"Ulf Reiman" gmail.com> writes:

Michael Jørgensen wrote:

Schwartau and Make von Saarelainen have been quite good ... in the
history of the U.S.A.

Winn Schwartau, Afterward: Practical Proactive Security and Privacy,
pp. 671-687.

Information Warfare and Its Impacts on Commercial Enterprises by Markku
J. Saarelainen

http://www.cosc.georgetown.edu/~denning/cosc511/spring97/schedule.html

loki hotmail.com> wrote:

You don't learn cryptology by doing, you learn by breaking.

Studying classical ciphers and how to break them may give your
cryptanalytic intuition a kick-start.

anil gmail.com> wrote:

lcm(2,4) is generally recognized to be 4 ...

Ok there is a comp at work to decrypt a stream of cyphertext for a case of
beer.

It's been years since I've played with cryptography, and I don't have the
time to re-learn the basics in a rush. Can anyone recommend a good tool for
doing a quick decrypt of a transposition cipher text?

Gregory G Rose qualcomm.com> wrote:

In article news.mc.ntu.edu.tw>,
Mike Amling nospam.com> wrote:
<> I've already learned, from this thread, that a 2048-bit RSA key is going
<> to result in a 2048-bit encrypted payload (for data sizes smaller than
<> the key size). My calculations, if not in error, tell me that even a
<> 1024-bit key will result in 128 bytes of encrypted data, which when
<> base64-encoded will be 4/3 that size or about 171 (172? rounded up?)
<> bytes in length.
<>
<> Elliptic-Curve encryption was something I'd mentioned in passing, but I
<> am not expert in the technology and so I do not know if it can produce
<> encrypted payloads small enough for our needs. I believe based on my
<> reading that its smaller key sizes are said to be roughly equivalent to...

I only know some basics about SSL, symmetric keys and asymmetric keys,
and I'd greatly appreciate anyone who can shed some light on this question!

My understanding (and feel free to correct anything below here!) is that
SSL transactions between a web browser and a web server involve first a
handshake, then the actual data transmission. The handshake is handled
by a public/private key pair, then switches over to the symmetric key
(256-bit AES, 162-bit 3DES, or whatever) for the bulk of the data
transmission.

Now, it seems from what I've read that 128-bit symmetric keys are still
considered secure given the current state of computing power, and may
stay that way for a long time. But for asymmetric keys, 1024 bits is
considered by at least some to be getting into the realms of being
feasibly crackable. Longer keys (2048 bit, 3072 bit) are recommended
for data that needs to be protected for years to come.

Hi, I am trying to write a toy cipher and I am stuck at this point, I
do know that at this stage this cipher can be broken very easily as I
posted a challenge in a small forum. the key had a period of 47 and it
was only a matter of hours before it was broken and the plaintext
revieled.

could anyone point me in the right direction?

/* Baldr : an 8 bit block toy cipher
Version: 0.3
*/

/* Usage: baldr key input_file output_file */

/* includes */
#include

/* defines */
#define decrypt 100
#define encrypt 101

/* error codes */
#define BAD_FO "\n:: ERROR WRITING OUTPUT FILE ::\n"
#define BAD_FI "\n:: ERROR READING INPUT FILE ::\n"
#define BAD_KEY "\n:: ERROR READING KEY ::\n"