MVP, no mod tools or anything but it works

vendor/gopkg.in/hlandau/passlib.v1/hash/bcrypt/bcrypt.go

@@ -0,0 +1,72 @@
+// Package bcrypt implements the bcrypt password hashing mechanism.
+//
+// Please note that bcrypt truncates passwords to 72 characters in length. Consider using
+// a more modern hashing scheme such as scrypt or sha-crypt. If you must use bcrypt,
+// consider using bcrypt-sha256 instead.
+package bcrypt
+
+import "golang.org/x/crypto/bcrypt"
+import "gopkg.in/hlandau/passlib.v1/abstract"
+import "fmt"
+
+// An implementation of Scheme implementing bcrypt.
+//
+// Uses RecommendedCost.
+var Crypter abstract.Scheme
+
+// The recommended cost for bcrypt. This may change with subsequent releases.
+const RecommendedCost = 12
+
+// bcrypt.DefaultCost is a bit low (10), so use 12 instead.
+
+func init() {
+	Crypter = New(RecommendedCost)
+}
+
+// Create a new scheme implementing bcrypt. The recommended cost is RecommendedCost.
+func New(cost int) abstract.Scheme {
+	return &scheme{
+		Cost: cost,
+	}
+}
+
+type scheme struct {
+	Cost int
+}
+
+func (s *scheme) SupportsStub(stub string) bool {
+	return len(stub) >= 3 && stub[0] == '$' && stub[1] == '2' &&
+		(stub[2] == '$' || (len(stub) >= 4 && stub[3] == '$' &&
+			(stub[2] == 'a' || stub[2] == 'b' || stub[2] == 'y')))
+}
+
+func (s *scheme) Hash(password string) (string, error) {
+	h, err := bcrypt.GenerateFromPassword([]byte(password), s.Cost)
+	if err != nil {
+		return "", err
+	}
+
+	return string(h), nil
+}
+
+func (s *scheme) Verify(password, hash string) error {
+	err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
+	if err == bcrypt.ErrMismatchedHashAndPassword {
+		err = abstract.ErrInvalidPassword
+	}
+
+	return err
+}
+
+func (s *scheme) NeedsUpdate(stub string) bool {
+	cost, err := bcrypt.Cost([]byte(stub))
+	if err != nil {
+		return false
+	}
+
+	return cost < s.Cost
+}
+
+func (s *scheme) String() string {
+	return fmt.Sprintf("bcrypt(%d)", s.Cost)
+}

