr_mont(t0, t0); // t0 = (X1-Z1)^2
sike_fp2sqr_mont(t1, t1); // t1 = (X1+Z1)^2
sike_fp2mul_mont(C24, t0, Q->Z); // Z2 = C24*(X1-Z1)^2
sike_fp2mul_mont(t1, Q->Z, Q->X); // X2 = C24*(X1-Z1)^2*(X1+Z1)^2
sike_fp2sub(t1, t0, t1); // t1 = (X1+Z1)^2-(X1-Z1)^2
sike_fp2mul_mont(A24plus, t1, t0); // t0 = A24plus*[(X1+Z1)^2-(X1-Z1)^2]
sike_fp2add(Q->Z, t0, Q->Z); // Z2 = A24plus*[(X1+Z1)^2-(X1-Z1)^2] + C24*(X1-Z1)^2
sike_fp2mul_mont(Q->Z, t1, Q->Z); // Z2 = [A24plus*[(X1+Z1)^2-(X1-Z1)^2] + C24*(X1-Z1)^2]*[(X1+Z1)^2-(X1-Z1)^2]
}
void xDBLe(const point_proj_t P, point_proj_t Q, const f2elm_t A24plus, const f2elm_t C24, size_t e)
{ // Computes [2^e](X:Z) on Montgomery curve with projective constant via e repeated doublings.
// Input: projective Montgomery x-coordinates P = (XP:ZP), such that xP=XP/ZP and Montgomery curve constants A+2C and 4C.
// Output: projective Montgomery x-coordinates Q <- (2^e)*P.
memcpy(Q, P, sizeof(*P));
for (size_t i = 0; i < e; i++) {
xDBL(Q, Q, A24plus, C24);
}
}
void get_4_isog(const point_proj_t P, f2elm_t A24plus, f2elm_t C24, f2elm_t* coeff)
{ // Computes the corresponding 4-isogeny of a projective Montgomery point (X4:Z4) of order 4.
// Input: projective point of order four P = (X4:Z4).
// Output: the 4-isogenous Montgomery curve with projective coefficients A+2C/4C and the 3 coefficients
// that are used to evaluate the isogeny at a point in eval_4_isog().
sike_fp2sub(P->X, P->Z, coeff[1]); // coeff[1] = X4-Z4
sike_fp2add(P->X, P->Z, coeff[2]); // coeff[2] = X4+Z4
sike_fp2sqr_mont(P->Z, coeff[0]); // coeff[0] = Z4^2
sike_fp2add(coeff[0], coeff[0], coeff[0]); // coeff[0] = 2*Z4^2
sike_fp2sqr_mont(coeff[0], C24); // C24 = 4*Z4^4
sike_fp2add(coeff[0], coeff[0], coeff[0]); // coeff[0] = 4*Z4^2
sike_fp2sqr_mont(P->X, A24plus); // A24plus = X4^2
sike_fp2add(A24plus, A24plus, A24plus); // A24plus = 2*X4^2
sike_fp2sqr_mont(A24plus, A24plus); // A24plus = 4*X4^4
}
void eval_4_isog(point_proj_t P, f2elm_t* coeff)
{ // Evaluates the isogeny at the point (X:Z) in the domain of the isogeny, given a 4-isogeny phi defined
// by the 3 coefficients in coeff (computed in the function get_4_isog()).
// Inputs: the coefficients defining the isogeny, and the projective point P = (X:Z).
// Output: the projective point P = phi(P) = (X:Z) in the codomain.
