解密AES/OFB/NoPadding

Question

我需要解密使用 C# 中的 AES/OFB/NoPadding 组合编码的内容。这似乎不受本地支持：以下代码不会像

var aes = new AesManaged
{
   Padding = PaddingMode.None,
   Mode = CipherMode.OFB,
   KeySize = 128,
   BlockSize = 128
};

生产：

System.Security.Cryptography.CryptographicException:
Specified cipher mode is not valid for this algorithm.

我能在 SO 上找到的最接近的问题是 this one, which uses BouncyCastle 进行加密：

Public Function DoEncryption(ByVal KeyArray() As Byte, ByVal IVArray() As Byte, ByVal Buffer     As Byte()) As Byte()

    Dim ae As New CipherKeyGenerator()
    ae.Init(New KeyGenerationParameters(New SecureRandom(), 256))
    Dim aesKeyParam As KeyParameter = ParameterUtilities.CreateKeyParameter("AES",     KeyArray)
    Dim aesIVKeyParam As ParametersWithIV = New ParametersWithIV(aesKeyParam, IVArray)
    Dim cipher As IBufferedCipher = CipherUtilities.GetCipher("AES/OFB/NoPadding")
    cipher.Init(True, aesIVKeyParam)
    Dim encrypted() As Byte = cipher.DoFinal(Buffer)
    Return encrypted

End Function

其他问题（如 this one）包含更多信息，但也包含大量自定义代码 - 我宁愿使用 BouncyCastle。谁能帮我解密，或者给我一些有用的文档？

Answer 1

从实际问题的代码来看，触发解密而不是加密的唯一必要步骤是更改 cipher.Init 调用中的布尔参数：

cipher.Init(False, aesIVKeyParam) // False == decryption, True == encryption

C# 中的最后一个片段是

private static byte[] DoDecryption(byte[] keyArray, byte[] ivArray, byte[] encoded)
{
    var aesKeyParam = ParameterUtilities.CreateKeyParameter("AES", keyArray);
    var aesIvKeyParam = new ParametersWithIV(aesKeyParam, ivArray);
    var cipher = CipherUtilities.GetCipher("AES/OFB/NOPADDING");
    cipher.Init(false, aesIvKeyParam);
    var decrypted = cipher.DoFinal(encoded);
    return decrypted;
}

解密AES/OFB/NoPadding

Decrypt AES/OFB/NoPadding

c#

encryption

bouncycastle

aes

asp.net-core