vendor/gopkg.in/hlandau/passlib.v1/hash/bcryptsha256/bcryptsha256.go

@@ -0,0 +1,96 @@
+// Package bcryptsha256 implements bcrypt with a SHA256 prehash in a format that is compatible with Python passlib's equivalent bcrypt-sha256 scheme.
+//
+// This is preferred over bcrypt because the prehash essentially renders bcrypt's password length
+// limitation irrelevant; although of course it is less compatible.
+package bcryptsha256
+
+import "gopkg.in/hlandau/passlib.v1/abstract"
+import "gopkg.in/hlandau/passlib.v1/hash/bcrypt"
+import "encoding/base64"
+import "crypto/sha256"
+import "strings"
+import "fmt"
+
+type scheme struct {
+	underlying abstract.Scheme
+	cost       int
+}
+
+// An implementation of Scheme implementing Python passlib's `$bcrypt-sha256$`
+// bcrypt variant. This is bcrypt with a SHA256 prehash, which removes bcrypt's
+// password length limitation.
+var Crypter abstract.Scheme
+
+// The recommended cost for bcrypt-sha256. This may change with subsequent releases.
+const RecommendedCost = bcrypt.RecommendedCost
+
+func init() {
+	Crypter = New(bcrypt.RecommendedCost)
+}
+
+// Instantiates a new Scheme implementing bcrypt with the given cost.
+//
+// The recommended cost is RecommendedCost.
+func New(cost int) abstract.Scheme {
+	return &scheme{
+		underlying: bcrypt.New(cost),
+		cost:       cost,
+	}
+}
+
+func (s *scheme) Hash(password string) (string, error) {
+	p := s.prehash(password)
+	h, err := s.underlying.Hash(p)
+	if err != nil {
+		return "", err
+	}
+
+	return mangle(h), nil
+}
+
+func (s *scheme) Verify(password, hash string) error {
+	p := s.prehash(password)
+	return s.underlying.Verify(p, demangle(hash))
+}
+
+func (s *scheme) prehash(password string) string {
+	h := sha256.New()
+	h.Write([]byte(password))
+	v := base64.StdEncoding.EncodeToString(h.Sum(nil))
+	return v
+}
+
+func (s *scheme) SupportsStub(stub string) bool {
+	return strings.HasPrefix(stub, "$bcrypt-sha256$") && s.underlying.SupportsStub(demangle(stub))
+}
+
+func (s *scheme) NeedsUpdate(stub string) bool {
+	return s.underlying.NeedsUpdate(demangle(stub))
+}
+
+func (s *scheme) String() string {
+	return fmt.Sprintf("bcrypt-sha256(%d)", s.cost)
+}
+
+func demangle(stub string) string {
+	if strings.HasPrefix(stub, "$bcrypt-sha256$2") {
+		parts := strings.Split(stub[15:], "$")
+		// 0: 2a,12
+		// 1: salt
+		// 2: hash
+		parts0 := strings.Split(parts[0], ",")
+		return "$" + parts0[0] + "$" + fmt.Sprintf("%02s", parts0[1]) + "$" + parts[1] + parts[2]
+	} else {
+		return stub
+	}
+}
+
+func mangle(hash string) string {
+	parts := strings.Split(hash[1:], "$")
+	// 0: 2a
+	// 1: rounds
+	// 2: salt + hash
+	salt := parts[2][0:22]
+	h := parts[2][22:]
+	return "$bcrypt-sha256$" + parts[0] + "," + parts[1] + "$" + salt + "$" + h
+}

vendor/gopkg.in/hlandau/passlib.v1/hash/scrypt/raw/scrypt.go

@@ -0,0 +1,95 @@
+// Package raw provides a raw implementation of the modular-crypt-wrapped scrypt primitive.
+package raw
+
+import "golang.org/x/crypto/scrypt"
+import "encoding/base64"
+import "strings"
+import "strconv"
+import "fmt"
+
+// The current recommended N value for interactive logins.
+const RecommendedN = 16384
+
+// The current recommended r value for interactive logins.
+const Recommendedr = 8
+
+// The current recommended p value for interactive logins.
+const Recommendedp = 1
+
+// Wrapper for golang.org/x/crypto/scrypt implementing a sensible
+// modular crypt interface.
+//
+// password should be a UTF-8 plaintext password.
+// salt should be a random salt value in binary form.
+//
+// N, r and p are parameters to scrypt.
+//
+// Returns a modular crypt hash.
+func ScryptSHA256(password string, salt []byte, N, r, p int) string {
+	passwordb := []byte(password)
+
+	hash, err := scrypt.Key(passwordb, salt, N, r, p, 32)
+	if err != nil {
+		panic(err)
+	}
+
+	hstr := base64.StdEncoding.EncodeToString(hash)
+	sstr := base64.StdEncoding.EncodeToString(salt)
+
+	return fmt.Sprintf("$s2$%d$%d$%d$%s$%s", N, r, p, sstr, hstr)
+}
+
+// Indicates that a password hash or stub is invalid.
+var ErrInvalidStub = fmt.Errorf("invalid scrypt password stub")
+
+// Parses an scrypt modular hash or stub string.
+//
+// The format is as follows:
+//
+//   $s2$N$r$p$salt$hash    // hash
+//   $s2$N$r$p$salt         // stub
+//
+func Parse(stub string) (salt, hash []byte, N, r, p int, err error) {
+	if len(stub) < 10 || !strings.HasPrefix(stub, "$s2$") {
+		err = ErrInvalidStub
+		return
+	}
+
+	// $s2$  N$r$p$salt-base64$hash-base64
+	parts := strings.Split(stub[4:], "$")
+
+	if len(parts) < 4 {
+		err = ErrInvalidStub
+		return
+	}
+
+	var Ni, ri, pi uint64
+
+	Ni, err = strconv.ParseUint(parts[0], 10, 31)
+	if err != nil {
+		return
+	}
+
+	ri, err = strconv.ParseUint(parts[1], 10, 31)
+	if err != nil {
+		return
+	}
+
+	pi, err = strconv.ParseUint(parts[2], 10, 31)
+	if err != nil {
+		return
+	}
+
+	N, r, p = int(Ni), int(ri), int(pi)
+
+	salt, err = base64.StdEncoding.DecodeString(parts[3])
+	if err != nil {
+		return
+	}
+
+	if len(parts) >= 5 {
+		hash, err = base64.StdEncoding.DecodeString(parts[4])
+	}
+
+	return
+}

