Transcript Network Security - IIS Windows Server

Network Security
CPSC6128 – Lecture 5
Cryptography
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Cryptography
Overview
Symmetric Key Cryptography
Public Key Cryptography
Message integrity and digital signatures
References:
Stamp
Schneier
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Cryptography basics
The process of converting plaintext into ciphertext
Plaintext
Readable text
Ciphertext
Unreadable or encrypted text
It is used to hide information from unauthorized users
Decryption
the process of converting ciphertext back to plaintext
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History of Cryptography
Substitution Cipher
Replaces one letter with another letter based on some key
Example: Julius Ceasar’s Cipher
Key value of 3
ABCDEFGHIJKLMNOPQRSTUVWXYZ
DEFGHIJKLMNOPQRSTUVWXYZABC
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History of Cryptography (cont)
Cryptanalysis
studies the process of breaking encryption algorithms
When a new encryption algorithm is developed
 cryptanalysts study it and try to break it
This is an important part of the development cycle of a new
encryption algorithm
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World War I
 Zimmerman Telegram
Encrypted telegram from
foreign secretary of the German
empire to German ambassador
in Mexico
Intercepted and decrypted by
the British
Indicated that unrestricted sub
warfare would commence
Proposed an alliance with
Mexico to reclaim lost land to
US.
Pivotal in US entering WWI
Cortesty: Wikipedia
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World War II
Enigma
Used by the Germans
Replaced letters as they were typed
Substitutions were computed using a key and a set of
switches and rotors
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Cryptography Issues
Confidentiality
only sender, intended receiver should “understand” message
contents:
sender encrypts message
receiver decrypts message
End-Point Authentication
send, receiver want to confirm identity of each other.
Message Integrity
sender, receiver want to ensure message not altered
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Friends and enemies: Alice, Bob, Eve (or Trudy)
Well known model in network security world
Bob, Alice want to communicate securely
Trudy (intruder) may intercept, delete, add to message
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Who might Bob, Alice be?
...well, real-life Bobs and Alices
Web browsers/server for electronic transactions
online banking client/server
DNS servers
routers exchanging routing table updates
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The Language of Cryptography
 m plaintext message
 KA(m) is ciphertext, encrypted with key KA
 m = KB(KA(m))
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Simple Encryption Scheme
Substitution Cipher
substituting one thing for another
Mono-alphabetic cipher: substitute one letter for another
Plaintext: abcdefghijklmnopqrstuvwxyz
Ciphertext: mnbvcxzasdfghjklpoiuytrewq
Example:
Plaintext: bob. i love you. alice
ciphertext: nkn. s gktc wky. mgsbc
Key: The mapping from the set of 26 letters to the set of 26 letters
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Poly-alphabetic Encryption - Vignere
n monoalphabetic ciphers M1, M2, ...., Mn
Cycling pattern:
e.g. n=4, M1, M3, M4, M3, M2; M1, M3, M4, M3, M2
For each new plaintext symbol, use subsequent
monoalphabetic pattern in a cyclic pattern.
dog: d from M1, o from M3, g from M4
Key: the n ciphers and the cyclic pattern
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Vigenere Square
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Vernam – Perfect Substitution Cipher
 If we use Vignere with keylength as long as the plaintext
then cryptanalysis will become very difficult.
 If we change key every time we encrypt
then cryptanalyst’s job becomes even more difficult
One-time pad or Vernam Cipher
 How do we get such long keys?
A large book shared by transmitter and receiver
Initial key followed by previous messages themselves!!
Random number sequence based on common shared and
secret seed
 Such a cipher is difficult to break
 but not very practical
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Breaking an Encryption Scheme
Ciphertext only attack
Eve has ciphertext that she can analyze
Two approaches
Search through all keys
must be able to differentiate resulting plaintext from gibbersh
Statistical analysis
Know-plaintext attack
Eve has some plaintext corresponding to some ciphertext
eg, in monoalphabetic cipher, trudy determines pairings for
a,l,i,c,e,b,o
Chosen-plaintext attack
Eve can get the ciphertext from some chosen plaintext
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Computational Effort Required
Time
Number of primitive operations required
Computational time required for the attack
Some attacks become more feasible as computing power becomes
cheaper and faster
Memory
Amount of storage required to complete the attack
This can be either hard disk or memory
Data
Amount of captured data required to complete the attack
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Rainbow Tables attack
Time/Memory Tradeoff
Used to recover the plaintext from a given HASH value
Commonly used to attack HASHed password
SALT
random number concatenated to the HASH value to prevent Rainbow
table attacks
saltedhash(password) = hash(password.salt)
Since SALT is a random number
the attacker would have to compute a Rainbow table for each SALT value
Large SALT value is critical
More on Hashes Later
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Types of Cryptography
Crypto often uses keys:
Algorithm is known to everyone
Only “keys” are secret
Kerckhoff’s Principle
Can be extended to security systems design in general
Public Key Cryptography
Involves the use of two keys
Symmetric key cryptography
Involves the use of one key
Hash functions
Involves the use of no keys
Nothing secret: How can this be useful?
