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