vendor/gopkg.in/hlandau/passlib.v1/hash/scrypt/scrypt.go

@@ -0,0 +1,113 @@
+// Package scrypt implements the scrypt password hashing mechanism, wrapped in
+// the modular crypt format.
+package scrypt
+
+import "fmt"
+import "expvar"
+import "strings"
+import "crypto/rand"
+import "encoding/base64"
+import "gopkg.in/hlandau/passlib.v1/hash/scrypt/raw"
+import "gopkg.in/hlandau/passlib.v1/abstract"
+
+var cScryptSHA256HashCalls = expvar.NewInt("passlib.scryptsha256.hashCalls")
+var cScryptSHA256VerifyCalls = expvar.NewInt("passlib.scryptsha256.verifyCalls")
+
+// An implementation of Scheme performing scrypt-sha256.
+//
+// Uses the recommended values for N,r,p defined in raw.
+var SHA256Crypter abstract.Scheme
+
+func init() {
+	SHA256Crypter = NewSHA256(
+		raw.RecommendedN,
+		raw.Recommendedr,
+		raw.Recommendedp,
+	)
+}
+
+// Returns an implementation of Scheme implementing scrypt-sha256
+// with the specified parameters.
+func NewSHA256(N, r, p int) abstract.Scheme {
+	return &scryptSHA256Crypter{
+		nN: N,
+		r:  r,
+		p:  p,
+	}
+}
+
+type scryptSHA256Crypter struct {
+	nN, r, p int
+}
+
+func (c *scryptSHA256Crypter) SetParams(N, r, p int) error {
+	c.nN = N
+	c.r = r
+	c.p = p
+	return nil
+}
+
+func (c *scryptSHA256Crypter) SupportsStub(stub string) bool {
+	return strings.HasPrefix(stub, "$s2$")
+}
+
+func (c *scryptSHA256Crypter) Hash(password string) (string, error) {
+	cScryptSHA256HashCalls.Add(1)
+
+	stub, err := c.makeStub()
+	if err != nil {
+		return "", err
+	}
+
+	_, newHash, _, _, _, _, err := c.hash(password, stub)
+	return newHash, err
+}
+
+func (c *scryptSHA256Crypter) Verify(password, hash string) (err error) {
+	cScryptSHA256VerifyCalls.Add(1)
+
+	_, newHash, _, _, _, _, err := c.hash(password, hash)
+	if err == nil && !abstract.SecureCompare(hash, newHash) {
+		err = abstract.ErrInvalidPassword
+	}
+
+	return
+}
+
+func (c *scryptSHA256Crypter) NeedsUpdate(stub string) bool {
+	salt, _, N, r, p, err := raw.Parse(stub)
+	if err != nil {
+		return false // ...
+	}
+
+	return c.needsUpdate(salt, N, r, p)
+}
+
+func (c *scryptSHA256Crypter) needsUpdate(salt []byte, N, r, p int) bool {
+	return len(salt) < 18 || N < c.nN || r < c.r || p < c.p
+}
+
+func (c *scryptSHA256Crypter) hash(password, stub string) (oldHashRaw []byte, newHash string, salt []byte, N, r, p int, err error) {
+	salt, oldHashRaw, N, r, p, err = raw.Parse(stub)
+	if err != nil {
+		return
+	}
+
+	return oldHashRaw, raw.ScryptSHA256(password, salt, N, r, p), salt, N, r, p, nil
+}
+
+func (c *scryptSHA256Crypter) makeStub() (string, error) {
+	buf := make([]byte, 18)
+	_, err := rand.Read(buf)
+	if err != nil {
+		return "", err
+	}
+
+	salt := base64.StdEncoding.EncodeToString(buf)
+
+	return fmt.Sprintf("$s2$%d$%d$%d$%s", c.nN, c.r, c.p, salt), nil
+}
+
+func (c *scryptSHA256Crypter) String() string {
+	return fmt.Sprintf("scrypt-sha256(%d,%d,%d)", c.nN, c.r, c.p)
+}