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Shannon Characteristics of Good Ciphers
The amount of secrecy needed should determine
the amount of labor appropriate for encryption and decryption
The set of keys and enciphering algorithms
should be free from complexity
The implementation of the process
should be as simple as possible
Errors in ciphering should not
propagate and cause corruption of future information in the message
The size of enciphered text
Should not be longer than the text of the original message
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Confusion and Diffusion
Confusion
The cryptanalyst should not be able to predict what changing one
character in the plaintext will do to the ciphertext
Diffusion
Changes in the key should affect many parts in the ciphertext
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Symmetric Key Cryptography
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Symmetric key Cryptography
Symmetric Key crypto
Bob and Alice share same symmetric key: Ks
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Two Types of Symmetric Ciphers
Stream Ciphers
Encrypt one bit at a time
Block Ciphers
Break plaintext message into equal-size blocks
Encrypt each block as a unit
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Stream Ciphers:
Combine each bit of keystream with bit of plaintext to get
bit of ciphertext
m(i) = ith bit of message
ks(i) = ith bit of keystream
c(i) = ith bit of ciphertext
c(i) = ks(i)  m(i) ( = exclusive or)
m(i) = ks(i)  c(i)
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Problems With Stream Ciphers
Known plain-text attack
There’s often predictable and repetitive data in communication messages
attacker receives some cipher text c and correctly guesses corresponding
plaintext m
ks = m  c
Attacker now observes c', obtained with same sequence ks
M' = ks  c'
 Even easier

Attacker obtains two ciphertexts, c and c', generating with same key
sequence
 c  c' = m  m'

There are well known methods for decrypting 2 plaintexts given their XOR
 Integrity problem too




suppose attacker knows c and m (eg, plaintext attack);
wants to change m to m'
calculates c' = c  (m  m')
sends c' to destination
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Example: RC4 Stream Cipher
RC4 is a popular stream cipher
Extensively analyzed and considered good
Key can be from 1 to 256 bytes
Used in WEP for 802.11
Can be used in SSL
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Block Ciphers
Message to be encrypted
is processed in blocks of k bits (e.g., 64-bit blocks).
1-to-1 mapping is used to
map k-bit block of plaintext to k-bit block of ciphertext
Example with k=3
input
000
001
010
011
output
110
111
101
100
input
100
101
110
111
output
011
010
000
001
What is the ciphertext for 010110001111 ?
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Block Ciphers
How many possible mappings are there for k=3?
How many 3-bit inputs?
How many permutations of the 3-bit inputs?
Answer: 40,320 ; not very many!
In general, 2k! mappings; huge for k=64
Problem:
Table approach requires table with 264 entries
Each entry with 64 bits
Table is too big
instead use function that simulates a randomly permuted table
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Prototype Function
From Kaufman
et al
64-bit input
8bits
8bits
8bits
8bits
8bits
8bits
8bits
8bits
S1
S2
S3
S4
S5
S6
S7
S8
8 bits
8 bits
8 bits
8 bits
8 bits
8 bits
8 bits
8 bits
64-bit intermediate
Loop for
n rounds
64-bit output
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Why Rounds in Prototype?
If only a single round, then one bit of input affects at most
8 bits of output.
In 2nd round, the 8 affected bits get scattered and
inputted into multiple substitution boxes.
How many rounds?
How many times do you need to shuffle cards?
Becomes less efficient as n increases
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Encrypting a Large Message
Why not just break message in 64-bit blocks, encrypt each
block separately?
If same block of plaintext appears twice, will give same cyphertext
How to fix it?
Generate random 64-bit number r(i) for each plaintext block m(i)
Calculate c(i) = KS( m(i)  r(i) )
Transmit c(i), r(i), i=1,2,…
At receiver: m(i) = KS(c(i))  r(i)
Problem: inefficient, need to send c(i) and r(i)
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Cipher Block Chaining (CBC)
CBC generates its own random numbers
Have encryption of current block depending on result of previous block
c(i) = KS( m(i)  c(i-1) )
m(i) = KS( c(i))  c(i-1)
How to encrypt the first block?
