236 lines
6.4 KiB
Go
236 lines
6.4 KiB
Go
package i2pkeys
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import (
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"bytes"
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"crypto/sha256"
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"encoding/base32"
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"encoding/base64"
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"errors"
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"io"
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"os"
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"strings"
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)
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var (
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i2pB64enc *base64.Encoding = base64.NewEncoding("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-~")
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i2pB32enc *base32.Encoding = base32.NewEncoding("abcdefghijklmnopqrstuvwxyz234567")
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)
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// The public and private keys associated with an I2P destination. I2P hides the
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// details of exactly what this is, so treat them as blobs, but generally: One
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// pair of DSA keys, one pair of ElGamal keys, and sometimes (almost never) also
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// a certificate. String() returns you the full content of I2PKeys and Addr()
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// returns the public keys.
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type I2PKeys struct {
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Address I2PAddr // only the public key
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Both string // both public and private keys
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}
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// Creates I2PKeys from an I2PAddr and a public/private keypair string (as
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// generated by String().)
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func NewKeys(addr I2PAddr, both string) I2PKeys {
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return I2PKeys{addr, both}
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}
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// fileExists checks if a file exists and is not a directory before we
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// try using it to prevent further errors.
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func fileExists(filename string) (bool, error) {
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info, err := os.Stat(filename)
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if os.IsNotExist(err) {
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return false, nil
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} else if err != nil {
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return false, err
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}
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return !info.IsDir(), nil
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}
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// load keys from non standard format
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func LoadKeysIncompat(r io.Reader) (k I2PKeys, err error) {
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var buff bytes.Buffer
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_, err = io.Copy(&buff, r)
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if err == nil {
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parts := strings.Split(buff.String(), "\n")
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k = I2PKeys{I2PAddr(parts[0]), parts[1]}
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}
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return
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}
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// load keys from non-standard format by specifying a text file.
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// If the file does not exist, generate keys, otherwise, fail
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// closed.
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func LoadKeys(r string) (I2PKeys, error) {
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exists, err := fileExists(r)
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if err != nil {
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return I2PKeys{}, err
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}
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if exists {
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fi, err := os.Open(r)
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if err != nil {
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return I2PKeys{}, err
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}
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defer fi.Close()
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return LoadKeysIncompat(fi)
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}
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return I2PKeys{}, err
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}
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// store keys in non standard format
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func StoreKeysIncompat(k I2PKeys, w io.Writer) (err error) {
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_, err = io.WriteString(w, k.Address.Base64()+"\n"+k.Both)
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return
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}
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func StoreKeys(k I2PKeys, r string) error {
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fi, err := os.Open(r)
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if err != nil {
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return err
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}
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defer fi.Close()
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return StoreKeysIncompat(k, fi)
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}
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// Returns the public keys of the I2PKeys.
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func (k I2PKeys) Addr() I2PAddr {
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return k.Address
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}
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// Returns the keys (both public and private), in I2Ps base64 format. Use this
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// when you create sessions.
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func (k I2PKeys) String() string {
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return k.Both
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}
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// I2PAddr represents an I2P destination, almost equivalent to an IP address.
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// This is the humongously huge base64 representation of such an address, which
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// really is just a pair of public keys and also maybe a certificate. (I2P hides
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// the details of exactly what it is. Read the I2P specifications for more info.)
