Function mbedtls_pk_setup_rsa_alt 

pub unsafe extern "C" fn mbedtls_pk_setup_rsa_alt(
    ctx: *mut mbedtls_pk_context,
    key: *mut c_void,
    decrypt_func: Option<unsafe extern "C" fn(*mut c_void, *mut usize, *const u8, *mut u8, usize) -> i32>,
    sign_func: Option<unsafe extern "C" fn(*mut c_void, Option<unsafe extern "C" fn(*mut c_void, *mut u8, usize) -> i32>, *mut c_void, u32, u32, *const u8, *mut u8) -> i32>,
    key_len_func: Option<unsafe extern "C" fn(*mut c_void) -> usize>,
) -> i32

\brief Initialize an RSA-alt context

\param ctx Context to initialize. It must not have been set up yet (type #MBEDTLS_PK_NONE). \param key RSA key pointer \param decrypt_func Decryption function \param sign_func Signing function \param key_len_func Function returning key length in bytes

\return 0 on success, or MBEDTLS_ERR_PK_BAD_INPUT_DATA if the context wasn’t already initialized as RSA_ALT.

\note This function replaces \c mbedtls_pk_setup() for RSA-alt.