[英]RSA signature generated with mbedtls, can't verify with C# (bouncycastle) application
[英]ECDiffieHellman - mbedTLS vs C#
我需要在 ARM cortex M3 和 PC 之間使用橢圓曲線 Diffie Hellman。 在 ARM 上,我使用mbed TLS 。 在 PC 端,我想要我們 C# 和ECDiffieHellman(Cng) class。
我可以在 ARM 與 ARM 上進行 ECDH,但是當我嘗試用 PC 替換一側時確實遇到了麻煩。
<LEN><0x04><X><Y>
。因此,在 C# 中,我正在使用
私有 static EC
DiffieHellmanPublicKey ToPublicKey(byte[] publicKey)
{
var keyLength = 32;
if (publicKey[0] != (2 + 2 * keyLength) - 1)
throw new ArgumentException("Invalid key length", nameof(publicKey));
if (publicKey[1] != 0x04)
throw new ArgumentException("Invalid key format", nameof(publicKey));
var parameters = new ECParameters()
{
Curve = ECCurve.NamedCurves.brainpoolP256r1,
Q = new ECPoint()
{
X = publicKey.Skip(2).Take(keyLength).ToArray(),
Y = publicKey.Skip(2 + keyLength).Take(keyLength).ToArray()
}
};
using (var tmp = ECDiffieHellman.Create(parameters))
{
return tmp.PublicKey;
}
}
var ecdh = new ECDiffieHellmanCng(ECCurve.NamedCurves.brainpoolP256r1);
ecdh.KeyDerivationFunction = ECDiffieHellmanKeyDerivationFunction.Tls;
ecdh.Seed = new byte[32];
ecdh.Label = Encoding.ASCII.GetBytes("ECDiffieHellman");
new RNGCryptoServiceProvider().GetBytes(ecdh.Seed);
// ...
var sharedSecret = ecdh.DeriveKeyMaterial(peersPublicKey);
我的問題是生成的共享密鑰與 mbed TLS 生成的共享密鑰長度不同,並且不匹配。
有人已經解決了這個問題嗎?
謝謝!
編輯1:
我忘了提到,我在 ARM 上使用了裸 ECDH。 所以我認為沒有執行任何密鑰派生 function 。 hash (SHA256) 結果是否足以匹配 C# 端(在那里將 SHA256 配置為 KDF 時)?
我解決了這個問題。 簡而言之:只是 hash ECDH 結果。
C/C++ 方面:
mbedtls_ecdh_init(...);
mbedtls_ecdh_setup(...);
mbedtls_ecdh_make_public(...); //make own public key and send it to peer
mbedtls_ecdh_read_public(...); //reed peers public key
mbedtls_ecdh_calc_secret(...); //note: i pass in my own RND func because of no OS
mbedtls_ecdh_free(...);
mbedtls_sha256_init(...);
mbedtls_sha256_starts_ret(...);
mbedtls_sha256_update_ret(...);
mbedtls_sha256_finish_ret(...);
mbedtls_sha256_free(...);
C#側:
private void EllipticCurveDiffieHellman()
{
var ecdh = new ECDiffieHellmanCng(ECCurve.NamedCurves.brainpoolP256r1);
ecdh.KeyDerivationFunction = ECDiffieHellmanKeyDerivationFunction.Hash;
ecdh.HashAlgorithm = CngAlgorithm.Sha256;
//get relevant point from own public key
var ownPublicKey = ecdh.PublicKey.ExportExplicitParameters().Q;
var peersPublicKey = SendPublicKey(ownPublicKey); //key exchange
var sharedSecret = ecdh.DeriveKeyMaterial(peersPublicKey);
Console.WriteLine("Key: " + HexValue.Parse(sharedSecret.ToArray()));
}
DiffieHellmanPublicKey ToPublicKey(byte[] publicKey)
{
var keyLength = 32;
if (publicKey[0] != (2 + 2 * keyLength) - 1)
throw new ArgumentException("Invalid key length", nameof(publicKey));
if (publicKey[1] != 0x04)
throw new ArgumentException("Invalid key format", nameof(publicKey));
var parameters = new ECParameters()
{
Curve = ECCurve.NamedCurves.brainpoolP256r1,
Q = new ECPoint()
{
X = publicKey.Skip(2).Take(keyLength).ToArray(),
Y = publicKey.Skip(2 + keyLength).Take(keyLength).ToArray()
}
};
using (var tmp = ECDiffieHellman.Create(parameters))
{
return tmp.PublicKey;
}
}
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