vendor/gopkg.in/hlandau/passlib.v1/hash/sha2crypt/raw/base64.go

@@ -0,0 +1,34 @@
+package raw
+
+const bmap = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+
+// Encodes a byte string using the sha2-crypt base64 variant.
+func EncodeBase64(b []byte) string {
+	o := make([]byte, len(b)/3*4+4)
+
+	for i, j := 0, 0; i < len(b); {
+		b1 := b[i]
+		b2 := byte(0)
+		b3 := byte(0)
+
+		if (i + 1) < len(b) {
+			b2 = b[i+1]
+		}
+		if (i + 2) < len(b) {
+			b3 = b[i+2]
+		}
+
+		o[j] = bmap[(b1 & 0x3F)]
+		o[j+1] = bmap[((b1&0xC0)>>6)|((b2&0x0F)<<2)]
+		o[j+2] = bmap[((b2&0xF0)>>4)|((b3&0x03)<<4)]
+		o[j+3] = bmap[(b3&0xFC)>>2]
+		i += 3
+		j += 4
+	}
+
+	s := string(o)
+	return s[0 : len(b)*4/3-(len(b)%4)+1]
+}
+
+// © 2008-2012 Assurance Technologies LLC.  (Python passlib)  BSD License
+// © 2014 Hugo Landau <hlandau@devever.net>  BSD License

vendor/gopkg.in/hlandau/passlib.v1/hash/sha2crypt/raw/parse.go

@@ -0,0 +1,82 @@
+package raw
+
+import "fmt"
+import "strings"
+import "strconv"
+
+// Indicates that a password hash or stub is invalid.
+var ErrInvalidStub = fmt.Errorf("invalid stub")
+
+// Indicates that the number of rounds specified is not in the valid range.
+var ErrInvalidRounds = fmt.Errorf("invalid number of rounds")
+
+// Scans a sha256-crypt or sha512-crypt modular crypt stub or modular crypt hash
+// to determine configuration parameters.
+func Parse(stub string) (isSHA512 bool, salt, hash string, rounds int, err error) {
+	// $5$
+	if len(stub) < 3 || stub[0] != '$' || stub[2] != '$' {
+		err = ErrInvalidStub
+		return
+	}
+
+	if stub[1] == '6' {
+		isSHA512 = true
+	} else if stub[1] != '5' {
+		err = ErrInvalidStub
+		return
+	}
+
+	rest := stub[3:]
+	parts := strings.Split(rest, "$")
+	roundsStr := ""
+
+	switch len(parts) {
+	case 1:
+		// $5$
+		// $5$salt
+		salt = parts[0]
+	case 2:
+		// $5$salt$hash
+		// $5$rounds=1000$salt
+		if strings.HasPrefix(parts[0], "rounds=") {
+			roundsStr = parts[0]
+			salt = parts[1]
+		} else {
+			salt = parts[0]
+			hash = parts[1]
+		}
+	case 3:
+		// $5$rounds=1000$salt$hash
+		roundsStr = parts[0]
+		salt = parts[1]
+		hash = parts[2]
+	default:
+		err = ErrInvalidStub
+	}
+
+	if roundsStr != "" {
+		if !strings.HasPrefix(roundsStr, "rounds=") {
+			err = ErrInvalidStub
+			return
+		}
+
+		roundsStr = roundsStr[7:]
+		var n uint64
+		n, err = strconv.ParseUint(roundsStr, 10, 31)
+		if err != nil {
+			err = ErrInvalidStub
+			return
+		}
+
+		rounds = int(n)
+
+		if rounds < MinimumRounds || rounds > MaximumRounds {
+			err = ErrInvalidRounds
+			return
+		}
+	} else {
+		rounds = DefaultRounds
+	}
+
+	return
+}

