CODEWITHSUNDEEP
c#rsadigital-signature
hl3mukkel
hl3mukkel

Reputation: 6049

RSASSA-PSS in C#

Does anyone know which signature algorithm is used for RSACryptoServiceProvider.SignHash? I believe it is RSAPKCS1, is that still secure?

Does anyone have an idea of configuring RSASSA-PSS as the signature algorithm for the RSACryptoServiceProvider without using some third-party library like BouncyCastle?

Thanks in advance.

Upvotes: 7

Views: 5028

Answers (1)

bartonjs
bartonjs

Reputation: 33256

RSACryptoServiceProvider can only do PKCS-1 signatures.

In .NET 4.6 a new set of methods was added on the RSA base class which added an RSASignaturePadding parameter. The RSACng class can do RSASSA-PSS via the RSASignaturePadding.Pss value (PSS with MGF-1, MGF digest and PSS digest are both the message digest, and the salt size is the digest size).

.NET 4.6 also added better type-safety to getting keys from certificates, and the new approaches will most likely return RSACng:

using (RSA privateKey = cert.GetRSAPrivateKey())
{
    return privateKey.SignHash(hash, HashAlgorithmName.SHA256, RSASignaturePadding.Pss);
}

Upvotes: 2

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