mirror of
https://github.com/ceph/ceph-csi.git
synced 2024-11-18 12:20:24 +00:00
94 lines
2.7 KiB
Go
94 lines
2.7 KiB
Go
// Copyright 2014 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 hkdf implements the HMAC-based Extract-and-Expand Key Derivation
|
|
// Function (HKDF) as defined in RFC 5869.
|
|
//
|
|
// HKDF is a cryptographic key derivation function (KDF) with the goal of
|
|
// expanding limited input keying material into one or more cryptographically
|
|
// strong secret keys.
|
|
package hkdf // import "golang.org/x/crypto/hkdf"
|
|
|
|
import (
|
|
"crypto/hmac"
|
|
"errors"
|
|
"hash"
|
|
"io"
|
|
)
|
|
|
|
// Extract generates a pseudorandom key for use with Expand from an input secret
|
|
// and an optional independent salt.
|
|
//
|
|
// Only use this function if you need to reuse the extracted key with multiple
|
|
// Expand invocations and different context values. Most common scenarios,
|
|
// including the generation of multiple keys, should use New instead.
|
|
func Extract(hash func() hash.Hash, secret, salt []byte) []byte {
|
|
if salt == nil {
|
|
salt = make([]byte, hash().Size())
|
|
}
|
|
extractor := hmac.New(hash, salt)
|
|
extractor.Write(secret)
|
|
return extractor.Sum(nil)
|
|
}
|
|
|
|
type hkdf struct {
|
|
expander hash.Hash
|
|
size int
|
|
|
|
info []byte
|
|
counter byte
|
|
|
|
prev []byte
|
|
buf []byte
|
|
}
|
|
|
|
func (f *hkdf) Read(p []byte) (int, error) {
|
|
// Check whether enough data can be generated
|
|
need := len(p)
|
|
remains := len(f.buf) + int(255-f.counter+1)*f.size
|
|
if remains < need {
|
|
return 0, errors.New("hkdf: entropy limit reached")
|
|
}
|
|
// Read any leftover from the buffer
|
|
n := copy(p, f.buf)
|
|
p = p[n:]
|
|
|
|
// Fill the rest of the buffer
|
|
for len(p) > 0 {
|
|
f.expander.Reset()
|
|
f.expander.Write(f.prev)
|
|
f.expander.Write(f.info)
|
|
f.expander.Write([]byte{f.counter})
|
|
f.prev = f.expander.Sum(f.prev[:0])
|
|
f.counter++
|
|
|
|
// Copy the new batch into p
|
|
f.buf = f.prev
|
|
n = copy(p, f.buf)
|
|
p = p[n:]
|
|
}
|
|
// Save leftovers for next run
|
|
f.buf = f.buf[n:]
|
|
|
|
return need, nil
|
|
}
|
|
|
|
// Expand returns a Reader, from which keys can be read, using the given
|
|
// pseudorandom key and optional context info, skipping the extraction step.
|
|
//
|
|
// The pseudorandomKey should have been generated by Extract, or be a uniformly
|
|
// random or pseudorandom cryptographically strong key. See RFC 5869, Section
|
|
// 3.3. Most common scenarios will want to use New instead.
|
|
func Expand(hash func() hash.Hash, pseudorandomKey, info []byte) io.Reader {
|
|
expander := hmac.New(hash, pseudorandomKey)
|
|
return &hkdf{expander, expander.Size(), info, 1, nil, nil}
|
|
}
|
|
|
|
// New returns a Reader, from which keys can be read, using the given hash,
|
|
// secret, salt and context info. Salt and info can be nil.
|
|
func New(hash func() hash.Hash, secret, salt, info []byte) io.Reader {
|
|
prk := Extract(hash, secret, salt)
|
|
return Expand(hash, prk, info)
|
|
}
|