1 // Package document implements epoint document parsing and creation.
3 // An epoint document is an OpenPGP (RFC 4880) clear signed
4 // utf-8 text of key-value pairs.
5 // The body contains a content-type MIME header so the document
6 // can be used in OpenPGP/MIME (RFC 3156) emails.
7 // The format of the key-value pairs are similar to MIME header
8 // fields: keys and values are separated by ": ", repeated keys
9 // are not allowed, long values can be split before a space.
13 // -----BEGIN PGP SIGNED MESSAGE-----
16 // Content-Type: text/plain.epoint.type; charset=utf-8
19 // Another-Key: Value2
23 // -----BEGIN PGP SIGNATURE-----
26 // -----END PGP SIGNATURE-----
29 // TODO: error wrapper (so reporting to user or creating bounce cert is simple)
30 // TODO: optional fields: exact semantics ("" vs "-" vs nil)
31 // TODO: trailing space handling in ParseFields
32 // TODO: fields of notice (last notice, serial, failure notice,..)
33 // TODO: limits and cert type specific input validation
34 // TODO: fix Cert mess
35 // TODO: nonce is id, id is even number of hex digits
36 // TODO: denom, issuer from key (key representation: armor?)
42 "crypto/openpgp/armor"
43 "crypto/openpgp/packet"
56 MaxLineLength = 160 // 1 sha512 + 1 key (without \n)
57 MaxValueLength = 1300 // 20 sha256 space separated (without \n)
59 MaxDenominationLength = 100
62 const ClearSignedHeader = "-----BEGIN PGP SIGNED MESSAGE-----"
64 // MIME type for epoint documents, see RFC 4288
65 var ContentType = map[string]string{
66 "Draft": "text/vnd.epoint.draft; charset=utf-8",
67 "Notice": "text/vnd.epoint.notice; charset=utf-8",
68 "DebitCert": "text/vnd.epoint.debit; charset=utf-8",
69 "CreditCert": "text/vnd.epoint.credit; charset=utf-8",
70 "BounceCert": "text/vnd.epoint.bounce; charset=utf-8",
73 // OpenPGP signed cleartext document representation
75 // Sign and CleanSigned sets Hash for FormatSigned
78 // Signed text (no dash escape, no trailing space, \n new lines)
80 // Armored detached text signature of the Body
84 // parsed epoint document
85 type Document struct {
87 Fields map[string]string
91 var fieldtype = map[string]string{
93 "Authorized-By": "id",
98 "Denomination": "text",
102 "Expiry-Date": "date",
106 "Last-Credit-Serial": "int",
107 "Last-Debit-Serial": "int",
108 "Maturity-Date": "date",
115 var fieldname = map[string]string{
116 "AuthorizedBy": "Authorized-By",
117 "DebitCert": "Debit-Cert",
118 "ExpiryDate": "Expiry-Date",
119 "LastCert": "Last-Cert",
120 "LastCreditSerial": "Last-Credit-Serial",
121 "LastDebitSerial": "Last-Debit-Serial",
122 "MaturityDate": "Maturity-Date",
132 MaturityDate *int64 // optional
133 ExpiryDate *int64 // optional
135 Notes *string // optional
141 Notes *string // optional
142 References []string // may be empty (startup notice)
155 Beneficiary *string // only in debit cert
156 Drawer *string // only in credit cert
157 DebitCert *string // only in credit cert
159 Notes *string // optional
160 LastDebitSerial int64 // 0 if none
161 LastCreditSerial int64 // 0 if none
162 LastCert *string // nil if serial == 1
166 type DebitCert struct {
177 Notes *string // optional
178 LastDebitSerial int64 // 0 if none
179 LastCreditSerial int64 // 0 if none
180 LastCert *string // nil if serial == 1
184 type CreditCert struct {
196 Notes *string // optional
197 LastDebitSerial int64 // 0 if none
198 LastCreditSerial int64 // 0 if none
199 LastCert *string // ? if serial == 1
203 type BounceCert struct {
206 LastCert *string // optional
207 Balance int64 // 0 if none
210 Notes *string // optional
214 func ToCert(v interface{}) (cert *Cert, err error) {
216 switch x := v.(type) {
219 cert.Beneficiary = &x.Beneficiary
221 cert.Holder = x.Holder
222 cert.Serial = x.Serial
223 cert.Balance = x.Balance
224 cert.Denomination = x.Denomination
225 cert.Issuer = x.Issuer
227 cert.Difference = x.Difference
229 cert.AuthorizedBy = x.AuthorizedBy
231 cert.LastDebitSerial = x.LastDebitSerial
232 cert.LastCreditSerial = x.LastCreditSerial
233 cert.LastCert = x.LastCert
234 cert.References = x.References
238 cert.Drawer = &x.Drawer
239 cert.DebitCert = &x.DebitCert
241 cert.Holder = x.Holder
242 cert.Serial = x.Serial
243 cert.Balance = x.Balance
244 cert.Denomination = x.Denomination
245 cert.Issuer = x.Issuer
247 cert.Difference = x.Difference
249 cert.AuthorizedBy = x.AuthorizedBy
251 cert.LastDebitSerial = x.LastDebitSerial
252 cert.LastCreditSerial = x.LastCreditSerial
253 cert.LastCert = x.LastCert
254 cert.References = x.References
256 err = fmt.Errorf("ToCert: only debit or credit document can be converted to cert")
261 // sha1 sum of the (cleaned) document body as uppercase hex string
262 func Id(c *Signed) string {
265 return fmt.Sprintf("%040X", h.Sum())
268 // parse an epoint document without checking the signature and format details
269 func Parse(s []byte) (iv interface{}, c *Signed, err error) {
270 c, err = ParseSigned(s)
