;;
;; Copyright (c) 2021-2024, Intel Corporation
;;
;; Redistribution and use in source and binary forms, with or without
;; modification, are permitted provided that the following conditions are met:
;;
;;     * Redistributions of source code must retain the above copyright notice,
;;       this list of conditions and the following disclaimer.
;;     * Redistributions in binary form must reproduce the above copyright
;;       notice, this list of conditions and the following disclaimer in the
;;       documentation and/or other materials provided with the distribution.
;;     * Neither the name of Intel Corporation nor the names of its contributors
;;       may be used to endorse or promote products derived from this software
;;       without specific prior written permission.
;;
;; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
;; AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
;; IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
;; DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
;; FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
;; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
;; SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
;; CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
;; OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
;; OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
;;

;;  Implementation based on
;; Patrik Ekdahl1, Thomas Johansson2, Alexander Maximov1 and Jing Yang2
;; abstract : 'A new SNOW stream cipher called SNOW-V'
;; https://eprint.iacr.org/2018/1143.pdf

%include "include/os.inc"
%include "include/reg_sizes.inc"
%include "include/memcpy.inc"
%include "include/imb_job.inc"
%include "include/clear_regs.inc"
%include "include/cet.inc"

%ifndef SNOW_V
%define SNOW_V snow_v_sse
%endif

%ifndef SNOW_V_AEAD_INIT
%define SNOW_V_AEAD_INIT snow_v_aead_init_sse
%endif

mksection .rodata

align 16
alpha:
times 8 dw 0x990f

align 16
alpha_inv:
times 8 dw -0xcc87

align 16
beta:
times 8 dw 0xc963

align 16
beta_inv:
times 8 dw -0xe4b1

;; permutation: [ 0, 4, 8, 12, 1, 5, 9, 13, 2, 6, 10, 14, 3, 7, 11, 15 ]
align 16
sigma:
dq 0xd0905010c080400
dq 0xf0b07030e0a0602

align 16
aead_lsfr_b_lo:
dq 0x20646b4578656c41
dq 0x6d6f6854676E694a

%ifdef LINUX
        %define arg1      rdi
        %define offset    rcx
%else
        %define arg1      rcx
        %define offset    r8
%endif

%define job     arg1

;; stack frame for saving registers (windows only)
struc STACK
_xmm_save:      resq    10 * 2  ; space for 10 xmm registers
_rsp_save:      resq    1       ; space for rsp pointer
endstruc

mksection .text

;; Registers usage
;; xmm0, xmm1, xmm2, xmm3   : temporary space
;; xmm4                     : generated keystream
;; xmm5, xmm6, xmm7         : FSM (R1, R2, R3)
;; xmm8, xmm9, xmm10, xmm11 : LFSR_A, LFSR_B
;; xmm13, xmm14, xmm15      : constants gA, gB, inv_gA

%define gA      xmm13
%define gB      xmm14
%define inv_gA  xmm15

%define FSM_R1  xmm5
%define FSM_R2  xmm6
%define FSM_R3  xmm7

%define LFSR_A_LDQ      xmm8   ;; LSFR A: (a7, ..., a0)
%define LFSR_A_HDQ      xmm9   ;; LSFR A: (a15, ..., a8)
%define LFSR_B_LDQ      xmm10  ;; LSFR B: (b7, ..., b0)
%define LFSR_B_HDQ      xmm11  ;; LSFR B: (b15, ..., b8)

%define temp4   xmm12

;; =============================================================================
;; =============================================================================
;; Calculate 128-bit keystream
;; =============================================================================
%macro SNOW_V_KEYSTREAM 4

;; all input is expected to be xmm registers
%define %%KEYSTREAM   %1  ;; [out]  128 bit keystream
%define %%LFSR_B_HDQ  %2  ;; [in]  128 bit LFSR_B_HDQ (b15, ..., b8)
%define %%FSM_R1      %3  ;; [in]  128 bit FSM: R1
%define %%FSM_R2      %4  ;; [in]  128 bit FSM: R2

        movdqa  %%KEYSTREAM, %%LFSR_B_HDQ
        paddd   %%KEYSTREAM, %%FSM_R1
        pxor    %%KEYSTREAM, %%FSM_R2