Initialization vector (IV): random block = c(0)
IV does not have to be secret
Change IV for each message (or session)
Guarantees that even if the same message is sent repeatedly, the ciphertext will be completely
different each time
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Cipher Block Chaining (CBC)
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Symmetric Key Crypto: DES
DES: Data Encryption Standard
US encryption standard [NIST 1993]
56-bit symmetric key, 64-bit plaintext input
Block cipher with cipher block chaining
How secure is DES?
DES Challenge: 56-bit-key-encrypted phrase decrypted (brute force) in
less than a day
No known good analytic attack making DES more secure
3DES: encrypt/decrypt 3 times with 3 different keys
ciphertext = EK3(DK2(EK1(plaintext)))
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Symmetric Key Crypto: DES
DES Operation:
initial permutation
16 identical “rounds” of function application
each using different 48 bits of key
Final permutation
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Advanced Encryption Standard
New (Nov. 2001) symmetric-key NIST standard
Used to replace DES
Processes data in 128 bit blocks
128, 192, or 256 bit keys
Brute force decryption (try each key)
takes 1 day on DES, but 149 trillion years for AES
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Public Key Cryptography
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Why Public Key Cryptography
 Symmetric Key Cryptography

Requires Sender and Receiver know shared key
 Q: How do we agree on the key in the first place?
Public Key Cryptography
radically different approach [Diffie-Hellman76, RSA78]
Sender and receiver do not share secret key
 public encryption key known to all
 private decryption key known only to receiver
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Public Key Cryptography
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Public Key Encryption Algorithms:
Requirements:
+
need KB and KB such that:
-
+
B
B
K (K (m)) = m
+
Given public key K , it should be impossible to
compute private key K
B
-
B
RSA: Rivest, Shamir, Adelson algorithm
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Prereq: Modular Arithmetic
 x mod n = remainder of x when divide by n
 Facts:
[(a mod n) + (b mod n)] mod n = (a+b) mod n
[(a mod n) - (b mod n)] mod n = (a-b) mod n
[(a mod n) * (b mod n)] mod n = (a*b) mod n
 Thus
(a mod n)d mod n = ad mod n
 Example: x=14, n=10, d=2:
(x mod n)d mod n = 42 mod 10 = 6
xd = 142 = 196 xd mod 10 = 6
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RSA: Getting Ready
A message is a bit pattern
A bit pattern can be uniquely represented by an integer number
Thus encrypting a message is equivalent to encrypting a number
Example
m= 10010001 . This message is uniquely represented by the decimal
number 145. i.e. 14510 = 100100012
To encrypt m, we encrypt the corresponding number
which gives a new number (the cyphertext)
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RSA: Creating Public/Private Keypair
1. Choose two large prime numbers p, q
(e.g., 1024 bits each)
2. Compute n = pq, Φ = (p-1)(q-1)
3. Choose e (with e<n) that has no common factors
with Φ. (e, Φ are “relatively prime”). There may be many
choices for w
4. Choose d such that ed-1 is exactly divisible by Φ.
(in other words: ed mod Φ = 1 ; or d = e -1 mod Φ)
{
{
5. Public key is (n,e). Private key is (n,d).
+
-
KB
KB
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RSA: Encryption and Decryption
0. Given (n,e) and (n,d) as computed above
1. To encrypt message m (<n), compute
c = me mod n
2. To decrypt received bit pattern, c, compute
m = cd mod n
d
e
m = (m mod n)
mod n
c
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RSA Example
Bob chooses p=5, q=7. Then n=35, Φ=24.
e=5 (so e, Φ relatively prime).
d=29 (so ed-1 exactly divisible by Φ).
Encrypting 8-bit messages.
e
bit pattern
m
m
0000l000
12*
248832
e
c = m mod n
encrypt:
decrypt:
c
17
c
d
481968572106750915091411825223071697
17
d
m = c mod n
12
* The letter “l”
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RSA: Another Important Property
The following property will be very useful later:
-
+
K (K (m))
B B
+ = m = K (K (m))
B B
use public key
first, followed by
private key
use private key
first, followed by
public key
Result is the same!
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Why Does RSA Work?
Must show that cd mod n = m
where c = me mod n
Fact: for any x and y: xy mod n = x(y mod z) mod n
where n= pq and z = (p-1)(q-1)
Thus,
cd mod n = (me mod n)d mod n
= med mod n
= m(ed mod z) mod n
= m1 mod n
=m
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Why is RSA Secure?
