chacha20poly1305_amd64.go

Documentation: vendor/golang.org/x/crypto/chacha20poly1305

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build gc && !purego
     6  
     7  package chacha20poly1305
     8  
     9  import (
    10  	"encoding/binary"
    11  
    12  	"golang.org/x/crypto/internal/alias"
    13  	"golang.org/x/sys/cpu"
    14  )
    15  
    16  //go:noescape
    17  func chacha20Poly1305Open(dst []byte, key []uint32, src, ad []byte) bool
    18  
    19  //go:noescape
    20  func chacha20Poly1305Seal(dst []byte, key []uint32, src, ad []byte)
    21  
    22  var (
    23  	useAVX2 = cpu.X86.HasAVX2 && cpu.X86.HasBMI2
    24  )
    25  
    26  // setupState writes a ChaCha20 input matrix to state. See
    27  // https://tools.ietf.org/html/rfc7539#section-2.3.
    28  func setupState(state *[16]uint32, key *[32]byte, nonce []byte) {
    29  	state[0] = 0x61707865
    30  	state[1] = 0x3320646e
    31  	state[2] = 0x79622d32
    32  	state[3] = 0x6b206574
    33  
    34  	state[4] = binary.LittleEndian.Uint32(key[0:4])
    35  	state[5] = binary.LittleEndian.Uint32(key[4:8])
    36  	state[6] = binary.LittleEndian.Uint32(key[8:12])
    37  	state[7] = binary.LittleEndian.Uint32(key[12:16])
    38  	state[8] = binary.LittleEndian.Uint32(key[16:20])
    39  	state[9] = binary.LittleEndian.Uint32(key[20:24])
    40  	state[10] = binary.LittleEndian.Uint32(key[24:28])
    41  	state[11] = binary.LittleEndian.Uint32(key[28:32])
    42  
    43  	state[12] = 0
    44  	state[13] = binary.LittleEndian.Uint32(nonce[0:4])
    45  	state[14] = binary.LittleEndian.Uint32(nonce[4:8])
    46  	state[15] = binary.LittleEndian.Uint32(nonce[8:12])
    47  }
    48  
    49  func (c *chacha20poly1305) seal(dst, nonce, plaintext, additionalData []byte) []byte {
    50  	if !cpu.X86.HasSSSE3 {
    51  		return c.sealGeneric(dst, nonce, plaintext, additionalData)
    52  	}
    53  
    54  	var state [16]uint32
    55  	setupState(&state, &c.key, nonce)
    56  
    57  	ret, out := sliceForAppend(dst, len(plaintext)+16)
    58  	if alias.InexactOverlap(out, plaintext) {
    59  		panic("chacha20poly1305: invalid buffer overlap")
    60  	}
    61  	chacha20Poly1305Seal(out[:], state[:], plaintext, additionalData)
    62  	return ret
    63  }
    64  
    65  func (c *chacha20poly1305) open(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) {
    66  	if !cpu.X86.HasSSSE3 {
    67  		return c.openGeneric(dst, nonce, ciphertext, additionalData)
    68  	}
    69  
    70  	var state [16]uint32
    71  	setupState(&state, &c.key, nonce)
    72  
    73  	ciphertext = ciphertext[:len(ciphertext)-16]
    74  	ret, out := sliceForAppend(dst, len(ciphertext))
    75  	if alias.InexactOverlap(out, ciphertext) {
    76  		panic("chacha20poly1305: invalid buffer overlap")
    77  	}
    78  	if !chacha20Poly1305Open(out, state[:], ciphertext, additionalData) {
    79  		for i := range out {
    80  			out[i] = 0
    81  		}
    82  		return nil, errOpen
    83  	}
    84  
    85  	return ret, nil
    86  }
    87
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