Source file src/pkg/vendor/golang.org/x/crypto/poly1305/sum_amd64.go

     1	// Copyright 2012 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	// +build amd64,!gccgo,!appengine
     6	
     7	package poly1305
     8	
     9	//go:noescape
    10	func initialize(state *[7]uint64, key *[32]byte)
    11	
    12	//go:noescape
    13	func update(state *[7]uint64, msg []byte)
    14	
    15	//go:noescape
    16	func finalize(tag *[TagSize]byte, state *[7]uint64)
    17	
    18	// Sum generates an authenticator for m using a one-time key and puts the
    19	// 16-byte result into out. Authenticating two different messages with the same
    20	// key allows an attacker to forge messages at will.
    21	func Sum(out *[16]byte, m []byte, key *[32]byte) {
    22		h := newMAC(key)
    23		h.Write(m)
    24		h.Sum(out)
    25	}
    26	
    27	func newMAC(key *[32]byte) (h mac) {
    28		initialize(&h.state, key)
    29		return
    30	}
    31	
    32	type mac struct {
    33		state [7]uint64 // := uint64{ h0, h1, h2, r0, r1, pad0, pad1 }
    34	
    35		buffer [TagSize]byte
    36		offset int
    37	}
    38	
    39	func (h *mac) Write(p []byte) (n int, err error) {
    40		n = len(p)
    41		if h.offset > 0 {
    42			remaining := TagSize - h.offset
    43			if n < remaining {
    44				h.offset += copy(h.buffer[h.offset:], p)
    45				return n, nil
    46			}
    47			copy(h.buffer[h.offset:], p[:remaining])
    48			p = p[remaining:]
    49			h.offset = 0
    50			update(&h.state, h.buffer[:])
    51		}
    52		if nn := len(p) - (len(p) % TagSize); nn > 0 {
    53			update(&h.state, p[:nn])
    54			p = p[nn:]
    55		}
    56		if len(p) > 0 {
    57			h.offset += copy(h.buffer[h.offset:], p)
    58		}
    59		return n, nil
    60	}
    61	
    62	func (h *mac) Sum(out *[16]byte) {
    63		state := h.state
    64		if h.offset > 0 {
    65			update(&state, h.buffer[:h.offset])
    66		}
    67		finalize(out, &state)
    68	}
    69	

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