diff options
Diffstat (limited to 'vendor/golang.org/x/crypto/poly1305/sum_generic.go')
-rw-r--r-- | vendor/golang.org/x/crypto/poly1305/sum_generic.go | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/vendor/golang.org/x/crypto/poly1305/sum_generic.go b/vendor/golang.org/x/crypto/poly1305/sum_generic.go new file mode 100644 index 000000000..bab76ef0d --- /dev/null +++ b/vendor/golang.org/x/crypto/poly1305/sum_generic.go @@ -0,0 +1,172 @@ +// Copyright 2018 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. + +package poly1305 + +import "encoding/binary" + +const ( + msgBlock = uint32(1 << 24) + finalBlock = uint32(0) +) + +// sumGeneric generates an authenticator for msg using a one-time key and +// puts the 16-byte result into out. This is the generic implementation of +// Sum and should be called if no assembly implementation is available. +func sumGeneric(out *[TagSize]byte, msg []byte, key *[32]byte) { + h := newMACGeneric(key) + h.Write(msg) + h.Sum(out) +} + +func newMACGeneric(key *[32]byte) (h macGeneric) { + h.r[0] = binary.LittleEndian.Uint32(key[0:]) & 0x3ffffff + h.r[1] = (binary.LittleEndian.Uint32(key[3:]) >> 2) & 0x3ffff03 + h.r[2] = (binary.LittleEndian.Uint32(key[6:]) >> 4) & 0x3ffc0ff + h.r[3] = (binary.LittleEndian.Uint32(key[9:]) >> 6) & 0x3f03fff + h.r[4] = (binary.LittleEndian.Uint32(key[12:]) >> 8) & 0x00fffff + + h.s[0] = binary.LittleEndian.Uint32(key[16:]) + h.s[1] = binary.LittleEndian.Uint32(key[20:]) + h.s[2] = binary.LittleEndian.Uint32(key[24:]) + h.s[3] = binary.LittleEndian.Uint32(key[28:]) + return +} + +type macGeneric struct { + h, r [5]uint32 + s [4]uint32 + + buffer [TagSize]byte + offset int +} + +func (h *macGeneric) 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 + updateGeneric(h.buffer[:], msgBlock, &(h.h), &(h.r)) + } + if nn := len(p) - (len(p) % TagSize); nn > 0 { + updateGeneric(p, msgBlock, &(h.h), &(h.r)) + p = p[nn:] + } + if len(p) > 0 { + h.offset += copy(h.buffer[h.offset:], p) + } + return n, nil +} + +func (h *macGeneric) Sum(out *[16]byte) { + H, R := h.h, h.r + if h.offset > 0 { + var buffer [TagSize]byte + copy(buffer[:], h.buffer[:h.offset]) + buffer[h.offset] = 1 // invariant: h.offset < TagSize + updateGeneric(buffer[:], finalBlock, &H, &R) + } + finalizeGeneric(out, &H, &(h.s)) +} + +func updateGeneric(msg []byte, flag uint32, h, r *[5]uint32) { + h0, h1, h2, h3, h4 := h[0], h[1], h[2], h[3], h[4] + r0, r1, r2, r3, r4 := uint64(r[0]), uint64(r[1]), uint64(r[2]), uint64(r[3]), uint64(r[4]) + R1, R2, R3, R4 := r1*5, r2*5, r3*5, r4*5 + + for len(msg) >= TagSize { + // h += msg + h0 += binary.LittleEndian.Uint32(msg[0:]) & 0x3ffffff + h1 += (binary.LittleEndian.Uint32(msg[3:]) >> 2) & 0x3ffffff + h2 += (binary.LittleEndian.Uint32(msg[6:]) >> 4) & 0x3ffffff + h3 += (binary.LittleEndian.Uint32(msg[9:]) >> 6) & 0x3ffffff + h4 += (binary.LittleEndian.Uint32(msg[12:]) >> 8) | flag + + // h *= r + d0 := (uint64(h0) * r0) + (uint64(h1) * R4) + (uint64(h2) * R3) + (uint64(h3) * R2) + (uint64(h4) * R1) + d1 := (d0 >> 26) + (uint64(h0) * r1) + (uint64(h1) * r0) + (uint64(h2) * R4) + (uint64(h3) * R3) + (uint64(h4) * R2) + d2 := (d1 >> 26) + (uint64(h0) * r2) + (uint64(h1) * r1) + (uint64(h2) * r0) + (uint64(h3) * R4) + (uint64(h4) * R3) + d3 := (d2 >> 26) + (uint64(h0) * r3) + (uint64(h1) * r2) + (uint64(h2) * r1) + (uint64(h3) * r0) + (uint64(h4) * R4) + d4 := (d3 >> 26) + (uint64(h0) * r4) + (uint64(h1) * r3) + (uint64(h2) * r2) + (uint64(h3) * r1) + (uint64(h4) * r0) + + // h %= p + h0 = uint32(d0) & 0x3ffffff + h1 = uint32(d1) & 0x3ffffff + h2 = uint32(d2) & 0x3ffffff + h3 = uint32(d3) & 0x3ffffff + h4 = uint32(d4) & 0x3ffffff + + h0 += uint32(d4>>26) * 5 + h1 += h0 >> 26 + h0 = h0 & 0x3ffffff + + msg = msg[TagSize:] + } + + h[0], h[1], h[2], h[3], h[4] = h0, h1, h2, h3, h4 +} + +func finalizeGeneric(out *[TagSize]byte, h *[5]uint32, s *[4]uint32) { + h0, h1, h2, h3, h4 := h[0], h[1], h[2], h[3], h[4] + + // h %= p reduction + h2 += h1 >> 26 + h1 &= 0x3ffffff + h3 += h2 >> 26 + h2 &= 0x3ffffff + h4 += h3 >> 26 + h3 &= 0x3ffffff + h0 += 5 * (h4 >> 26) + h4 &= 0x3ffffff + h1 += h0 >> 26 + h0 &= 0x3ffffff + + // h - p + t0 := h0 + 5 + t1 := h1 + (t0 >> 26) + t2 := h2 + (t1 >> 26) + t3 := h3 + (t2 >> 26) + t4 := h4 + (t3 >> 26) - (1 << 26) + t0 &= 0x3ffffff + t1 &= 0x3ffffff + t2 &= 0x3ffffff + t3 &= 0x3ffffff + + // select h if h < p else h - p + t_mask := (t4 >> 31) - 1 + h_mask := ^t_mask + h0 = (h0 & h_mask) | (t0 & t_mask) + h1 = (h1 & h_mask) | (t1 & t_mask) + h2 = (h2 & h_mask) | (t2 & t_mask) + h3 = (h3 & h_mask) | (t3 & t_mask) + h4 = (h4 & h_mask) | (t4 & t_mask) + + // h %= 2^128 + h0 |= h1 << 26 + h1 = ((h1 >> 6) | (h2 << 20)) + h2 = ((h2 >> 12) | (h3 << 14)) + h3 = ((h3 >> 18) | (h4 << 8)) + + // s: the s part of the key + // tag = (h + s) % (2^128) + t := uint64(h0) + uint64(s[0]) + h0 = uint32(t) + t = uint64(h1) + uint64(s[1]) + (t >> 32) + h1 = uint32(t) + t = uint64(h2) + uint64(s[2]) + (t >> 32) + h2 = uint32(t) + t = uint64(h3) + uint64(s[3]) + (t >> 32) + h3 = uint32(t) + + binary.LittleEndian.PutUint32(out[0:], h0) + binary.LittleEndian.PutUint32(out[4:], h1) + binary.LittleEndian.PutUint32(out[8:], h2) + binary.LittleEndian.PutUint32(out[12:], h3) +} |