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type I2PAddr string
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// an i2p destination hash, the .b32.i2p address if you will
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type I2PDestHash [32]byte
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// create a desthash from a string b32.i2p address
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func DestHashFromString(str string) (dhash I2PDestHash, err error) {
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if strings.HasSuffix(str, ".b32.i2p") && len(str) == 60 {
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// valid
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_, err = i2pB32enc.Decode(dhash[:], []byte(str[:52]+"===="))
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} else {
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// invalid
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err = errors.New("invalid desthash format")
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}
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return
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}
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// get string representation of i2p dest hash(base32 version)
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func (h I2PDestHash) String() string {
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b32addr := make([]byte, 56)
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i2pB32enc.Encode(b32addr, h[:])
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return string(b32addr[:52]) + ".b32.i2p"
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}
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// get base64 representation of i2p dest sha256 hash(the 44-character one)
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func (h I2PDestHash) Hash() string {
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hash := sha256.New()
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hash.Write(h[:])
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digest := hash.Sum(nil)
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buf := make([]byte, 44)
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i2pB64enc.Encode(buf, digest)
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return string(buf)
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}
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// Returns "I2P"
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func (h *I2PDestHash) Network() string {
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return "I2P"
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}
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// Returns the base64 representation of the I2PAddr
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func (a I2PAddr) Base64() string {
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return string(a)
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}
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// Returns the I2P destination (base64-encoded)
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func (a I2PAddr) String() string {
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return string(a)
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}
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// Returns "I2P"
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func (a I2PAddr) Network() string {
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return "I2P"
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}
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// Creates a new I2P address from a base64-encoded string. Checks if the address
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// addr is in correct format. (If you know for sure it is, use I2PAddr(addr).)
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func NewI2PAddrFromString(addr string) (I2PAddr, error) {
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if strings.HasSuffix(addr, ".i2p") {
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if strings.HasSuffix(addr, ".b32.i2p") {
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return I2PAddr(""), errors.New("cannot convert .b32.i2p to full destination")
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}
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// strip off .i2p if it's there
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addr = addr[:len(addr)-4]
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}
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addr = strings.Trim(addr, "\t\n\r\f ")
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// very basic check
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if len(addr) > 4096 || len(addr) < 516 {
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return I2PAddr(""), errors.New("Not an I2P address")
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}
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buf := make([]byte, i2pB64enc.DecodedLen(len(addr)))
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if _, err := i2pB64enc.Decode(buf, []byte(addr)); err != nil {
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return I2PAddr(""), errors.New("Address is not base64-encoded")
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}
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return I2PAddr(addr), nil
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}
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func FiveHundredAs() I2PAddr {
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s := ""
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for x := 0; x < 517; x++ {
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s += "A"
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}
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r, _ := NewI2PAddrFromString(s)
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return r
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}
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// Creates a new I2P address from a byte array. The inverse of ToBytes().
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func NewI2PAddrFromBytes(addr []byte) (I2PAddr, error) {
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if len(addr) > 4096 || len(addr) < 384 {
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return I2PAddr(""), errors.New("Not an I2P address")
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}
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buf := make([]byte, i2pB64enc.EncodedLen(len(addr)))
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i2pB64enc.Encode(buf, addr)
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return I2PAddr(string(buf)), nil
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}
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// Turns an I2P address to a byte array. The inverse of NewI2PAddrFromBytes().
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func (addr I2PAddr) ToBytes() ([]byte, error) {
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return i2pB64enc.DecodeString(string(addr))
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}
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func (addr I2PAddr) Bytes() []byte {
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b, _ := addr.ToBytes()
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return b
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}
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// Returns the *.b32.i2p address of the I2P address. It is supposed to be a
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// somewhat human-manageable 64 character long pseudo-domain name equivalent of
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// the 516+ characters long default base64-address (the I2PAddr format). It is
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// not possible to turn the base32-address back into a usable I2PAddr without
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// performing a Lookup(). Lookup only works if you are using the I2PAddr from
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// which the b32 address was generated.
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func (addr I2PAddr) Base32() (str string) {
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return addr.DestHash().String()
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}
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func (addr I2PAddr) DestHash() (h I2PDestHash) {
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hash := sha256.New()
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b, _ := addr.ToBytes()
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hash.Write(b)
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digest := hash.Sum(nil)
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copy(h[:], digest)
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return
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}
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// Makes any string into a *.b32.i2p human-readable I2P address. This makes no
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// sense, unless "anything" is an I2P destination of some sort.
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func Base32(anything string) string {
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return I2PAddr(anything).Base32()
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}
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