274 doc, err := ParseDocument(c.Body)
278 iv, err = ParseStruct(doc)
282 // format and sign an epoint document
283 func Format(iv interface{}, key *openpgp.Entity) (s []byte, c *Signed, err error) {
284 doc, err := FormatStruct(iv)
288 body, err := FormatDocument(doc)
292 c, err = Sign(body, key)
296 s, err = FormatSigned(c)
300 // verify an epoint document, return the cleaned version as well
301 func Verify(c *Signed, key openpgp.KeyRing) (err error) {
302 msg := bytes.NewBuffer(c.Body)
303 sig := bytes.NewBuffer(c.Signature)
304 // TODO: verify signature
306 // _, err = openpgp.CheckArmoredDetachedSignature(key, msg, sig)
310 // sign body with given secret key
311 func Sign(body []byte, key *openpgp.Entity) (c *Signed, err error) {
315 w := new(bytes.Buffer)
316 err = openpgp.ArmoredDetachSignText(w, key, bytes.NewBuffer(c.Body))
320 // close armored document with a \n
321 _, _ = w.Write([]byte{'\n'})
322 c.Signature = w.Bytes()
326 // split a clear signed document into body and armored signature
327 func ParseSigned(s []byte) (c *Signed, err error) {
328 // look for clear signed header
329 for !bytes.HasPrefix(s, []byte(ClearSignedHeader)) {
332 err = fmt.Errorf("ParseSigned: clear signed header is missing")
336 s = s[len(ClearSignedHeader):]
337 // end of line after the header
338 empty, s := getLine(s)
340 err = fmt.Errorf("ParseSigned: bad clear signed header")
343 // skip all hash headers, section 7.
344 for bytes.HasPrefix(s, []byte("Hash: ")) {
348 empty, s = getLine(s)
350 err = fmt.Errorf("ParseSigned: expected an empty line after armor headers")
354 for !bytes.HasPrefix(s, []byte("-----BEGIN")) {
357 // dash unescape, section 7.1.
358 if bytes.HasPrefix(line, []byte("- ")) {
361 // empty values are not supported: "Key: \n"
362 lines = append(lines, bytes.TrimRight(line, " \t"))
365 // last line is not closed by \n
366 c.Body = bytes.Join(lines, []byte("\n"))
367 // signature is just the rest of the input data
372 // clean up, check and reencode signature
373 // used on drafts before calculating the signed document hash
374 func CleanSigned(c *Signed) (err error) {
375 b, err := armor.Decode(bytes.NewBuffer(c.Signature))
379 if b.Type != openpgp.SignatureType {
380 err = fmt.Errorf("CleanSigned: invalid armored signature type")
383 p, err := packet.Read(b.Body)
387 sig, ok := p.(*packet.Signature)
389 err = fmt.Errorf("CleanSigned: invalid signature packet")
393 if sig.SigType != packet.SigTypeText {
394 err = fmt.Errorf("CleanSigned: expected text signature")
403 err = fmt.Errorf("CleanSigned: expected SHA1 or SHA256 signature hash")
406 // TODO: check CreationTime and other subpackets
407 if sig.SigLifetimeSecs != nil && *sig.SigLifetimeSecs != 0 {
408 err = fmt.Errorf("CleanSigned: signature must not expire")
411 out := new(bytes.Buffer)
412 w, err := armor.Encode(out, openpgp.SignatureType, nil)
416 err = sig.Serialize(w)
424 c.Signature = out.Bytes()
428 // create clear signed document
429 func FormatSigned(c *Signed) (data []byte, err error) {
430 s := ClearSignedHeader + "\n"
432 s += "Hash: " + c.Hash + "\n"
437 s += string(c.Signature)
442 // parse type and fields of a document body
443 func ParseDocument(body []byte) (doc *Document, err error) {
444 // parse content type header first
445 fields, s, err := ParseFields(body)
449 ctype, ok := fields["Content-Type"]
450 if len(fields) != 1 || !ok {
451 return nil, fmt.Errorf("ParseBody: expected a single Content-Type header field")
454 for k, v := range ContentType {
461 return nil, fmt.Errorf("ParseBody: unknown Content-Type: %s", ctype)
464 doc.Fields, s, err = ParseFields(s)
465 if err == nil && len(s) > 0 {
466 err = fmt.Errorf("ParseBody: extra data after fields: %q", s)
471 // create document body
472 func FormatDocument(doc *Document) (body []byte, err error) {
473 ctype, ok := ContentType[doc.Type]
475 err = fmt.Errorf("FormatDocument: unknown document type: %s", doc.Type)
478 s := "Content-Type: " + ctype + "\n\n"
479 for _, k := range doc.Order {
480 s += k + ": " + doc.Fields[k] + "\n"
482 return []byte(s), nil
485 // parse doc fields into a struct according to the document type
486 func ParseStruct(doc *Document) (iv interface{}, err error) {
499 err = fmt.Errorf("ParseStruct: unkown doc type: %s", doc.Type)
502 seen := make(map[string]bool)
503 v := reflect.ValueOf(iv).Elem()
507 for i := 0; i < n; i++ {
510 key := fieldname[ft.Name]
515 s, ok := doc.Fields[key]
517 if fv.Kind() == reflect.Ptr {
518 // missing optional key: leave the pointer as nil
522 return nil, fmt.Errorf("ParseStruct: field %s of %s is missing\n", key, t.Name())
524 if fv.Kind() == reflect.Ptr {
525 if s == "" || s == "-" {
527 // empty optional key: same as missing
530 fv.Set(reflect.New(fv.Type().Elem()))
533 switch fieldtype[key] {
536 val, err = parseId(s)
540 val, err = parseString(s)
544 val, err = strconv.Atoi64(s)
548 val, err = parseDate(s)
551 // TODO: empty slice?