f2elm_t t0, t1;
sike_fp2add(P->X, P->Z, t0); // t0 = X+Z
sike_fp2sub(P->X, P->Z, t1); // t1 = X-Z
sike_fp2mul_mont(t0, coeff[1], P->X); // X = (X+Z)*coeff[1]
sike_fp2mul_mont(t1, coeff[2], P->Z); // Z = (X-Z)*coeff[2]
sike_fp2mul_mont(t0, t1, t0); // t0 = (X+Z)*(X-Z)
sike_fp2mul_mont(t0, coeff[0], t0); // t0 = coeff[0]*(X+Z)*(X-Z)
sike_fp2add(P->X, P->Z, t1); // t1 = (X-Z)*coeff[2] + (X+Z)*coeff[1]
sike_fp2sub(P->X, P->Z, P->Z); // Z = (X-Z)*coeff[2] - (X+Z)*coeff[1]
sike_fp2sqr_mont(t1, t1); // t1 = [(X-Z)*coeff[2] + (X+Z)*coeff[1]]^2
sike_fp2sqr_mont(P->Z, P->Z); // Z = [(X-Z)*coeff[2] - (X+Z)*coeff[1]]^2
sike_fp2add(t1, t0, P->X); // X = coeff[0]*(X+Z)*(X-Z) + [(X-Z)*coeff[2] + (X+Z)*coeff[1]]^2
sike_fp2sub(P->Z, t0, t0); // t0 = [(X-Z)*coeff[2] - (X+Z)*coeff[1]]^2 - coeff[0]*(X+Z)*(X-Z)
sike_fp2mul_mont(P->X, t1, P->X); // Xfinal
sike_fp2mul_mont(P->Z, t0, P->Z); // Zfinal
}
void xTPL(const point_proj_t P, point_proj_t Q, const f2elm_t A24minus, const f2elm_t A24plus)
{ // Tripling of a Montgomery point in projective coordinates (X:Z).
// Input: projective Montgomery x-coordinates P = (X:Z), where x=X/Z and Montgomery curve constants A24plus = A+2C and A24minus = A-2C.
// Output: projective Montgomery x-coordinates Q = 3*P = (X3:Z3).
f2elm_t t0, t1, t2, t3, t4, t5, t6;
sike_fp2sub(P->X, P->Z, t0); // t0 = X-Z
sike_fp2sqr_mont(t0, t2); // t2 = (X-Z)^2
sike_fp2add(P->X, P->Z, t1); // t1 = X+Z
sike_fp2sqr_mont(t1, t3); // t3 = (X+Z)^2
sike_fp2add(t0, t1, t4); // t4 = 2*X
sike_fp2sub(t1, t0, t0); // t0 = 2*Z
sike_fp2sqr_mont(t4, t1); // t1 = 4*X^2
sike_fp2sub(t1, t3, t1); // t1 = 4*X^2 - (X+Z)^2
sike_fp2sub(t1, t2, t1); // t1 = 4*X^2 - (X+Z)^2 - (X-Z)^2
sike_fp2mul_mont(t3, A24plus, t5); // t5 = A24plus*(X+Z)^2
sike_fp2mul_mont(t3, t5, t3); // t3 = A24plus*(X+Z)^3
sike_fp2mul_mont(A24minus, t2, t6); // t6 = A24minus*(X-Z)^2
sike_fp2mul_mont(t2, t6, t2); // t2 = A24minus*(X-Z)^3
sike_fp2sub(t2, t3, t3); // t3 = A24minus*(X-Z)^3 - coeff*(X+Z)^3
sike_fp2sub(t5, t6, t2); // t2 = A24plus*(X+Z)^2 - A24minus*(X-Z)^2
sike_fp2mul_mont(t1, t2, t1); // t1 = [4*X^2 - (X+Z)^2 - (X-Z)^2]*[A24plus*(X+Z)^2 - A24minus*(X-Z)^2]
sike_fp2add(t3, t1, t2); // t2 = [4*X^2 - (X+Z)^2 - (X-Z)^2]*[A24plus*(X+Z)^2 - A24minus*(X-Z)^2] + A24minus*(X-Z)^3 - coeff*(X+Z)^3
sike_fp2sqr_mont(t2, t2); // t2 = t2^2
sike_fp2mul_mont(t4, t2, Q->X); // X3 = 2*X*t2
sike_fp2sub(t3, t1, t1); // t1 = A24minus*(X-Z)^3 - A24plus*(X+Z)^3 - [4*X^2 - (X+Z)^2 - (X-Z)^2]*[A24plus*(X+Z)^2 - A24minus*(X-Z)^2]
sike_fp2sqr_mont(t1, t1); // t1 = t1^2
sike_fp2mul_mont(t0, t1, Q->Z); // Z3 = 2*Z*t1
}
void xTPLe(const point_proj_t P, point_proj_t Q, const f2elm_t A24minus, const f2elm_t A24plus, size_t e)
{ // Computes [3^e](X:Z) on Montgomery curve with projective constant via e repeated triplings.
