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Cryptography provides 4 essential services:
- Confidentiality
- Integrity
- Authentication
- Non-repudiation
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A _____ is a type of encryption, which has been proven to be impossible to to crack if used correctly.
One-time pad (OTP)
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What is a way to make a short cryptovariable longer so that it is more immune from attack. Give two examples.
- Key Stretching
- Salting a password:
- PBKDF2
- Bcrypt()
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What are three types of substitution Ciphers?
- Shift Cipher
- Mono-alphabetic Cipher
- Polyalphabetic Cipher
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What is Steganography and some usages?
- Process of hiding or concealing one's message within something else
- Least significant bits
- Examples:
- Removing two color bits from a picture and replacing with message / virus
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What is cryptography?
The study of encryption.
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_____ is converting information to a secret format / cipher text. _______ is conversion back to plain text.
Encryption ; decryption
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_______ ______ uses _ separate networks working simultaneously to authenticate a user.
Out-of-Band Authentication; 2
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________ uses the same key to encrypt or decrypt.
Symmetric Encryption
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Give some AKAs for Symmetric Encryption and give one advantage and disadvantage.
- AKA: Single, same, secret and session key
- Advantage: fastest form of encryption
- Disadvantage: unique key to each party
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______ solves key distribution problem. Has a public and private key pair.
Asymmetric encryption
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Asymmetric encryption uses a ______ that is freely distributed to encrypt, and a _____ that is secret to decrypt.
Public; Private
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List meaning of, block, key size and type for the following:
AES
- Advanced Encryption Standard (based on Rijndael cipher)
- Block: 128
- Bits: 128, 192, 256
- Type: Symmetrical
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List meaning of, block, key size and type for the following: Blowfish?
- Block size: 64
- Key size: 32 to 448
- Type: Symmetrical
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List meaning of, block, key size and type for the following: CAST-128
- Carlisle Adams/Stafford Tavares
- Block: 64
- Bit: 40-128
- Type: Symmetrical
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List meaning of, block, key size and type for the following: DES
- Data Encryption Standard
- Block: 64
- Key: 56 bits
- Type: Symmetrical
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List meaning of, block, key size and type for the following: IDEA
- International Data Encryption Algorithm
- Block: 64
- Key: 128
- Type: Symmetrical
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List meaning of, block, key size and type for the following: RC5
- Rivest Cipher 5
- Block: 32, 64, 128
- Key: 0-2040
- Type: Symmetrical
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List meaning of, block, key size and type for the following: RC6
- Rivest Cipher 6
- Block: 128
- Key: 128, 192, or 256
- Type: Symmetrical
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List meaning of, block, key size and type for the following: 3DES
- Triple Data Encryption Standard
- Block: 64
- Key: 168
- Type: Symmetrical
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List meaning of, block, key size and type for the following: Twofish
- Twofish
- Block: 128
- Key: 168
- Type: Symmetrical
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List meaning of, block, key size and type for the following: RC4
- Rivest Cipher 4
- Stream Cipher
- variable key length: 0-2048
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List meaning of, block, key size and type for the following: SAFER
- Secure and Fast Encryption Routine
- Block: 128 Bit
- used for Bluetooth
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_______ encrypt one character of data at a time. The output is the same size as the input.
Stream Cipher
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______ covers encryption data in transit. Gives some examples.
- Transport Encryption
- Examples: VPN, SSL, TLS, HTTPS, SSH.
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______ is the concept that a sender cannot deny sending a message and is provided by a hash.
Non-repudiation
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_____ takes a variable sized input, runs it through an algorithm and creates a fixed output. Proves authentication.
Hashing
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A ____ is when two inputs provide the same hash. What can prevent this?
collision; Longer hashes are more collision resistant.
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In asymmetric encryption there are four keys, what are they?
- Public Key of sender
- Private key of the sender
- Public key of the recipient
- Private key of the recipient
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List meaning of, block, key size and type for the following: Diffie-Hellman
- First asymmetric algorithm
- provided for key exhange
- based on difficulty of computing discrete logarithms
- Variable key length
- 512-bit to arbitrarily long
- 1024-2048 considered secure
- Same strength as 3072-bit RSA key
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Give brief synopsis of: El Gamal
- Encryption, Digital Signatures, Key exhanges
- Based on Diffie-Hellman
- Slower than comparable algorithms.
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Give brief synopsis of: RSA
- Rivest, Shamir, Adleman
- Encryption, Digital Signatures, Key Exchange
- De facto standard
- Variable block and key length
- 512-bit to arbitrarily long
- 1024-2048 considered secure
- Used in PGP
Can be 100 times slower than conventional encryption software; 1000-10000 slower than hardware.
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Give brief synopsis of: ECC
- Elliptic Curve Cryptography
- Encryption, Digital Signatures, Key exchange
- Requires less computing power
- 160 bit ECC is equivalent to 1024bit RSA
- Use on wireless and smart cards
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_____: The length of the key is equal to the length of the data. The key has variable offsets for each character; virtually unbreakable.
One-Time Pad (OTP)
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____ would be used to send an encrypted email.
S/MIME
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PKI elements:
- Certificate Authorities (CA)
- Certificates
- PKI
- recovery agents
- public key
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____ issues keys and maintains the CRL
Certificate Authorities
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The standard format for digital certificates is what?
x.509
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What is included in a digital certificate?
- Certificate verision
- certificate holder's public key
- serial number
- Distinguished name
- validity period
- unique name of cert issuer
- digital signature of issuer
- signature algorithm identifier
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What is a CSR?
Certificate Signing Request; it is a request from an applicant to a CA for a certificate.
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The ___ contains a list of certificates that are compromised and invalid. It is comprised of public keys
CRL; Certificate Revocation List
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An alternate to the CRL is the ____; use it to check individual certificates.
Online Certificate Status Protocol (OCSP)
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What are some types of trust models?
- Single-Authority Trust (third-party trust)
- Hierarchical trust
- Bridge trust
- WEB of trust
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