Suppose you know Bob’s public key (n,e)
How hard is it to determine d?
Essentially need to find factors of n without knowing the two factors p and q
Fact: factoring a big number is hard.
Remember e is not unique!! Recent literature
Generating RSA Keys
 Have to find big primes p and q
 Approach: make good guess then apply testing rules
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Session Keys KS
Exponentiation is computationally intensive
DES is at least 100 times faster than RSA
Bob and Alice use RSA to exchange a symmetric key KS
Once both have KS, they use symmetric key cryptography
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Diffie-Hellman
Allows two entities to agree on shared key
But does not provide encryption
n is a large prime; g is a number less than n.
n and g are made public
a, g, n
a
b
g, n, A
A=g mod n
a
K=B mod n
b
B=g mod n
B
b
K=A mod n
a,b – Alice, Bob private key
A,B – Alice, Bob public key
K – Shared secrete
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Diffie-Hellman Example
Alice and Bob agree to use a prime number
n=23 and base g=5.
Alice chooses a secret integer a=6
then sends Bob A = ga mod n
A = 56 mod 23 = 8.
Bob chooses a secret integer b=15
then sends Alice B = gb mod n
B = 515 mod 23 = 19.
Alice computes s = Ba mod n
196 mod 23 = 2.
Bob computes s = Ab mod n
815 mod 23 = 2.
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Message Integrity and
Digital Signatures
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Message Integrity
Allows communicating parties to verify the received
messages are authentic
Content of message has not been altered
Source of message is who/what you think it is
Message has not been artificially delayed (playback attack)
Sequence of messages is maintained
Let’s first talk about message digests
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Encryption vs. Hashing
PlainText
Message
CipherText
Encryption( )
or
Hash
Decryption( )
Message Digest
 Encryption keeps
 Hash transforms message into
communications private
 Encryption and decryption can
use same or different keys
 Achieved by various algorithms,
e.g. DES, CAST
 Need key management
fixed-size string
 One-way hash function
 Strongly collision-free hash
 Message digest can be viewed as
“digital fingerprint”
 Used for message integrity check
and digital certificates
 Hash is generally faster than
encryption
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Message Digests
Function H( ) that takes as input
an arbitrary length message and
outputs a fixed-length string:
“message signature”
Note that H( ) is a many-to-1
function
 Desirable properties:
H( ) is often called a “hash
 Easy to calculate
function”
 Irreversibility

Can’t determine
m from H(m)
 Collision resistance:
Computationally
difficult to produce m and
m’ such that H(m) =
H(m’)
 Seemingly random output
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Hash Function Algorithms
MD5 hash function widely used (RFC 1321)
computes 128-bit message digest in 4-step process
SHA-1 is also used
US standard [NIST, FIPS PUB 180-1]
160-bit message digest
kobrien-laptop:~ kobrien$ echo "test" | md5sum
d8e8fca2dc0f896fd7cb4cb0031ba249 kobrien-laptop:~ kobrien$ echo "test" | md5sum
d8e8fca2dc0f896fd7cb4cb0031ba249 kobrien-laptop:~ kobrien$ echo "test1" | md5sum
3e7705498e8be60520841409ebc69bc1 kobrien-laptop:~ kobrien$ echo "test1" | md5sum
3e7705498e8be60520841409ebc69bc1 -
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Commonly Used Hash Functions
(MD5 and SHA)
 Both MD5 and SHA are derived based on MD4
 MD5 provides 128-bit output
 SHA provide 160-bit output (only first 96 bits used in IPSec)
 Both of MD5 and SHA are considered
 one-way strongly collision-free hash functions
 SHA is computationally slower than MD5, but more secure
MD5, SHA1 not collision resistant
Relevance to non-repudiation, commitment
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So What Does This Mean?
SHA1 is still much safer than MD5
Best known attack has effort > 2^64
HMAC SHA1 (keyed SHA1)
believed to be unaffected by current attacks
Industry making a move towards SHA256
and other secure crypto methods
Actual transition will take place within standard groups first
IETF and NIST among others addressing this issue
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Birthday Attack
If 23 people are in the room, what is the chance that they
all have different birthdays?
