// encrypts a message to a user given their public key is known
// returns an encrypted box
func CryptoBox(msg, nounce, pk, sk []byte) []byte {
msgbuff := NewBuffer(msg)
defer msgbuff.Free()
// check sizes
if len(pk) != int(C.crypto_box_publickeybytes()) {
log.Println("len(pk) != crypto_box_publickey_bytes")
return nil
}
if len(sk) != int(C.crypto_box_secretkeybytes()) {
log.Println("len(sk) != crypto_box_secretkey_bytes")
return nil
}
if len(nounce) != int(C.crypto_box_macbytes()) {
log.Println("len(nounce) != crypto_box_macbytes()")
return nil
}
pkbuff := NewBuffer(pk)
defer pkbuff.Free()
skbuff := NewBuffer(sk)
defer skbuff.Free()
nouncebuff := NewBuffer(nounce)
defer nouncebuff.Free()
resultbuff := malloc(msgbuff.size + nouncebuff.size)
defer resultbuff.Free()
res := C.crypto_box_easy(resultbuff.uchar(), msgbuff.uchar(), C.ulonglong(msgbuff.size), nouncebuff.uchar(), pkbuff.uchar(), skbuff.uchar())
if res != 0 {
log.Println("crypto_box_easy failed:", res)
return nil
}
return resultbuff.Bytes()
}
// open an encrypted box
func CryptoBoxOpen(box, nounce, sk, pk []byte) ([]byte, error) {
boxbuff := NewBuffer(box)
defer boxbuff.Free()
// check sizes
if len(pk) != int(C.crypto_box_publickeybytes()) {
err := errors.New("len(pk) != crypto_box_publickey_bytes")
return nil, err
}
if len(sk) != int(C.crypto_box_secretkeybytes()) {
err := errors.New("len(sk) != crypto_box_secretkey_bytes")
return nil, err
}
if len(nounce) != int(C.crypto_box_macbytes()) {
err := errors.New("len(nounce) != crypto_box_macbytes()")
return nil, err
}
pkbuff := NewBuffer(pk)
defer pkbuff.Free()
skbuff := NewBuffer(sk)
defer skbuff.Free()
nouncebuff := NewBuffer(nounce)
defer nouncebuff.Free()
resultbuff := malloc(boxbuff.size - nouncebuff.size)
defer resultbuff.Free()
// decrypt
res := C.crypto_box_open_easy(resultbuff.uchar(), boxbuff.uchar(), C.ulonglong(boxbuff.size), nouncebuff.uchar(), pkbuff.uchar(), skbuff.uchar())
if res != 0 {
return nil, errors.New("crypto_box_open_easy failed")
}
// return result
return resultbuff.Bytes(), nil
}
// generate a new nounce
func NewBoxNounce() []byte {
return RandBytes(int(C.crypto_box_macbytes()))
}
// BoxMacBytes specifies the size, in bytes, of the MAC (Message Authentication Code) which is
// inserted into the cipher text to enable the message to be validated prior to decrypting it.
func BoxMacBytes() int {
return int(C.crypto_box_macbytes())
}
// return how many bytes overhead does CryptoBox have
func CryptoBoxOverhead() int {
return int(C.crypto_box_macbytes())
}
// length of a nounce
func NounceLen() int {
return int(C.crypto_box_macbytes())
}