diff --git a/crypto/src/crypto/signers/PlainDsaEncoding.cs b/crypto/src/crypto/signers/PlainDsaEncoding.cs
new file mode 100644
index 000000000..2e1f65a1f
--- /dev/null
+++ b/crypto/src/crypto/signers/PlainDsaEncoding.cs
@@ -0,0 +1,58 @@
+using System;
+
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Signers
+{
+ public class PlainDsaEncoding
+ : IDsaEncoding
+ {
+ public static readonly PlainDsaEncoding Instance = new PlainDsaEncoding();
+
+ public virtual BigInteger[] Decode(BigInteger n, byte[] encoding)
+ {
+ int valueLength = BigIntegers.GetUnsignedByteLength(n);
+ if (encoding.Length != valueLength * 2)
+ throw new ArgumentException("Encoding has incorrect length", "encoding");
+
+ return new BigInteger[] {
+ DecodeValue(n, encoding, 0, valueLength),
+ DecodeValue(n, encoding, valueLength, valueLength),
+ };
+ }
+
+ public virtual byte[] Encode(BigInteger n, BigInteger r, BigInteger s)
+ {
+ int valueLength = BigIntegers.GetUnsignedByteLength(n);
+ byte[] result = new byte[valueLength * 2];
+ EncodeValue(n, r, result, 0, valueLength);
+ EncodeValue(n, s, result, valueLength, valueLength);
+ return result;
+ }
+
+ protected virtual BigInteger CheckValue(BigInteger n, BigInteger x)
+ {
+ if (x.SignValue < 0 || x.CompareTo(n) >= 0)
+ throw new ArgumentException("Value out of range", "x");
+
+ return x;
+ }
+
+ protected virtual BigInteger DecodeValue(BigInteger n, byte[] buf, int off, int len)
+ {
+ return CheckValue(n, new BigInteger(1, buf, off, len));
+ }
+
+ protected virtual void EncodeValue(BigInteger n, BigInteger x, byte[] buf, int off, int len)
+ {
+ byte[] bs = CheckValue(n, x).ToByteArrayUnsigned();
+ int bsOff = System.Math.Max(0, bs.Length - len);
+ int bsLen = bs.Length - bsOff;
+
+ int pos = len - bsLen;
+ Arrays.Fill(buf, off, off + pos, 0);
+ Array.Copy(bs, bsOff, buf, off + pos, bsLen);
+ }
+ }
+}
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