365 x 364 x 363 x 362 x 361 x 360 x . . . 343
365 365 365 365 365 365
365 = 49%
So there is a 51% chance that two of them have the same
birthday
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Birthday Attack (Cont)
If there are N possible hash values,
You’ll find collisions when you have calculated 1.2 x sqrt(N)
values
SHA-1 uses a 160-bit key
Theoretically, it would require 280 computations to break
SHA-1 has already been broken, because of other weaknesses
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Security Level of Crypto Algorithms
Security Level
Work Factor
Algorithms
Weak
O(240)
DES, MD5
Legacy
O(264)
RC4, SHA1
Minimum
O(280)
3DES, SEAL, SKIPJACK
Standard
O(2128)
AES-128, SHA-256
High
O(2192)
AES-192, SHA-384
Ultra
O(2256)
AES-256, SHA-512
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Message Authentication Code (MAC)
Authenticates sender
Verifies message integrity
No encryption !
Also called “keyed hash”
Notation: MDm = H(s||m); send m||MDm
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HMAC
 Popular MAC standard
 Addresses some subtle security flaws
1.
2.
3.
4.
Concatenates secret to front of message
Hashes concatenated message
Concatenates the secret to front of digest
Hashes the combination again
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Example: OSPF
Recall that OSPF is an intra-AS routing protocol
Each router creates map of entire AS (or area) and
runs shortest path algorithm over map
Router receives link-state advertisements (LSAs) from all
other routers in AS
 Attacks:




Message insertion
Message deletion
Message modification
How do we know if an OSPF message is authentic?
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OSPF Authentication
Within an Autonomous
System, routers send OSPF messages to each other
OSPF provides authentication choices
No authentication
Shared password
inserted in clear in 64-bit authentication field in OSPF packet
Cryptographic hash
 Cryptographic hash with MD5




64-bit authentication field includes 32-bit sequence number
MD5 is run over a concatenation of the OSPF packet and shared secret key
MD5 hash then appended to OSPF packet
encapsulated in IP datagram
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End Point Authentication
Want to be sure of the originator of the message
 end-point authentication
Assuming Alice and Bob have a shared secret, but will
MAC provide message authentication?
We do know that Alice created the message
But did she send it?
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Playback Attack
 Bob cannot distinguish
 between the original communication and the later playback
 The Problem is that the shared secret is used over and over
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Defending Against Playback Attack: Nonce
1) Alice sends the message, ”I
am Alice," to Bob
2) Bob chooses a nonce,
R, and sends it to Alice
3) Alice encrypts the nonce
using Alice and Bob's
symmetric secret key, KA-B.
, and sends the encrypted
nonce, KA-B (R) back to
Bob.
A nonce is a number that a protocol will only ever use once-ina-lifetime
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Nonce (con’t)
It is the fact that Alice knows KA-B and uses it to encrypt
a value that lets Bob know that the message he receives
was generated by Alice.
The nonce is used to insure that Alice is "live."
Bob decrypts the received message
If the decrypted nonce equals the nonce he sent Alice
 then Alice is authenticated.
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PKI: IKE Authentication Architecture
Registration and
Certification Issuance
Certificate
Authority
Key
Recovery
Certificate
Revocation
Key
Generation
Certificate
Distribution
Trusted
Time Service
Key Storage
Support for Non-Repudiation
CPSC6128- Network Security
Digital Signatures
Public
Private
Entity authentication
Data origin authentication
Integrity
Non-repudiation
CPSC6128- Network Security
Digital Signatures
 One-Way Function
 Easy to Produce Hash from Message
 “Impossible” to Produce Message from Hash
Hash
Function
Alice
Hash of Message
Sign Hash with Private Key
s74hr7sh7040236fw
7sr7ewq7ytoj56o457
Signature = “Encrypted” Hash of Message
CPSC6128- Network Security
Signature Verification
Message
Decrypt the Received
Signature
Re-Hash the
Received
Message
Signature
Signature
Message with
Appended
Signature
Decrypt Using
Alice’s Public Key
Alice
Hash of
Message
Hash
Function
Hash Message
If Hashes Are
Equal, Signature
Is Authentic
CPSC6128- Network Security
Digital Signature = signed message digest
Bob sends digitally signed
message:
large
message
m
H: Hash
function
Bob’s
private
key K
B
+
Alice verifies signature and
integrity of digitally
signed message:
encrypted
msg digest
KB(H(m))
H(m)
digital
signature
(encrypt)
encrypted
msg digest
KB(H(m))
large
message
Bob’s
m
public
K+
key
H: Hash
B
function
digital
signature
(decrypt)
H(m)
H(m)
equal
?
