← Back

#### Chapter 10: Interception

Previously: The investigations of disappearance of Mr. Wright led to a shadowy organization called COATIS. While the investigations regarding the case continued, you witnessed a strange case in which a client's digital files were encrypted automatically with a strong cryptographic mechanism; and the client was asked for a huge amount of money to decrypt her files.
You never thought that cryptography could be harmful to anyone, and here it is - an unusual case!
Who could have encrypted those files? Who owns the secret RSA private key which the previous report talked about?
And, what about the investigation regarding COATIS? What did they made out of the IP address that you decrypted?
After few days of wait, your next assignment comes. Possibly, A big revelation awaits ahead.
A G I L I n v e s t i g a t i o n I n c .
Spellborough, U.K.
18 May, 2009
Assignment #10
OBJECTIVE: Decrypt the Message.
DESCRIPTION: It's been quite some time since we assigned you any challenge. But finally, here it is - a very important one. Read carefully.
The IP address of COATIS indeed turned out to be a very crucial piece of information. Our cyber security personnels worked hard as the IP itself was non functional, but after a series of highly intelligent efforts, they traced it to the original IP of COATIS.
The delay in your assignment was also, in part, due to these efforts. Further, we needed the permissions of the court for our next step. It also took laborious legal efforts and lengthy time. But in the end, we got the permissions and took the necesary step. We intercepted the emails of COATIS, and now have those in our possession.
We have sent to you one of those emails, but it is encrypted using DES. The message containing the DES key itself, is encrypted using RSA. The details are attached herewith.
Decrypt the RSA message, Get the DES key, Decrypt the DES email, and submit the plaintext to us soon.
CIPHER INFO: DES for plaintext. RSA for key
Encl. (2)

1. Email encrypted using DES.
2. The RSA-encrypted Message containing the DES key.

EVIDENCE
TYPE: DES Encrypted Email
Date: 18 May, 2009
EVIDENCE
TYPE: RSA Encrypted Message Containing the DES Key
Date: 18 May, 2009
2ZqVCu0LtO-KkwD:UPIUIao^1P[b(y@
RSA Private Key (to decrypt above):
Exponent:
960579666006549817560236322319983030053924297595951478922705
Modulus:
1058059960185402366316160067497052659354567879221060758600659
Private emails of COATIS!!!
Certainly, it would have their deepest and darkest secrets.
Let's decrypt.
Solution
done