OpenSSL::PKCS7#cipher=

static VALUE
ossl_pkcs7_set_cipher(VALUE self, VALUE cipher)
{
    PKCS7 *pkcs7;

    GetPKCS7(self, pkcs7);
    if (!PKCS7_set_cipher(pkcs7, ossl_evp_get_cipherbyname(cipher))) {
        ossl_raise(ePKCS7Error, NULL);
    }

    return cipher;
}