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billbuchanan
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@@ -1,564 +0,0 @@
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A.6
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print 0x43 | 0x21
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print 0x43 & 0x21
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print 0x43 ^ 0x21
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A.7
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val1=93
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print "Dec:\t",val1
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print "Bin:\t",bin(val1)
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print "Hex:\t",hex(val1)
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print "Oct:\t",oct(val1)
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print "Char:\t",chr(val1)
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A.8
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val=93
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console.log(val.toString(2))
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console.log(val.toString(16))
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console.log(val.toString(8))
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console.log(String.fromCharCode(val))
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A.9
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import base64
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str=”crypto”
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print base64.b64encode(val)
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A.10
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import sys
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val1="00110101"
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if (len(sys.argv)>1):
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val1=sys.argv[1]
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print "Binary form: \t\t",val1
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dec=int(val1,2)
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print "Decimal form: \t\t",dec,"\t",bin(dec)[2:10].rjust(8,'0')
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res=(dec << 1) & 0xff
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print "Shift left (1):\t",res,"\t",bin(res)[2:10].rjust(8,'0')
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res=(dec << 2) & 0xff
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print "Shift left (2):\t",res,"\t",bin(res)[2:].rjust(8,'0')
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res=(dec >> 1) & 0xff
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print "Shift right (1):\t",res,"\t",bin(res)[2:10].rjust(8,'0')
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res=(dec >> 2) & 0xff
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print "Shift right (2):\t",res,"\t",bin(res)[2:10].rjust(8,'0')
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B.1
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def gcd(a, b):
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while( b != 0 ):
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Remainder = a % b;
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a = b;
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b = Remainder;
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return a;
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g = gcd(54,8)
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print g
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C.3
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message = raw_input('Enter message: ')
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e = raw_input('Enter exponent: ')
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p = raw_input('Enter prime ')
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cipher = (int(message) ** int(e)) % int(p)
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print cipher
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D.1
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import math
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def get_if_prime(val):
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max = math.sqrt(val);
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if (val % 2 == 0):
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return (False);
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if (val % 3 == 0):
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return (False);
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for k in range(0, 10000):
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testval = 6 * k + 1;
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if (testval>max):
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break
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if (val % testval == 0):
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return (False)
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testval = 6 * k - 1;
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if (testval>max):
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break
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if (val % testval == 0):
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return (False)
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return (true)
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val=93
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res = get_if_prime(val)
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if (res==True):
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print str(val)+" is prime"
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else:
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print str(val)+" is not prime"
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D.2
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import sys
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test=1000
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if (len(sys.argv)>1):
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test=int(sys.argv[1])
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def sieve_for_primes_to(n):
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size = n//2
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sieve = [1]*size
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limit = int(n**0.5)
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for i in range(1,limit):
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if sieve[i]:
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val = 2*i+1
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tmp = ((size-1) - i)//val
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sieve[i+val::val] = [0]*tmp
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return [2] + [i*2+1 for i, v in enumerate(sieve) if v and i>0]
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print sieve_for_primes_to(test)
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Lab 2: Symmetric Key
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Lab sheet [here]
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Commands in Section A:
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openssl list-cipher-commands
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openssl version
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openssl prime –hex 1111
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openssl enc -aes-256-cbc -in myfile.txt -out encrypted.bin
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openssl enc -aes-256-cbc -in myfile.txt -out encrypted.bin –base64
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openssl enc -d -aes-256-cbc -in encrypted.bin -pass pass:napier -base64
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B.2
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from Crypto.Cipher import AES
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import hashlib
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import sys
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import binascii
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import Padding
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val='hello'
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password='hello'
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plaintext=val
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def encrypt(plaintext,key, mode):
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encobj = AES.new(key,mode)
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return(encobj.encrypt(plaintext))
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def decrypt(ciphertext,key, mode):
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encobj = AES.new(key,mode)
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return(encobj.decrypt(ciphertext))
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key = hashlib.sha256(password).digest()
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plaintext = Padding.appendPadding(plaintext,blocksize=Padding.AES_blocksize,mode='CMS')
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print "After padding (CMS): "+binascii.hexlify(bytearray(plaintext))
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ciphertext = encrypt(plaintext,key,AES.MODE_ECB)
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print "Cipher (ECB): "+binascii.hexlify(bytearray(ciphertext))