%endmacro ;; SNOW_V_KEYSTREAM

;; =============================================================================
;; =============================================================================
;; Update SNOW_V FSM
;; =============================================================================
%macro SNOW_V_FSM_UPDATE 5

;; this macro needs defined constant sigma
;; all input is expected to be xmm registers

%define %%FSM_R1      %1  ;; [in/out]  128 bit FSM: R1
%define %%FSM_R2      %2  ;; [in/out]  128 bit FSM: R2
%define %%FSM_R3      %3  ;; [in/out]  128 bit FSM: R3
%define %%T2          %4  ;; [in/clobbered] 128 bit T2 tap register
                          ;; containing copy of LFSR_A_LDQ (a7, ..., a0)
%define %%TEMP1       %5  ;; [clobbered] 128 bit register

        pxor    %%T2, %%FSM_R3         ;; T2 = R3 XOR LSFR_A [0:7]
        paddd   %%T2, %%FSM_R2         ;; T2 += R2
        pshufb  %%T2, [rel sigma]      ;; T2 = sigma(T2)

        movdqa  %%FSM_R3, %%FSM_R2     ;; R3 = R2
        movdqa  %%FSM_R2, %%FSM_R1     ;; R2 = R1
        pxor    %%TEMP1, %%TEMP1       ;; TEMP1 = 0

        movdqa  %%FSM_R1, %%T2         ;; R1 = sigma(T2)
        aesenc  %%FSM_R3, %%TEMP1      ;; R3 = AESR(R2) (encryption round key C1 = 0)
        aesenc  %%FSM_R2, %%TEMP1      ;; R2 = AESR(R1) (encryption round key C2 = 0)

%endmacro ;; SNOW_V_FSM_UPDATE

;; =============================================================================
;; =============================================================================
;; Update SNOW_V LSFR
;; =============================================================================
%macro SNOW_V_LFSR_UPDATE 11

;; this macro needs defined constant beta_inv
;; all input is expected to be xmm registers

%define %%LFSR_A_LDQ     %1   ;; [in/out]    128 bit LFSR_A_LDQ (a7, ..., a0)
%define %%LFSR_A_HDQ     %2   ;; [in/out]    128 bit LFSR_A_HDQ (a15, ..., a8)
%define %%LFSR_B_LDQ     %3   ;; [in/out]    128 bit LFSR_B_LDQ (b7, ..., b0)
%define %%LFSR_B_HDQ     %4   ;; [in/out]    128 bit LFSR_B_HDQ (b15, ..., b8)
%define %%T1             %5   ;; [in/out]    128 bit T1 tap register
%define %%T2             %6   ;; [out]       128 bit T2 tap register
%define %%TEMP1          %7   ;; [clobbered] 128 bit register
%define %%TEMP2          %8   ;; [clobbered] 128 bit register
%define %%gA             %9   ;; [in]        128 bit gA
%define %%gB             %10  ;; [in]        128 bit gB
%define %%inv_gA         %11  ;; [in]        128 bit inv_gA

;; LSFR Update
;; for i in [0,7]:
;;    tmpa_i = alpha*a_i + alpha^-1*a_(i+8) + b_i + a_(i+1) mod g^A(alpha)
;;    tmpb_i =  beta*b_i +  beta^−1*b_(i+8) + a_i + b_(i+3) mod g^ B(β)
;;
;; (a15, a14, ..., a0) = (tmpa_7, ..., tmpa_0, a15, ..., a8)
;; (b15, b14, ..., b0) = (tmpb_7, ..., tmpb_0, b15, ..., b8)
;;
;; alpha*x      = (x<<1) xor ((x >> 15) and gA)
;;
;; (alpha^-1)*x = if (x & 0x0001): (x >> 1) xor [inv_gA]
;;                else:            (x >> 1)
;;              = (x >> 1) xor signw(inv_gA, x << 15)

