Hello again, Stephen.
If you encrypt then base-64 encode, you must base-64 decode then decrypt. You
are attempting to decrypt base-64 encoded ciphertext, not the ciphertext
itself.
>From test.cpp:
string DecryptString(const char *instr, const char *passPhrase)
{
string outstr;
HexDecoder decryptor(new DefaultDecryptorWithMAC(passPhrase, new
StringSink(outstr)));
decryptor.Put((byte *)instr, strlen(instr));
decryptor.MessageEnd();
return outstr;
}
Which means your cfbDecrypter should look more like:
StreamTransformationFilter *cfbDecryptor =
new StreamTransformationFilter (aes_decrypt,
new StringSink (plaintext));
and your StringSource should look more like:
StringSource source (new Base64Decoder(ciphertext), true, cfbDecryptor);
NOTE that I haven't tested this, you may have to make some "adjustments" to
it.
I don't use them quite like that.
Rickey
----- Original Message -----
From: "Stephen torri" <[EMAIL PROTECTED]>
To: "Rickey Braddam" <[EMAIL PROTECTED]>
Cc: "cryptopp" <[EMAIL PROTECTED]>
Sent: Saturday, November 15, 2003 1:46 PM
Subject: Decryption in CFB_Mode<AES>
> Here is the code that I am using to encrypt and decrypt a text. What I
> do not see is how the decryption is failing to work. Below is the output
> (char and hex for both the plain text). Question is why is the decrypt
> code rubbish and not the original plain text?
>
> -----------------------
> encrypt code
> -----------------------
> string plaintext = ... input text ...
> string ciphertext;
>
> CFB_Mode<AES>::Encryption aes_encrypt (m_encryKey,
> AES::DEFAULT_KEYLENGTH, m_iv);
>
> StreamTransformationFilter *cfbEncryptor =
> new StreamTransformationFilter (aes_encrypt,
> new Base64Encoder (new StringSink (ciphertext)));
>
> StringSource source (plaintext, true, cfbEncryptor);
>
> -------------------------
> encrypt output
> -------------------------
>
> Plaintext char: J i m C a r r e y
> B r u c e A l m i g h t y
>
> Plaintext hex: 0x4a 0x69 0x6d 0x20 0x43 0x61 0x72 0x72 0x65
> 0x79 0xa 0x42 0x72 0x75 0x63 0x65 0x20 0x41 0x6c 0x6d 0x69
> 0x67 0x68 0x74 0x79
>
> Ciphertext char: 3 i P n 2 M U 6 D j E c / P 9 d / 5
> g h O z 3 v f u 6 X V W n 5 c w
>
> Ciphertext hex: 0x33 0x69 0x50 0x6e 0x32 0x4d 0x55 0x36 0x44
> 0x6a 0x45 0x63 0x2f 0x50 0x39 0x64 0x2f 0x35 0x67 0x68 0x4f
> 0x7a 0x33 0x76 0x66 0x75 0x36 0x58 0x56 0x57 0x6e 0x35 0x63
> 0x77 0xa
>
> Open the file and decrypt contents: Loading
> /home/storri/Documents/StephenTorri/cs502_project/src/data.txt
>
> -----------------------
> decrypt code
> -----------------------
> CFB_Mode<AES>::Decryption aes_decrypt (m_encryKey,
> AES::DEFAULT_KEYLENGTH, m_iv);
>
> StreamTransformationFilter *cfbDecryptor =
> new StreamTransformationFilter (aes_decrypt,
> new Base64Decoder (new StringSink (plaintext)));
>
> StringSource source (ciphertext, true, cfbDecryptor);
>
> -----------------------
> decrypt output
> -----------------------
>
> Ciphertext char: 3 i P n 2 M U 6 D j E c / P 9 d / 5
> g h O z 3 v f u 6 X V W n 5 c w
>
> Ciphertext hex: 0x33 0x69 0x50 0x6e 0x32 0x4d 0x55 0x36 0x44
> 0x6a 0x45 0x63 0x2f 0x50 0x39 0x64 0x2f 0x35 0x67 0x68 0x4f
> 0x7a 0x33 0x76 0x66 0x75 0x36 0x58 0x56 0x57 0x6e 0x35 0x63
> 0x77 0xa
>
> Plaintext hex: 0xffffffba 0x48 0x32
>
> Plaintext char: º H 2
>
> Stephen
>
