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author | Péter Szilágyi <peterke@gmail.com> | 2016-11-03 00:22:53 +0800 |
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committer | Péter Szilágyi <peterke@gmail.com> | 2016-11-03 16:32:57 +0800 |
commit | bad0de0dcbae82d96f68d1eec1701042d5dfa985 (patch) | |
tree | 7b6e585f47a0c4bb9f6e3a17d549ca1d0ddbd642 /vendor/golang.org/x/crypto/openpgp/s2k/s2k.go | |
parent | 3b62c145f8d699767e13770d1bb21d07c2ba9b46 (diff) | |
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vendor: pull in azure sdk and openpgp signer
Diffstat (limited to 'vendor/golang.org/x/crypto/openpgp/s2k/s2k.go')
-rw-r--r-- | vendor/golang.org/x/crypto/openpgp/s2k/s2k.go | 273 |
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 000000000..4b9a44ca2 --- /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 +} |