new

static VALUE
ossl_cipher_initialize(VALUE self, VALUE str)
{
    EVP_CIPHER_CTX *ctx;
    const EVP_CIPHER *cipher;
    char *name;
    unsigned char key[EVP_MAX_KEY_LENGTH];

    name = StringValuePtr(str);
    GetCipherInit(self, ctx);
    if (ctx) {
        ossl_raise(rb_eRuntimeError, "Cipher already inititalized!");
    }
    AllocCipher(self, ctx);
    EVP_CIPHER_CTX_init(ctx);
    if (!(cipher = EVP_get_cipherbyname(name))) {
        ossl_raise(rb_eRuntimeError, "unsupported cipher algorithm (%s)", name);
    }
    /*
     * The EVP which has EVP_CIPH_RAND_KEY flag (such as DES3) allows
     * uninitialized key, but other EVPs (such as AES) does not allow it.
     * Calling EVP_CipherUpdate() without initializing key causes SEGV so we
     * set the data filled with "\0" as the key by default.
     */
    memset(key, 0, EVP_MAX_KEY_LENGTH);
    if (EVP_CipherInit_ex(ctx, cipher, NULL, key, NULL, -1) != 1)
        ossl_raise(eCipherError, NULL);

    return self;
}