63 lines
1.4 KiB
Go
63 lines
1.4 KiB
Go
package crypto
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import (
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"crypto/rc4"
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"encoding/binary"
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)
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type Ciphers struct {
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client *rc4.Cipher // For decryption (client->server)
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server *rc4.Cipher // For encryption (server->client)
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}
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// NewCiphers returns a new pair of ciphers based on the given key
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func NewCiphers(key int64) (*Ciphers, error) {
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// Encryption only when key > 0
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if key <= 0 {
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return &Ciphers{}, nil
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}
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// key (little-endian bytes)
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keyBytes := make([]byte, 8)
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binary.LittleEndian.PutUint64(keyBytes, uint64(key))
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// ~key (little-endian bytes)
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notKeyBytes := make([]byte, 8)
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binary.LittleEndian.PutUint64(notKeyBytes, uint64(^key))
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clientCipher, err := rc4.NewCipher(notKeyBytes)
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if err != nil {
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return nil, err
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}
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serverCipher, err := rc4.NewCipher(keyBytes)
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if err != nil {
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return nil, err
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}
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// Burn first 20 bytes on both streams
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drop := make([]byte, 20)
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clientCipher.XORKeyStream(drop, drop)
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serverCipher.XORKeyStream(drop, drop)
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return &Ciphers{client: clientCipher, server: serverCipher}, nil
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}
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// Decrypt decrypts data received from the client
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func (c *Ciphers) Decrypt(data []byte) {
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if c.client != nil {
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c.client.XORKeyStream(data, data)
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}
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}
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// Encrypt encrypts data to be sent to the client
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func (c *Ciphers) Encrypt(data []byte) {
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if c.server != nil {
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c.server.XORKeyStream(data, data)
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}
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}
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// IsEncrypted returns true if encryption is active
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func (c *Ciphers) IsEncrypted() bool {
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return c != nil && c.server != nil
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}
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