Add, test and fix CryptoAEADAES256GCM functions

- Fix CryptoAEADAES256GCMNSecBytes()
- Remove nsec from CryptoAEADAES256GCMEncrypt() and Decrypt()
- Add support.CheckSizeMin for things with a minimum size
- Add support.BytePointer to get a pointer for things than can have 0 length
- Add CryptoAEADAES256GCMIsAvailable(), CryptoAEADAES256GCMEncryptDetached(),
  CryptoAEADAES256GCMDecryptDetached() and CryptoAEADAES256GCMKeyGen()
- Add tests for all encryption and decryption functions (related to GoKillers#1)

Closes GoKillers#9

cryptoaead/crypto_aead_aes256gcm.go

@@ -6,12 +6,17 @@ package cryptoaead
 import "C"
 import "github.com/GoKillers/libsodium-go/support"
 
+func CryptoAEADAES256GCMIsAvailable() bool {
+	C.sodium_init()
+	return int(C.crypto_aead_aes256gcm_is_available()) != 0
+}
+
 func CryptoAEADAES256GCMKeyBytes() int {
 	return int(C.crypto_aead_aes256gcm_keybytes())
 }
 
 func CryptoAEADAES256GCMNSecBytes() int {
-	return int(C.crypto_aead_aes256gcm_keybytes())
+	return int(C.crypto_aead_aes256gcm_nsecbytes())
 }
 
 func CryptoAEADAES256GCMNPubBytes() int {
@@ -26,47 +31,95 @@ func CryptoAEADAES256GCMStateBytes() int {
 	return int(C.crypto_aead_aes256gcm_statebytes())
 }
 
-func CryptoAESAES256GCMIsAvailable() int {
-	return int(C.crypto_aead_aes256gcm_is_available())
-}
-
-func CryptoAEADAES256GCMEncrypt(m []byte, ad []byte, nsec []byte, npub []byte, k []byte) ([]byte, int) {
+func CryptoAEADAES256GCMEncrypt(m []byte, ad []byte, npub []byte, k []byte) ([]byte, int) {
 	support.CheckSize(k, CryptoAEADAES256GCMKeyBytes(), "secret key")
 	support.CheckSize(npub, CryptoAEADAES256GCMNPubBytes(), "public nonce")
+
 	c := make([]byte, len(m)+CryptoAEADAES256GCMABytes())
-	cLen := len(c)
-	cLenLongLong := (C.ulonglong(cLen))
+	cLen := C.ulonglong(len(c))
+
 	exit := int(C.crypto_aead_aes256gcm_encrypt(
-		(*C.uchar)(&c[0]),
-		&cLenLongLong,
-		(*C.uchar)(&m[0]),
+		(*C.uchar)(support.BytePointer(c)),
+		(*C.ulonglong)(&cLen),
+		(*C.uchar)(support.BytePointer(m)),
 		(C.ulonglong)(len(m)),
-		(*C.uchar)(&ad[0]),
+		(*C.uchar)(support.BytePointer(ad)),
 		(C.ulonglong)(len(ad)),
-		(*C.uchar)(&nsec[0]),
+		(*C.uchar)(nil),
 		(*C.uchar)(&npub[0]),
 		(*C.uchar)(&k[0])))
 
 	return c, exit
 }
 
-func CryptoAEADAES256GCMDecrypt(nsec []byte, c []byte, ad []byte, npub []byte, k []byte) ([]byte, int) {
+func CryptoAEADAES256GCMDecrypt(c []byte, ad []byte, npub []byte, k []byte) ([]byte, int) {
 	support.CheckSize(k, CryptoAEADAES256GCMKeyBytes(), "secret key")
 	support.CheckSize(npub, CryptoAEADAES256GCMNPubBytes(), "public nonce")
+	support.CheckSizeMin(c, CryptoAEADAES256GCMABytes(), "ciphertext")
+
 	m := make([]byte, len(c)-CryptoAEADAES256GCMABytes())
-	mLen := len(m)
-	mLenLongLong := (C.ulonglong)(mLen)
+	mLen := (C.ulonglong)(len(m))
 
 	exit := int(C.crypto_aead_aes256gcm_decrypt(
-		(*C.uchar)(&m[0]),
-		&mLenLongLong,
-		(*C.uchar)(&nsec[0]),
+		(*C.uchar)(support.BytePointer(m)),
+		(*C.ulonglong)(&mLen),
+		(*C.uchar)(nil),
 		(*C.uchar)(&c[0]),
 		(C.ulonglong)(len(c)),
-		(*C.uchar)(&ad[0]),
+		(*C.uchar)(support.BytePointer(ad)),
+		(C.ulonglong)(len(ad)),
+		(*C.uchar)(&npub[0]),
+		(*C.uchar)(&k[0])))
+
+	return m, exit
+}
+
+func CryptoAEADAES256GCMEncryptDetached(m []byte, ad []byte, npub []byte, k []byte) ([]byte, []byte, int) {
+	support.CheckSize(k, CryptoAEADAES256GCMKeyBytes(), "secret key")
+	support.CheckSize(npub, CryptoAEADAES256GCMNPubBytes(), "public nonce")
+
+	c := make([]byte, len(m))
+	mac := make([]byte , CryptoAEADAES256GCMABytes())
+	macLen := C.ulonglong(len(c))
+
+	exit := int(C.crypto_aead_aes256gcm_encrypt_detached(
+		(*C.uchar)(support.BytePointer(c)),
+		(*C.uchar)(&mac[0]),
+		(*C.ulonglong)(&macLen),
+		(*C.uchar)(support.BytePointer(m)),
+		(C.ulonglong)(len(m)),
+		(*C.uchar)(support.BytePointer(ad)),
+		(C.ulonglong)(len(ad)),
+		(*C.uchar)(nil),
+		(*C.uchar)(&npub[0]),
+		(*C.uchar)(&k[0])))
+
+	return c, mac, exit
+}
+
+func CryptoAEADAES256GCMDecryptDetached(c, mac, ad, npub, k []byte) ([]byte, int) {
+	support.CheckSize(k, CryptoAEADAES256GCMKeyBytes(), "secret key")
+	support.CheckSize(npub, CryptoAEADAES256GCMNPubBytes(), "public nonce")
+	support.CheckSize(mac, CryptoAEADAES256GCMABytes(), "mac")
+
+	m := make([]byte, len(c))
+
+	exit := int(C.crypto_aead_aes256gcm_decrypt_detached(
+		(*C.uchar)(support.BytePointer(m)),
+		(*C.uchar)(nil),
+		(*C.uchar)(support.BytePointer(c)),
+		(C.ulonglong)(len(c)),
+		(*C.uchar)(&mac[0]),
+		(*C.uchar)(support.BytePointer(ad)),
 		(C.ulonglong)(len(ad)),
 		(*C.uchar)(&npub[0]),
 		(*C.uchar)(&k[0])))
 
 	return m, exit
 }
+
+func CryptoAEADAES256GCMKeyGen() []byte {
+	k := make([]byte, CryptoAEADAES256GCMKeyBytes())
+	C.crypto_aead_aes256gcm_keygen((*C.uchar)(&k[0]))
+	return k
+}