RSACryptoServiceProvider.VerifyHash Method

Definition

Namespace:

System.Security.Cryptography

Assembly:

System.Security.Cryptography.dll

Verifies that a digital signature is valid.

Overloads

VerifyHash(Byte[], String, Byte[])	Verifies that a digital signature is valid by determining the hash value in the signature using the provided public key and comparing it to the provided hash value.
VerifyHash(Byte[], Byte[], HashAlgorithmName, RSASignaturePadding)	Verifies that a digital signature is valid by determining the hash value in the signature using the specified hashing algorithm and padding, and comparing it to the provided hash value.

VerifyHash(Byte[], String, Byte[])

Source:

RSACryptoServiceProvider.Unix.cs

Verifies that a digital signature is valid by determining the hash value in the signature using the provided public key and comparing it to the provided hash value.

public:
 bool VerifyHash(cli::array <System::Byte> ^ rgbHash, System::String ^ str, cli::array <System::Byte> ^ rgbSignature);

public bool VerifyHash (byte[] rgbHash, string str, byte[] rgbSignature);

override this.VerifyHash : byte[] * string * byte[] -> bool

Public Function VerifyHash (rgbHash As Byte(), str As String, rgbSignature As Byte()) As Boolean

Parameters

rgbHash

Byte[]

The hash value of the signed data.

str

String

The hash algorithm identifier (OID) used to create the hash value of the data.

rgbSignature

Byte[]

The signature data to be verified.

Returns

Boolean

true if the signature is valid; otherwise, false.

Exceptions

ArgumentNullException

The rgbHash parameter is null.

-or-

The rgbSignature parameter is null.

CryptographicException

The cryptographic service provider (CSP) cannot be acquired.

-or-

The signature cannot be verified.

Examples

The following example shows how to use the VerifyHash method to verify a signature. This code example is part of a larger example provided for the SignHash method.

bool VerifyHash( RSAParameters rsaParams, array<Byte>^signedData, array<Byte>^signature )
{
   RSACryptoServiceProvider^ rsaCSP = gcnew RSACryptoServiceProvider;
   SHA1Managed^ hash = gcnew SHA1Managed;
   array<Byte>^hashedData;
   rsaCSP->ImportParameters( rsaParams );
   bool dataOK = rsaCSP->VerifyData(signedData, CryptoConfig::MapNameToOID("SHA1"), signature);
   hashedData = hash->ComputeHash( signedData );
   return rsaCSP->VerifyHash( hashedData, CryptoConfig::MapNameToOID( "SHA1" ), signature );
}

public bool VerifyHash(RSAParameters rsaParams, byte[] signedData, byte[] signature)
{
    RSACryptoServiceProvider rsaCSP = new RSACryptoServiceProvider();
    SHA1Managed hash = new SHA1Managed();
    byte[] hashedData;

    rsaCSP.ImportParameters(rsaParams);
    bool dataOK = rsaCSP.VerifyData(signedData, CryptoConfig.MapNameToOID("SHA1"), signature);
    hashedData = hash.ComputeHash(signedData);
    return rsaCSP.VerifyHash(hashedData, CryptoConfig.MapNameToOID("SHA1"), signature);
}

Public Function VerifyHash(ByVal rsaParams As RSAParameters, ByVal signedData() As Byte, ByVal signature() As Byte) As Boolean
    Dim rsaCSP As New RSACryptoServiceProvider()
    Dim hash As New SHA1Managed()
    Dim hashedData() As Byte
    Dim dataOK As Boolean

    rsaCSP.ImportParameters(rsaParams)
    dataOK = rsaCSP.VerifyData(signedData, CryptoConfig.MapNameToOID("SHA1"), signature)
    hashedData = hash.ComputeHash(signedData)
    Return rsaCSP.VerifyHash(hashedData, CryptoConfig.MapNameToOID("SHA1"), signature)
End Function 'VerifyHash

Remarks

This method verifies the RSA digital signature produced by the SignHash method. The signature is verified by obtaining the hash value from the signature using the public key it was signed with, and comparing that value to the hash value of the provided data.

The valid hash algorithms are SHA1 and MD5. The algorithm identifier can be derived from the hash name by using the MapNameToOID method.

Due to collision problems with SHA1 and MD5, Microsoft recommends a security model based on SHA256 or better.

See also

• VerifyHash(Byte[], Byte[], HashAlgorithmName, RSASignaturePadding)
• Cryptographic Services

VerifyHash(Byte[], Byte[], HashAlgorithmName, RSASignaturePadding)

Source:

RSACryptoServiceProvider.Unix.cs

Verifies that a digital signature is valid by determining the hash value in the signature using the specified hashing algorithm and padding, and comparing it to the provided hash value.

public:
 override bool VerifyHash(cli::array <System::Byte> ^ hash, cli::array <System::Byte> ^ signature, System::Security::Cryptography::HashAlgorithmName hashAlgorithm, System::Security::Cryptography::RSASignaturePadding ^ padding);

public override bool VerifyHash (byte[] hash, byte[] signature, System.Security.Cryptography.HashAlgorithmName hashAlgorithm, System.Security.Cryptography.RSASignaturePadding padding);

override this.VerifyHash : byte[] * byte[] * System.Security.Cryptography.HashAlgorithmName * System.Security.Cryptography.RSASignaturePadding -> bool

Public Overrides Function VerifyHash (hash As Byte(), signature As Byte(), hashAlgorithm As HashAlgorithmName, padding As RSASignaturePadding) As Boolean

Parameters

hash

Byte[]

The hash value of the signed data.

signature

Byte[]

The signature data to be verified.

hashAlgorithm

HashAlgorithmName

The hash algorithm name used to create the hash value.

padding

RSASignaturePadding

The padding.

Returns

Boolean

true if the signature is valid; otherwise, false.

Exceptions

ArgumentException

hashAlgorithm is null or Empty.

ArgumentNullException

hash is null.

-or-

padding is null.

CryptographicException

padding does not equal Pkcs1.