1
Q
Public Key
A
A cryptographic key that can be shared publicly and is used to encrypt data or verify (decrypt) digital signatures. It’s part of a pair with a private key.
2
Q
Private Key
A
A cryptographic key that is kept secret and is used to decrypt data or create (encrypt) digital signatures. It’s part of a pair with a public key.
3
Q
Key Escrow
A
A process where encryption keys are stored securely by a third party, allowing access under certain conditions, often used in government, legal, or corporate environments.
* There’s not actually a good / secure way to carry this out
4
Q
Full-disk Encryption
A
Encrypts the entire disk, including the operating system, ensuring that all data is protected when the system is powered off.
5
Q
Partition Encryption
A
Encrypts specific partitions on a disk, allowing selective protection of sensitive data without encrypting the entire disk.
6
Q
File Encryption
A
Encrypts individual files, providing flexibility to protect only specific documents or files as needed.
7
Q
Volume Encryption
A
Encrypts a storage volume, which can contain multiple partitions or logical drives, providing protection for a larger data set than file encryption.
8
Q
Database Encryption
A
Encrypts data within a database, protecting sensitive information stored in structured formats from unauthorized access.
9
Q
Record Encryption
A
Encrypts specific records within a database, allowing granular protection of individual data entries.
10
Q
Transport/Communication Encryption
A
Encrypts data in transit, protecting it from interception or tampering as it moves across networks. Examples: SSL/TLS, HTTPS.
11
Q
Asymmetric Encryption
A
Encryption that uses a pair of keys—a public key for encryption and a private key for decryption—offering secure key exchange and authentication
* Sender encrypts message using recipient’s public key, recipient decrypts the message using their private key
* security is based upon the difficulty of solving extremely complex math problems
12
Q
Symmetric Encryption
A
Encryption that uses a single key for both encryption and decryption, providing faster performance but requiring secure key management.
13
Q
Key Exchange
A
- Allows two parties to securely generate a shared secret key over an insecure channel without exchanging the key itself.
- This enables symmetric encrypted communication. Methods include out-of-band (e.g., in person, mail) or in-band using algorithms like Diffie-Hellman.
14
Q
Algorithms
A
Mathematical formulas used to encrypt and decrypt data. Examples include AES, RSA, and SHA-256.
15
Q
Key Length
A
The size of a cryptographic key, typically measured in bits, which determines the strength of the encryption. Longer keys provide stronger security.
16
Q
TPM
A
Trusted Platform Module
* A hardware-based security chip that provides secure storage and processing of cryptographic keys, enhancing platform integrity.
17
Q
HSM
A
Hardware Security Module
* A physical device that manages cryptographic keys and performs cryptographic operations
* provides a higher level of security and performance for key management and operations.
18
Q
Key Management System
A
A system or software that manages cryptographic keys throughout their lifecycle, including generation, storage, distribution, and destruction.
19
Q
Secure Enclave
A
A secure area within a processor that provides isolated and protected execution of security-sensitive operations, often used in mobile devices.
20
Q
Steganography
A
The practice of hiding data within other non-secret data, such as embedding a message in an image, video, or audio file, to avoid detection.
* hide the fact that you are even communicating in the first place
21
Q
Tokenization
A
Replacing sensitive data with non-sensitive tokens that can be mapped back to the original data through the use of a relational database (which itself must be kept secure)
22
Q
Data Masking
A
The process of obscuring specific data within a dataset to protect it, often used in non-production environments to prevent unauthorized access to sensitive information.
23
Q
Hashing
A
The irreversible process of converting an input of any size into a fixed-size string of characters, which represents the data uniquely. Used for integrity verification. Examples: SHA-256, MD5.
24
Q
Salting
A
Adding random data to a hash input to prevent attackers from using precomputed hash values (rainbow tables) to crack passwords.
25
Digital Signatures
A cryptographic mechanism used to verify the integrity and authenticity of a message, software, or digital document. It uses asymmetric encryption with two keys:
* Private Key: The sender signs the data with their private key.
* Public Key: The recipient uses the sender’s public key to verify the signature.
* Note that this is reversed from how ssymmetric crpytography normally works!
**Key Concepts:**
* Ensures **Integrity**: Verifies that the message or document has not been altered.
* Ensures **Authenticity**: Confirms the identity of the sender.
* **Non-Repudiation**: The sender cannot deny sending the message since only their private key could have created the signature.
* Commonly used with **digital certificates** in **Public Key Infrastructure (PKI)**.
* Add **confidentiality** by also encyrpying the *message* portion of the signature with the recipients public key (the way these things are normally used outside of signatures!)
26
Key Stretching
A technique used to make a weak password stronger by applying a salt and one or more rounds of hashing, making it more resistant to brute-force attacks.
27
Blockchain
A distributed ledger technology used to track transactions. Every participant in the blockchain network maintains an identical copy of the ledger. It ensures immutability, decentralization, and transparency. Blockchain is used in a variety of applications such as:
* Payment processing (e.g., cryptocurrencies)
* Digital identification
* Supply chain monitoring
* Digital voting
* Property ownership records
* Vital records
28
Open Public Ledger
A ledger that is accessible to the public and contains a record of all transactions, typically associated with blockchain technology.
