func encryptSymmsg(password string, msg []byte) string {
symmsg := new(Symmsg)
rounds := 42
copy(symmsg.symalg[:], "SP")
copy(symmsg.kdfalg[:], "BK")
symmsg.kdfrounds = uint32(rounds)
rand.Read(symmsg.salt[:])
rand.Read(symmsg.nonce[:])
key, _ := bcrypt_pbkdf.Key([]byte(password), symmsg.salt[:], rounds, 32)
var symkey [32]byte
copy(symkey[:], key)
enc := secretbox.Seal(nil, msg, &symmsg.nonce, &symkey)
copy(symmsg.tag[:], enc[0:16])
enc = enc[16:]
var buf bytes.Buffer
buf.Write(symmsg.symalg[:])
buf.Write(symmsg.kdfalg[:])
binary.Write(&buf, binary.BigEndian, symmsg.kdfrounds)
buf.Write(symmsg.salt[:])
buf.Write(symmsg.nonce[:])
buf.Write(symmsg.tag[:])
hdr := base64.StdEncoding.EncodeToString(buf.Bytes())
hdr = wraplines(hdr)
str := base64.StdEncoding.EncodeToString(enc)
str = wraplines(str)
return "-----BEGIN REOP ENCRYPTED MESSAGE-----\n" +
"ident:<symmetric>\n" +
hdr + "\n" +
"-----BEGIN REOP ENCRYPTED MESSAGE DATA-----\n" +
str + "\n" +
"-----END REOP ENCRYPTED MESSAGE-----\n"
}
func decryptMsg(seckeyfile, pubkeyfile string, ciphertext []byte) string {
var ident string
var msglen int
var msgraw []byte
var hdr []byte
if len(ciphertext) >= 6 && string(ciphertext[0:4]) == "RBF\u0000" {
algorithm := string(ciphertext[4:6])
switch algorithm {
case "SP":
if len(ciphertext) <= 68 {
fmt.Fprintln(os.Stderr, "Badly formatted message!")
os.Exit(1)
}
hdr = ciphertext[4:68]
ciphertext = ciphertext[68:]
break
default:
nyi("Binary decryption")
}
identlen := readUint32(ciphertext[0:4])
ident = string(ciphertext[4 : 4+identlen])
msgraw = ciphertext[4+identlen:]
} else {
// in the C, these are pointers to halfway through ciphertext
// that's not fun
var begin int
var end int
var beginmsg = []byte("-----BEGIN REOP ENCRYPTED MESSAGE-----\n")
var begindata = []byte("-----BEGIN REOP ENCRYPTED MESSAGE DATA-----\n")
var endmsg = []byte("-----END REOP ENCRYPTED MESSAGE-----\n")
if bytes.Index(ciphertext, beginmsg) != 0 {
fmt.Fprintln(os.Stderr, "Badly formatted message!")
os.Exit(1)
}
begin, ident = readIdent(ciphertext[len(beginmsg):])
begin = begin + len(beginmsg)
end = begin + bytes.Index(ciphertext[begin:], begindata)
if end == -1 {
fmt.Fprintln(os.Stderr, "Badly formatted message!")
os.Exit(1)
}
// this was nasty to figure out; it's a sizeof() a union with several structs
hdr = b64pton(ciphertext[begin:end], 128)
begin = end + len(begindata)
end = begin + bytes.Index(ciphertext[begin:], endmsg)
if end == -1 {
fmt.Fprintln(os.Stderr, "Badly formatted message!")
os.Exit(1)
}
msglen = (end - begin - 1) / 4 * 3
msgraw = b64pton(ciphertext[begin:end], msglen)
for msgraw[len(msgraw)-1] == 0 {
msgraw = msgraw[:len(msgraw)-1]
}
}
algorithm := string(hdr[:2])
switch algorithm {
case "SP":
msg := new(Symmsg)
copy(msg.symalg[:], hdr[0:2])
copy(msg.kdfalg[:], hdr[2:4])
msg.kdfrounds = readUint32(hdr[4:8])
copy(msg.salt[:], hdr[8:24])
copy(msg.nonce[:], hdr[24:48])
copy(msg.tag[:], hdr[48:64])
if string(msg.kdfalg[:]) != "BK" {
fmt.Fprintln(os.Stderr, "unsupported KDF")
os.Exit(1)
}
password := os.Getenv("REOP_PASSPHRASE")
if password == "" {
fmt.Print("passphrase: ")
password = string(gopass.GetPasswd())
}
key, _ := bcrypt_pbkdf.Key([]byte(password), msg.salt[:], int(msg.kdfrounds), 32)
var symkey [32]byte
copy(symkey[:], key)
raw := append(msg.tag[:], msgraw...)
var dec []byte
dec, worked := secretbox.Open(nil, raw, &msg.nonce, &symkey)
if !worked {
fmt.Fprintln(os.Stderr, "Decryption failed!")
os.Exit(1)
}
return string(dec)
case "eC":
//seckey := readSeckey(seckeyfile)
//pubkey := readPubkey(pubkeyfile)
nyi("Public-key decryption with identity " + ident)
case "CS":
nyi("Old public-key algorithm")
case "eS":
nyi("Old symmetric algorithm")
}
return ""
}
