85 lines
2.0 KiB
Go
85 lines
2.0 KiB
Go
package mucp
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"crypto/sha256"
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"github.com/micro/go-micro/v3/network/tunnel"
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"github.com/oxtoacart/bpool"
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)
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var (
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// the local buffer pool
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// gcmStandardNonceSize from crypto/cipher/gcm.go is 12 bytes
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// 100 - is max size of pool
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noncePool = bpool.NewBytePool(100, 12)
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)
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// hash hahes the data into 32 bytes key and returns it
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// hash uses sha256 underneath to hash the supplied key
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func hash(key []byte) []byte {
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sum := sha256.Sum256(key)
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return sum[:]
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}
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// Encrypt encrypts data and returns the encrypted data
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func Encrypt(gcm cipher.AEAD, data []byte) ([]byte, error) {
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var err error
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// get new byte array the size of the nonce from pool
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// NOTE: we might use smaller nonce size in the future
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nonce := noncePool.Get()
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if _, err = rand.Read(nonce); err != nil {
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return nil, err
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}
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defer noncePool.Put(nonce)
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// NOTE: we prepend the nonce to the payload
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// we need to do this as we need the same nonce
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// to decrypt the payload when receiving it
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return gcm.Seal(nonce, nonce, data, nil), nil
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}
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// Decrypt decrypts the payload and returns the decrypted data
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func newCipher(key []byte) (cipher.AEAD, error) {
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var err error
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// generate a new AES cipher using our 32 byte key for decrypting the message
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c, err := aes.NewCipher(hash(key))
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if err != nil {
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return nil, err
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}
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// gcm or Galois/Counter Mode, is a mode of operation
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// for symmetric key cryptographic block ciphers
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// - https://en.wikipedia.org/wiki/Galois/Counter_Mode
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gcm, err := cipher.NewGCM(c)
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if err != nil {
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return nil, err
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}
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return gcm, nil
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}
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func Decrypt(gcm cipher.AEAD, data []byte) ([]byte, error) {
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var err error
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nonceSize := gcm.NonceSize()
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if len(data) < nonceSize {
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return nil, tunnel.ErrDecryptingData
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}
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// NOTE: we need to parse out nonce from the payload
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// we prepend the nonce to every encrypted payload
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nonce, ciphertext := data[:nonceSize], data[nonceSize:]
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ciphertext, err = gcm.Open(ciphertext[:0], nonce, ciphertext, nil)
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if err != nil {
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return nil, err
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}
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return ciphertext, nil
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}
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