diff --git a/Crypto/src/util/encoders/Base64Encoder.cs b/Crypto/src/util/encoders/Base64Encoder.cs
new file mode 100644
index 000000000..c94ce9d3c
--- /dev/null
+++ b/Crypto/src/util/encoders/Base64Encoder.cs
@@ -0,0 +1,307 @@
+using System;
+using System.IO;
+
+namespace Org.BouncyCastle.Utilities.Encoders
+{
+ public class Base64Encoder
+ : IEncoder
+ {
+ protected readonly byte[] encodingTable =
+ {
+ (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G',
+ (byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N',
+ (byte)'O', (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U',
+ (byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z',
+ (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f', (byte)'g',
+ (byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n',
+ (byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u',
+ (byte)'v',
+ (byte)'w', (byte)'x', (byte)'y', (byte)'z',
+ (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6',
+ (byte)'7', (byte)'8', (byte)'9',
+ (byte)'+', (byte)'/'
+ };
+
+ protected byte padding = (byte)'=';
+
+ /*
+ * set up the decoding table.
+ */
+ protected readonly byte[] decodingTable = new byte[128];
+
+ protected void InitialiseDecodingTable()
+ {
+ for (int i = 0; i < encodingTable.Length; i++)
+ {
+ decodingTable[encodingTable[i]] = (byte)i;
+ }
+ }
+
+ public Base64Encoder()
+ {
+ InitialiseDecodingTable();
+ }
+
+ /**
+ * encode the input data producing a base 64 output stream.
+ *
+ * @return the number of bytes produced.
+ */
+ public int Encode(
+ byte[] data,
+ int off,
+ int length,
+ Stream outStream)
+ {
+ int modulus = length % 3;
+ int dataLength = (length - modulus);
+ int a1, a2, a3;
+
+ for (int i = off; i < off + dataLength; i += 3)
+ {
+ a1 = data[i] & 0xff;
+ a2 = data[i + 1] & 0xff;
+ a3 = data[i + 2] & 0xff;
+
+ outStream.WriteByte(encodingTable[(int) ((uint) a1 >> 2) & 0x3f]);
+ outStream.WriteByte(encodingTable[((a1 << 4) | (int) ((uint) a2 >> 4)) & 0x3f]);
+ outStream.WriteByte(encodingTable[((a2 << 2) | (int) ((uint) a3 >> 6)) & 0x3f]);
+ outStream.WriteByte(encodingTable[a3 & 0x3f]);
+ }
+
+ /*
+ * process the tail end.
+ */
+ int b1, b2, b3;
+ int d1, d2;
+
+ switch (modulus)
+ {
+ case 0: /* nothing left to do */
+ break;
+ case 1:
+ d1 = data[off + dataLength] & 0xff;
+ b1 = (d1 >> 2) & 0x3f;
+ b2 = (d1 << 4) & 0x3f;
+
+ outStream.WriteByte(encodingTable[b1]);
+ outStream.WriteByte(encodingTable[b2]);
+ outStream.WriteByte(padding);
+ outStream.WriteByte(padding);
+ break;
+ case 2:
+ d1 = data[off + dataLength] & 0xff;
+ d2 = data[off + dataLength + 1] & 0xff;
+
+ b1 = (d1 >> 2) & 0x3f;
+ b2 = ((d1 << 4) | (d2 >> 4)) & 0x3f;
+ b3 = (d2 << 2) & 0x3f;
+
+ outStream.WriteByte(encodingTable[b1]);
+ outStream.WriteByte(encodingTable[b2]);
+ outStream.WriteByte(encodingTable[b3]);
+ outStream.WriteByte(padding);
+ break;
+ }
+
+ return (dataLength / 3) * 4 + ((modulus == 0) ? 0 : 4);
+ }
+
+ private bool ignore(
+ char c)
+ {
+ return (c == '\n' || c =='\r' || c == '\t' || c == ' ');
+ }
+
+ /**
+ * decode the base 64 encoded byte data writing it to the given output stream,
+ * whitespace characters will be ignored.
+ *
+ * @return the number of bytes produced.