// Input: projective Montgomery x-coordinates P = (XP:ZP), such that xP=XP/ZP and Montgomery curve constants A24plus = A+2C and A24minus = A-2C.
// Output: projective Montgomery x-coordinates Q <- (3^e)*P.
memcpy(Q, P, sizeof(*P));
for (size_t i = 0; i < e; i++) {
xTPL(Q, Q, A24minus, A24plus);
}
}
void get_3_isog(const point_proj_t P, f2elm_t A24minus, f2elm_t A24plus, f2elm_t* coeff)
{ // Computes the corresponding 3-isogeny of a projective Montgomery point (X3:Z3) of order 3.
// Input: projective point of order three P = (X3:Z3).
// Output: the 3-isogenous Montgomery curve with projective coefficient A/C.
f2elm_t t0, t1, t2, t3, t4;
sike_fp2sub(P->X, P->Z, coeff[0]); // coeff0 = X-Z
sike_fp2sqr_mont(coeff[0], t0); // t0 = (X-Z)^2
sike_fp2add(P->X, P->Z, coeff[1]); // coeff1 = X+Z
sike_fp2sqr_mont(coeff[1], t1); // t1 = (X+Z)^2
sike_fp2add(t0, t1, t2); // t2 = (X+Z)^2 + (X-Z)^2
sike_fp2add(coeff[0], coeff[1], t3); // t3 = 2*X
sike_fp2sqr_mont(t3, t3); // t3 = 4*X^2
sike_fp2sub(t3, t2, t3); // t3 = 4*X^2 - (X+Z)^2 - (X-Z)^2
sike_fp2add(t1, t3, t2); // t2 = 4*X^2 - (X-Z)^2
sike_fp2add(t3, t0, t3); // t3 = 4*X^2 - (X+Z)^2
sike_fp2add(t0, t3, t4); // t4 = 4*X^2 - (X+Z)^2 + (X-Z)^2
sike_fp2add(t4, t4, t4); // t4 = 2(4*X^2 - (X+Z)^2 + (X-Z)^2)
sike_fp2add(t1, t4, t4); // t4 = 8*X^2 - (X+Z)^2 + 2*(X-Z)^2
sike_fp2mul_mont(t2, t4, A24minus); // A24minus = [4*X^2 - (X-Z)^2]*[8*X^2 - (X+Z)^2 + 2*(X-Z)^2]
sike_fp2add(t1, t2, t4); // t4 = 4*X^2 + (X+Z)^2 - (X-Z)^2
sike_fp2add(t4, t4, t4); // t4 = 2(4*X^2 + (X+Z)^2 - (X-Z)^2)
sike_fp2add(t0, t4, t4); // t4 = 8*X^2 + 2*(X+Z)^2 - (X-Z)^2
sike_fp2mul_mont(t3, t4, t4); // t4 = [4*X^2 - (X+Z)^2]*[8*X^2 + 2*(X+Z)^2 - (X-Z)^2]
sike_fp2sub(t4, A24minus, t0); // t0 = [4*X^2 - (X+Z)^2]*[8*X^2 + 2*(X+Z)^2 - (X-Z)^2] - [4*X^2 - (X-Z)^2]*[8*X^2 - (X+Z)^2 + 2*(X-Z)^2]
sike_fp2add(A24minus, t0, A24plus); // A24plus = 8*X^2 - (X+Z)^2 + 2*(X-Z)^2
}
void eval_3_isog(point_proj_t Q, f2elm_t* coeff)
{ // Computes the 3-isogeny R=phi(X:Z), given projective point (X3:Z3) of order 3 on a Montgomery curve and
// a point P with 2 coefficients in coeff (computed in the function get_3_isog()).
// Inputs: projective points P = (X3:Z3) and Q = (X:Z).
