RSACryptoServiceProvider.VerifyData Method (Byte(), Object, 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 hash value of the provided data.

Namespace:   System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)

Public Function VerifyData (
	buffer As Byte(),
	halg As Object,
	signature As Byte()
) As Boolean


Type: System.Byte()

The data that was signed.

Type: System.Object

The name of the hash algorithm used to create the hash value of the data.

Type: System.Byte()

The signature data to be verified.

Return Value

Type: System.Boolean

true if the signature is valid; otherwise, false.

Exception Condition

The halg parameter is null.


The halg parameter is not a valid type.

This method verifies the RSA digital signature produced by the SignData 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 halg parameter can accept a String, a HashAlgorithm, or a Type.

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

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

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

.NET Framework
Available since 1.1
Windows Phone Silverlight
Available since 7.1
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