Crypto ch 8 Flashcards
Asymmetric cipher
Crypto algorithms that use two different keys-1 key to encrypt and another to decrypt. Also called public key crypto
Chap
Challenge hand shake authentication protocol
A authentication protocol that PERIODICALLY reauthenticates
Collision
When 2 different inputs into crypto hash produce the same output, this is known as a collision.
Cryptographic hash
A function that is 1 way (non reversible) has a fixed length output and is collision resistant.
PRNG
A pseudo-random number generator is and algorithm used to generate a number that is sufficiently random for cryptographic purposes.
Rainbow table
A table precomputed hashes used to guess passwords by searching for the hash of a password.
Salt
Bits added to a hash to make it resistant to rainbow table attacks.
Symmetric cipher
Any cryptographic algorithm that uses the same key to encrypt and decrypt. DES, AES, and Blowfish are examples
Skl and taclanes
Gost
X.509
X.509 standard is the most widely used standard for digital certificates
Cryptool 1.4.40
Md-message digest md5 56bits has a high rate of collision
2 diff inputs has same output
Sha-has different bits
Hex value based on integrity
Cast 3des*168 bits Blowfish/2fish/Bruce schneir 64bit Blck Rcx(rc4/rc5)*2,048bits Aes * by joan daemen/ Vincent rijmen 128/192/256 (hard drive) Idea Des* Skipjack,safer,safer+secpent
Sym Same key encrypt to decrypt Out of band delivery, different times Otr-over the air rekey Great for bulk encryption
-Different-Hellman founder pub/Pvt key
E-lliptic curve cryp-sim to rsa strng shrt Mobile
-ElgMal-transmitting dig sig and key exchanges
-Ecdhe
-Rsa-widely used .ron rivest, adi Shamir, Leonard adleman public key uses large integers
Asym
Strong and slower
SHA
Secure hash algorithm-provides hash value that can be used and encryption protocol
160bithash
Sha2-224,256,334,512
Sha3-
None as keccak
Key stretching
Password based key function derevation 2
Making the key stronger
Crypto-analysis methods
- Brute force
- frequency analysis
- known plain text
- chosen plain text
- related key attack
- birthday attack
- other methods
- exploiting human error
- wi-if encryption
Cryptographic systems
Confidentiality & strength Integrity When to encrypt Digital signatures Authentication Nonrepudiation Key features
Pgp
Proprietary and is (pretty good privacy)
Tunneling protocols
PPTP
L2f
Tunneling protocol
FIPS
Federal information processing standards
PkI
Scaling up security
Two way, asymmetric system w 4 main components
- certificate authority -issue/revoking/distro certs
- registration authority-take a req on behalf and send to ca. Can distro keys, valid indent
- rsa
- digital certificates
- lra-local registration authority
Certificate revocation list
Revoking before it expires
Crl-certificate revoc list
Ocsp-online certificate status protocol
Repository-database our database server where the certs are stored
Trust models with pki
- Hierarchical -aka tree at the top provides all information
- bridge-p2p relationships exists between root ca’s
- mesh-expands bridge model by supporting multiple paths and multiple roots
- hybrid-can use the capabilities of any or all of the structures discussed in previous sections