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plaintext = decrypt(ciphertext,key,AES.MODE_ECB)
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plaintext = Padding.removePadding(plaintext,mode='CMS')
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print " decrypt: "+plaintext
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plaintext=val
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plaintext = Padding.appendPadding(plaintext,blocksize=Padding.AES_blocksize,mode='ZeroLen')
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print "\nAfter padding (Bit): "+binascii.hexlify(bytearray(plaintext))
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ciphertext = encrypt(plaintext,key,AES.MODE_ECB)
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print "Cipher (ECB): "+binascii.hexlify(bytearray(ciphertext))
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plaintext = decrypt(ciphertext,key,AES.MODE_ECB)
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plaintext = Padding.removePadding(plaintext,blocksize=Padding.AES_blocksize,mode='ZeroLen')
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print " decrypt: "+plaintext
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plaintext=val
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plaintext = Padding.appendPadding(plaintext,blocksize=Padding.AES_blocksize,mode='Space')
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print "\nAfter padding (Null): "+binascii.hexlify(bytearray(plaintext))
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ciphertext = encrypt(plaintext,key,AES.MODE_ECB)
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print "Cipher (ECB): "+binascii.hexlify(bytearray(ciphertext))
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plaintext = decrypt(ciphertext,key,AES.MODE_ECB)
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plaintext = Padding.removePadding(plaintext,blocksize=Padding.AES_blocksize,mode='Space')
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print " decrypt: "+plaintext
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plaintext=val
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plaintext = Padding.appendPadding(plaintext,blocksize=Padding.AES_blocksize,mode='Random')
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print "\nAfter padding (Random): "+binascii.hexlify(bytearray(plaintext))
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ciphertext = encrypt(plaintext,key,AES.MODE_ECB)
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print "Cipher (ECB): "+binascii.hexlify(bytearray(ciphertext))
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plaintext = decrypt(ciphertext,key,AES.MODE_ECB)
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plaintext = Padding.removePadding(plaintext,mode='Random')
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print " decrypt: "+plaintext
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C.2
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from Crypto.Cipher import DES
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import hashlib
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import sys
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import binascii
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import Padding
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val='hello'
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password='hello'
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plaintext=val
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def encrypt(plaintext,key, mode):
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encobj = DES.new(key,mode)
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return(encobj.encrypt(plaintext))
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def decrypt(ciphertext,key, mode):
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encobj = DES.new(key,mode)
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return(encobj.decrypt(ciphertext))
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print "\nDES"
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key = hashlib.sha256(password).digest()[:8]
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plaintext = Padding.appendPadding(plaintext,blocksize=Padding.DES_blocksize,mode='CMS')
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print "After padding (CMS): "+binascii.hexlify(bytearray(plaintext))
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ciphertext = encrypt(plaintext,key,DES.MODE_ECB)
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print "Cipher (ECB): "+binascii.hexlify(bytearray(ciphertext))
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plaintext = decrypt(ciphertext,key,DES.MODE_ECB)
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plaintext = Padding.removePadding(plaintext,mode='CMS')
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print " decrypt: "+plaintext
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D.1
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from Crypto.Cipher import AES
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import hashlib
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import sys
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import binascii
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import Padding
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val='hello'
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password='hello'
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plaintext=val
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def encrypt(plaintext,key, mode):
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encobj = AES.new(key,mode)
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return(encobj.encrypt(plaintext))
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def decrypt(ciphertext,key, mode):
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encobj = AES.new(key,mode)
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return(encobj.decrypt(ciphertext))
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key = hashlib.sha256(password).digest()
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plaintext = Padding.appendPadding(plaintext,blocksize=Padding.AES_blocksize,mode='CMS')
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print "After padding (CMS): "+binascii.hexlify(bytearray(plaintext))
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ciphertext = encrypt(plaintext,key,AES.MODE_ECB)
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print "Cipher (ECB): "+binascii.hexlify(bytearray(ciphertext))
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plaintext = decrypt(ciphertext,key,AES.MODE_ECB)
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plaintext = Padding.removePadding(plaintext,mode='CMS')
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print " decrypt: "+plaintext
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plaintext=val
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Possible solution for E.1:
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from Crypto.Cipher import AES
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import hashlib
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import sys
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import binascii
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import Padding
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val='fox'
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password='hello'
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cipher=''
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import sys
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if (len(sys.argv)>1):
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cipher=(sys.argv[1])
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if (len(sys.argv)>2):
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password=(sys.argv[2])
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plaintext=val
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def encrypt(plaintext,key, mode):
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encobj = AES.new(key,mode)
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return(encobj.encrypt(plaintext))
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def decrypt(ciphertext,key, mode):
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encobj = AES.new(key,mode)
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return(encobj.decrypt(ciphertext))
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key = hashlib.sha256(password).digest()
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ciphertext=binascii.unhexlify(cipher)
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plaintext = decrypt(ciphertext,key,AES.MODE_ECB)
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print plaintext
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plaintext = Padding.removePadding(plaintext,mode='CMS')
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print " decrypt: "+plaintext
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plaintext=val
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F.1
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try:
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plaintext = Padding.removePadding(plaintext,mode='CMS')
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print " decrypt: "+plaintext
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except:
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print("Error!")
