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blake2b.go (1103B)

      1 // Copyright 2017 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 package argon2
      6 
      7 import (
      8 	"encoding/binary"
      9 	"hash"
     10 
     11 	"golang.org/x/crypto/blake2b"
     12 )
     13 
     14 // blake2bHash computes an arbitrary long hash value of in
     15 // and writes the hash to out.
     16 func blake2bHash(out []byte, in []byte) {
     17 	var b2 hash.Hash
     18 	if n := len(out); n < blake2b.Size {
     19 		b2, _ = blake2b.New(n, nil)
     20 	} else {
     21 		b2, _ = blake2b.New512(nil)
     22 	}
     23 
     24 	var buffer [blake2b.Size]byte
     25 	binary.LittleEndian.PutUint32(buffer[:4], uint32(len(out)))
     26 	b2.Write(buffer[:4])
     27 	b2.Write(in)
     28 
     29 	if len(out) <= blake2b.Size {
     30 		b2.Sum(out[:0])
     31 		return
     32 	}
     33 
     34 	outLen := len(out)
     35 	b2.Sum(buffer[:0])
     36 	b2.Reset()
     37 	copy(out, buffer[:32])
     38 	out = out[32:]
     39 	for len(out) > blake2b.Size {
     40 		b2.Write(buffer[:])
     41 		b2.Sum(buffer[:0])
     42 		copy(out, buffer[:32])
     43 		out = out[32:]
     44 		b2.Reset()
     45 	}
     46 
     47 	if outLen%blake2b.Size > 0 { // outLen > 64
     48 		r := ((outLen + 31) / 32) - 2 // ⌈τ /32⌉-2
     49 		b2, _ = blake2b.New(outLen-32*r, nil)
     50 	}
     51 	b2.Write(buffer[:])
     52 	b2.Sum(out[:0])
     53 }