vendor/gopkg.in/hlandau/passlib.v1/hash/sha2crypt/raw/sha2crypt.go

@@ -0,0 +1,187 @@
+// Package raw provides a raw implementation of the sha256-crypt and sha512-crypt primitives.
+package raw
+
+import "io"
+import "fmt"
+import "hash"
+import "crypto/sha256"
+import "crypto/sha512"
+
+// The minimum number of rounds permissible for sha256-crypt and sha512-crypt.
+const MinimumRounds = 1000
+
+// The maximum number of rounds permissible for sha256-crypt and sha512-crypt.
+// Don't use this!
+const MaximumRounds = 999999999
+
+// This is the 'default' number of rounds for sha256-crypt and sha512-crypt. If
+// this rounds value is used the number of rounds is not explicitly specified
+// in the modular crypt format, as it is the default.
+const DefaultRounds = 5000
+
+// This is the recommended number of rounds for sha256-crypt and sha512-crypt.
+// This may change with subsequent releases of this package. It is recommended
+// that you invoke sha256-crypt or sha512-crypt with this value, or a value
+// proportional to it.
+const RecommendedRounds = 10000
+
+// Calculates sha256-crypt. The password must be in plaintext and be a UTF-8
+// string.
+//
+// The salt must be a valid ASCII between 0 and 16 characters in length
+// inclusive.
+//
+// See the constants in this package for suggested values for rounds.
+//
+// Rounds must be in the range 1000 <= rounds <= 999999999. The function panics
+// if this is not the case.
+//
+// The output is in modular crypt format.
+func Crypt256(password, salt string, rounds int) string {
+	return "$5" + shaCrypt(password, salt, rounds, sha256.New, transpose256)
+}
+
+// Calculates sha256-crypt. The password must be in plaintext and be a UTF-8
+// string.
+//
+// The salt must be a valid ASCII between 0 and 16 characters in length
+// inclusive.
+//
+// See the constants in this package for suggested values for rounds.
+//
+// Rounds must be in the range 1000 <= rounds <= 999999999. The function panics
+// if this is not the case.
+//
+// The output is in modular crypt format.
+func Crypt512(password, salt string, rounds int) string {
+	return "$6" + shaCrypt(password, salt, rounds, sha512.New, transpose512)
+}
+
+func shaCrypt(password, salt string, rounds int, newHash func() hash.Hash, transpose func(b []byte)) string {
+	if rounds < MinimumRounds || rounds > MaximumRounds {
+		panic("sha256-crypt rounds must be in 1000 <= rounds <= 999999999")
+	}
+
+	passwordb := []byte(password)
+	saltb := []byte(salt)
+	if len(saltb) > 16 {
+		panic("salt must not exceed 16 bytes")
+	}
+
+	// B
+	b := newHash()
+	b.Write(passwordb)
+	b.Write(saltb)
+	b.Write(passwordb)
+	bsum := b.Sum(nil)
+
+	// A
+	a := newHash()
+	a.Write(passwordb)
+	a.Write(saltb)
+	repeat(a, bsum, len(passwordb))
+
+	plen := len(passwordb)
+	for plen != 0 {
+		if (plen & 1) != 0 {
+			a.Write(bsum)
+		} else {
+			a.Write(passwordb)
