diff options
Diffstat (limited to 'vendor/golang.org/x/crypto/openpgp/clearsign')
| -rw-r--r-- | vendor/golang.org/x/crypto/openpgp/clearsign/clearsign.go | 376 |
1 files changed, 376 insertions, 0 deletions
diff --git a/vendor/golang.org/x/crypto/openpgp/clearsign/clearsign.go b/vendor/golang.org/x/crypto/openpgp/clearsign/clearsign.go new file mode 100644 index 00000000..def4caba --- /dev/null +++ b/vendor/golang.org/x/crypto/openpgp/clearsign/clearsign.go @@ -0,0 +1,376 @@ +// Copyright 2012 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 clearsign generates and processes OpenPGP, clear-signed data. See +// RFC 4880, section 7. +// +// Clearsigned messages are cryptographically signed, but the contents of the +// message are kept in plaintext so that it can be read without special tools. +package clearsign // import "golang.org/x/crypto/openpgp/clearsign" + +import ( + "bufio" + "bytes" + "crypto" + "hash" + "io" + "net/textproto" + "strconv" + + "golang.org/x/crypto/openpgp/armor" + "golang.org/x/crypto/openpgp/errors" + "golang.org/x/crypto/openpgp/packet" +) + +// A Block represents a clearsigned message. A signature on a Block can +// be checked by passing Bytes into openpgp.CheckDetachedSignature. +type Block struct { + Headers textproto.MIMEHeader // Optional message headers + Plaintext []byte // The original message text + Bytes []byte // The signed message + ArmoredSignature *armor.Block // The signature block +} + +// start is the marker which denotes the beginning of a clearsigned message. +var start = []byte("\n-----BEGIN PGP SIGNED MESSAGE-----") + +// dashEscape is prefixed to any lines that begin with a hyphen so that they +// can't be confused with endText. +var dashEscape = []byte("- ") + +// endText is a marker which denotes the end of the message and the start of +// an armored signature. +var endText = []byte("-----BEGIN PGP SIGNATURE-----") + +// end is a marker which denotes the end of the armored signature. +var end = []byte("\n-----END PGP SIGNATURE-----") + +var crlf = []byte("\r\n") +var lf = byte('\n') + +// getLine returns the first \r\n or \n delineated line from the given byte +// array. The line does not include the \r\n or \n. The remainder of the byte +// array (also not including the new line bytes) is also returned and this will +// always be smaller than the original argument. +func getLine(data []byte) (line, rest []byte) { + i := bytes.Index(data, []byte{'\n'}) + var j int + if i < 0 { + i = len(data) + j = i + } else { + j = i + 1 + if i > 0 && data[i-1] == '\r' { + i-- + } + } + return data[0:i], data[j:] +} + +// Decode finds the first clearsigned message in data and returns it, as well +// as the suffix of data which remains after the message. +func Decode(data []byte) (b *Block, rest []byte) { + // start begins with a newline. However, at the very beginning of + // the byte array, we'll accept the start string without it. + rest = data + if bytes.HasPrefix(data, start[1:]) { + rest = rest[len(start)-1:] + } else if i := bytes.Index(data, start); i >= 0 { + rest = rest[i+len(start):] + } else { + return nil, data + } + + // Consume the start line. + _, rest = getLine(rest) + + var line []byte + b = &Block{ + Headers: make(textproto.MIMEHeader), + } + + // Next come a series of header lines. + for { + // This loop terminates because getLine's second result is + // always smaller than its argument. + if len(rest) == 0 { + return nil, data + } + // An empty line marks the end of the headers. + if line, rest = getLine(rest); len(line) == 0 { + break + } + + i := bytes.Index(line, []byte{':'}) + if i == -1 { + return nil, data + } + + key, val := line[0:i], line[i+1:] + key = bytes.TrimSpace(key) + val = bytes.TrimSpace(val) + b.Headers.Add(string(key), string(val)) + } + + firstLine := true + for { + start := rest + + line, rest = getLine(rest) + if len(line) == 0 && len(rest) == 0 { + // No armored data was found, so this isn't a complete message. + return nil, data + } + if bytes.Equal(line, endText) { + // Back up to the start of the line because armor expects to see the + // header line. + rest = start + break + } + + // The final CRLF isn't included in the hash so we don't write it until + // we've seen the next line. + if firstLine { + firstLine = false + } else { + b.Bytes = append(b.Bytes, crlf...) + } + + if bytes.HasPrefix(line, dashEscape) { + line = line[2:] + } + line = bytes.TrimRight(line, " \t") + b.Bytes = append(b.Bytes, line...) + + b.Plaintext = append(b.Plaintext, line...) + b.Plaintext = append(b.Plaintext, lf) + } + + // We want to find the extent of the armored data (including any newlines at + // the end). + i := bytes.Index(rest, end) + if i == -1 { + return nil, data + } + i += len(end) + for i < len(rest) && (rest[i] == '\r' || rest[i] == '\n') { + i++ + } + armored := rest[:i] + rest = rest[i:] + + var err error + b.ArmoredSignature, err = armor.Decode(bytes.NewBuffer(armored)) + if err != nil { + return nil, data + } + + return b, rest +} + +// A dashEscaper