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G.1 Node.js code:
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var Chacha20KeySize = 32;
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var Chacha20NonceSize = 8;
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key = '0000000000000000000000000000000000000000000000000000000000000000';
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nce = '0000000000000000';
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document.getElementById("val1").innerHTML = nce;
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document.getElementById("key").innerHTML = key;
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go();
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function go() {
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n = document.getElementById('val1').value;
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k = document.getElementById('key').value;
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document.getElementById("encrypted").innerHTML = "Key:\t" + k;
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document.getElementById("encrypted").innerHTML += "\nNouce:\t" + n;
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n = from_Hex(n);
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k = from_Hex(k);
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var ctx, out;
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out = new Array(k.length);
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ctx = chacha20_init(k, n);
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chacha20_keystream(ctx, out, out, k.length);
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document.getElementById("encrypted").innerHTML += "\n---\nKey generation: " + bytes2hex(out);
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}
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var Chacha20Ctx = function () {
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this.input = new Array(16);
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};
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function load32(x, i) {
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return x[i] | (x[i + 1] << 8) | (x[i + 2] << 16) | (x[i + 3] << 24);
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}
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function store32(x, i, u) {
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x[i] = u & 0xff; u >>>= 8;
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x[i + 1] = u & 0xff; u >>>= 8;
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x[i + 2] = u & 0xff; u >>>= 8;
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x[i + 3] = u & 0xff;
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}
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function rotl32(v, c) {
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return (v << c) | (v >>> (32 - c));
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}
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function chacha20_round(x, a, b, c, d) {
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x[a] += x[b]; x[d] = rotl32(x[d] ^ x[a], 16);
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x[c] += x[d]; x[b] = rotl32(x[b] ^ x[c], 12);
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x[a] += x[b]; x[d] = rotl32(x[d] ^ x[a], 8);
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x[c] += x[d]; x[b] = rotl32(x[b] ^ x[c], 7);
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}
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function chacha20_init(key, nonce) {
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var x = new Chacha20Ctx();
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||||
x.input[0] = 1634760805;
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||||
x.input[1] = 857760878;
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x.input[2] = 2036477234;
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x.input[3] = 1797285236;
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x.input[12] = 0;
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x.input[13] = 0;