// Output: the projective point Q <- phi(Q) = (X3:Z3).
f2elm_t t0, t1, t2;
sike_fp2add(Q->X, Q->Z, t0); // t0 = X+Z
sike_fp2sub(Q->X, Q->Z, t1); // t1 = X-Z
sike_fp2mul_mont(t0, coeff[0], t0); // t0 = coeff0*(X+Z)
sike_fp2mul_mont(t1, coeff[1], t1); // t1 = coeff1*(X-Z)
sike_fp2add(t0, t1, t2); // t2 = coeff0*(X+Z) + coeff1*(X-Z)
sike_fp2sub(t1, t0, t0); // t0 = coeff1*(X-Z) - coeff0*(X+Z)
sike_fp2sqr_mont(t2, t2); // t2 = [coeff0*(X+Z) + coeff1*(X-Z)]^2
sike_fp2sqr_mont(t0, t0); // t0 = [coeff1*(X-Z) - coeff0*(X+Z)]^2
sike_fp2mul_mont(Q->X, t2, Q->X); // X3final = X*[coeff0*(X+Z) + coeff1*(X-Z)]^2
sike_fp2mul_mont(Q->Z, t0, Q->Z); // Z3final = Z*[coeff1*(X-Z) - coeff0*(X+Z)]^2
}
void inv_3_way(f2elm_t z1, f2elm_t z2, f2elm_t z3)
{ // 3-way simultaneous inversion
// Input: z1,z2,z3
// Output: 1/z1,1/z2,1/z3 (override inputs).
f2elm_t t0, t1, t2, t3;
sike_fp2mul_mont(z1, z2, t0); // t0 = z1*z2
sike_fp2mul_mont(z3, t0, t1); // t1 = z1*z2*z3
sike_fp2inv_mont(t1); // t1 = 1/(z1*z2*z3)
sike_fp2mul_mont(z3, t1, t2); // t2 = 1/(z1*z2)
sike_fp2mul_mont(t2, z2, t3); // t3 = 1/z1
sike_fp2mul_mont(t2, z1, z2); // z2 = 1/z2
sike_fp2mul_mont(t0, t1, z3); // z3 = 1/z3
sike_fp2copy(t3, z1); // z1 = 1/z1
}
void get_A(const f2elm_t xP, const f2elm_t xQ, const f2elm_t xR, f2elm_t A)
{ // Given the x-coordinates of P, Q, and R, returns the value A corresponding to the Montgomery curve E_A: y^2=x^3+A*x^2+x such that R=Q-P on E_A.
// Input: the x-coordinates xP, xQ, and xR of the points P, Q and R.
// Output: the coefficient A corresponding to the curve E_A: y^2=x^3+A*x^2+x.
f2elm_t t0, t1, one = F2ELM_INIT;
extern const struct params_t p503;
sike_fpcopy((crypto_word_t*)&p503.mont_one, one->c0);
sike_fp2add(xP, xQ, t1); // t1 = xP+xQ
sike_fp2mul_mont(xP, xQ, t0); // t0 = xP*xQ
sike_fp2mul_mont(xR, t1, A); // A = xR*t1
sike_fp2add(t0, A, A); // A = A+t0
sike_fp2mul_mont(t0, xR, t0); // t0 = t0*xR
sike_fp2sub(A, one, A); // A = A-1
sike_fp2add(t0, t0, t0); // t0 = t0+t0
sike_fp2add(t1, xR, t1); // t1 = t1+xR
sike_fp2add(t0, t0, t0); // t0 = t0+t0
sike_fp2sqr_mont(A, A); // A = A^2
sike_fp2inv_mont(t0); // t0 = 1/t0
sike_fp2mul_mont(A, t0, A); // A = A*t0
sike_fp2sub(A, t1, A); // Afinal = A-t1
}
void j_inv(const f2elm_t A, const f2elm_t C, f2elm_t jinv)
{ // Computes the j-invariant of a Montgomery curve with projective constant.
// Input: A,C in GF(p^2).
