gcm_init
return gcm_init(vctx, key, keylen, iv, ivlen, params, 1);
return gcm_init(vctx, key, keylen, iv, ivlen, params, 0);
gcm_init(ctx, key, klen);
.init = gcm_init,
gcm_init(ctx, key, klen);
gcm_init(ctx, key, klen);