Add crypto_secretbox_macbytes()

src/libsodium/crypto_secretbox/crypto_secretbox.c

@@ -25,6 +25,12 @@ crypto_secretbox_boxzerobytes(void)
     return crypto_secretbox_BOXZEROBYTES;
 }
 
+size_t
+crypto_secretbox_macbytes(void)
+{
+    return crypto_secretbox_MACBYTES;
+}
+
 const char *
 crypto_secretbox_primitive(void)
 {

src/libsodium/crypto_secretbox/xsalsa20poly1305/secretbox_xsalsa20poly1305_api.c

@@ -20,6 +20,11 @@ crypto_secretbox_xsalsa20poly1305_boxzerobytes(void) {
     return crypto_secretbox_xsalsa20poly1305_BOXZEROBYTES;
 }
 
+size_t
+crypto_secretbox_xsalsa20poly1305_macbytes(void) {
+    return crypto_secretbox_xsalsa20poly1305_MACBYTES;
+}
+
 const char *
 crypto_secretbox_xsalsa20poly1305_primitive(void) {
     return "xsalsa20poly1305";

src/libsodium/include/sodium/crypto_secretbox.h

@@ -26,6 +26,10 @@ size_t  crypto_secretbox_zerobytes(void);
 SODIUM_EXPORT
 size_t  crypto_secretbox_boxzerobytes(void);
 
+#define crypto_secretbox_MACBYTES crypto_secretbox_xsalsa20poly1305_MACBYTES
+SODIUM_EXPORT
+size_t  crypto_secretbox_macbytes(void);
+
 #define crypto_secretbox_PRIMITIVE "xsalsa20poly1305"
 SODIUM_EXPORT
 const char *crypto_secretbox_primitive(void);

src/libsodium/include/sodium/crypto_secretbox_xsalsa20poly1305.h

@@ -8,6 +8,7 @@
 #define crypto_secretbox_xsalsa20poly1305_NONCEBYTES 24U
 #define crypto_secretbox_xsalsa20poly1305_ZEROBYTES 32U
 #define crypto_secretbox_xsalsa20poly1305_BOXZEROBYTES 16U
+#define crypto_secretbox_xsalsa20poly1305_MACBYTES (crypto_secretbox_xsalsa20poly1305_ZEROBYTES - crypto_secretbox_xsalsa20poly1305_BOXZEROBYTES)
 
 #ifdef __cplusplus
 extern "C" {
@@ -25,6 +26,9 @@ size_t crypto_secretbox_xsalsa20poly1305_zerobytes(void);
 SODIUM_EXPORT
 size_t crypto_secretbox_xsalsa20poly1305_boxzerobytes(void);
 
+SODIUM_EXPORT
+size_t crypto_secretbox_xsalsa20poly1305_macbytes(void);
+
 SODIUM_EXPORT
 const char * crypto_secretbox_xsalsa20poly1305_primitive(void);