/* * ChaCha20 256-bit cipher algorithm, RFC7539, x64 SSSE3 functions * * Copyright (C) 2015 Martin Willi * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. */ #include .section .rodata.cst16.ROT8, "aM", @progbits, 16 .align 16 ROT8: .octa 0x0e0d0c0f0a09080b0605040702010003 .section .rodata.cst16.ROT16, "aM", @progbits, 16 .align 16 ROT16: .octa 0x0d0c0f0e09080b0a0504070601000302 .section .rodata.cst16.CTRINC, "aM", @progbits, 16 .align 16 CTRINC: .octa 0x00000003000000020000000100000000 .text ENTRY(chacha20_block_xor_ssse3) # %rdi: Input state matrix, s # %rsi: 1 data block output, o # %rdx: 1 data block input, i # This function encrypts one ChaCha20 block by loading the state matrix # in four SSE registers. It performs matrix operation on four words in # parallel, but requireds shuffling to rearrange the words after each # round. 8/16-bit word rotation is done with the slightly better # performing SSSE3 byte shuffling, 7/12-bit word rotation uses # traditional shift+OR. # x0..3 = s0..3 movdqa 0x00(%rdi),%xmm0 movdqa 0x10(%rdi),%xmm1 movdqa 0x20(%rdi),%xmm2 movdqa 0x30(%rdi),%xmm3 movdqa %xmm0,%xmm8 movdqa %xmm1,%xmm9 movdqa %xmm2,%xmm10 movdqa %xmm3,%xmm11 movdqa ROT8(%rip),%xmm4 movdqa ROT16(%rip),%xmm5 mov $10,%ecx .Ldoubleround: # x0 += x1, x3 = rotl32(x3 ^ x0, 16) paddd %xmm1,%xmm0 pxor %xmm0,%xmm3 pshufb %xmm5,%xmm3 # x2 += x3, x1 = rotl32(x1 ^ x2, 12) paddd %xmm3,%xmm2 pxor %xmm2,%xmm1 movdqa %xmm1,%xmm6 pslld $12,%xmm6 psrld $20,%xmm1 por %xmm6,%xmm1 # x0 += x1, x3 = rotl32(x3 ^ x0, 8) paddd %xmm1,%xmm0 pxor %xmm0,%xmm3 pshufb %xmm4,%xmm3 # x2 += x3, x1 = rotl32(x1 ^ x2, 7) paddd %xmm3,%xmm2 pxor %xmm2,%xmm1 movdqa %xmm1,%xmm7 pslld $7,%xmm7 psrld $25,%xmm1 por %xmm7,%xmm1 # x1 = shuffle32(x1, MASK(0, 3, 2, 1)) pshufd $0x39,%xmm1,%xmm1 # x2 = shuffle32(x2, MASK(1, 0, 3, 2)) pshufd $0x4e,%xmm2,%xmm2 # x3 = shuffle32(x3, MASK(2, 1, 0, 3)) pshufd $0x93,%xmm3,%xmm3 # x0 += x1, x3 = rotl32(x3 ^ x0, 16) paddd %xmm1,%xmm0 pxor %xmm0,%xmm3 pshufb %xmm5,%xmm3 # x2 += x3, x1 = rotl32(x1 ^ x2, 12) paddd %xmm3,%xmm2 pxor %xmm2,%xmm1 movdqa %xmm1,%xmm6 pslld $12,%xmm6 psrld $20,%xmm1 por %xmm6,%xmm1 # x0 += x1, x3 = rotl32(x3 ^ x0, 8) paddd %xmm1,%xmm0 pxor %xmm0,%xmm3 pshufb %xmm4,%xmm3 # x2 += x3, x1 = rotl32(x1 ^ x2, 7) paddd %xmm3,%xmm2 pxor %xmm2,%xmm1 movdqa %xmm1,%xmm7 pslld $7,%xmm7 psrld $25,%xmm1 por %xmm7,%xmm1 # x1 = shuffle32(x1, MASK(2, 1, 0, 3)) pshufd $0x93,%xmm1,%xmm1 # x2 = shuffle32(x2, MASK(1, 0, 3, 2)) pshufd $0x4e,%xmm2,%xmm2 # x3 = shuffle32(x3, MASK(0, 3, 2, 1)) pshufd $0x39,%xmm3,%xmm3 dec %ecx jnz .Ldoubleround # o0 = i0 ^ (x0 + s0) movdqu 0x00(%rdx),%xmm4 paddd %xmm8,%xmm0 pxor %xmm4,%xmm0 movdqu %xmm0,0x00(%rsi) # o1 = i1 ^ (x1 + s1) movdqu 0x10(%rdx),%xmm5 paddd %xmm9,%xmm1 pxor %xmm5,%xmm1 movdqu %xmm1,0x10(%rsi) # o2 = i2 ^ (x2 + s2) movdqu 0x20(%rdx),%xmm6 paddd %xmm10,%xmm2 pxor %xmm6,%xmm2 movdqu %xmm2,0x20(%rsi) # o3 = i3 ^ (x3 + s3) movdqu 0x30(%rdx),%xmm7 paddd %xmm11,%xmm3 pxor %xmm7,%xmm3 movdqu %xmm3,0x30(%rsi) ret ENDPROC(chacha20_block_xor_ssse3) ENTRY(chacha20_4block_xor_ssse3) # %rdi: Input state matrix, s # %rsi: 4 data blocks output, o # %rdx: 4 data blocks input, i # This function encrypts four consecutive ChaCha20 blocks by loading the # the state matrix in SSE registers four times. As we need some scratch # registers, we save the first four registers on the stack. The # algorithm performs each operation on the corresponding word of each # state matrix, hence requires no word shuffling. For final XORing step # we transpose the matrix by interleaving 32- and then 64-bit words, # which allows us to do XOR in SSE registers. 8/16-bit word rotation is # done with the slightly better performing SSSE3 byte shuffling, # 7/12-bit word rotation uses traditional shift+OR. lea 8(%rsp),%r10 sub $0x80,%rsp and $~63,%rsp # x0..15[0-3] = s0..3[0..3] movq 0x00(%rdi),%xmm1 pshufd $0x00,%xmm1,%xmm0 pshufd $0x55,%xmm1,%xmm1 movq 0x08(%rdi),%xmm3 pshufd $0x00,%xmm3,%xmm2 pshufd $0x55,%xmm3,%xmm3 movq 0x10(%rdi),%xmm5 pshufd $0x00,%xmm5,%xmm4 pshufd $0x55,%xmm5,%xmm5 movq 0x18(%rdi),%xmm7 pshufd $0x00,%xmm7,%xmm6 pshufd $0x55,%xmm7,%xmm7 movq 0x20(%rdi),%xmm9 pshufd $0x00,%xmm9,%xmm8 pshufd $0x55,%xmm9,%xmm9 movq 0x28(%rdi),%xmm11 pshufd $0x00,%xmm11,%xmm10 pshufd $0x55,%xmm11,%xmm11 movq 0x30(%rdi),%xmm13 pshufd $0x00,%xmm13,%xmm12 pshufd $0x55,%xmm13,%xmm13 movq 0x38(%rdi),%xmm15 pshufd $0x00,%xmm15,%xmm14 pshufd $0x55,%xmm15,%xmm15 # x0..3 on stack movdqa %xmm0,0x00(%rsp) movdqa %xmm1,0x10(%rsp) movdqa %xmm2,0x20(%rsp) movdqa %xmm3,0x30(%rsp) movdqa CTRINC(%rip),%xmm1 movdqa ROT8(%rip),%xmm2 movdqa ROT16(%rip),%xmm3 # x12 += counter values 0-3 paddd %xmm1,%xmm12 mov $10,%ecx .Ldoubleround4: # x0 += x4, x12 = rotl32(x12 ^ x0, 16) movdqa 0x00(%rsp),%xmm0 paddd %xmm4,%xmm0 movdqa %xmm0,0x00(%rsp) pxor %xmm0,%xmm12 pshufb %xmm3,%xmm12 # x1 += x5, x13 = rotl32(x13 ^ x1, 16) movdqa 0x10(%rsp),%xmm0 paddd %xmm5,%xmm0 movdqa %xmm0,0x10(%rsp) pxor %xmm0,%xmm13 pshufb %xmm3,%xmm13 # x2 += x6, x14 = rotl32(x14 ^ x2, 16) movdqa 0x20(%rsp),%xmm0 paddd %xmm6,%xmm0 movdqa %xmm0,0x20(%rsp) pxor %xmm0,%xmm14 pshufb %xmm3,%xmm14 # x3 += x7, x15 = rotl32(x15 ^ x3, 16) movdqa 0x30(%rsp),%xmm0 paddd %xmm7,%xmm0 movdqa %xmm0,0x30(%rsp) pxor %xmm0,%xmm15 pshufb %xmm3,%xmm15 # x8 += x12, x4 = rotl32(x4 ^ x8, 12) paddd %xmm12,%xmm8 pxor %xmm8,%xmm4 movdqa %xmm4,%xmm0 pslld $12,%xmm0 psrld $20,%xmm4 por %xmm0,%xmm4 # x9 += x13, x5 = rotl32(x5 ^ x9, 12) paddd %xmm13,%xmm9 pxor %xmm9,%xmm5 movdqa %xmm5,%xmm0 pslld $12,%xmm0 psrld $20,%xmm5 por %xmm0,%xmm5 # x10 += x14, x6 = rotl32(x6 ^ x10, 12) paddd %xmm14,%xmm10 pxor %xmm10,%xmm6 movdqa %xmm6,%xmm0 pslld $12,%xmm0 psrld $20,%xmm6 por %xmm0,%xmm6 # x11 += x15, x7 = rotl32(x7 ^ x11, 12) paddd %xmm15,%xmm11 pxor %xmm11,%xmm7 movdqa %xmm7,%xmm0 pslld $12,%xmm0 psrld $20,%xmm7 por %xmm0,%xmm7 # x0 += x4, x12 = rotl32(x12 ^ x0, 8) movdqa 0x00(%rsp),%xmm0 paddd %xmm4,%xmm0 movdqa %xmm0,0x00(%rsp) pxor %xmm0,%xmm12 pshufb %xmm2,%xmm12 # x1 += x5, x13 = rotl32(x13 ^ x1, 8) movdqa 0x10(%rsp),%xmm0 paddd %xmm5,%xmm0 movdqa %xmm0,0x10(%rsp) pxor %xmm0,%xmm13 pshufb %xmm2,%xmm13 # x2 += x6, x14 = rotl32(x14 ^ x2, 8) movdqa 0x20(%rsp),%xmm0 paddd %xmm6,%xmm0 movdqa %xmm0,0x20(%rsp) pxor %xmm0,%xmm14 pshufb %xmm2,%xmm14 # x3 += x7, x15 = rotl32(x15 ^ x3, 8) movdqa 0x30(%rsp),%xmm0 paddd %xmm7,%xmm0 movdqa %xmm0,0x30(%rsp) pxor %xmm0,%xmm15 pshufb %xmm2,%xmm15 # x8 += x12, x4 = rotl32(x4 ^ x8, 7) paddd %xmm12,%xmm8 pxor %xmm8,%xmm4 movdqa %xmm4,%xmm0 pslld $7,%xmm0 psrld $25,%xmm4 por %xmm0,%xmm4 # x9 += x13, x5 = rotl32(x5 ^ x9, 7) paddd %xmm13,%xmm9 pxor %xmm9,%xmm5 movdqa %xmm5,%xmm0 pslld $7,%xmm0 psrld $25,%xmm5 por %xmm0,%xmm5 # x10 += x14, x6 = rotl32(x6 ^ x10, 7) paddd %xmm14,%xmm10 pxor %xmm10,%xmm6 movdqa %xmm6,%xmm0 pslld $7,%xmm0 psrld $25,%xmm6 por %xmm0,%xmm6 # x11 += x15, x7 = rotl32(x7 ^ x11, 7) paddd %xmm15,%xmm11 pxor %xmm11,%xmm7 movdqa %xmm7,%xmm0 pslld $7,%xmm0 psrld $25,%xmm7 por %xmm0,%xmm7 # x0 += x5, x15 = rotl32(x15 ^ x0, 16) movdqa 0x00(%rsp),%xmm0 paddd %xmm5,%xmm0 movdqa %xmm0,0x00(%rsp) pxor %xmm0,%xmm15 pshufb %xmm3,%xmm15 # x1 += x6, x12 = rotl32(x12 ^ x1, 16) movdqa 0x10(%rsp),%xmm0 paddd %xmm6,%xmm0 movdqa %xmm0,0x10(%rsp) pxor %xmm0,%xmm12 pshufb %xmm3,%xmm12 # x2 += x7, x13 = rotl32(x13 ^ x2, 16) movdqa 0x20(%rsp),%xmm0 paddd %xmm7,%xmm0 movdqa %xmm0,0x20(%rsp) pxor %xmm0,%xmm13 pshufb %xmm3,%xmm13 # x3 += x4, x14 = rotl32(x14 ^ x3, 16) movdqa 0x30(%rsp),%xmm0 paddd %xmm4,%xmm0 movdqa %xmm0,0x30(%rsp) pxor %xmm0,%xmm14 pshufb %xmm3,%xmm14 # x10 += x15, x5 = rotl32(x5 ^ x10, 12) paddd %xmm15,%xmm10 pxor %xmm10,%xmm5 movdqa %xmm5,%xmm0 pslld $12,%xmm0 psrld $20,%xmm5 por %xmm0,%xmm5 # x11 += x12, x6 = rotl32(x6 ^ x11, 12) paddd %xmm12,%xmm11 pxor %xmm11,%xmm6 movdqa %xmm6,%xmm0 pslld $12,%xmm0 psrld $20,%xmm6 por %xmm0,%xmm6 # x8 += x13, x7 = rotl32(x7 ^ x8, 12) paddd %xmm13,%xmm8 pxor %xmm8,%xmm7 movdqa %xmm7,%xmm0 pslld $12,%xmm0 psrld $20,%xmm7 por %xmm0,%xmm7 # x9 += x14, x4 = rotl32(x4 ^ x9, 12) paddd %xmm14,%xmm9 pxor %xmm9,%xmm4 movdqa %xmm4,%xmm0 pslld $12,%xmm0 psrld $20,%xmm4 por %xmm0,%xmm4 # x0 += x5, x15 = rotl32(x15 ^ x0, 8) movdqa 0x00(%rsp),%xmm0 paddd %xmm5,%xmm0 movdqa %xmm0,0x00(%rsp) pxor %xmm0,%xmm15 pshufb %xmm2,%xmm15 # x1 += x6, x12 = rotl32(x12 ^ x1, 8) movdqa 0x10(%rsp),%xmm0 paddd %xmm6,%xmm0 movdqa %xmm0,0x10(%rsp) pxor %xmm0,%xmm12 pshufb %xmm2,%xmm12 # x2 += x7, x13 = rotl32(x13 ^ x2, 8) movdqa 0x20(%rsp),%xmm0 paddd %xmm7,%xmm0 movdqa %xmm0,0x20(%rsp) pxor %xmm0,%xmm13 pshufb %xmm2,%xmm13 # x3 += x4, x14 = rotl32(x14 ^ x3, 8) movdqa 0x30(%rsp),%xmm0 paddd %xmm4,%xmm0 movdqa %xmm0,0x30(%rsp) pxor %xmm0,%xmm14 pshufb %xmm2,%xmm14 # x10 += x15, x5 = rotl32(x5 ^ x10, 7) paddd %xmm15,%xmm10 pxor %xmm10,%xmm5 movdqa %xmm5,%xmm0 pslld $7,%xmm0 psrld $25,%xmm5 por %xmm0,%xmm5 # x11 += x12, x6 = rotl32(x6 ^ x11, 7) paddd %xmm12,%xmm11 pxor %xmm11,%xmm6 movdqa %xmm6,%xmm0 pslld $7,%xmm0 psrld $25,%xmm6 por %xmm0,%xmm6 # x8 += x13, x7 = rotl32(x7 ^ x8, 7) paddd %xmm13,%xmm8 pxor %xmm8,%xmm7 movdqa %xmm7,%xmm0 pslld $7,%xmm0 psrld $25,%xmm7 por %xmm0,%xmm7 # x9 += x14, x4 = rotl32(x4 ^ x9, 7) paddd %xmm14,%xmm9 pxor %xmm9,%xmm4 movdqa %xmm4,%xmm0 pslld $7,%xmm0 psrld $25,%xmm4 por %xmm0,%xmm4 dec %ecx jnz .Ldoubleround4 # x0[0-3] += s0[0] # x1[0-3] += s0[1] movq 0x00(%rdi),%xmm3 pshufd $0x00,%xmm3,%xmm2 pshufd $0x55,%xmm3,%xmm3 paddd 0x00(%rsp),%xmm2 movdqa %xmm2,0x00(%rsp) paddd 0x10(%rsp),%xmm3 movdqa %xmm3,0x10(%rsp) # x2[0-3] += s0[2] # x3[0-3] += s0[3] movq 0x08(%rdi),%xmm3 pshufd $0x00,%xmm3,%xmm2 pshufd $0x55,%xmm3,%xmm3 paddd 0x20(%rsp),%xmm2 movdqa %xmm2,0x20(%rsp) paddd 0x30(%rsp),%xmm3 movdqa %xmm3,0x30(%rsp) # x4[0-3] += s1[0] # x5[0-3] += s1[1] movq 0x10(%rdi),%xmm3 pshufd $0x00,%xmm3,%xmm2 pshufd $0x55,%xmm3,%xmm3 paddd %xmm2,%xmm4 paddd %xmm3,%xmm5 # x6[0-3] += s1[2] # x7[0-3] += s1[3] movq 0x18(%rdi),%xmm3 pshufd $0x00,%xmm3,%xmm2 pshufd $0x55,%xmm3,%xmm3 paddd %xmm2,%xmm6 paddd %xmm3,%xmm7 # x8[0-3] += s2[0] # x9[0-3] += s2[1] movq 0x20(%rdi),%xmm3 pshufd $0x00,%xmm3,%xmm2 pshufd $0x55,%xmm3,%xmm3 paddd %xmm2,%xmm8 paddd %xmm3,%xmm9 # x10[0-3] += s2[2] # x11[0-3] += s2[3] movq 0x28(%rdi),%xmm3 pshufd $0x00,%xmm3,%xmm2 pshufd $0x55,%xmm3,%xmm3 paddd %xmm2,%xmm10 paddd %xmm3,%xmm11 # x12[0-3] += s3[0] # x13[0-3] += s3[1] movq 0x30(%rdi),%xmm3 pshufd $0x00,%xmm3,%xmm2 pshufd $0x55,%xmm3,%xmm3 paddd %xmm2,%xmm12 paddd %xmm3,%xmm13 # x14[0-3] += s3[2] # x15[0-3] += s3[3] movq 0x38(%rdi),%xmm3 pshufd $0x00,%xmm3,%xmm2 pshufd $0x55,%xmm3,%xmm3 paddd %xmm2,%xmm14 paddd %xmm3,%xmm15 # x12 += counter values 0-3 paddd %xmm1,%xmm12 # interleave 32-bit words in state n, n+1 movdqa 0x00(%rsp),%xmm0 movdqa 0x10(%rsp),%xmm1 movdqa %xmm0,%xmm2 punpckldq %xmm1,%xmm2 punpckhdq %xmm1,%xmm0 movdqa %xmm2,0x00(%rsp) movdqa %xmm0,0x10(%rsp) movdqa 0x20(%rsp),%xmm0 movdqa 0x30(%rsp),%xmm1 movdqa %xmm0,%xmm2 punpckldq %xmm1,%xmm2 punpckhdq %xmm1,%xmm0 movdqa %xmm2,0x20(%rsp) movdqa %xmm0,0x30(%rsp) movdqa %xmm4,%xmm0 punpckldq %xmm5,%xmm4 punpckhdq %xmm5,%xmm0 movdqa %xmm0,%xmm5 movdqa %xmm6,%xmm0 punpckldq %xmm7,%xmm6 punpckhdq %xmm7,%xmm0 movdqa %xmm0,%xmm7 movdqa %xmm8,%xmm0 punpckldq %xmm9,%xmm8 punpckhdq %xmm9,%xmm0 movdqa %xmm0,%xmm9 movdqa %xmm10,%xmm0 punpckldq %xmm11,%xmm10 punpckhdq %xmm11,%xmm0 movdqa %xmm0,%xmm11 movdqa %xmm12,%xmm0 punpckldq %xmm13,%xmm12 