        ;; calculate mulx_A = (alpha*a7, ..., alpha*a0)
        movdqa  %%TEMP1, %%LFSR_A_LDQ
        psraw   %%TEMP1, 15             ;; 16-bit mask with sign bits preserved
        pand    %%TEMP1, %%gA
        movdqa  %%TEMP2, %%LFSR_A_LDQ
        psllw   %%TEMP2, 1
        pxor    %%TEMP2, %%TEMP1        ;; TEMP2 = mulx_A

        ;; calculate invx_A = (alpha^-1*a15, ..., alpha^-1*a8)
        movdqa  %%TEMP1, %%LFSR_A_HDQ
        psllw   %%TEMP1, 15
        movdqa  %%T2, %%inv_gA
        psignw  %%T2, %%TEMP1           ;; negate bits in inv_gA depending on LFSR_A_HDQ << 15
        movdqa  %%TEMP1, %%LFSR_A_HDQ
        psrlw   %%TEMP1, 1
        pxor    %%TEMP1, %%T2           ;; TEMP1 = invx_A

        movdqa  %%T2, %%LFSR_A_HDQ      ;; make copy of LFSR_A_HDQ

        ;; LFSR_A_HDQ = mulx_A XOR invx_A XOR (b7, ..., b0) XOR (a8, ..., a1)
        pxor    %%TEMP1, %%TEMP2               ;; TEMP1 = invx_A xor mulx_A
        palignr %%LFSR_A_HDQ, %%LFSR_A_LDQ, 2  ;; T2 = (tmpa_8, ..., tmpa_1)
        pxor    %%LFSR_A_HDQ, %%LFSR_B_LDQ
        pxor    %%LFSR_A_HDQ, %%TEMP1

        ;; calculate mulx_B
        movdqa  %%TEMP1, %%LFSR_B_LDQ
        psraw   %%TEMP1, 15
        pand    %%TEMP1, %%gB
        movdqa  %%TEMP2, %%LFSR_B_LDQ
        psllw   %%TEMP2, 1
        pxor    %%TEMP1, %%TEMP2

        ;; T1 = mulx_B XOR (a7, ..., a0) XOR (b10, ..., b3)
        pxor    %%TEMP1, %%LFSR_A_LDQ
        palignr %%T1, %%LFSR_B_LDQ, 6    ;; (b10, ..., b3)
        pxor    %%T1, %%TEMP1

        ;; calculate invx_B
        movdqa  %%TEMP1, %%LFSR_B_HDQ
        psllw   %%TEMP1, 15
        movdqa  %%TEMP2, [rel beta_inv]
        psignw  %%TEMP2, %%TEMP1
        movdqa  %%TEMP1, %%LFSR_B_HDQ
        psrlw   %%TEMP1, 1
        pxor    %%TEMP1, %%TEMP2

        ;; LFSR_B_HDQ = mulx_B XOR invx_B XOR (a7, ..., a0) XOR (b10, ..., b3)
        pxor     %%T1, %%TEMP1

        movdqa  %%LFSR_B_LDQ, %%LFSR_B_HDQ   ;; LFSR_B_LDQ = LFSR_B_HDQ
        movdqa  %%LFSR_A_LDQ, %%T2           ;; LFSR_A_LDQ = LFSR_A_HDQ
        movdqa  %%LFSR_B_HDQ, %%T1

%endmacro ;; SNOW_V_LFSR_UPDATE

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

%macro FUNC_START 0
%ifidn __OUTPUT_FORMAT__, win64
        ; xmm6:xmm15 need to be maintained for Windows
        mov     rax, rsp
        sub     rsp, STACK_size
        and     rsp, -16
        mov     [rsp + _rsp_save], rax
        movdqa  [rsp + _xmm_save + 0*16], xmm6
        movdqa  [rsp + _xmm_save + 1*16], xmm7
        movdqa  [rsp + _xmm_save + 2*16], xmm8
        movdqa  [rsp + _xmm_save + 3*16], xmm9
        movdqa  [rsp + _xmm_save + 4*16], xmm10
        movdqa  [rsp + _xmm_save + 5*16], xmm11
        movdqa  [rsp + _xmm_save + 6*16], xmm12
        movdqa  [rsp + _xmm_save + 7*16], xmm13
        movdqa  [rsp + _xmm_save + 8*16], xmm14
        movdqa  [rsp + _xmm_save + 9*16], xmm15
%endif
%endmacro

