问题描述
我正在寻找一种非对称密码，其特征是输入很短会导致输出很短。
I am looking for an asymmetric cipher which has the property that very short inputs result in very short outputs.
.NET的标准 RSACryptoService 似乎为任何简短的纯文本（包括空的纯文本）输出最少128个字节。最小支持的BlockSize为128，唯一支持的模式为CBC。
.NET's standard RSACryptoService seems to output a minimum of 128 bytes for any short plaintext, including the empty plaintext. Minimum supported BlockSize is 128 and the only supported Mode is CBC.
理想的算法在提供非对称属性的同时，根本不会扩展明文。预期的输入大小为50-100字节，肯定不会超过150。
The perfect algorithm would not expand the plaintext at all, while providing the asymmetric property. Expected input size is 50-100 bytes, certainly never more than 150.
推荐答案
当然有可能实现您的目标您可以通过使用椭圆曲线和变体来选择大小。 是一种实现方式。
It is certainly possible to achieve your goals for the sizes you are interested in by using elliptic curve ElGamal encryption and variants. The Bouncycastle C# library is one option for implementation.
例如，使用NIST P-256曲线，您可以加密32字节的数据并获得64字节的结果。如果使用适当的填充，则可以加密较少的数据。我相信PGP曾经考虑过实施此操作，但我不知道他们是否曾经这样做过。
So for example by using the NIST P-256 curve you can encrypt 32 bytes of data and get a 64 byte result. If you use proper padding you can encrypt less data. I believe PGP once considered implementing this but I don't know if they ever did.
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