punpckhdq %xmm13,%xmm0 movdqa %xmm0,%xmm13 movdqa %xmm14,%xmm0 punpckldq %xmm15,%xmm14 punpckhdq %xmm15,%xmm0 movdqa %xmm0,%xmm15 # interleave 64-bit words in state n, n+2 movdqa 0x00(%rsp),%xmm0 movdqa 0x20(%rsp),%xmm1 movdqa %xmm0,%xmm2 punpcklqdq %xmm1,%xmm2 punpckhqdq %xmm1,%xmm0 movdqa %xmm2,0x00(%rsp) movdqa %xmm0,0x20(%rsp) movdqa 0x10(%rsp),%xmm0 movdqa 0x30(%rsp),%xmm1 movdqa %xmm0,%xmm2 punpcklqdq %xmm1,%xmm2 punpckhqdq %xmm1,%xmm0 movdqa %xmm2,0x10(%rsp) movdqa %xmm0,0x30(%rsp) movdqa %xmm4,%xmm0 punpcklqdq %xmm6,%xmm4 punpckhqdq %xmm6,%xmm0 movdqa %xmm0,%xmm6 movdqa %xmm5,%xmm0 punpcklqdq %xmm7,%xmm5 punpckhqdq %xmm7,%xmm0 movdqa %xmm0,%xmm7 movdqa %xmm8,%xmm0 punpcklqdq %xmm10,%xmm8 punpckhqdq %xmm10,%xmm0 movdqa %xmm0,%xmm10 movdqa %xmm9,%xmm0 punpcklqdq %xmm11,%xmm9 punpckhqdq %xmm11,%xmm0 movdqa %xmm0,%xmm11 movdqa %xmm12,%xmm0 punpcklqdq %xmm14,%xmm12 punpckhqdq %xmm14,%xmm0 movdqa %xmm0,%xmm14 movdqa %xmm13,%xmm0 punpcklqdq %xmm15,%xmm13 punpckhqdq %xmm15,%xmm0 movdqa %xmm0,%xmm15 # xor with corresponding input, write to output movdqa 0x00(%rsp),%xmm0 movdqu 0x00(%rdx),%xmm1 pxor %xmm1,%xmm0 movdqu %xmm0,0x00(%rsi) movdqa 0x10(%rsp),%xmm0 movdqu 0x80(%rdx),%xmm1 pxor %xmm1,%xmm0 movdqu %xmm0,0x80(%rsi) movdqa 0x20(%rsp),%xmm0 movdqu 0x40(%rdx),%xmm1 pxor %xmm1,%xmm0 movdqu %xmm0,0x40(%rsi) movdqa 0x30(%rsp),%xmm0 movdqu 0xc0(%rdx),%xmm1 pxor %xmm1,%xmm0 movdqu %xmm0,0xc0(%rsi) movdqu 0x10(%rdx),%xmm1 pxor %xmm1,%xmm4 movdqu %xmm4,0x10(%rsi) movdqu 0x90(%rdx),%xmm1 pxor %xmm1,%xmm5 movdqu %xmm5,0x90(%rsi) movdqu 0x50(%rdx),%xmm1 pxor %xmm1,%xmm6 movdqu %xmm6,0x50(%rsi) movdqu 0xd0(%rdx),%xmm1 pxor %xmm1,%xmm7 movdqu %xmm7,0xd0(%rsi) movdqu 0x20(%rdx),%xmm1 pxor %xmm1,%xmm8 movdqu %xmm8,0x20(%rsi) movdqu 0xa0(%rdx),%xmm1 pxor %xmm1,%xmm9 movdqu %xmm9,0xa0(%rsi) movdqu 0x60(%rdx),%xmm1 pxor %xmm1,%xmm10 movdqu %xmm10,0x60(%rsi) movdqu 0xe0(%rdx),%xmm1 pxor %xmm1,%xmm11 movdqu %xmm11,0xe0(%rsi) movdqu 0x30(%rdx),%xmm1 pxor %xmm1,%xmm12 movdqu %xmm12,0x30(%rsi) movdqu 0xb0(%rdx),%xmm1 pxor %xmm1,%xmm13 movdqu %xmm13,0xb0(%rsi) movdqu 0x70(%rdx),%xmm1 pxor %xmm1,%xmm14 movdqu %xmm14,0x70(%rsi) movdqu 0xf0(%rdx),%xmm1 pxor %xmm1,%xmm15 movdqu %xmm15,0xf0(%rsi) lea -8(%r10),%rsp ret ENDPROC(chacha20_4block_xor_ssse3)