diff --git a/crypto/src/util/ssh/OpenSSHPrivateKeyUtil.cs b/crypto/src/util/ssh/OpenSSHPrivateKeyUtil.cs
new file mode 100644
index 000000000..a918d3483
--- /dev/null
+++ b/crypto/src/util/ssh/OpenSSHPrivateKeyUtil.cs
@@ -0,0 +1,314 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+using System.Threading.Tasks;
+using Org.BouncyCastle.Asn1;
+using Org.BouncyCastle.Asn1.Nist;
+using Org.BouncyCastle.Asn1.Pkcs;
+using Org.BouncyCastle.Asn1.Sec;
+using Org.BouncyCastle.Asn1.X9;
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Pkcs;
+
+namespace Org.BouncyCastle.Utilities.SSH
+{
+ public class OpenSSHPrivateKeyUtil
+ {
+ private OpenSSHPrivateKeyUtil()
+ {
+
+ }
+
+ /**
+ * Magic value for proprietary OpenSSH private key.
+ **/
+ static readonly byte[] AUTH_MAGIC = Strings.ToByteArray("openssh-key-v1\0"); // C string so null terminated
+
+ /**
+ * Encode a cipher parameters into an OpenSSH private key.
+ * This does not add headers like ----BEGIN RSA PRIVATE KEY----
+ *
+ * @param parameters the cipher parameters.
+ * @return a byte array
+ */
+ public static byte[] EncodePrivateKey(AsymmetricKeyParameter parameters)
+ {
+ if (parameters == null)
+ {
+ throw new ArgumentException("parameters is null");
+ }
+
+ if (parameters is RsaPrivateCrtKeyParameters || parameters is ECPrivateKeyParameters)
+ {
+ PrivateKeyInfo pInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(parameters);
+ return pInfo.ParsePrivateKey().GetEncoded();
+ }
+ else if (parameters is DsaPrivateKeyParameters dsaPrivateKey)
+ {
+ DsaParameters dsaparameters = dsaPrivateKey.Parameters;
+
+ Asn1EncodableVector vec = new Asn1EncodableVector
+ {
+ new DerInteger(0),
+ new DerInteger(dsaparameters.P),
+ new DerInteger(dsaparameters.Q),
+ new DerInteger(dsaparameters.G)
+ };
+
+ // public key = g.modPow(x, p);
+ BigInteger pubKey = dsaparameters.P.ModPow(dsaPrivateKey.X, dsaparameters.P);
+ vec.Add(new DerInteger(pubKey));
+ vec.Add(new DerInteger(dsaPrivateKey.X));
+ try
+ {
+ return new DerSequence(vec).GetEncoded();
+ }
+ catch (Exception ex)
+ {
+ throw new InvalidOperationException("unable to encode DSAPrivateKeyParameters " + ex.Message);
+ }
+ }
+ else if (parameters is Ed25519PrivateKeyParameters ed25519PrivateKey)
+ {
+ Ed25519PublicKeyParameters publicKeyParameters = ed25519PrivateKey.GeneratePublicKey();
+
+ SSHBuilder builder = new SSHBuilder();
+ builder.WriteBytes(AUTH_MAGIC);
+ builder.WriteString("none"); // cipher name
+ builder.WriteString("none"); // KDF name
+ builder.WriteString(""); // KDF options
+
+ builder.U32(1); // Number of keys
+
+ {
+ byte[] pkEncoded = OpenSSHPublicKeyUtil.EncodePublicKey(publicKeyParameters);
+ builder.WriteBlock(pkEncoded);
+ }
+
+ {
+ SSHBuilder pkBuild = new SSHBuilder();
+
+ int checkint = CryptoServicesRegistrar.GetSecureRandom().NextInt();
+ pkBuild.U32((uint)checkint);
+ pkBuild.U32((uint)checkint);
+
+ pkBuild.WriteString("ssh-ed25519");
+
+ // Public key (as part of private key pair)
+ byte[] pubKeyEncoded = publicKeyParameters.GetEncoded();
+ pkBuild.WriteBlock(pubKeyEncoded);
+
+ // The private key in SSH is 64 bytes long and is the concatenation of the private and the public keys
+ pkBuild.WriteBlock(Arrays.Concatenate(ed25519PrivateKey.GetEncoded(), pubKeyEncoded));
+
+ // Comment for this private key (empty)
+ pkBuild.WriteString("");
+
+ builder.WriteBlock(pkBuild.GetPaddedBytes());
+ }
+
+ return builder.GetBytes();
+ }
+
+ throw new ArgumentException("unable to convert " + parameters.GetType().Name + " to openssh private key");
+
+ }
+
+ /**
+ * Parse a private key.
