Cryptography (Animation)

00:05:20
https://www.youtube.com/watch?v=YXbdHqtQCKE

摘要

TLDRThe video provides an overview of cryptography, explaining its importance in protecting information through various techniques. It outlines five primary functions: key exchange, confidentiality, integrity, authentication, and non-repudiation. The video distinguishes between symmetric and asymmetric encryption methods, detailing how they use keys for encryption and decryption. It also introduces popular encryption algorithms like DES, AES, and RSA, and demonstrates simple encryption techniques such as the Caesar cipher and the rail fence cipher.

心得

  • 🔑 Cryptography protects information using codes.
  • 🔒 Key exchange is essential for secure communication.
  • 📜 Confidentiality ensures only intended parties can read messages.
  • ✅ Integrity verifies that information hasn't been altered.
  • 👤 Authentication proves the identity of the receiver.
  • ✉️ Non-repudiation confirms the sender's identity.
  • 🔄 Symmetric keys use one private key for encryption and decryption.
  • 🔑 Asymmetric keys use a public key for encryption and a private key for decryption.
  • 📊 Common algorithms include DES, AES, and RSA.
  • 🔤 The Caesar cipher is a simple shifting technique for encryption.

时间轴

  • 00:00:00 - 00:05:20

    In this lesson, we explore cryptography, defined as the method of protecting information through codes to prevent unauthorized access. It has been utilized for over 4,000 years and serves five primary functions: key exchange, confidentiality, integrity, authentication, and non-repudiation. Cryptography is ubiquitous, found in secure communications, file encryption, and even phone passwords. Understanding encryption begins with plain text, which is converted into ciphertext using an encryption method and a key. There are two types of keys: symmetric, which uses a single shared key for both encryption and decryption, and asymmetric, which employs a public key for encryption and a private key for decryption. Hash functions also play a role in providing data integrity. Various encryption algorithms exist, including DES, AES, and RSA, each optimized for specific applications. The lesson concludes with examples of encryption techniques, such as the Caesar cipher and the rail fence cipher, illustrating how cryptography ensures information remains unreadable to unauthorized parties.

思维导图

视频问答

  • What is cryptography?

    Cryptography is the method of protecting information through the use of codes.

  • What are the primary functions of cryptography?

    The primary functions include key exchange, confidentiality, integrity, authentication, and non-repudiation.

  • What are symmetric and asymmetric keys?

    Symmetric keys use one private key for both encryption and decryption, while asymmetric keys use a public key for encryption and a private key for decryption.

  • What are some common encryption algorithms?

    Common algorithms include DES, AES, and RSA.

  • What is a Caesar cipher?

    The Caesar cipher is a simple encryption technique that shifts letters in the alphabet by a fixed number.

  • What is the rail fence cipher?

    The rail fence cipher is an encryption technique that arranges letters in a diagonal pattern.

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  • 00:00:00
    welcome students today we're going to
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    learn about cryptography what is
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    cryptography professor photography is
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    the method of protecting information
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    through the use of codes that prevent
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    any other party from revealing the
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    secret information in fact people have
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    been using cryptography to protect
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    information for at least four thousand
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    years
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    there are five primary functions of
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    cryptography first of which is that it
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    allows cryptography keys to be exchanged
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    between sender and receiver this is also
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    known as key exchange next is that it
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    assures that no one can read the message
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    except the intended party this is also
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    known as confidentiality the next
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    primary function of cryptography is that
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    it assures that the information has not
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    been altered in any way this is also
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    known as integrity
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    next is that cryptography must prove the
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    receiver's identity this is also known
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    as authentication
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    and finally the last primary function of
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    cryptography is that it proves that the
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    sender really sent the information this
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    is also known as non-repudiation
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    i see but where is cryptography used
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    cryptography is used everywhere from
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    securing communications with browsers to
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    encrypting files on disks and more
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    cryptography is found everywhere
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    including your phone's password before
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    we get into some cryptography techniques
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    it's important to understand how
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    encryption works first we start with
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    plain text this is our visible
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    unencrypted information
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    next we must pick an encryption method
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    this is the process of converting
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    information into secret code to hide its
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    true meaning after that a key is
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    required keys are used to encrypt data
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    from plain text to ciphertext and
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    ciphertext is the unreadable output from
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    the encryption method
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    professor can you explain more about
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    keys i'm still confused about how
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    they're used
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    of course now there are actually two
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    different kinds of keys symmetric and
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    asymmetric encryption techniques or
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    methods can use either one of them those
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    that use symmetric keys share only one
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    private key between the sender and
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    receiver the same key encrypts and
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    decrypts the data it's fast but since
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    private keys are shared it's easy to
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    gain access to your confidential emails
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    with the same key
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    on the other hand methods that use
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    asymmetric keys share two keys a public
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    and a private key the public key
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    encrypts data while it's corresponding
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    private key decrypts it the great thing
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    about this is that senders don't need to
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    share their private key with others but
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    this method is much slower than using
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    symmetric keys
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    another thing to know is that some
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    methods also use hash functions which is
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    basically some math equation to
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    irreversibly encrypt data and it
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    provides a digital fingerprint
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    why are there so many things used to
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    encrypt information well each one is
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    optimized for a specific application
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    public keys are used for confidentiality
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    private keys are also used for
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    confidentiality and non-repudiation and
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    hash functions are used for message
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    integrity some of the main encryption
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    algorithms are des a symmetric key
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    encryption that is no longer widely used
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    nowadays but serves as a standard for
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    other encryption tools aes and other
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    symmetric key encryption used by
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    governments and other secure
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    organizations and rsa an asymmetric key
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    encryption widely used for data sent
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    online
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    now i will be showing off a few small
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    examples of some encryption techniques
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    first i will be showing off caesar
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    cipher it is one of the simplest and
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    most widely known encryption techniques
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    the first step is picking a word in
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    plain text that we want to encrypt as an
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    example i will be using war next we must
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    decide the shift for this example i'm
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    going to use a right shift of 3. now
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    that we have all we need the first thing
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    i'm going to do is plot our word war on
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    the outer ring next is to rotate the
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    inner wheel by our shift which is three
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    times to the right
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    and now as we see our green marked
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    letters on the outer ring are now lined
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    up with new letters on the inner ring
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    these new letters are what form our
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    encrypted cipher text and that is all
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    there is to caesar cipher next we're
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    going to be looking at the rail fence
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    cipher
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    as with any cipher our first step is
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    going to be choosing a message for now
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    i'll use battle as an example now that
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    we have our message the next step in the
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    rail fence technique is to write this
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    message in a diagonal fashion like this
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    and now you can simply write the top
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    line followed by the bottom line and
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    this is our cipher text so what did we
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    learn today
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    cryptography is used to protect
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    information through the use of
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    techniques to make sure that it cannot
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    be readable to anyone that is not
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    supposed to see it there are various
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    different methods to encrypt information
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    and many popular methods choose to use
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    either symmetric or asymmetric keys
标签
  • cryptography
  • encryption
  • symmetric keys
  • asymmetric keys
  • key exchange
  • confidentiality
  • integrity
  • authentication
  • non-repudiation
  • encryption algorithms