PGP Decryption

  • Thread starter Thread starter Cdudej
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Cdudej

I have encrypted a text file into pgp using Bouncy Castel but now i
need to decrypt it. How can i go about reading the text from the pgp
file. Thanks in advance.
 
Cdudej said:
I have encrypted a text file into pgp using Bouncy Castel but now i
need to decrypt it. How can i go about reading the text from the pgp
file. Thanks in advance.
Click to expand...

"Assembly is the reverse of disassembly."

Why don't you just use the same library you used for encryption?
 
I have encrypted a text file into pgp using Bouncy Castel but now i
need to decrypt it. How can i go about reading the text from the pgp
file.
Click to expand...

This is one of those question where first reaction is: when you
encrypt with FoobarEncrypt class/method, then you just decrypt
with the FoobarDecrypt class/method.

But looking at the API reveals that encryption and decryption
is very asymmetric, so the question actually makes sense.

The code you need to look at is:

csharp\crypto\test\src\openpgp\examples\KeyBasedLargeFileProcessor.cs

But I have created a slightly simpler example. See below.

Arne

====================

using System;
using System.IO;

using Org.BouncyCastle.Bcpg;
using Org.BouncyCastle.Bcpg.OpenPgp;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities.IO;

namespace E
{
public class PGPWrapper
{
private const int BUFSIZ = 10240;
public static void Encrypt(string infnm, string outfnm, string pp)
{
Stream instm = new FileStream(infnm, FileMode.Open,
FileAccess.Read);
Stream outstm = new FileStream(outfnm, FileMode.Create,
FileAccess.Write);
PgpEncryptedDataGenerator pedg = new
PgpEncryptedDataGenerator(SymmetricKeyAlgorithmTag.Aes128, new
SecureRandom());
pedg.AddMethod(pp.ToCharArray());
Stream encstm = pedg.Open(outstm, new byte[BUFSIZ]);
PgpCompressedDataGenerator pcdg = new
PgpCompressedDataGenerator(CompressionAlgorithmTag.Zip);
Stream compstm = pcdg.Open(encstm);
PgpUtilities.WriteFileToLiteralData(compstm,
PgpLiteralData.Binary, new FileInfo(infnm), new byte[BUFSIZ]);
compstm.Close();
encstm.Close();
outstm.Close();
instm.Close();
}
public static void Decrypt(string infnm, string outfnm, string pp)
{
Stream instm = new FileStream(infnm, FileMode.Open,
FileAccess.Read);
Stream outstm = new FileStream(outfnm, FileMode.Create,
FileAccess.Write);
Stream utilstm = PgpUtilities.GetDecoderStream(instm);
PgpObjectFactory pof = new PgpObjectFactory(utilstm);
PgpObject po;
for(;;)
{
po = pof.NextPgpObject();
if(po is PgpEncryptedDataList) break;
}
PgpEncryptedDataList pedl = (PgpEncryptedDataList)po;
PgpPbeEncryptedData pped = (PgpPbeEncryptedData)pedl[0];
Stream encstm = pped.GetDataStream(pp.ToCharArray());
pof = new PgpObjectFactory(encstm);
PgpCompressedData pcd = (PgpCompressedData)pof.NextPgpObject();
Stream compstm = pcd.GetDataStream();
pof = new PgpObjectFactory(compstm);
PgpLiteralData pld = (PgpLiteralData)pof.NextPgpObject();
Stream litstm = pld.GetInputStream();
Streams.PipeAll(litstm, outstm);
litstm.Close();
compstm.Close();
encstm.Close();
utilstm.Close();
outstm.Close();
instm.Close();
}
}
public class Program
{
public static void Main(string[] args)
{
PGPWrapper.Encrypt(@"C:\z1.txt", @"C:\z.pgp", "This is a
super secret passphrase");
PGPWrapper.Decrypt(@"C:\z.pgp", @"C:\z2.txt", "This is a
super secret passphrase");
Console.ReadKey();
}
}
}
 
Arne said:
I have encrypted a text file into pgp using Bouncy Castel but now i
need to decrypt it. How can i go about reading the text from the pgp
file.
Click to expand...

This is one of those question where first reaction is: when you
encrypt with FoobarEncrypt class/method, then you just decrypt
with the FoobarDecrypt class/method.

But looking at the API reveals that encryption and decryption
is very asymmetric, so the question actually makes sense. [...]
Click to expand...

Not as a C# question, it doesn't. Just because the API is asymmetric,
that doesn't mean you don't use the original library for decrypting.

Pete
 
string PublicKeyFileName = strPublicKeyFileName;
string PrivateKeyFileName = strPrivateKeyFileName;
string EncryptedFileName = "EncryptedFile.txt";
string FileToEncrypt = strFileToEncrypt;

PgpEncryptionKeys encryptionKeys = new PgpEncryptionKeys(
PublicKeyFileName,
PrivateKeyFileName, "vergeet10191");
PgpEncrypt encrypter = new PgpEncrypt(encryptionKeys);
using (Stream outputStream = File.Create(FileToEncrypt))
{
encrypter.EncryptAndSign(outputStream, new
FileInfo(FileToEncrypt));
}

This is what i am using to encrypt.
 
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