OpenSSL::PKCS7#cipher=

static VALUE
ossl_pkcs7_set_cipher(VALUE self, VALUE cipher)
{
    PKCS7 *pkcs7;
    const EVP_CIPHER *ciph;
    VALUE cipher_holder;

    GetPKCS7(self, pkcs7);
    ciph = ossl_evp_cipher_fetch(cipher, &cipher_holder);
    if (!PKCS7_set_cipher(pkcs7, ciph))
        ossl_raise(ePKCS7Error, "PKCS7_set_cipher");
    rb_ivar_set(self, id_cipher_holder, cipher_holder);

    return cipher;
}