93 lines
2.5 KiB
Go
93 lines
2.5 KiB
Go
package main
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import (
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"bufio"
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"crypto/rand"
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"crypto/rsa"
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"crypto/sha256"
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"encoding/hex"
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"fmt"
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"github.com/rs/zerolog"
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"github.com/rs/zerolog/log"
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"net"
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"os"
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"strings"
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)
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// Generate RSA keypair
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func GenerateRSAKeypair() (*rsa.PrivateKey, *rsa.PublicKey) {
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// Use ConsoleWriter logger
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log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr}).Hook(FatalHook{})
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// Generate private/public RSA keypair
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privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
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if err != nil {
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log.Fatal().Err(err).Msg("Error generating RSA keypair")
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}
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// Get public key
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publicKey := privateKey.PublicKey
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// Return keypair
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return privateKey, &publicKey
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}
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// Get public key from sender
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func GetKey(connection net.Conn) []byte {
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// Use ConsoleWriter logger
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log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr}).Hook(FatalHook{})
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// Send key request to connection
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_, err := fmt.Fprintln(connection, "key;")
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if err != nil {
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log.Fatal().Err(err).Msg("Error sending key request")
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}
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// Read received message
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message, err := bufio.NewReader(connection).ReadString('\n')
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if err != nil {
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log.Fatal().Err(err).Msg("Error getting key")
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}
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// Process received message
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procMessage := strings.Split(strings.TrimSpace(message), ";")
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// If ok code returned
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if procMessage[0] == "OK" {
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// Decode received hex string into key
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key, err := hex.DecodeString(procMessage[1])
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if err != nil {
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log.Fatal().Err(err).Msg("Error reading key")
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}
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// Return key
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return key
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// Otherwise
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} else {
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// Fatally log
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if err != nil {
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log.Fatal().Msg("Server reported error")
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}
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}
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// Return nil if all else fails
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return nil
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}
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// Encrypt shared key with received public key
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func EncryptKey(sharedKey string, recvPubKey *rsa.PublicKey) []byte {
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// Use ConsoleWriter logger
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log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr}).Hook(FatalHook{})
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// Encrypt shared key using RSA
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encryptedSharedKey, err := rsa.EncryptOAEP(sha256.New(), rand.Reader, recvPubKey, []byte(sharedKey), nil)
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if err != nil {
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log.Fatal().Err(err).Msg("Error encrypting shared key")
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}
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// Return encrypted key
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return encryptedSharedKey
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}
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// Decrypt shared key using private RSA key
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func DecryptKey(encryptedKey []byte, privateKey *rsa.PrivateKey) string {
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// Decrypt shared key using RSA
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decryptedKey, err := rsa.DecryptOAEP(sha256.New(), rand.Reader, privateKey, encryptedKey, nil)
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if err != nil {
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log.Fatal().Err(err).Msg("Error decrypting shared key")
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}
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// Get string of decrypted key
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sharedKey := string(decryptedKey)
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// Return shared key
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return sharedKey
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}
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