Using Regex HTTPS Legacy 2019R3.3 on a Windows Embedded Handheld 6.5.3 device we get the exception mentioned. We are connecting to api.reservix.de, here is the Rebex log file:
2020-01-22 12:30:57 INFO HttpRequest(5)[841718926] TLS: Negotiating TLS 1.2, RSA with ephemeral Diffie-Hellman, AES with 128-bit key in GCM mode, AEAD.
2020-01-22 12:30:57 DEBUG HttpRequest(5)[841718926] TLS: The server supports secure renegotiation.
2020-01-22 12:30:57 DEBUG HttpRequest(5)[841718926] TLS: HandshakeMessage:Certificate was received.
2020-01-22 12:30:57 DEBUG HttpRequest(5)[841718926] TLS: HandshakeMessage:ServerKeyExchange was received.
2020-01-22 12:30:57 DEBUG HttpRequest(5)[841718926] TLS: HandshakeMessage:ServerHelloDone was received.
2020-01-22 12:30:57 DEBUG HttpRequest(5)[841718926] TLS: Verifying server certificate ('CN=*.reservix.de').
2020-01-22 12:30:57 DEBUG HttpRequest(5)[841718926] TLS: Certificate verification result: Accept
2020-01-22 12:30:57 DEBUG HttpRequest(5)[841718926] TLS: Verifying server key exchange signature.
2020-01-22 12:30:58 DEBUG HttpRequest(5)[841718926] TLS: Received ephemeral Diffie-Hellman prime.
2020-01-22 12:30:58 DEBUG HttpRequest(5)[841718926] TLS: Error while processing TLS packet: System.Security.Cryptography.CryptographicException: Unsupported key size (4096).
at Rebex.Security.Cryptography.DiffieHellmanManaged.ImportParameters(DiffieHellmanParameters parameters)
at Rebex.Security.Cryptography.CryptoHelper.jacf(DiffieHellmanParameters coj)
at Rebex.Security.Cryptography.AsymmetricKeyAlgorithm.ImportKey(DiffieHellmanParameters key)
at xube.ybwt(Byte[] azb, Int32 azc, Int32 azd, xuam aze)
at xube.ybxf(Byte[] bjj, Int32 bjk, Int32 bjl)
at xubb.krpi(Byte[] atg, Int32 ath, Int32 ati)
at xubb.krpn()
at xubb.krpu()
at Rebex.Net.TlsSocket.Negotiate()
at xtvj.lxrx(String bke, Int32 bkf, Boolean bkg)
at qhio.lxre()
at qhio.lxri(Boolean aj)
at qhio.lxrk()
at Rebex.Net.HttpRequest.mxyh()
at Rebex.Net.HttpRequest.bjwi.pwjx()
at qhvi.rnjr(Object ejo)
at qhyj.aucr.xyrn()
at qhwo.wuib()
Is this a restriction of Rebex or Windows?
Is there a list of key supported sizes?