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Digital Signatures (more)
Alice thus verifies that:
m was signed by Bob (or some else used Bob’s private
key) by applying Bob’s public key KB to KB(m) then
checks KB(KB(m) ) = m.
• Bob signed m.
• No one else signed m.
• Bob signed m and not m’.
Non-repudiation:
• Alice can take m, and signature KB(m) to court and prove that
Bob signed m.
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Public Key Certifcation
Motivation
Trudy plays pizza prank on Bob
Trudy creates e-mail order:
Dear Pizza Store, Please deliver to me four pepperoni pizzas. Thank you,
Bob
Trudy signs order with her private key
Trudy sends order to Pizza Store
Trudy sends to Pizza Store her public key, but says it’s Bob’s public key.
Pizza Store verifies signature; then delivers four pizzas to Bob.
Bob doesn’t even like Pepperoni
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Certificate Authorities
Certification authority (CA)
binds public key to particular entity, E.
E (person, router) registers its public key with CA.
E provides “proof of identity” to CA.
CA creates certificate binding E to its public key.
certificate containing E’s public key digitally signed by CA – CA says
“this is E’s public key”
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Certificate Authorities
When Alice wants Bob’s public key:
gets Bob’s certificate (Bob or elsewhere).
apply CA’s public key to Bob’s certificate, get Bob’s public key
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X.509 v3 Certificate
Version
Serial Number
Signing Algorithm,
e.g. SHA1withRSA
Signature Algorithm ID
Issuer (CA) X.500 Name
CA’s Identity
Validity Period
Lifetime of this Cert
Subject X.500 Name
User’s Identity, e.g. cn, ou, o
Subject Public Algorithm ID
Key Info
Public Key Value
User’s Public Key (Bound
to User’s Subject Name)
Issuer Unique ID
Subject Unique ID
Other User Info,
e.g. subAltName, CDP
Extension
Signed by CA’s Private Key
CA Digital Signature
CPSC6128- Network Security
Example X.509 Certificate
Certificate:
Data:
Version: 1 (0x0)
Serial Number: 7829 (0x1e95)
Signature Algorithm: md5WithRSAEncryption
Issuer: C=ZA, ST=Western Cape, L=Cape Town, O=Thawte Consulting cc,
OU=Certification Services Division,
CN=Thawte Server CA/[email protected]
Validity
Not Before: Jul 9 16:04:02 1998 GMT
Not After : Jul 9 16:04:02 1999 GMT
Subject: C=US, ST=Maryland, L=Pasadena, O=Brent Baccala,
OU=FreeSoft, CN=www.freesoft.org/[email protected]
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
RSA Public Key: (1024 bit)
Modulus (1024 bit):
00:b4:31:98:0a:c4:bc:62:c1:88:aa:dc:b0:c8:bb:
33:35:19:d5:0c:64:b9:3d:41:b2:96:fc:f3:31:e1:
66:36:d0:8e:56:12:44:ba:75:eb:e8:1c:9c:5b:66:
70:33:52:14:c9:ec:4f:91:51:70:39:de:53:85:17:
16:94:6e:ee:f4:d5:6f:d5:ca:b3:47:5e:1b:0c:7b:
c5:cc:2b:6b:c1:90:c3:16:31:0d:bf:7a:c7:47:77:
8f:a0:21:c7:4c:d0:16:65:00:c1:0f:d7:b8:80:e3:
d2:75:6b:c1:ea:9e:5c:5c:ea:7d:c1:a1:10:bc:b8:
e8:35:1c:9e:27:52:7e:41:8f
Exponent: 65537 (0x10001)
Signature Algorithm: md5WithRSAEncryption
93:5f:8f:5f:c5:af:bf:0a:ab:a5:6d:fb:24:5f:b6:59:5d:9d:
92:2e:4a:1b:8b:ac:7d:99:17:5d:cd:19:f6:ad:ef:63:2f:92:
ab:2f:4b:cf:0a:13:90:ee:2c:0e:43:03:be:f6:ea:8e:9c:67:
d0:a2:40:03:f7:ef:6a:15:09:79:a9:46:ed:b7:16:1b:41:72:
0d:19:aa:ad:dd:9a:df:ab:97:50:65:f5:5e:85:a6:ef:19:d1:
5a:de:9d:ea:63:cd:cb:cc:6d:5d:01:85:b5:6d:c8:f3:d9:f7:
8f:0e:fc:ba:1f:34:e9:96:6e:6c:cf:f2:ef:9b:bf:de:b5:22:
68:9f
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