Exemplo n.º 1
0
        /// <summary>
        /// Returns PEM encoded RSA PublicKey
        /// </summary>
        /// <param name="key">CngKey containing RSA PublicKey</param>
        /// <returns>PEM encoded PublicKey</returns>
        public static string ExportToPem(CngKey key)
        {
            RSACng rsaCng = new RSACng(key);

            RSAParameters parameters = rsaCng.ExportParameters(false);

            byte[] modulusBytes  = DerUtils.EncodeUnsignedInteger(parameters.Modulus);
            byte[] exponentBytes = DerUtils.EncodeUnsignedInteger(parameters.Exponent);
            byte[] dataSeqBytes  = DerUtils.EncodeSequenceOf(new List <byte[]> {
                modulusBytes, exponentBytes
            });
            byte[] bitStringBytes = DerUtils.EncodeBitString(dataSeqBytes, 0);

            byte[] oidBytes    = DerUtils.EncodeOid(RSA_ENCRYPTION_OID);
            byte[] oidSeqBytes = DerUtils.EncodeSequenceOf(new List <byte[]> {
                oidBytes, DerUtils.EncodeNull()
            });
            byte[] derBytes = DerUtils.EncodeSequenceOf(new List <byte[]> {
                oidSeqBytes, bitStringBytes
            });

            char[] derB64 = Convert.ToBase64String(derBytes, 0, (int)derBytes.Length).ToCharArray();

            TextWriter outputWriter = new StringWriter();

            outputWriter.WriteLine(PEM_PUBLIC_KEY_HEADER);
            for (var i = 0; i < derB64.Length; i += 64)
            {
                outputWriter.WriteLine(derB64, i, Math.Min(64, derB64.Length - i));
            }
            outputWriter.WriteLine(PEM_PUBLIC_KEY_FOOTER);

            return(outputWriter.ToString());
        }
Exemplo n.º 2
0
        /// <summary>
        /// Decodes a PEM RSA public key file
        /// </summary>
        /// <param name="filePath">The path to the PEM file</param>
        /// <returns>A CngKey object that constains the public key from the PEM file</returns>
        public static CngKey ImportFromPem(string filePath)
        {
            string pemStr;

            using (StreamReader fileStream = File.OpenText(filePath))
            {
                pemStr = fileStream.ReadToEnd();
            }
            if (!pemStr.StartsWith(PEM_PUBLIC_KEY_HEADER))
            {
                throw new FileFormatException("Not a public key PEM file. PEM Header formatted incorrectly.");
            }
            StringBuilder pemB64 = new StringBuilder(pemStr);

            pemB64.Replace(PEM_PUBLIC_KEY_HEADER, "").Replace(PEM_PUBLIC_KEY_FOOTER, "");

            byte[] derBytes = Convert.FromBase64String(pemB64.ToString());

            List <byte[]> mainBodySeqBytes = DerUtils.DecodeSequenceOf(derBytes);

            List <byte[]> oidSeqBytes = DerUtils.DecodeSequenceOf(mainBodySeqBytes[0]);

            if (DerUtils.DecodeOid(oidSeqBytes[0]) != RSA_ENCRYPTION_OID)
            {
                throw new FileFormatException("Not labelled as a public key OID.");
            }

            DerUtils.DecodeNull(oidSeqBytes[1]);

            byte[] bitStringBytes = DerUtils.DecodeBitstring(mainBodySeqBytes[1], out _);

            List <byte[]> dataSeqBytes = DerUtils.DecodeSequenceOf(bitStringBytes);

            byte[] modulusBytes = DerUtils.DecodeUnsignedInteger(dataSeqBytes[0]);
            byte[] exponenBytes = DerUtils.DecodeUnsignedInteger(dataSeqBytes[1]);

            RSACng        rsaCng    = new RSACng();
            RSAParameters rsaParams = new RSAParameters();

            rsaParams.Modulus  = modulusBytes;
            rsaParams.Exponent = exponenBytes;
            rsaCng.ImportParameters(rsaParams);
            return(rsaCng.Key);
        }