mirror of https://gogs.blitter.com/RLabs/xs
97 lines
2.5 KiB
Go
97 lines
2.5 KiB
Go
// Package bcryptsha256 implements bcrypt with a SHA256 prehash in a format that is compatible with Python passlib's equivalent bcrypt-sha256 scheme.
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//
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// This is preferred over bcrypt because the prehash essentially renders bcrypt's password length
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// limitation irrelevant; although of course it is less compatible.
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package bcryptsha256
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import "gopkg.in/hlandau/passlib.v1/abstract"
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import "gopkg.in/hlandau/passlib.v1/hash/bcrypt"
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import "encoding/base64"
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import "crypto/sha256"
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import "strings"
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import "fmt"
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type scheme struct {
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underlying abstract.Scheme
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cost int
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}
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// An implementation of Scheme implementing Python passlib's `$bcrypt-sha256$`
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// bcrypt variant. This is bcrypt with a SHA256 prehash, which removes bcrypt's
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// password length limitation.
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var Crypter abstract.Scheme
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// The recommended cost for bcrypt-sha256. This may change with subsequent releases.
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const RecommendedCost = bcrypt.RecommendedCost
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func init() {
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Crypter = New(bcrypt.RecommendedCost)
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}
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// Instantiates a new Scheme implementing bcrypt with the given cost.
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//
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// The recommended cost is RecommendedCost.
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func New(cost int) abstract.Scheme {
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return &scheme{
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underlying: bcrypt.New(cost),
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cost: cost,
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}
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}
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func (s *scheme) Hash(password string) (string, error) {
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p := s.prehash(password)
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h, err := s.underlying.Hash(p)
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if err != nil {
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return "", err
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}
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return mangle(h), nil
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}
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func (s *scheme) Verify(password, hash string) error {
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p := s.prehash(password)
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return s.underlying.Verify(p, demangle(hash))
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}
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func (s *scheme) prehash(password string) string {
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h := sha256.New()
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h.Write([]byte(password))
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v := base64.StdEncoding.EncodeToString(h.Sum(nil))
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return v
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}
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func (s *scheme) SupportsStub(stub string) bool {
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return strings.HasPrefix(stub, "$bcrypt-sha256$") && s.underlying.SupportsStub(demangle(stub))
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}
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func (s *scheme) NeedsUpdate(stub string) bool {
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return s.underlying.NeedsUpdate(demangle(stub))
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}
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func (s *scheme) String() string {
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return fmt.Sprintf("bcrypt-sha256(%d)", s.cost)
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}
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func demangle(stub string) string {
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if strings.HasPrefix(stub, "$bcrypt-sha256$2") {
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parts := strings.Split(stub[15:], "$")
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// 0: 2a,12
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// 1: salt
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// 2: hash
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parts0 := strings.Split(parts[0], ",")
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return "$" + parts0[0] + "$" + fmt.Sprintf("%02s", parts0[1]) + "$" + parts[1] + parts[2]
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} else {
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return stub
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}
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}
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func mangle(hash string) string {
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parts := strings.Split(hash[1:], "$")
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// 0: 2a
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// 1: rounds
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// 2: salt + hash
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salt := parts[2][0:22]
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h := parts[2][22:]
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return "$bcrypt-sha256$" + parts[0] + "," + parts[1] + "$" + salt + "$" + h
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}
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