+ * <p>
+ * This method accepts the body of the OpenSSH private key.
+ * The easiest way to extract the body is to use PemReader, for example:
+ * <p>
+ * byte[] blob = new PemReader([reader]).readPemObject().getContent();
+ * CipherParameters params = parsePrivateKeyBlob(blob);
+ *
+ * @param blob The key.
+ * @return A cipher parameters instance.
+ */
+ public static AsymmetricKeyParameter ParsePrivateKeyBlob(byte[] blob)
+ {
+ AsymmetricKeyParameter result = null;
+
+ if (blob[0] == 0x30)
+ {
+ Asn1Sequence sequence = Asn1Sequence.GetInstance(blob);
+
+ if (sequence.Count == 6)
+ {
+ if (AllIntegers(sequence) && ((DerInteger)sequence[0]).PositiveValue.Equals(BigIntegers.Zero))
+ {
+ // length of 6 and all Integers -- DSA
+ result = new DsaPrivateKeyParameters(
+ ((DerInteger)sequence[5]).PositiveValue,
+ new DsaParameters(
+ ((DerInteger)sequence[1]).PositiveValue,
+ ((DerInteger)sequence[2]).PositiveValue,
+ ((DerInteger)sequence[3]).PositiveValue)
+ );
+ }
+ }
+ else if (sequence.Count == 9)
+ {
+ if (AllIntegers(sequence) && ((DerInteger)sequence[0]).PositiveValue.Equals(BigIntegers.Zero))
+ {
+ // length of 8 and all Integers -- RSA
+ RsaPrivateKeyStructure rsaPrivateKey = RsaPrivateKeyStructure.GetInstance(sequence);
+
+ result = new RsaPrivateCrtKeyParameters(
+ rsaPrivateKey.Modulus,
+ rsaPrivateKey.PublicExponent,
+ rsaPrivateKey.PrivateExponent,
+ rsaPrivateKey.Prime1,
+ rsaPrivateKey.Prime2,
+ rsaPrivateKey.Exponent1,
+ rsaPrivateKey.Exponent2,
+ rsaPrivateKey.Coefficient);
+ }
+ }
+ else if (sequence.Count == 4)
+ {
+ if (sequence[3] is Asn1TaggedObject && sequence[2] is Asn1TaggedObject)
+ {
+ ECPrivateKeyStructure ecPrivateKey = ECPrivateKeyStructure.GetInstance(sequence);
+ DerObjectIdentifier curveOID = DerObjectIdentifier.GetInstance(ecPrivateKey.GetParameters());
+ X9ECParameters x9Params = ECNamedCurveTable.GetByOid(curveOID);
+ result = new ECPrivateKeyParameters(
+ ecPrivateKey.GetKey(),
+ new ECNamedDomainParameters(
+ curveOID,
+ x9Params));
+ }
+ }
+ }
+ else
+ {
+ SSHBuffer kIn = new SSHBuffer(AUTH_MAGIC, blob);
+
+ String cipherName = kIn.ReadString();
+ if (!"none".Equals(cipherName))
+ {
+ throw new InvalidOperationException("encrypted keys not supported");
+ }
+
+ // KDF name
+ kIn.SkipBlock();
+
+ // KDF options
+ kIn.SkipBlock();
+
+ int publicKeyCount = kIn.ReadU32();
+ if (publicKeyCount != 1)
+ {
+ throw new InvalidOperationException("multiple keys not supported");
+ }
+
+ // Burn off public key.
