1 files changed, 273 insertions, 0 deletions
diff --git a/vendor/golang.org/x/crypto/openpgp/s2k/s2k.go b/vendor/golang.org/x/crypto/openpgp/s2k/s2k.go
new file mode 100644
index 00000000..4b9a44ca
--- /dev/null
+++ b/vendor/golang.org/x/crypto/openpgp/s2k/s2k.go
@@ -0,0 +1,273 @@
+// Copyright 2011 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 s2k implements the various OpenPGP string-to-key transforms as
+// specified in RFC 4800 section 3.7.1.
+package s2k // import "golang.org/x/crypto/openpgp/s2k"
+
+import (
+	"crypto"
+	"hash"
+	"io"
+	"strconv"
+
+	"golang.org/x/crypto/openpgp/errors"
+)
+
+// Config collects configuration parameters for s2k key-stretching
+// transformatioms. A nil *Config is valid and results in all default
+// values. Currently, Config is used only by the Serialize function in
+// this package.
+type Config struct {
+	// Hash is the default hash function to be used. If
+	// nil, SHA1 is used.
+	Hash crypto.Hash
+	// S2KCount is only used for symmetric encryption. It
+	// determines the strength of the passphrase stretching when
+	// the said passphrase is hashed to produce a key. S2KCount
+	// should be between 1024 and 65011712, inclusive. If Config
+	// is nil or S2KCount is 0, the value 65536 used. Not all
+	// values in the above range can be represented. S2KCount will
+	// be rounded up to the next representable value if it cannot
+	// be encoded exactly. When set, it is strongly encrouraged to
+	// use a value that is at least 65536. See RFC 4880 Section
+	// 3.7.1.3.
+	S2KCount int
+}
+
+func (c *Config) hash() crypto.Hash {
+	if c == nil || uint(c.Hash) == 0 {
+		// SHA1 is the historical default in this package.
+		return crypto.SHA1
+	}
+
+	return c.Hash
+}
+
+func (c *Config) encodedCount() uint8 {
+	if c == nil || c.S2KCount == 0 {
+		return 96 // The common case. Correspoding to 65536
+	}
+
+	i := c.S2KCount
+	switch {
+	// Behave like GPG. Should we make 65536 the lowest value used?
+	case i < 1024:
+		i = 1024
+	case i > 65011712:
+		i = 65011712
+	}
+
+	return encodeCount(i)
+}
+
+// encodeCount converts an iterative "count" in the range 1024 to
+// 65011712, inclusive, to an encoded count. The return value is the
+// octet that is actually stored in the GPG file. encodeCount panics
+// if i is not in the above range (encodedCount above takes care to
+// pass i in the correct range). See RFC 4880 Section 3.7.7.1.
+func encodeCount(i int) uint8 {
+	if i < 1024 || i > 65011712 {
+		panic("count arg i outside the required range")
+	}
+
+	for encoded := 0; encoded < 256; encoded++ {
+		count := decodeCount(uint8(encoded))
+		if count >= i {
+			return uint8(encoded)
+		}
+	}
+
+	return 255
+}
+
+// decodeCount returns the s2k mode 3 iterative "count" corresponding to
+// the encoded octet c.
+func decodeCount(c uint8) int {
+	return (16 + int(c&15)) << (uint32(c>>4) + 6)
+}
+
+// Simple writes to out the result of computing the Simple S2K function (RFC
+// 4880, section 3.7.1.1) using the given hash and input passphrase.
+func Simple(out []byte, h hash.Hash, in []byte) {
+	Salted(out, h, in, nil)
+}
+
+var zero [1]byte
+
+// Salted writes to out the result of computing the Salted S2K function (RFC
+// 4880, section 3.7.1.2) using the given hash, input passphrase and salt.
+func Salted(out []byte, h hash.Hash, in []byte, salt []byte) {
+	done := 0
+	var digest []byte
+
+	for i := 0; done < len(out); i++ {
+		h.Reset()
+		for j := 0; j < i; j++ {
+			h.Write(zero[:])
+		}
+		h.Write(salt)
+		h.Write(in)
+		digest = h.Sum(digest[:0])
+		n := copy(out[done:], digest)
+		done += n
+	}
+}
+
+// Iterated writes to out the result of computing the Iterated and Salted S2K
+// function (RFC 4880, section 3.7.1.3) using the given hash, input passphrase,
+// salt and iteration count.