552 ids := strings.Split(s, " ")
553 val := make([]string, len(ids))
554 for j, id := range ids {
555 val[j], err = parseId(id)
560 fv.Set(reflect.ValueOf(val))
562 panic("bad field type " + key + " " + fieldtype[key])
568 if len(doc.Fields)+nokey != n {
569 for k := range doc.Fields {
571 err = fmt.Errorf("ParseStruct: unknown field %s in %s", k, t.Name())
579 // turn a struct into a document
580 func FormatStruct(iv interface{}) (doc *Document, err error) {
581 v := reflect.ValueOf(iv)
582 if v.Kind() != reflect.Ptr || v.IsNil() || v.Elem().Kind() != reflect.Struct {
583 panic("input is not a pointer to struct")
590 doc.Fields = make(map[string]string)
591 for i := 0; i < n; i++ {
594 key := fieldname[ft.Name]
599 if fv.Kind() == reflect.Ptr {
601 // keep empty optional fields but mark them
607 switch fieldtype[key] {
609 val = formatId(fv.String())
611 val = formatString(fv.String())
613 val = strconv.Itoa64(fv.Int())
615 val = formatDate(fv.Int())
618 for j := 0; j < k; j++ {
622 val += formatId(fv.Index(j).String())
625 panic("bad field type " + key + " " + fieldtype[key])
628 doc.Fields[key] = val
629 doc.Order = append(doc.Order, key)
634 func ParseFields(s []byte) (fields map[string]string, rest []byte, err error) {
636 fields = make(map[string]string)
638 // \n is optional after the last field and an extra \n is allowed as well
641 line, rest = getLine(rest)
642 // empty line after the last field is consumed
646 if line[0] == ' ' && key != "" {
647 // "Key: v1\n v2\n" is equivalent to "Key: v1 v2\n"
648 fields[key] += string(line)
651 if line[0] < 'A' || line[0] > 'Z' {
652 err = fmt.Errorf("ParseFields: field name must start with an upper-case ascii letter")
655 i := bytes.IndexByte(line, ':')
657 err = fmt.Errorf("ParseFields: missing ':'")
660 key = string(line[:i])
661 if _, ok := fields[key]; ok {
662 err = fmt.Errorf("ParseFields: repeated fields are not allowed")
665 fields[key] = string(line[i+1:])
667 for key, v := range fields {
668 // either a single space follows ':' or the value is empty
669 // good: "Key:\n", "Key:\n value\n", "Key: value\n", "Key: v1\n v2\n"
670 // bad: "Key:value\n", "Key: \nvalue\n"
671 // bad but not checked here: "Key: \n", "Key: value \n", "Key:\n \n value\n"
676 err = fmt.Errorf("ParseFields: ':' is not followed by ' '")
684 // TODO: limit errors
686 func parseId(s string) (string, error) {
687 // check if hex decodable
688 // TODO: length check
689 dst := make([]byte, len(s)/2)
690 _, err := hex.Decode(dst, []byte(s))
694 func formatId(s string) string {
698 func parseString(s string) (string, error) {
699 if len(s) > MaxValueLength {
700 return "", fmt.Errorf("parseString: length limit is exceeded")
705 func formatString(s string) string {
709 func parseDate(s string) (int64, error) {
710 // TODO: fractional seconds?
711 t, err := time.Parse(time.RFC3339, s)
715 return t.Seconds(), nil
718 func formatDate(i int64) string {
719 return time.SecondsToUTC(i).Format(time.RFC3339)
722 func getLine(data []byte) (line, rest []byte) {
723 i := bytes.IndexByte(data, '\n')
728 } else if i > 0 && data[i-1] == '\r' {
731 return data[:i], data[j:]