ECES-Certified-Encryption-Specialist
Questions and Answers Already Passed
.cer/.crt/.der ✔✔x.509 Digital Certificates extensions - Typically binary encoded. (.cer is
IKE ✔✔Internet Key Exchange - Used by IPSec for Key exchange.
EC Formula ✔✔(y2 = x3 + Ax + B) - Developed by Victor Miller and Neil Koblitz in 1985
Rijndael Algorithm ✔✔Symmetric Algorithm used for AES
3 Cryptanalysis Resources ✔✔• Time (amount of time needed to perform the number of
calculations to crack encryption)
,• Memory (the amount of storage required to perform the attack)
• Data (the amount of plaintext/ciphertext required for the attack)
Birthday Problem ✔✔How likely would it be for any two people in a room of 23 to share the
same birthday?
22+21+20+19+18+17+16+15+14+13+12+11+10+9+8+7+6+5+4+3+2+1 = 253, the total number
of combinations with 23 people. This is approximately a 50% chance for a match(square root of
365 is approximately 23). The probability reaches 100% at 367 people (since there's 366 days in
leap years), but with just 70 people, you are at over a 99.9% chance for a match.
Block cipher ✔✔Encryption function for fixed-size blocks of data (typically 64 or 128 bits) - If
you want to encrypt something that isn't exactly one block long, you have to use a block cipher
mode. Slower than stream ciphers
• Larger block sizes increase security
• Larger key sizes increase security
• If the round is secure, then more rounds increase security
Blowfish ✔✔Fastest Symmetric algorithm. Designed in 1993 by Bruce Schneier.
• Feistel cipher
,• 16 rounds
• 64 bit blocks.
• Key size ranges from 32 to 448 bits.
• Designed as a replacement for DES.
Classes of Digital Certificates ✔✔• Class 1 - general certificate meant for individuals, usually
used for digitally signing/securing e-mail.
• Class 2 - for organizations where you have to prove identities.
• Class 3 - for server and software signing identification.
• Class 4 - Online business transactions between companies.
• Class 5 - Private organizations or governmental agencies. Used between governmental
agencies.
Criteria for Quality of Random Number Generators ✔✔Established by The German Office for
Information Security (BSI)
• K1: A sequence of random numbers with a low probability of containing identical numbers.
• K2: A sequence of numbers which is indistinguishable from ""true random"" numbers
according to statistical tests.
, • K3: It should be impossible for any attacker to calculate, or otherwise guess, from any given
subsequence, any previous or future values in the sequence.
• K4: It should be impossible for any attacker to calculate, or otherwise guess from the inner
state of the generator, any previous values in the sequence or any previous inner generator states.
• To be suitable for cryptography, any PRNG should meet K3 or K4 standards.
DES ✔✔Symmetric algorithm - Block Cipher - Based on Lucifer Algorithm
• One of the most widely deployed algorithms in the world, even though it is no longer
recommended or considered secure.
• Restricted key size of 56 bits and small block size of 64 bits (has a 64-bit plaintext, which is
split into two 32-bit halves L and R).
• Consists of 16 rounds numbered 1 through 16. Each round i uses a separate 48-bit round key
Ki. Each round key is formed by selecting 48 bits from the 56-bit key, and this selection is
different for each round key.
• The algorithm that derives these round keys from the main block cipher key is called the key
schedule.
Digital Certificate - DC ✔✔Standard template is x.509 V3. It's been around since 1988 and it's
the most commonly used format today. Used to identify the certificate holder when conducting
electronic transactions. When modified, they typically become invalidated. The can expire as
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