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package main
import (
"crypto/aes"
"crypto/cipher"
"crypto/ecdh"
"crypto/rand"
"crypto/sha256"
"encoding/base64"
"encoding/hex"
"io"
"testing"
"golang.org/x/crypto/hkdf"
)
// Verifies the decryptMessage path still produces the correct plaintext after
// wrapping the ECDH/HKDF secrets in memguard.LockedBuffer, using the exact
// wire format the browser client (static/crypto.js) and relay produce.
func TestDecryptMessageAfterMemguard(t *testing.T) {
readerPriv, err := ecdh.X25519().GenerateKey(rand.Reader)
if err != nil {
t.Fatal(err)
}
ephPriv, err := ecdh.X25519().GenerateKey(rand.Reader)
if err != nil {
t.Fatal(err)
}
shared, err := ephPriv.ECDH(readerPriv.PublicKey())
if err != nil {
t.Fatal(err)
}
aesKey := make([]byte, 32)
hkdfR := hkdf.New(sha256.New, shared, make([]byte, 32), []byte("nymdrop-v1"))
if _, err := io.ReadFull(hkdfR, aesKey); err != nil {
t.Fatal(err)
}
block, err := aes.NewCipher(aesKey)
if err != nil {
t.Fatal(err)
}
gcm, err := cipher.NewGCM(block)
if err != nil {
t.Fatal(err)
}
iv := make([]byte, 12)
if _, err := rand.Read(iv); err != nil {
t.Fatal(err)
}
want := "E2E memguard verification message"
ciphertext := gcm.Seal(nil, iv, []byte(want), nil)
packet := append(append(append([]byte{}, ephPriv.PublicKey().Bytes()...), iv...), ciphertext...)
noncePrefix := hex.EncodeToString(make([]byte, 16)) + ":"
dataB64 := base64.StdEncoding.EncodeToString(append([]byte(noncePrefix), packet...))
got, err := decryptMessage(dataB64, readerPriv)
if err != nil {
t.Fatalf("decryptMessage: %v", err)
}
if got != want {
t.Fatalf("plaintext mismatch: got %q want %q", got, want)
}
}
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