+func Iterated(out []byte, h hash.Hash, in []byte, salt []byte, count int) {
+	combined := make([]byte, len(in)+len(salt))
+	copy(combined, salt)
+	copy(combined[len(salt):], in)
+
+	if count < len(combined) {
+		count = len(combined)
+	}
+
+	done := 0
+	var digest []byte
+	for i := 0; done < len(out); i++ {
+		h.Reset()
+		for j := 0; j < i; j++ {
+			h.Write(zero[:])
+		}
+		written := 0
+		for written < count {
+			if written+len(combined) > count {
+				todo := count - written
+				h.Write(combined[:todo])
+				written = count
+			} else {
+				h.Write(combined)
+				written += len(combined)
+			}
+		}
+		digest = h.Sum(digest[:0])
+		n := copy(out[done:], digest)
+		done += n
+	}
+}
+
+// Parse reads a binary specification for a string-to-key transformation from r
+// and returns a function which performs that transform.
+func Parse(r io.Reader) (f func(out, in []byte), err error) {
+	var buf [9]byte
+
+	_, err = io.ReadFull(r, buf[:2])
+	if err != nil {
+		return
+	}
+
+	hash, ok := HashIdToHash(buf[1])
+	if !ok {
+		return nil, errors.UnsupportedError("hash for S2K function: " + strconv.Itoa(int(buf[1])))
+	}
+	if !hash.Available() {
+		return nil, errors.UnsupportedError("hash not available: " + strconv.Itoa(int(hash)))
+	}
+	h := hash.New()
+
+	switch buf[0] {
+	case 0:
+		f := func(out, in []byte) {
+			Simple(out, h, in)
+		}
+		return f, nil
+	case 1:
+		_, err = io.ReadFull(r, buf[:8])
+		if err != nil {
+			return
+		}
+		f := func(out, in []byte) {
+			Salted(out, h, in, buf[:8])
+		}
+		return f, nil
+	case 3:
+		_, err = io.ReadFull(r, buf[:9])
+		if err != nil {
+			return
+		}
+		count := decodeCount(buf[8])
+		f := func(out, in []byte) {
+			Iterated(out, h, in, buf[:8], count)
+		}
+		return f, nil
+	}
+
+	return nil, errors.UnsupportedError("S2K function")
+}
+
+// Serialize salts and stretches the given passphrase and writes the
+// resulting key into key. It also serializes an S2K descriptor to
+// w. The key stretching can be configured with c, which may be
+// nil. In that case, sensible defaults will be used.
+func Serialize(w io.Writer, key []byte, rand io.Reader, passphrase []byte, c *Config) error {
+	var buf [11]byte
+	buf[0] = 3 /* iterated and salted */
+	buf[1], _ = HashToHashId(c.hash())
+	salt := buf[2:10]
+	if _, err := io.ReadFull(rand, salt); err != nil {
+		return err
+	}
+	encodedCount := c.encodedCount()
+	count := decodeCount(encodedCount)
+	buf[10] = encodedCount
+	if _, err := w.Write(buf[:]); err != nil {
+		return err
+	}
+
+	Iterated(key, c.hash().New(), passphrase, salt, count)
+	return nil
+}
+
+// hashToHashIdMapping contains pairs relating OpenPGP's hash identifier with
+// Go's crypto.Hash type. See RFC 4880, section 9.4.
+var hashToHashIdMapping = []struct {
+	id   byte
+	hash crypto.Hash
+	name string
+}{
+	{1, crypto.MD5, "MD5"},
+	{2, crypto.SHA1, "SHA1"},
+	{3, crypto.RIPEMD160, "RIPEMD160"},
+	{8, crypto.SHA256, "SHA256"},
+	{9, crypto.SHA384, "SHA384"},
+	{10, crypto.SHA512, "SHA512"},
+	{11, crypto.SHA224, "SHA224"},
+}
+
+// HashIdToHash returns a crypto.Hash which corresponds to the given OpenPGP
+// hash id.
+func HashIdToHash(id byte) (h crypto.Hash, ok bool) {
+	for _, m := range hashToHashIdMapping {
+		if m.id == id {
+			return m.hash, true
+		}
+	}
+	return 0, false
+}
+
+// HashIdToString returns the name of the hash function corresponding to the
+// given OpenPGP hash id.
+func HashIdToString(id byte) (name string, ok bool) {
+	for _, m := range hashToHashIdMapping {
+		if m.id == id {
+			return m.name, true
+		}
+	}
+
+	return "", false
+}
+
+// HashIdToHash returns an OpenPGP hash id which corresponds the given Hash.
+func HashToHashId(h crypto.Hash) (id byte, ok bool) {
+	for _, m := range hashToHashIdMapping {
+		if m.hash == h {
+			return m.id, true
+		}
+	}
+	return 0, false
+}