Fix alignment of AEAD and Generic Hash states

cryptoaead/crypto_aead_aes256gcm.go

@@ -124,7 +124,7 @@ func CryptoAEADAES256GCMDecryptDetached(c, mac, ad, npub, k []byte) ([]byte, int
 func CryptoAEADAES256GCMBeforeNM(k []byte) ([]byte, int) {
 	support.CheckSize(k, CryptoAEADAES256GCMKeyBytes(), "secret key")
 
-	ctx := make([]byte, CryptoAEADAES256GCMStateBytes())
+	ctx := support.AlignedSlice(CryptoAEADAES256GCMStateBytes(), 16)
 
 	exit := int(C.crypto_aead_aes256gcm_beforenm(
 		(*C.crypto_aead_aes256gcm_state)(unsafe.Pointer(&ctx[0])),

cryptogenerichash/crypto_generichash.go

@@ -4,7 +4,10 @@ package generichash
 // #include <stdlib.h>
 // #include <sodium.h>
 import "C"
-import "github.com/GoKillers/libsodium-go/support"
+import (
+	"github.com/GoKillers/libsodium-go/support"
+	"unsafe"
+)
 
 func CryptoGenericHashBytesMin() int {
 	return int(C.crypto_generichash_bytes_min())
@@ -68,9 +71,11 @@ func CryptoGenericHashInit(key []byte, outlen int) (*C.struct_crypto_generichash
 		support.CheckSizeInRange(len(key), CryptoGenericHashKeyBytesMin(), CryptoGenericHashKeyBytesMax(), "key")
 	}
 
-	state := new(C.struct_crypto_generichash_blake2b_state)
+	state := (*C.struct_crypto_generichash_blake2b_state)(
+		unsafe.Pointer(&support.AlignedSlice(CryptoGenericHashStateBytes(), 64)[0]))
+
 	exit := int(C.crypto_generichash_init(
-		(*C.struct_crypto_generichash_blake2b_state)(state),
+		state,
 		(*C.uchar)(support.BytePointer(key)),
 		(C.size_t)(len(key)),
 		(C.size_t)(outlen)))

support/support.go

@@ -1,6 +1,9 @@
 package support
 
-import "fmt"
+import (
+	"fmt"
+	"unsafe"
+)
 
 //
 // Internal support functions
@@ -32,3 +35,10 @@ func BytePointer(b []byte) *uint8 {
 		return nil
 	}
 }
+
+// AlignedSlice returns a memory aligned slice
+func AlignedSlice(size, alignment int) []byte {
+	slice := make([]byte, size+alignment)
+	offset := alignment - int(uintptr(unsafe.Pointer(&slice[0])))%alignment
+	return slice[offset : offset+size]
+}