IG&cry
Discussion
Subject Name: Information Governance
Discussion: Cloud Computing
According to your readings, cloud computing represents one of the most significant paradigms shifts in information technology (IT) history, due to an extension of sharing an application-hosting provider that has been around for many years, and was common in highly regulated vertical industries like banks and health care institutions. The author’s knowledge from their research continue to assert that, the impetus behind cloud computing lies on the idea that it provides economies of scale by spreading costs across many client organizations and pooling computing resources while matching client computing needs to consumption in a flexible, real-time version.
Identify the issues and risks that pose concern to organizations storing data in the cloud – briefly support your discussion.
Make sure to cover 300 words and 2 references.
Subject Name: Information Governance
Discussion: Mobile Computing
We learn from our readings that the use of mobile devices in our society today has indeed become ubiquitous. In addition, CTIA asserted that over 326 million mobile devices were in use within The United States as of December 2012 – an estimated growth of more than 100 percent penetration rate with users carrying more than one device with notable continues growth. From this research, it’s evident that mobile computing has vastly accelerated in popularity over the last decade due to several factors noted by the authors in our chapter reading. In consideration with this revelation, identify and name these factors, and provide a brief discussion about them.
Make sure to cover 300 words and 2 references
SUBJECT: Cryptography
DISCUSSION
Find attached PPT as reference.
After reading chapter 13, analyze the advantages and disadvantages of digital signatures.
Make sure to cover 300 words and 2 references.
Stallings_8e_Accessibl
e_fullppt_13
Cryptography and Network Security:
Principles and Practice
Eighth Edition
Chapter 13
Digital Signatures
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Figure 13.1 Simplified Depiction of
Essential Elements of Digital
Signature Process
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Digital Signature Properties
• It must verify the author and the date and time of the
signature
• It must authenticate the contents at the time of the
signature
• It must be verifiable by third parties to resolve disputes
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Attacks
• Key-only attack
– C only knows A’s public key
• Known message attack
– C is given access to a set of messages and their signatures
• Generic chosen message attack
– C chooses a list of messages before attempting to break A’s
signature scheme, independent of A’s public key; C then obtains
from A valid signatures for the chosen messages
• Directed chosen message attack
– Similar to the generic attack, except that the list of messages to be
signed is chosen after C knows A’s public key but before any
signatures are seen
• Adaptive chosen message attack
– C may request from A signatures of messages that depend on
previously obtained message-signature pairs
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Forgeries
• Total break
– C determines A’s private key
• Universal forgery
– C finds an efficient signing algorithm that provides an
equivalent way of constructing signatures on arbitrary
messages
• Selective forgery
– C forges a signature for a particular message chosen
by C
• Existential forgery
– C forges a signature for at least one message; C has
no control over the message
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Digital Signature Requirements
• The signature must be a bit pattern that depends on the
message being signed
• The signature must use some information unique to the sender
to prevent both forgery and denial
• It must be relatively easy to produce the digital signature
• It must be relatively easy to recognize and verify the digital
signature
• It must be computationally infeasible to forge a digital signature,
either by constructing a new message for an existing digital
signature or by constructing a fraudulent digital signature for a
given message
• It must be practical to retain a copy of the digital signature in
storage
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Direct Digital Signature
• Refers to a digital signature scheme that involves only the communicating
parties
– It is assumed that the destination knows the public key of the source
• Confidentiality can be provided by encrypting the entire message plus
signature with a shared secret key
– It is important to perform the signature function first and then an outer
confidentiality function
– In case of dispute some third party must view the message and its
signature
• The validity of the scheme depends on the security of the sender’s private key
– If a sender later wishes to deny sending a particular message, the sender
can claim that the private key was lost or stolen and that someone else
forged his or her signature
– One way to thwart or at least weaken this ploy is to require every signed
message to include a timestamp and to require prompt reporting of
compromised keys to a central authority
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ElGamal Digital Signature
• Scheme involves the use of the private key for encryption
and the public key for decryption
• Global elements are a prime number q and a, which is a
primitive root of q
• Use private key for encryption (signing)
• Uses public key for decryption (verification)
• Each user generates their key
– Chooses a secret key (number): 1 < xA < q-1
– Compute their public key: yA = a
xA mod q
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Schnorr Digital Signature
• Scheme is based on discrete logarithms
• Minimizes the message-dependent amount of computation
required to generate a signature
– Multiplying a 2n-bit integer with an n-bit integer
• Main work can be done during the idle time of the
processor
• Based on using a prime modulus p, with p – 1 having a
prime factor q of appropriate size
– Typically p is a 1024-bit number, and q is a 160-bit
number
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N I S T Digital Signature Algorithm
• Published by N I S T as Federal Information Processing
Standard F I P S 186
• Makes use of the Secure Hash Algorithm (S H A)
• The latest version, F I P S 186-3, also incorporates digital
signature algorithms based on R S A and on elliptic curve
cryptography
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Figure 13.2 Two Approaches to
Digital Signatures
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Figure 13.3 The Digital Signature
Algorithm (D S A)
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Figure 13.4 D S A Signing and Verifying
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Elliptic Curve Digital Signature
Algorithm (E C D S A)
• Four elements are involved:
– All those participating in the digital signature scheme use
the same global domain parameters, which define an elliptic
curve and a point of origin on the curve
– A signer must first generate a public, private key pair
– A hash value is generated for the message to be signed;
using the private key, the domain parameters, and the hash
value, a signature is generated
– To verify the signature, the verifier uses as input the signer’s
public key, the domain parameters, and the integer s; the
output is a value v that is compared to r ; the signature is
verified if the v = r
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Figure 13.5 E C D S A Signing and
Verifying
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R S A-P S S
• R S A Probabilistic Signature Scheme
• Included in the 2009 version of F I P S 186
• Latest of the R S A schemes and the one that R S A Laboratories
recommends as the most secure of the R S A schemes
• For all schemes developed prior to P S S it has not been possible
to develop a mathematical proof that the signature scheme is as
secure as the underlying R S A encryption/decryption primitive
• The PSS approach was first proposed by Bellare and Rogaway
• This approach, unlike the other R S A-based schemes,
introduces a randomization process that enables the security of
the method to be shown to be closely related to the security of
the R S A algorithm itself
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Mask Generation Function (M G F)
• Typically based on a secure cryptographic hash function
such as S H A-1
– Is intended to be a cryptographically secure way of
generating a message digest, or hash, of variable
length based on an underlying cryptographic hash
function that produces a fixed-length output
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Figure 13.6 R S A-P S S Encoding
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Figure 13.7 R S A-P S S E M Verification
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Summary
• Present an overview of the digital signature process
• Understand the ElGamal digital signature scheme
• Understand the Schnorr digital signature scheme
• Understand the N I S T digital signature scheme
• Compare and contrast the N I S T digital signature scheme
with the ElGamal and Schnorr digital signature schemes
• Understand the elliptic curve digital signature scheme
• Understand the R S A-P S S digital signature scheme
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