似乎SignedXml.CheckSignature只对使用SHA1的签名文档工作正常.
我通过添加算法SHA256尝试了this code,CheckSignature工作正常,但WIF类开始抛出以下异常：
System.Security.Cryptography.CryptographicException：指定的无效算法.在这个方法调用
System.IdentityModel.Services.FederatedPassiveSecurityTokenServiceOperations.ProcessSignInRequest
看来ProcessSignInRequest使用的算法SHA1在内部被覆盖：
CryptoConfig.AddAlgorithm(typeof(RSAPKCS1SHA256SignatureDescription),"http://www.w3.org/2001/04/xmldsig-more#rsa-sha256");
我错过了什么？如何在CheckSignature中指定算法？
今天我也有同样的问题.原来,WIF签名证书是使用没有SHA256支持的CSP生成的(
more details).
我浏览了System.IdentityModel源代码,并发现它包含对这种情况的特殊处理.当您具有全局注册的相应算法时,WIF使用它而不是内部实现,RSAPKCS1SHA256SignatureDescription类不包括此特殊处理.
所以我做了我自己的SignatureDescription实现,它使用默认参数重新创建了RSACryptoServiceProvider,其中包括SHA256支持.
/// <summary>
/// Represents the sha256RSA signature algorithm.
/// </summary>
public sealed class RsaPkcs1Sha256SignatureDescription : SignatureDescription
{
/// <summary>
/// This type of CSP has SHA256 support
/// </summary>
private const int PROV_RSA_AES = 24;
public RsaPkcs1Sha256SignatureDescription()
{
KeyAlgorithm = typeof(RSACryptoServiceProvider).FullName;
DigestAlgorithm = typeof(SHA256Cng).FullName;
FormatterAlgorithm = typeof(RSAPKCS1SignatureFormatter).FullName;
DeformatterAlgorithm = typeof(RSAPKCS1SignatureDeformatter).FullName;
}
/// <summary>
/// Adds support for sha256RSA XML signatures.
/// </summary>
public static void RegisterForSignedXml()
{
CryptoConfig.AddAlgorithm(
typeof (RsaPkcs1Sha256SignatureDescription),"http://www.w3.org/2001/04/xmldsig-more#rsa-sha256");
}
public override AsymmetricSignatureDeformatter CreateDeformatter(AsymmetricAlgorithm key)
{
if (key == null) throw new ArgumentNullException("key");
key = GetSha2CompatibleKey(key);
var signatureDeformatter = new RSAPKCS1SignatureDeformatter(key);
signatureDeformatter.SetHashAlgorithm("SHA256");
return signatureDeformatter;
}
public override AsymmetricSignatureFormatter CreateFormatter(AsymmetricAlgorithm key)
{
if (key == null) throw new ArgumentNullException("key");
key = GetSha2CompatibleKey(key);
var signatureFormatter = new RSAPKCS1SignatureFormatter(key);
signatureFormatter.SetHashAlgorithm("SHA256");
return signatureFormatter;
}
// Some certificates are generated without SHA2 support,this method recreates the CSP for them.
// See https://stackoverflow.com/a/11223454/280778
// WIF handles this case internally if no sha256RSA support is installed globally.
private static AsymmetricAlgorithm GetSha2CompatibleKey(AsymmetricAlgorithm key)
{
var csp = key as RSACryptoServiceProvider;
if (csp == null || csp.CspKeyContainerInfo.ProviderType == PROV_RSA_AES)
return key;
var newKey = new RSACryptoServiceProvider(new CspParameters(PROV_RSA_AES));
newKey.ImportParameters(csp.ExportParameters(true));
return newKey;
}
}