%macro FUNC_END 0
%ifidn __OUTPUT_FORMAT__, win64
        movdqa  xmm6, [rsp + _xmm_save + 0*16]
        movdqa  xmm7, [rsp + _xmm_save + 1*16]
        movdqa  xmm8, [rsp + _xmm_save + 2*16]
        movdqa  xmm9, [rsp + _xmm_save + 3*16]
        movdqa  xmm10, [rsp + _xmm_save + 4*16]
        movdqa  xmm11, [rsp + _xmm_save + 5*16]
        movdqa  xmm12, [rsp + _xmm_save + 6*16]
        movdqa  xmm13, [rsp + _xmm_save + 7*16]
        movdqa  xmm14, [rsp + _xmm_save + 8*16]
        movdqa  xmm15, [rsp + _xmm_save + 9*16]
        mov     rsp, [rsp + _rsp_save]
%endif
%endmacro

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

MKGLOBAL(SNOW_V_AEAD_INIT,function,)
SNOW_V_AEAD_INIT:
        endbranch64
        FUNC_START
        ;; use offset to indicate AEAD mode
        mov     DWORD(offset), 1
        movdqa  LFSR_B_LDQ, [rel aead_lsfr_b_lo]
        jmp     snow_v_common_init

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

MKGLOBAL(SNOW_V,function,)
SNOW_V:
        endbranch64
        FUNC_START
        ;; use offset to indicate AEAD mode
        xor     DWORD(offset), DWORD(offset)
        pxor    LFSR_B_LDQ, LFSR_B_LDQ

snow_v_common_init:

        ;; Init LSFR
        mov     rax, [job + _enc_keys]
        movdqu  LFSR_A_HDQ, [rax]
        movdqu  LFSR_B_HDQ, [rax + 16]
        mov     rax, [job + _iv]
        movdqu  LFSR_A_LDQ, [rax]

        ;; Init FSM: R1 = R2 = R3 = 0
        pxor    FSM_R1, FSM_R1
        pxor    FSM_R2, FSM_R2
        pxor    FSM_R3, FSM_R3

        movdqa  gA, [rel alpha]
        movdqa  gB, [rel beta]
        movdqa  inv_gA, [rel alpha_inv]

        movdqa  xmm0, LFSR_B_HDQ ;; init T1 for LSFR update
        movdqa  xmm1, LFSR_A_LDQ ;; init T2 for FSM update

        mov     eax, 15

 init_fsm_lfsr_loop:

        SNOW_V_KEYSTREAM xmm4, LFSR_B_HDQ, FSM_R1, FSM_R2
        SNOW_V_FSM_UPDATE FSM_R1, FSM_R2, FSM_R3, xmm1, xmm2
        SNOW_V_LFSR_UPDATE LFSR_A_LDQ, LFSR_A_HDQ, LFSR_B_LDQ, LFSR_B_HDQ, \
                         xmm0, xmm1, xmm2, xmm3, gA, gB, inv_gA
        pxor    LFSR_A_HDQ, xmm4
        dec     eax
        jnz     init_fsm_lfsr_loop

        mov     rax, [job + _enc_keys]
        movdqu  temp4, [rax]
        pxor    FSM_R1, temp4