is an io.WriteCloser which processes the body of a clear-signed +// message. The clear-signed message is written to buffered and a hash, suitable +// for signing, is maintained in h. +// +// When closed, an armored signature is created and written to complete the +// message. +type dashEscaper struct { + buffered *bufio.Writer + h hash.Hash + hashType crypto.Hash + + atBeginningOfLine bool + isFirstLine bool + + whitespace []byte + byteBuf []byte // a one byte buffer to save allocations + + privateKey *packet.PrivateKey + config *packet.Config +} + +func (d *dashEscaper) Write(data []byte) (n int, err error) { + for _, b := range data { + d.byteBuf[0] = b + + if d.atBeginningOfLine { + // The final CRLF isn't included in the hash so we have to wait + // until this point (the start of the next line) before writing it. + if !d.isFirstLine { + d.h.Write(crlf) + } + d.isFirstLine = false + } + + // Any whitespace at the end of the line has to be removed so we + // buffer it until we find out whether there's more on this line. + if b == ' ' || b == '\t' || b == '\r' { + d.whitespace = append(d.whitespace, b) + d.atBeginningOfLine = false + continue + } + + if d.atBeginningOfLine { + // At the beginning of a line, hyphens have to be escaped. + if b == '-' { + // The signature isn't calculated over the dash-escaped text so + // the escape is only written to buffered. + if _, err = d.buffered.Write(dashEscape); err != nil { + return + } + d.h.Write(d.byteBuf) + d.atBeginningOfLine = false + } else if b == '\n' { + // Nothing to do because we delay writing CRLF to the hash. + } else { + d.h.Write(d.byteBuf) + d.atBeginningOfLine = false + } + if err = d.buffered.WriteByte(b); err != nil { + return + } + } else { + if b == '\n' { + // We got a raw \n. Drop any trailing whitespace and write a + // CRLF. + d.whitespace = d.whitespace[:0] + // We delay writing CRLF to the hash until the start of the + // next line. + if err = d.buffered.WriteByte(b); err != nil { + return + } + d.atBeginningOfLine = true + } else { + // Any buffered whitespace wasn't at the end of the line so + // we need to write it out. + if len(d.whitespace) > 0 { + d.h.Write(d.whitespace) + if _, err = d.buffered.Write(d.whitespace); err != nil { + return + } + d.whitespace = d.whitespace[:0] + } + d.h.Write(d.byteBuf) + if err = d.buffered.WriteByte(b); err != nil { + return + } + } + } + } + + n = len(data) + return +} + +func (d *dashEscaper) Close() (err error) { + if !d.atBeginningOfLine { + if err = d.buffered.WriteByte(lf); err != nil { + return + } + } + sig := new(packet.Signature) + sig.SigType = packet.SigTypeText + sig.PubKeyAlgo = d.privateKey.PubKeyAlgo + sig.Hash = d.hashType + sig.CreationTime = d.config.Now() + sig.IssuerKeyId = &d.privateKey.KeyId + + if err = sig.Sign(d.h, d.privateKey, d.config); err != nil { + return + } + + out, err := armor.Encode(d.buffered, "PGP SIGNATURE", nil) + if err != nil { + return + } + + if err = sig.Serialize(out); err != nil { + return + } + if err = out.Close(); err != nil { + return + } + if err = d.buffered.Flush(); err != nil { + return + } + return +} + +// Encode returns a WriteCloser which will clear-sign a message with privateKey +// and write it to w. If config is nil, sensible defaults are used. +func Encode(w io.Writer, privateKey *packet.PrivateKey, config *packet.Config) (plaintext io.WriteCloser, err error) { + if privateKey.Encrypted { + return nil, errors.InvalidArgumentError("signing key is encrypted") + } + + hashType := config.Hash() + name := nameOfHash(hashType) + if len(name) == 0 { + return nil, errors.UnsupportedError("unknown hash type: " + strconv.Itoa(int(hashType))) + } + + if !hashType.Available() { + return nil, errors.UnsupportedError("unsupported hash type: " + strconv.Itoa(int(hashType))) + } + h := hashType.New() + + buffered := bufio.NewWriter(w) + // start has a \n at the beginning that we don't want here. + if _, err = buffered.Write(start[1:]); err != nil { + return + } + if err = buffered.WriteByte(lf); err != nil { + return + } + if _, err = buffered.WriteString("Hash: "); err != nil { + return + } + if _, err = buffered.WriteString(name); err != nil { + return + } + if err = buffered.WriteByte(lf); err != nil { + return + } + if err = buffered.WriteByte(lf); err != nil { + return + } + + plaintext = &dashEscaper{ + buffered: buffered, + h: h, + hashType: hashType, + + atBeginningOfLine: true, + isFirstLine: true, + + byteBuf: make([]byte, 1), + + privateKey: privateKey, + config: config, + } + + return +} + +// nameOfHash returns the OpenPGP name for the given hash, or the empty string +// if the name isn't known. See RFC 4880, section 9.4. +func nameOfHash(h crypto.Hash) string { + switch h { + case crypto.MD5: + return "MD5" + case crypto.SHA1: + return "SHA1" + case crypto.RIPEMD160: + return "RIPEMD160" + case crypto.SHA224: + return "SHA224" + case crypto.SHA256: + return "SHA256" + case crypto.SHA384: + return "SHA384" + case crypto.SHA512: + return "SHA512" + } + return "" +} |