package xsalsa20symmetric import ( "errors" "fmt" "golang.org/x/crypto/nacl/secretbox" "github.com/tendermint/tendermint/crypto" ) // TODO, make this into a struct that implements crypto.Symmetric. const nonceLen = 24 const secretLen = 32 // secret must be 32 bytes long. Use something like Sha256(Bcrypt(passphrase)) // The ciphertext is (secretbox.Overhead + 24) bytes longer than the plaintext. func EncryptSymmetric(plaintext []byte, secret []byte) (ciphertext []byte) { if len(secret) != secretLen { panic(fmt.Sprintf("Secret must be 32 bytes long, got len %v", len(secret))) } nonce := crypto.CRandBytes(nonceLen) nonceArr := [nonceLen]byte{} copy(nonceArr[:], nonce) secretArr := [secretLen]byte{} copy(secretArr[:], secret) ciphertext = make([]byte, nonceLen+secretbox.Overhead+len(plaintext)) copy(ciphertext, nonce) secretbox.Seal(ciphertext[nonceLen:nonceLen], plaintext, &nonceArr, &secretArr) return ciphertext } // secret must be 32 bytes long. Use something like Sha256(Bcrypt(passphrase)) // The ciphertext is (secretbox.Overhead + 24) bytes longer than the plaintext. func DecryptSymmetric(ciphertext []byte, secret []byte) (plaintext []byte, err error) { if len(secret) != secretLen { panic(fmt.Sprintf("Secret must be 32 bytes long, got len %v", len(secret))) } if len(ciphertext) <= secretbox.Overhead+nonceLen { return nil, errors.New("Ciphertext is too short") } nonce := ciphertext[:nonceLen] nonceArr := [nonceLen]byte{} copy(nonceArr[:], nonce) secretArr := [secretLen]byte{} copy(secretArr[:], secret) plaintext = make([]byte, len(ciphertext)-nonceLen-secretbox.Overhead) _, ok := secretbox.Open(plaintext[:0], ciphertext[nonceLen:], &nonceArr, &secretArr) if !ok { return nil, errors.New("Ciphertext decryption failed") } return plaintext, nil }