+ OpenSSHPublicKeyUtil.ParsePublicKey(kIn.ReadBlock());
+
+ byte[] privateKeyBlock = kIn.ReadPaddedBlock();
+
+ if (kIn.HasRemaining())
+ {
+ throw new InvalidOperationException("decoded key has trailing data");
+ }
+
+ SSHBuffer pkIn = new SSHBuffer(privateKeyBlock);
+ int check1 = pkIn.ReadU32();
+ int check2 = pkIn.ReadU32();
+
+ if (check1 != check2)
+ {
+ throw new InvalidOperationException("private key check values are not the same");
+ }
+
+ String keyType = pkIn.ReadString();
+
+ if ("ssh-ed25519".Equals(keyType))
+ {
+ // Public key
+ pkIn.ReadBlock();
+ // Private key value..
+ byte[] edPrivateKey = pkIn.ReadBlock();
+ if (edPrivateKey.Length != Ed25519PrivateKeyParameters.KeySize + Ed25519PublicKeyParameters.KeySize)
+ {
+ throw new InvalidOperationException("private key value of wrong length");
+ }
+
+ result = new Ed25519PrivateKeyParameters(edPrivateKey, 0);
+ }
+ else if (keyType.StartsWith("ecdsa"))
+ {
+ DerObjectIdentifier oid = SSHNamedCurves.GetByName(Strings.FromByteArray(pkIn.ReadBlock())) ??
+ throw new InvalidOperationException("OID not found for: " + keyType);
+ X9ECParameters curveParams = NistNamedCurves.GetByOid(oid) ?? throw new InvalidOperationException("Curve not found for: " + oid);
+
+ // Skip public key.
+ pkIn.ReadBlock();
+ byte[] privKey = pkIn.ReadBlock();
+
+ result = new ECPrivateKeyParameters(new BigInteger(1, privKey),
+ new ECNamedDomainParameters(oid, curveParams));
+ }
+ else if (keyType.StartsWith("ssh-rsa"))
+ {
+ BigInteger modulus = new BigInteger(1, pkIn.ReadBlock());
+ BigInteger pubExp = new BigInteger(1, pkIn.ReadBlock());
+ BigInteger privExp = new BigInteger(1, pkIn.ReadBlock());
+ BigInteger coef = new BigInteger(1, pkIn.ReadBlock());
+ BigInteger p = new BigInteger(1, pkIn.ReadBlock());
+ BigInteger q = new BigInteger(1, pkIn.ReadBlock());
+
+ BigInteger pSub1 = p.Subtract(BigIntegers.One);
+ BigInteger qSub1 = q.Subtract(BigIntegers.One);
+ BigInteger dP = privExp.Remainder(pSub1);
+ BigInteger dQ = privExp.Remainder(qSub1);
+
+ result = new RsaPrivateCrtKeyParameters(
+ modulus,
+ pubExp,
+ privExp,
+ p,
+ q,
+ dP,
+ dQ,
+ coef);
+ }
+
+ // Comment for private key
+ pkIn.SkipBlock();
+
+ if (pkIn.HasRemaining())
+ {
+ throw new ArgumentException("private key block has trailing data");
+ }
+ }
+
+ if (result == null)
+ {
+ throw new ArgumentException("unable to parse key");
+ }
+
+ return result;
+ }
+
+ /**
+ * allIntegers returns true if the sequence holds only DerInteger types.
+ **/
+ private static Boolean AllIntegers(Asn1Sequence sequence)
+ {
+ for (int t = 0; t < sequence.Count; t++)
+ {
+ if (!(sequence[t] is DerInteger))
+ {
+ return false;
+ }
+ }
+ return true;
+ }
+}
+}
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