|
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x.input[14] = load32(nonce, 0);
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x.input[15] = load32(nonce, 4);
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||||
|
||||
for (var i = 0; i < 8; i++) {
|
||||
x.input[i + 4] = load32(key, i * 4);
|
||||
}
|
||||
return x;
|
||||
}
|
||||
|
||||
function chacha20_keystream(ctx, dst, src, len) {
|
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var x = new Array(16);
|
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var buf = new Array(64);
|
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var i = 0, dpos = 0, spos = 0;
|
||||
|
||||
while (len > 0) {
|
||||
for (i = 16; i--;) x[i] = ctx.input[i];
|
||||
for (i = 20; i > 0; i -= 2) {
|
||||
chacha20_round(x, 0, 4, 8, 12);
|
||||
chacha20_round(x, 1, 5, 9, 13);
|
||||
chacha20_round(x, 2, 6, 10, 14);
|
||||
chacha20_round(x, 3, 7, 11, 15);
|
||||
chacha20_round(x, 0, 5, 10, 15);
|
||||
chacha20_round(x, 1, 6, 11, 12);
|
||||
chacha20_round(x, 2, 7, 8, 13);
|
||||
chacha20_round(x, 3, 4, 9, 14);
|
||||
}
|
||||
for (i = 16; i--;) x[i] += ctx.input[i];
|
||||
for (i = 16; i--;) store32(buf, 4 * i, x[i]);
|
||||
|
||||
ctx.input[12] += 1;
|
||||
if (!ctx.input[12]) {
|
||||
ctx.input[13] += 1;
|
||||
}
|
||||
if (len <= 64) {
|
||||
for (i = len; i--;) {
|
||||
dst[i + dpos] = src[i + spos] ^ buf[i];
|
||||
}
|
||||
return;
|
||||
}
|
||||
for (i = 64; i--;) {
|
||||
dst[i + dpos] = src[i + spos] ^ buf[i];
|
||||
}
|
||||
len -= 64;
|
||||
spos += 64;
|
||||
dpos += 64;
|
||||
}
|
||||
}
|
||||
|
||||
//--------------------------- test -----------------------------//
|
||||
function bytes2hex(blk, dlm) {
|
||||
return Array.prototype.map.call(new Uint8Array(blk.buffer || blk),
|
||||
function (s) { return ('00' + s.toString(16)).slice(-2); }).join(dlm || '');
|
||||
}
|
||||
function from_Hex(h) {
|
||||
|
||||
h.replace(' ', '');
|
||||
var out = [], len = h.length, w = '';
|
||||
for (var i = 0; i < len; i += 2) {
|
||||
w = h[i];
|
||||
if (((i + 1) >= len) || typeof h[i + 1] === 'undefined') {
|
||||
w += '0';
|
||||
} else {
|
||||
w += h[i + 1];
|
||||
}
|
||||
out.push(parseInt(w, 16));
|
||||
}
|
||||
return out;
|
||||
}
|
||||
|
||||
function bytesEqual(a, b) {
|
||||
var dif = 0;
|
||||
if (a.length !== b.length) return 0;
|
||||
for (var i = 0; i < a.length; i++) {
|
||||
dif |= (a[i] ^ b[i]);
|
||||
}
|
||||
dif = (dif - 1) >>> 31;
|
||||
return (dif & 1);
|
||||
}
|
||||
|
||||
Sample answers
|
||||
|
||||
A possible answer for Section E is:
|
||||
|
||||
from Crypto.Cipher import AES
|
||||
import hashlib
|
||||
import sys
|
||||
import binascii
|
||||
import Padding
|
||||
|
||||
val='hello'
|
||||
password='hello'
|
||||
|
||||
|
||||
cipher=raw_input('Enter cipher:')
|
||||
password=raw_input('Enter password:')
|
||||
|
||||
plaintext=val
|
||||
|
||||
def encrypt(plaintext,key, mode):
|
||||
encobj = AES.new(key,mode)
|
||||
return(encobj.encrypt(plaintext))
|
||||
|
||||
def decrypt(ciphertext,key, mode):
|
||||
encobj = AES.new(key,mode)
|
||||
return(encobj.decrypt(ciphertext))
|
||||
|
||||
key = hashlib.sha256(password).digest()
|
||||
|
||||
|
||||
ciphertext = binascii.unhexlify(cipher)
|
||||
|
||||
print "Cipher (ECB): "+binascii.hexlify(bytearray(ciphertext))
|
||||
|
||||
plaintext = decrypt(ciphertext,key,AES.MODE_ECB)
|
||||
plaintext = Padding.removePadding(plaintext,mode='CMS')
|
||||
print " decrypt: "+plaintext
|
||||
|
||||
A sample code for Section F is:
|
||||
|
||||
pw = ["hello","ankle","changeme","123456"]
|
||||
|
||||
for password in pw:
|
||||
|
||||
try:
|
||||
key = hashlib.sha256(password).digest()
|
||||
cipherhex = base64.decodestring(cipher).encode('hex')
|
||||
|
||||
ciphertext = binascii.unhexlify(cipherhex)
|
||||
|
||||
print "Cipher (ECB): "+binascii.hexlify(bytearray(ciphertext))
|
||||
|
||||
plaintext = decrypt(ciphertext,key,AES.MODE_ECB)
|
||||
plaintext = Padding.removePadding(plaintext,mode='CMS')
|
||||
print " decrypt: "+plaintext
|
||||
print " Key found"+password
|
||||
|
||||
except:
|
||||
print(".")
|
||||
|
||||
Reference in New Issue
Block a user