+		}
+		plen = plen >> 1
+	}
+
+	asum := a.Sum(nil)
+
+	// DP
+	dp := newHash()
+	for i := 0; i < len(passwordb); i++ {
+		dp.Write(passwordb)
+	}
+
+	dpsum := dp.Sum(nil)
+
+	// P
+	p := make([]byte, len(passwordb))
+	repeatTo(p, dpsum)
+
+	// DS
+	ds := newHash()
+	for i := 0; i < (16 + int(asum[0])); i++ {
+		ds.Write(saltb)
+	}
+
+	dssum := ds.Sum(nil)[0:len(saltb)]
+
+	// S
+	s := make([]byte, len(saltb))
+	repeatTo(s, dssum)
+
+	// C
+	cur := asum[:]
+	for i := 0; i < rounds; i++ {
+		c := newHash()
+		if (i & 1) != 0 {
+			c.Write(p)
+		} else {
+			c.Write(cur)
+		}
+		if (i % 3) != 0 {
+			c.Write(s)
+		}
+		if (i % 7) != 0 {
+			c.Write(p)
+		}
+		if (i & 1) == 0 {
+			c.Write(p)
+		} else {
+			c.Write(cur)
+		}
+		cur = c.Sum(nil)[:]
+	}
+
+	// Transposition
+	transpose(cur)
+
+	// Hash
+	hstr := EncodeBase64(cur)
+
+	if rounds == DefaultRounds {
+		return fmt.Sprintf("$%s$%s", salt, hstr)
+	}
+
+	return fmt.Sprintf("$rounds=%d$%s$%s", rounds, salt, hstr)
+}
+
+func repeat(w io.Writer, b []byte, sz int) {
+	var i int
+	for i = 0; (i + len(b)) <= sz; i += len(b) {
+		w.Write(b)
+	}
+	w.Write(b[0 : sz-i])
+}
+
+func repeatTo(out []byte, b []byte) {
+	if len(b) == 0 {
+		return
+	}
+
+	var i int
+	for i = 0; (i + len(b)) <= len(out); i += len(b) {
+		copy(out[i:], b)
+	}
+	copy(out[i:], b)
+}
+
+func transpose256(b []byte) {
+	b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7], b[8], b[9], b[10], b[11], b[12], b[13], b[14], b[15], b[16], b[17], b[18], b[19], b[20], b[21], b[22], b[23], b[24], b[25], b[26], b[27], b[28], b[29], b[30], b[31] =
+		b[20], b[10], b[0], b[11], b[1], b[21], b[2], b[22], b[12], b[23], b[13], b[3], b[14], b[4], b[24], b[5], b[25], b[15], b[26], b[16], b[6], b[17], b[7], b[27], b[8], b[28], b[18], b[29], b[19], b[9], b[30], b[31]
+}
+
+func transpose512(b []byte) {
+	b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7], b[8], b[9], b[10], b[11], b[12], b[13], b[14], b[15], b[16], b[17], b[18], b[19], b[20], b[21], b[22], b[23], b[24], b[25], b[26], b[27], b[28], b[29], b[30], b[31], b[32], b[33], b[34], b[35], b[36], b[37], b[38], b[39], b[40], b[41], b[42], b[43], b[44], b[45], b[46], b[47], b[48], b[49], b[50], b[51], b[52], b[53], b[54], b[55], b[56], b[57], b[58], b[59], b[60], b[61], b[62], b[63] =
+		b[42], b[21], b[0], b[1], b[43], b[22], b[23], b[2], b[44], b[45], b[24], b[3], b[4], b[46], b[25], b[26], b[5], b[47], b[48], b[27], b[6], b[7], b[49], b[28], b[29], b[8], b[50], b[51], b[30], b[9], b[10], b[52], b[31], b[32], b[11], b[53], b[54], b[33], b[12], b[13], b[55], b[34], b[35], b[14], b[56], b[57], b[36], b[15], b[16], b[58], b[37], b[38], b[17], b[59], b[60], b[39], b[18], b[19], b[61], b[40], b[41], b[20], b[62], b[63]
+}
+
+// © 2008-2012 Assurance Technologies LLC.  (Python passlib)  BSD License
+// © 2014 Hugo Landau <hlandau@devever.net>  BSD License

vendor/gopkg.in/hlandau/passlib.v1/hash/sha2crypt/sha2crypt.go

@@ -0,0 +1,147 @@
+// Package sha2crypt implements sha256-crypt and sha512-crypt.
+package sha2crypt
+
+import "fmt"
+import "expvar"
+import "crypto/rand"
+import "gopkg.in/hlandau/passlib.v1/hash/sha2crypt/raw"
+import "gopkg.in/hlandau/passlib.v1/abstract"
+
+var cSHA2CryptHashCalls = expvar.NewInt("passlib.sha2crypt.hashCalls")
+var cSHA2CryptVerifyCalls = expvar.NewInt("passlib.sha2crypt.verifyCalls")
+
+// An implementation of Scheme performing sha256-crypt.
+//
+// The number of rounds is raw.RecommendedRounds.
+var Crypter256 abstract.Scheme
+
+// An implementation of Scheme performing sha512-crypt.
+//
+// The number of rounds is raw.RecommendedRounds.
+var Crypter512 abstract.Scheme
+
+func init() {
+	Crypter256 = NewCrypter256(raw.RecommendedRounds)
+	Crypter512 = NewCrypter512(raw.RecommendedRounds)
+}
+
+// Returns a Scheme implementing sha256-crypt using the number of rounds
+// specified.
+func NewCrypter256(rounds int) abstract.Scheme {
+	return &sha2Crypter{false, rounds}
+}
+
+// Returns a Scheme implementing sha512-crypt using the number of rounds
+// specified.
+func NewCrypter512(rounds int) abstract.Scheme {
+	return &sha2Crypter{true, rounds}
+}
+
+type sha2Crypter struct {
+	sha512 bool
+	rounds int
+}
+
+// Changes the default rounds for the crypter. Be warned that this
+// is a global setting. The default default value is RecommendedRounds.
+func (c *sha2Crypter) SetRounds(rounds int) error {
+	if rounds < raw.MinimumRounds || rounds > raw.MaximumRounds {
+		return raw.ErrInvalidRounds
+	}
+
+	c.rounds = rounds
+	return nil
+}
+
+func (c *sha2Crypter) SupportsStub(stub string) bool {
+	if len(stub) < 3 || stub[0] != '$' || stub[2] != '$' {
+		return false
+	}
+	return (stub[1] == '5' && !c.sha512) || (stub[1] == '6' && c.sha512)
+}
+
+func (c *sha2Crypter) Hash(password string) (string, error) {
+	cSHA2CryptHashCalls.Add(1)
+
+	stub, err := c.makeStub()
+	if err != nil {
+		return "", err
+	}
+
+	_, newHash, _, _, err := c.hash(password, stub)
+	return newHash, err
+}
+
+func (c *sha2Crypter) Verify(password, hash string) (err error) {
+	cSHA2CryptVerifyCalls.Add(1)
+
+	_, newHash, _, _, err := c.hash(password, hash)
+	if err == nil && !abstract.SecureCompare(hash, newHash) {
+		err = abstract.ErrInvalidPassword
+	}
+
+	return
+}
+
+func (c *sha2Crypter) NeedsUpdate(stub string) bool {
+	_, salt, _, rounds, err := raw.Parse(stub)
+	if err != nil {
+		return false // ...
+	}
+
+	return c.needsUpdate(salt, rounds)
+}
+
+func (c *sha2Crypter) needsUpdate(salt string, rounds int) bool {
+	return rounds < c.rounds || len(salt) < 16
+}
+
+var errInvalidStub = fmt.Errorf("invalid sha2 password stub")
+
+func (c *sha2Crypter) hash(password, stub string) (oldHash, newHash, salt string, rounds int, err error) {
+	isSHA512, salt, oldHash, rounds, err := raw.Parse(stub)
+	if err != nil {
+		return "", "", "", 0, err
+	}
+
+	if isSHA512 != c.sha512 {
+		return "", "", "", 0, errInvalidStub
+	}
+
+	if c.sha512 {
+		return oldHash, raw.Crypt512(password, salt, rounds), salt, rounds, nil
+	}
+
+	return oldHash, raw.Crypt256(password, salt, rounds), salt, rounds, nil
+}
+
+func (c *sha2Crypter) makeStub() (string, error) {
+	ch := "5"
+	if c.sha512 {
+		ch = "6"
+	}
+
+	buf := make([]byte, 12)
+	_, err := rand.Read(buf)
+	if err != nil {
+		return "", err
+	}
+
+	salt := raw.EncodeBase64(buf)[0:16]
+
+	if c.rounds == raw.DefaultRounds {
+		return fmt.Sprintf("$%s$%s", ch, salt), nil
+	}
+
+	return fmt.Sprintf("$%s$rounds=%d$%s", ch, c.rounds, salt), nil
+}
+
+func (c *sha2Crypter) String() string {
+	if c.sha512 {
+		return fmt.Sprintf("sha512-crypt(%d)", c.rounds)
+	} else {
+		return fmt.Sprintf("sha256-crypt(%d)", c.rounds)
+	}
+}
+
+// © 2014 Hugo Landau <hlandau@devever.net>  BSD License