OpenSSL::Cipher.new

static VALUE
ossl_cipher_initialize(VALUE self, VALUE str)
{
    EVP_CIPHER_CTX *ctx;
    const EVP_CIPHER *cipher;
    VALUE cipher_holder;

    GetCipherInit(self, ctx);
    if (ctx) {
        ossl_raise(rb_eRuntimeError, "Cipher already initialized!");
    }
    cipher = ossl_evp_cipher_fetch(str, &cipher_holder);
    AllocCipher(self, ctx);
    if (EVP_CipherInit_ex(ctx, cipher, NULL, NULL, NULL, -1) != 1)
        ossl_raise(eCipherError, "EVP_CipherInit_ex");
    rb_ivar_set(self, id_cipher_holder, cipher_holder);

    return self;
}