29
Certificate Authorites (CA)
Trusted organizations that verify the identity of individuals, systems, or organizations and issue digital certificates. These certificates include the subject's public key, and the CA uses its private key to digitally sign the certificate, ensuring authenticity and establishing trust in secure communications.
30
CRLs
| In the context of PKI
Certificate Revocation Lists (
* Lists published by Certificate Authorities that identify certificates that are no longer valid, helping to maintain trust in the PKI system.
* Inefficient and no longer used as it requires everyone on the internet to download these lists which themselves got longer and longer
31
OCSP
Online Certificate Status Protocol
* A protocol used to check the revocation status of a digital certificate in real-time with the CA, providing up-to-date information on certificate validity.
* Faster and more efficient than CRLs
32
Self-signed Certificates
Digital certificates signed by the entity that created them, often used for internal purposes but less trusted than certificates issued by a Certificate Authority.
33
Third-party Certificates
Digital certificates issued by a trusted Certificate Authority, used to establish trust between parties over the internet.
34
Root of Trust
A secure, trusted source within a system that provides the foundation for verifying the authenticity and integrity of other components.
35
Certificate Signing Request (CSR) Generation
A request to a Certificate Authority (CA) to sign a digital certificate. It includes a public key and entity information, used to bind a public key to an identity in Public Key Infrastructure (PKI)
36
Wildcard Certificates
Digital certificates that can be used to secure multiple subdomains under a single domain, simplifying certificate management.
* Only goes one level deep
* commonly used for load balancers
37
PKI
Public Key Infrastructure. A framework of policies, procedures, and technologies used to create, manage, distribute, and revoke digital certificates, ensuring secure communication and authentication.
38
Encryption
The process of converting information into a secure cipher to protect confidentiality, prevent unauthorized access.
39
Encryption Tools
Hardware and software solutions used to manage and protect cryptographic keys and secure operations.
* Trusted Platform Module (TPM)
* Hardware security module (HSM)
* Key management system
* Secure enclave
40
Obfuscation
The process of making data obscure or unclear to prevent unauthorized access or understanding.
* Steganography
* Tokenization
* Data Masking
41
Certificates
Digital documents used to certify the ownership of a public key, ensuring secure communication and authentication.
42
DES
* Data Encryption Standard
* Symmetric encryption algorithm
* 64 bit block cipher
* Key length of 56 bits
* one of the first, no longer secure -- would need a key length of 2048 bits
43
3DES
* Triple DES: Applies DES 3 times with 3 separate keys
* 64 bit block, 56 bit keys, max effective key length of 112 bits
* Bought some time for DES by getting around the vulnerabilities that were there for a short time
* **Why TRIPLE?**: Double DES is no more secure than standard DES due to Meet-in-the-Middle attack
* no longer secure! :) -- being phased out
44
AES
* Advanced Encryption Standard
* Symmetric encryption algorithm
* 128 bit block cipher
* Key lengths of 128, 192, or 256 bits
* Secure!
45
Blowfish
* Public domain algorithm
* Intended as a replacement of DES
* Symmetric
* 64 bit block chain
* Pick any key length from 32 to 448 bits
* Not secure
46
Twofish
* a competitor in the AES competition that lost out, now public domain
* Symmetric
* 128 bit block cipher
* Key lengths of 128, 192, or 256 bits
* Still considered secure
47
RSA
* Early asymmetric algorithm (1977), still used today
* Variable key length from 1024 to 4096 bits
* US authorities recommend key lengths of 2048 or more
* **Users create RSA key pairs using two very large prime numbers**
* It is slow and not used for long messages; often used to create initial secure channel over which symmetric key is exchanged
* RSA patent is expired
* Rivest, Shamir, Adleman
48
PGP
* Pretty Good Privacy
* Not an encryption algorithm itself, it's a framework for using other encryption algorithms
* Combines symmetric and assymmetric cryptography
* Sender generates random symmetric key to encrypt message, and uses recipient's asymmetric public key to encrypt the random symmetric key, which is sent along with the message to the recipient. The recipient uses their asymmetric private key to decrypt the random symmetric key, and is then able to use that key to decrypt the message
49
GnuPG / GPG
* Gnu Privacy Guard
* An open source package based on PGP
50
ECC
* Elliptic curve cryptography
* Unlike other asymmetric cryptographic algorithms, does not use prime factorization
* Uses the EC discrete log problem
* Ironically, would be easier for a quantum computer to crack than PF
51
PFS
* Perfect Forward Secrecy
* a property of secure communication protocols where compromise of long-term keys does not compromise past session keys
* Generates a unique and ephemeral session key for each session, ensuring that if one session key is compromised, it does not affect the security of other sessions
* Provides additional protection for past and future encrypted communications by isolating each session cryptographically
* Commonly used in protocols like TLS/SSL to enhance the security of web communications
* Implemented using methods like Diffie-Hellman key exchange
52
Diffie-Hellman Algorithm
* A method for securely exchanging shared cryptographic keys over a public channel.
* