Lecture 8 Flashcards
Cryptography: comes from ?
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Cryptology
Greek
Cryptography: Kryptos means ?
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Cryptology
hidden
Cryptography: Grahein means ?
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Cryptology
to write
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Process of making and using codes to secure the transmission of information
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Cryptology
Cryptography
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Process of obtaining the original message form encrypted message
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Cryptology
Cryptanalysis
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Process of converting an original message into a form that is unreadable to unauthorized individuals
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Cryptology
Encryption
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Process of converting the encrypted message (cipertext) into an easily read message (plain text)
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Cryptology
Decryption
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Programmatic steps to encrypt message
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Cryptology - Basic Definitions
Algorithm
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Encryption method or process
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Cryptology - Basic Definitions
Cipher
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Encrypted message
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Cryptology - Basic Definitions
Ciphertext or cryptogram
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Process of converting unencrypted components into encrypted components
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Cryptology - Basic Definitions
Code
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Convert to plaintext
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Cryptology - Basic Definitions
Decipher
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To encrypt
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Cryptology - Basic Definitions
Encipher
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Information used with the algorithm to encrypt
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Cryptology - Basic Definitions
Key or crypto-variable
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Entire range of values that can possibly be used to construct an individual key
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Cryptology - Basic Definitions
Key-space
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Series of encryptions /decryptions between a number of systems
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Cryptology - Basic Definitions
Link encryption
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The original message
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Cryptology - Basic Definitions
Plaintext or clear text
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Process of hiding messages
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Cryptology - Basic Definitions
Steganography
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Amount - effort required to perform cryptanalysis
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Cryptology - Basic Definitions
Work factor
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(2) Cipher methods
Enumerate
Cryptology - Cipher methods
- Bit stream method
- Block cipher method
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Each bit in the plaintext is transformed bit by bit
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Cryptology - 1/2 Cipher methods 1/2 ?
Bit stream method
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Most common use XOR
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Cryptology - 1/2 Cipher methods 2/2 ?
Bit stream method
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Messaged divided into blocks
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Cryptology - 2/2 Cipher methods 1/3 ?
Block cipher method
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Each block is encoded
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Cryptology - 2/2 Cipher methods 2/3 ?
Block cipher method
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Substitution, transposition, XOR or combination
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Cryptology - 2/2 Cipher methods 3/3 ?
Block cipher method
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Substitute one value for another
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Cryptology - 1/3 ?
Substitution Cipher
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3 character substitution to the right
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Cryptology - 2/3 ?
Substitution Cipher
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Simple by itself – powerful when combined with other operations
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Cryptology - 3/3 ?
Substitution Cipher
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3 shift to the right is know as the ?
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Cryptology - Substitution Cipher
Caesar Cipher
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Implemented using the Vigenere Square
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Cryptology - 1/6 ?
Vigenere Cipher
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26 distinct cipher alphabets
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Cryptology - 2/6 ?
Vigenere Cipher
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Header row – normal order
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Cryptology - 3/6 ?
Vigenere Cipher
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Each additional row – shift right
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Cryptology - 4/6 ?
Vigenere Cipher
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Start in first row and find a substitution for one letter
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Cryptology - 5/6 ?
Vigenere Cipher
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Move down the rows for each subsequent letter of plaintext
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Cryptology - 6/6 ?
Vigenere Cipher
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Simply rearranges the values within a block
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Cryptology - 1/4 ?
Transposition Cipher
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Can be done at the bit level or the byte level
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Cryptology - 2/4 ?
Transposition Cipher
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Julius Caesar was associated with the early version of this cipher also
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Cryptology - 3/4 ?
Transposition Cipher
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Larger blocks or keys makes cipher stronger
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Cryptology - 4/4 ?
Transposition Cipher
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- Function of Boolean algebra
- Two bits are compared
- If identical, result is binary 0
- If not identical, result is binary 1
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Cryptology - 1/2 ?
Exclusive OR (XOR)
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- Very simple encryption
- Not very secure
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Cryptology - 2/2 ?
Exclusive OR (XOR)
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One-time pad
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Cryptology - 1/4 ?
Vernam Cipher
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Uses a set of characters only one time for each encryption process
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Cryptology - 2/4 ?
Vernam Cipher
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- Each character of the plaintext is turned into a number and a pad value for that position is added
- Sum is then converted back to a cipher text
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Cryptology - 3/4 ?
Vernam Cipher
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Decryption requires knowledge of pad values or difficult cryptanalysis.
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Cryptology - 4/4 ?
Vernam Cipher
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List of codes representing a page number, line number, and word number of the plaintext word.
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Cryptology - Book or Running Key Cipher
Cipher text
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Not an encryption methodology
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Cryptology - 1/5 ?
Hash functions
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- Fingerprinting
- Used to determine if it is the same message
- Not used to decypher
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Cryptology - 2/5 ?
Hash functions
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Message always provide same hash value if unaltered
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Cryptology - 3/5 ?
Hash functions
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- Do not require keys
- Uses Message Authentication Code (MAC)
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Cryptology - 4/5 ?
Hash functions
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- Key-dependent
- Used in password verification systems
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Cryptology - 5/5 ?
Hash functions
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generates a message summary or digest
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Cryptology - Hash functions
Mathematical algorithm
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Secure algorithm
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Cryptology - 1/3 ?
Secure Hash Standard (SHS)
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Standard issued by National Institute of Standards and Technology (NIST)
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Cryptology - 2/3 ?
Secure Hash Standard (SHS)
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- SHA-1 Produces a 160 bit digest
- Family of SHA
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Cryptology - 3/3 ?
Secure Hash Standard (SHS)
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A 256-bit cipher algorithm
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Cryptology - Secure Hash Standard (SHS) - 1/2 ?
SHA-256
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Creates a key - encrypting the intermediate hash value with the message block functioning as the key
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Cryptology - Secure Hash Standard (SHS) - 2/2 ?
SHA-256
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Symmetric and asymmetric and hybrid
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Cryptology
Cryptographic Algorithms
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- Requires the same secret key
- Encryption methods use mathematical operations
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Cryptology - Cryptographic Algorithms - 1/3 ?
Symmetric Encryption
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Both the sender and receiver must have the secret key
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Cryptology - Cryptographic Algorithms - 2/3 ?
Symmetric Encryption
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Primary challenge – getting key to receiver
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Cryptology - Cryptographic Algorithms - 3/3 ?
Symmetric Encryption
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- Uses two different but related keys
- Either key can encrypt or decrypt
- Must use other to perform other function
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Cryptology - Cryptographic Algorithms - 1/5 ?
Asymmetric Encryption
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- One key private
- One key public
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Cryptology - Cryptographic Algorithms - 2/5 ?
Asymmetric Encryption
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- Also know as public key encryption
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Cryptology - Cryptographic Algorithms - 3/5 ?
Asymmetric Encryption
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- Based on one-way functions
- One is simple to compute , the opposite is complex
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Cryptology - Cryptographic Algorithms - 4/5 ?
Asymmetric Encryption
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- Based on hash value
- Uses mathematical trapdoor
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Cryptology - Cryptographic Algorithms - 5/5 ?
Asymmetric Encryption
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that enable you to easily accomplish the reverse function in a one-way function.
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Cryptology - Cryptographic Algorithms - Asymmetric Encryption
Secret mechanism
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becomes the true key
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Cryptology - Cryptographic Algorithms - Asymmetric Encryption
Public key
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is derived form public key using trapdoor
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Cryptology - Cryptographic Algorithms - Asymmetric Encryption
Private
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First public key encryption algorithm
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Cryptology - Public Key - 1/3 ?
RSA (Rivest-Shamir-Adlemann)
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- Published for commercial use
- E-commerce browsers
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Cryptology - Public Key - 2/3 ?
RSA (Rivest-Shamir-Adlemann)
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Has become the de facto standard
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Cryptology - Public Key - 3/3 ?
RSA (Rivest-Shamir-Adlemann)
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- Cryptovariable or key size must be decided
- Length of key increase the number of random selections to be guessed
- Length of key influences strength
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Cryptology - 1/2 ?
Encryption Key Size
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- The security of encrypted data is NOT dependent on keeping the algorithm secret
- Depends on keeping some or all of the elements of the keys secret
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Cryptology - 2/2 ?
Encryption Key Size
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Integrated system of software, encryption methodologies, protocols, legal agreements, and 3rd part services
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Cryptology - 1/2 ?
Public Key Infrastructure (PKI)
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- Based on public key
- Include digital certificates and certificate authorities
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Cryptology - 1/2 ?
Public Key Infrastructure (PKI)
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- Based on public key
- Include digital certificates and certificate authorities
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Cryptology - 2/2 ?
Public Key Infrastructure (PKI)
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Public key container files that allow computer program to validate the key and identify to whom it belongs.
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Cryptology
Digital Certificates
? ?? ??? ???? ?????
(5) Key characteristics to be integrated into business practices
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Cryptology - Digital Certificates
- Authentication
- Integrity
- Privacy
- Authorization
- Non-repudiation
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- Used by third party
- Certifies the authenticity of the
- Digital signature is attached
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Cryptology
Digital Certificate
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Created to verify information transferred using electronic systems
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Cryptology - 1/4 ?
Digital Signatures
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Currently asymmetric encryption processes are used to create digital signatures
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Cryptology - 2/4 ?
Digital Signatures
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Encrypted messages that can be mathematically authentic
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Cryptology - 3/4 ?
Digital Signatures
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Used when using DSS (digital Signature Standard)
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Cryptology - 4/4 ?
Digital Signatures
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Pure asymmetric keys encryption is not widely used except in digital certificates
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Cryptology - 1/3 ?
Hybrid Cryptography Systems
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More widely used as part of hybrid system
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Cryptology - 2/3 ?
Hybrid Cryptography Systems
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Diffie-Hellman Key Exchange method
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Cryptology - 3/3 ?
Hybrid Cryptography Systems
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Process of hiding information
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Cryptology - 1/4 ?
Steganography
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Not technically a form of cryptography
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Cryptology - 2/4 ?
Steganography
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Use one bit per color or bits per pixelo store information
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Cryptology - 3/4 ?
Steganography
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Compute files that don’t use all available bits
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Cryptology - 4/4 ?
Steganography
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(2) Protocols for Secure Communication
Enumerate
Cryptology - Protocols for Secure Communication
- Secure Socket Layer (SSL)
- Secure Hypertext Transfer Protocol (S-HTTP)
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Used public key encryption to secure channel
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Cryptology - 1/2 Protocols for Secure Communication
Secure Socket Layer (SSL)
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Two layers of Protocol
Enumerate
Cryptology - 1/2 Protocols for Secure Communication - SSL
- SSL Record Protocol
- Standard HTTP
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- Compression, encryption and attachment of SSL header
- Received encrypted messages are decrypted and reassembled
- Basic security at top level of SSL protocol stack
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Cryptology - 1/2 Protocols for Secure Communication - SSL - 1/2 Layers of protocol
SSL Record Protocol
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Internet communication services
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Cryptology - 1/2 Protocols for Secure Communication - SSL - 2/2 Layers of protocol
Standard HTTP
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Extended version of hypertext transfer protocol
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Cryptology - 2/2 Protocols for Secure Communication 1/3 ?
Secure Hypertext Transfer Protocol (S-HTTP)
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Provides for encryption of individual messages between client and server
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Cryptology - 2/2 Protocols for Secure Communication 2/3 ?
Secure Hypertext Transfer Protocol (S-HTTP)
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- No session
- Designed for sending individual messages
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Cryptology - 2/2 Protocols for Secure Communication 3/3 ?
Secure Hypertext Transfer Protocol (S-HTTP)
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Adds encryption of MIME (Multipurpose Internet Mail Extensions)
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Cryptology - Securing E-mail
Secure Multipurpose Internet mail Extensions (S/MIME)
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Uses 3DES symmetric key encryption and RSA for key
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Cryptology - Securing E-mail
PEM
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- Pretty Good Privacy
- Used IDEA Cipher
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Cryptology - Securing E-mail
PGP