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// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build amd64,!gccgo,!appengine
package poly1305
//go:noescape
func initialize(state *[7]uint64, key *[32]byte)
//go:noescape
func update(state *[7]uint64, msg []byte)
//go:noescape
func finalize(tag *[TagSize]byte, state *[7]uint64)
// Sum generates an authenticator for m using a one-time key and puts the
// 16-byte result into out. Authenticating two different messages with the same
// key allows an attacker to forge messages at will.
func Sum(out *[16]byte, m []byte, key *[32]byte) {
h := newMAC(key)
h.Write(m)
h.Sum(out)
}
func newMAC(key *[32]byte) (h mac) {
initialize(&h.state, key)
return
}
type mac struct {
state [7]uint64 // := uint64{ h0, h1, h2, r0, r1, pad0, pad1 }
buffer [TagSize]byte
offset int
}
func (h *mac) Write(p []byte) (n int, err error) {
n = len(p)
if h.offset > 0 {
remaining := TagSize - h.offset
if n < remaining {
h.offset += copy(h.buffer[h.offset:], p)
return n, nil
}
copy(h.buffer[h.offset:], p[:remaining])
p = p[remaining:]
h.offset = 0
update(&h.state, h.buffer[:])
}
if nn := len(p) - (len(p) % TagSize); nn > 0 {
update(&h.state, p[:nn])
p = p[nn:]
}
if len(p) > 0 {
h.offset += copy(h.buffer[h.offset:], p)
}
return n, nil
}
func (h *mac) Sum(out *[16]byte) {
state := h.state
if h.offset > 0 {
update(&state, h.buffer[:h.offset])
}
finalize(out, &state)
}
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