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RSACng and DSACng are once again usable in Partial Trust scenarios

Scope

Edge

Version Introduced

4.6.2

Version Reverted

4.7.1

Source Analyzer Status

NotPlanned

Change Description

CngLightup (used in several higher-level crypto apis, such as T:System.Security.Cryptography.Xml.EncryptedXml) and T:System.Security.Cryptography.RSACng in some cases rely on full trust. These include P/Invokes without asserting F:System.Security.Permissions.SecurityPermissionFlag.UnmanagedCode permissions, and code paths where T:System.Security.Cryptography.CngKey has permission demands for F:System.Security.Permissions.SecurityPermissionFlag.UnmanagedCode. Starting with the .NET Framework 4.6.2, CngLightup was used to switch to T:System.Security.Cryptography.RSACng wherever possible. As a result, partial trust apps that successfully used T:System.Security.Cryptography.Xml.EncryptedXml began to fail and throw T:System.Security.SecurityException exceptions.

This change adds the required asserts so that all functions using CngLightup have the required permissions.

Quirked
Build-time break

Recommended Action

If this change in the .NET Framework 4.6.2 has negatively impacted your partial trust apps, upgrade to the .NET Framework 4.7.1.

Affected APIs

M:System.Security.Cryptography.DSACng.#ctor(System.Security.Cryptography.CngKey)
P:System.Security.Cryptography.DSACng.Key
P:System.Security.Cryptography.DSACng.LegalKeySizes
M:System.Security.Cryptography.DSACng.CreateSignature(System.Byte[])
M:System.Security.Cryptography.DSACng.VerifySignature(System.Byte[],System.Byte[])
M:System.Security.Cryptography.RSACng.#ctor(System.Security.Cryptography.CngKey)
P:System.Security.Cryptography.RSACng.Key
M:System.Security.Cryptography.RSACng.Decrypt(System.Byte[], System.Security.Cryptography.RSAEncryptionPadding)
M:System.Security.Cryptography.RSACng.SignHash(System.Byte[], System.Security.Cryptography.HashAlgorithmName, System.Security.Cryptography.RSASignaturePadding)

2.1 KiB Raw Blame History