// Output: j=256*(A^2-3*C^2)^3/(C^4*(A^2-4*C^2)), which is the j-invariant of the Montgomery curve B*y^2=x^3+(A/C)*x^2+x or (equivalently) j-invariant of B'*y^2=C*x^3+A*x^2+C*x.
f2elm_t t0, t1;
sike_fp2sqr_mont(A, jinv); // jinv = A^2
sike_fp2sqr_mont(C, t1); // t1 = C^2
sike_fp2add(t1, t1, t0); // t0 = t1+t1
sike_fp2sub(jinv, t0, t0); // t0 = jinv-t0
sike_fp2sub(t0, t1, t0); // t0 = t0-t1
sike_fp2sub(t0, t1, jinv); // jinv = t0-t1
sike_fp2sqr_mont(t1, t1); // t1 = t1^2
sike_fp2mul_mont(jinv, t1, jinv); // jinv = jinv*t1
sike_fp2add(t0, t0, t0); // t0 = t0+t0
sike_fp2add(t0, t0, t0); // t0 = t0+t0
sike_fp2sqr_mont(t0, t1); // t1 = t0^2
sike_fp2mul_mont(t0, t1, t0); // t0 = t0*t1
sike_fp2add(t0, t0, t0); // t0 = t0+t0
sike_fp2add(t0, t0, t0); // t0 = t0+t0
sike_fp2inv_mont(jinv); // jinv = 1/jinv
sike_fp2mul_mont(jinv, t0, jinv); // jinv = t0*jinv
}
void xDBLADD(point_proj_t P, point_proj_t Q, const f2elm_t xPQ, const f2elm_t A24)
{ // Simultaneous doubling and differential addition.
// Input: projective Montgomery points P=(XP:ZP) and Q=(XQ:ZQ) such that xP=XP/ZP and xQ=XQ/ZQ, affine difference xPQ=x(P-Q) and Montgomery curve constant A24=(A+2)/4.
// Output: projective Montgomery points P <- 2*P = (X2P:Z2P) such that x(2P)=X2P/Z2P, and Q <- P+Q = (XQP:ZQP) such that = x(Q+P)=XQP/ZQP.
f2elm_t t0, t1, t2;
sike_fp2add(P->X, P->Z, t0); // t0 = XP+ZP
sike_fp2sub(P->X, P->Z, t1); // t1 = XP-ZP
sike_fp2sqr_mont(t0, P->X); // XP = (XP+ZP)^2
sike_fp2sub(Q->X, Q->Z, t2); // t2 = XQ-ZQ
sike_fp2correction(t2);
sike_fp2add(Q->X, Q->Z, Q->X); // XQ = XQ+ZQ
sike_fp2mul_mont(t0, t2, t0); // t0 = (XP+ZP)*(XQ-ZQ)
sike_fp2sqr_mont(t1, P->Z); // ZP = (XP-ZP)^2
sike_fp2mul_mont(t1, Q->X, t1); // t1 = (XP-ZP)*(XQ+ZQ)
sike_fp2sub(P->X, P->Z, t2); // t2 = (XP+ZP)^2-(XP-ZP)^2
sike_fp2mul_mont(P->X, P->Z, P->X); // XP = (XP+ZP)^2*(XP-ZP)^2
sike_fp2mul_mont(t2, A24, Q->X); // XQ = A24*[(XP+ZP)^2-(XP-ZP)^2]
sike_fp2sub(t0, t1, Q->Z); // ZQ = (XP+ZP)*(XQ-ZQ)-(XP-ZP)*(XQ+ZQ)
sike_fp2add(Q->X, P->Z, P->Z); // ZP = A24*[(XP+ZP)^2-(XP-ZP)^2]+(XP-ZP)^2
sike_fp2add(t0, t1, Q->X); // XQ = (XP+ZP)*(XQ-ZQ)+(XP-ZP)*(XQ+ZQ)
sike_fp2mul_mont(P->Z, t2, P->Z); // ZP = [A24*[(XP+ZP)^2-(XP-ZP)^2]+(XP-ZP)^2]*[(XP+ZP)^2-(XP-ZP)^2]
sike_fp2sqr_mont(Q->Z, Q->Z); // ZQ = [(XP+ZP)*(XQ-ZQ)-(XP-ZP)*(XQ+ZQ)]^2
sike_fp2sqr_mont(Q->X, Q->X); // XQ = [(XP+ZP)*(XQ-ZQ)+(XP-ZP)*(XQ+ZQ)]^2
sike_fp2mul_mont(Q->Z, xPQ, Q->Z); // ZQ = xPQ*[(XP+ZP)*(XQ-ZQ)-(XP-ZP)*(XQ+ZQ)]^2
}
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