+ */
+ public int Decode(
+ byte[] data,
+ int off,
+ int length,
+ Stream outStream)
+ {
+ byte b1, b2, b3, b4;
+ int outLen = 0;
+
+ int end = off + length;
+
+ while (end > off)
+ {
+ if (!ignore((char)data[end - 1]))
+ {
+ break;
+ }
+
+ end--;
+ }
+
+ int i = off;
+ int finish = end - 4;
+
+ i = nextI(data, i, finish);
+
+ while (i < finish)
+ {
+ b1 = decodingTable[data[i++]];
+
+ i = nextI(data, i, finish);
+
+ b2 = decodingTable[data[i++]];
+
+ i = nextI(data, i, finish);
+
+ b3 = decodingTable[data[i++]];
+
+ i = nextI(data, i, finish);
+
+ b4 = decodingTable[data[i++]];
+
+ outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
+ outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
+ outStream.WriteByte((byte)((b3 << 6) | b4));
+
+ outLen += 3;
+
+ i = nextI(data, i, finish);
+ }
+
+ outLen += decodeLastBlock(outStream, (char)data[end - 4], (char)data[end - 3], (char)data[end - 2], (char)data[end - 1]);
+
+ return outLen;
+ }
+
+ private int nextI(
+ byte[] data,
+ int i,
+ int finish)
+ {
+ while ((i < finish) && ignore((char)data[i]))
+ {
+ i++;
+ }
+ return i;
+ }
+
+ /**
+ * decode the base 64 encoded string data writing it to the given output stream,
+ * whitespace characters will be ignored.
+ *
+ * @return the number of bytes produced.
+ */
+ public int DecodeString(
+ string data,
+ Stream outStream)
+ {
+ // Platform Implementation
+// byte[] bytes = Convert.FromBase64String(data);
+// outStream.Write(bytes, 0, bytes.Length);
+// return bytes.Length;
+
+ byte b1, b2, b3, b4;
+ int length = 0;
+
+ int end = data.Length;
+
+ while (end > 0)
+ {
+ if (!ignore(data[end - 1]))
+ {
+ break;
+ }
+
+ end--;
+ }
+
+ int i = 0;
+ int finish = end - 4;
+
+ i = nextI(data, i, finish);
+
+ while (i < finish)
+ {
+ b1 = decodingTable[data[i++]];
+
+ i = nextI(data, i, finish);
+
+ b2 = decodingTable[data[i++]];
+
+ i = nextI(data, i, finish);
+
+ b3 = decodingTable[data[i++]];
+
+ i = nextI(data, i, finish);
+
+ b4 = decodingTable[data[i++]];
+
+ outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
+ outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
+ outStream.WriteByte((byte)((b3 << 6) | b4));
+
+ length += 3;
+
+ i = nextI(data, i, finish);
+ }
+
+ length += decodeLastBlock(outStream, data[end - 4], data[end - 3], data[end - 2], data[end - 1]);
+
+ return length;
+ }
+
+ private int decodeLastBlock(
+ Stream outStream,
+ char c1,
+ char c2,
+ char c3,
+ char c4)
+ {
+ if (c3 == padding)
+ {
+ byte b1 = decodingTable[c1];
+ byte b2 = decodingTable[c2];
+
+ outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
+
+ return 1;
+ }
+
+ if (c4 == padding)
+ {
+ byte b1 = decodingTable[c1];
+ byte b2 = decodingTable[c2];
+ byte b3 = decodingTable[c3];
+
+ outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
+ outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
+
+ return 2;
+ }
+
+ {
+ byte b1 = decodingTable[c1];
+ byte b2 = decodingTable[c2];
+ byte b3 = decodingTable[c3];
+ byte b4 = decodingTable[c4];
+
+ outStream.WriteByte((byte)((b1 << 2) | (b2 >> 4)));
+ outStream.WriteByte((byte)((b2 << 4) | (b3 >> 2)));
+ outStream.WriteByte((byte)((b3 << 6) | b4));
+
+ return 3;
+ }
+ }
+
+ private int nextI(string data, int i, int finish)
+ {
+ while ((i < finish) && ignore(data[i]))
+ {
+ i++;
+ }
+ return i;
+ }
+ }
+}
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