blake2b.go

Documentation: golang.org/x/crypto/argon2

     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  }
    54
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