        SNOW_V_KEYSTREAM xmm4, LFSR_B_HDQ, FSM_R1, FSM_R2
        SNOW_V_FSM_UPDATE FSM_R1, FSM_R2, FSM_R3, xmm1, xmm2
        SNOW_V_LFSR_UPDATE LFSR_A_LDQ, LFSR_A_HDQ,LFSR_B_LDQ, LFSR_B_HDQ, \
                         xmm0, xmm1, xmm2, xmm3, gA, gB, inv_gA
        pxor    LFSR_A_HDQ, xmm4
        movdqu  temp4, [rax + 16]
        pxor    FSM_R1, temp4

        ;; At this point FSM and LSFR are initialized

        or      DWORD(offset), DWORD(offset)
        jz      no_aead

        ;; in AEAD mode hkey = keystream_0 and endpad = keystream_1
        mov     r11, [job + _snow_v_reserved]
        ;; generate hkey
        SNOW_V_KEYSTREAM xmm4, LFSR_B_HDQ, FSM_R1, FSM_R2
        movdqu  [r11], xmm4

        ;; generate endpad
        SNOW_V_FSM_UPDATE FSM_R1, FSM_R2, FSM_R3, xmm1, xmm2
        SNOW_V_LFSR_UPDATE LFSR_A_LDQ, LFSR_A_HDQ,LFSR_B_LDQ, LFSR_B_HDQ, \
                         xmm0, xmm1, xmm2, xmm3, gA, gB, inv_gA
        SNOW_V_KEYSTREAM xmm4, LFSR_B_HDQ, FSM_R1, FSM_R2

        SNOW_V_FSM_UPDATE FSM_R1, FSM_R2, FSM_R3, xmm1, xmm2
        SNOW_V_LFSR_UPDATE LFSR_A_LDQ, LFSR_A_HDQ,LFSR_B_LDQ, LFSR_B_HDQ, \
                         xmm0, xmm1, xmm2, xmm3, gA, gB, inv_gA

        mov offset, [r11 + 24]
        movdqu [r11 + 16], xmm4
        or offset, offset
        ;; if last 8 bytes endpad are not 0 skip encrypt/decrypt operation
        ;; option used to calculate auth tag for decrypt and not overwrite
        ;; cipher by plain when the same src/dst pointer is used
        jnz no_partial_block_left

no_aead:

        ;; Process input
        mov r10, [job + _src]
        add r10, [job + _cipher_start_src_offset_in_bytes]
        mov r11, [job + _dst]
        mov rax, [job + _msg_len_to_cipher_in_bytes]
        xor offset, offset
        ;; deal with partial block less than 16b outside main loop
        and rax, 0xfffffffffffffff0
        jz final_bytes

encrypt_loop:

        movdqu temp4, [r10 + offset]

        SNOW_V_KEYSTREAM xmm4, LFSR_B_HDQ, FSM_R1, FSM_R2

        SNOW_V_FSM_UPDATE FSM_R1, FSM_R2, FSM_R3, xmm1, xmm2

        SNOW_V_LFSR_UPDATE LFSR_A_LDQ, LFSR_A_HDQ,LFSR_B_LDQ, LFSR_B_HDQ, \
                         xmm0, xmm1, xmm2, xmm3, gA, gB, inv_gA

        pxor   temp4, xmm4
        movdqu [r11 + offset], temp4
        add    offset, 16
        sub    rax, 16
        jnz    encrypt_loop

final_bytes:
        mov rax, [job + _msg_len_to_cipher_in_bytes]
        and rax, 0xf
        jz no_partial_block_left

        ;; load partial block into XMM register
        add    r10, offset
        simd_load_sse_15_1 temp4, r10, rax
        SNOW_V_KEYSTREAM xmm4, LFSR_B_HDQ, FSM_R1, FSM_R2
        pxor   temp4, xmm4
        add    r11, offset
        ;; use r10 and offset as temp [clobbered]
        simd_store_sse_15 r11, temp4, rax, r10, offset

no_partial_block_left:
        ;; Clear registers and return data
%ifdef SAFE_DATA
        clear_scratch_xmms_sse_asm
%endif

        mov   rax, job
        or    dword [rax + _status], IMB_STATUS_COMPLETED_CIPHER
        FUNC_END
        ret

mksection stack-noexec
