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Update possible_ans.md

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Bill Buchanan
2022-02-03 15:24:28 +00:00
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unit02_symmetric/lab/possible_ans.md
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@@ -62,7 +62,8 @@ print(" decrypt: ",plaintext.decode())
A sample is [here](https://replit.com/@billbuchanan/des2#main.py).
A sample run is:
<pre>
```
napier@napier-virtual-machine:~$ python d1.py hello hello123
After padding (CMS): 68656c6c6f0b0b0b0b0b0b0b0b0b0b0b
Cipher (ECB): 0a7ec77951291795bac6690c9e7f4c0d
@@ -79,74 +80,9 @@ napier@napier-virtual-machine:~$ python d1.py Africa changme
After padding (CMS): 4166726963610a0a0a0a0a0a0a0a0a0a
Cipher (ECB): ab453ac52cd3b1a61b35d6e85e4568f8
decrypt: Africa
</pre>
## D.2
Sample code is:
```python
from Crypto.Cipher import DES
import hashlib
import sys
import binascii
import Padding
val='hello'
password='hello'
if (len(sys.argv)>1):
val=sys.argv[1]
if (len(sys.argv)>2):
password=sys.argv[2]
plaintext=val
def encrypt(plaintext,key, mode):
encobj = DES.new(key,mode)
return(encobj.encrypt(plaintext))
def decrypt(ciphertext,key, mode):
encobj = DES.new(key,mode)
return(encobj.decrypt(ciphertext))
key = hashlib.sha256(password.encode()).digest()
plaintext = Padding.appendPadding(plaintext,blocksize=Padding.DES_blocksize,mode='CMS')
print ("After padding (CMS): ",binascii.hexlify(plaintext.encode()))
ciphertext = encrypt(plaintext.encode(),key[:8],DES.MODE_ECB)
print ("Cipher (ECB): ",binascii.hexlify(ciphertext))
plaintext = decrypt(ciphertext,key[:8],DES.MODE_ECB)
plaintext = Padding.removePadding(plaintext.decode(),blocksize=Padding.DES_blocksize,mode='CMS')
print (" decrypt: ",plaintext)
```
A sample is [here](https://repl.it/@billbuchanan/ch02ans04#main.py).
A sample run is:
<pre>
napier@napier-virtual-machine:~$ python d2.py hello hello123
After padding (CMS): 68656c6c6f030303
Cipher (ECB): 8f770898ddb9fb38
decrypt: hello
napier@napier-virtual-machine:~$ python d2.py inkwell orange
After padding (CMS): 696e6b77656c6c01
Cipher (ECB): 1086a73ab5273254
decrypt: inkwell
napier@napier-virtual-machine:~$ python d2.py security qwerty
After padding (CMS): 73656375726974790808080808080808
Cipher (ECB): d19c86b3fc7e924f148652c183caa922
decrypt: security
napier@napier-virtual-machine:~$ python d2.py Africa changeme
After padding (CMS): 4166726963610202
Cipher (ECB): 6e11929fe6a3c081
decrypt: Africa
</pre>
## D.3
Answer: