Can't read GOST2012 key with BouncyCastle

Question

We have private key (GOST3410-2012). But we can't read it using BouncyCastle 1.8.6.1

Here is a key data:

-----BEGIN PRIVATE KEY----- MIGiAgEAMCEGCCqFAwcBAQECMBUGCSqFAwcBAgECAQYIKoUDBwEBAgMEQIXnWrZ6 ajvbCU6x9jK49PgQqCP00T/lW3laXCXueMF8X4Q1y3N9zfOJT2s/IgyPJVrUhgtO 1Akp+Roh8bCPPlqgODA2BggqhQMCCQMIATEqBCi72ZvrBVW6mFL/bQeXeMTf8Jh8 p/diI7Cg8ig4mXg3tsIUf4vBi61b -----END PRIVATE KEY-----

And here is a code to read it:

        const string keyPath = "D:\\testkey\\priv.key";
        using (var textReader = File.OpenText(keyPath))
        {
            var pemReader = new Org.BouncyCastle.OpenSsl.PemReader(textReader);
            var pemObj = pemReader.ReadPemObject();
            var seq = (Asn1Sequence)Asn1Object.FromByteArray(pemObj.Content);
            var keyInfo = PrivateKeyInfo.GetInstance(seq);
            var akp = Org.BouncyCastle.Security.PrivateKeyFactory.CreateKey(keyInfo);
        }

this code provide exception: "DER length more than 4 bytes: 103". Does anyone knows how to read it?

Answer 1

If you make your key with OpenSSL, try to add the following parameter in the "gost_section" of your OpennSSL config file:

GOST_PK_FORMAT = LEGACY_PK_WRAP

then export the key again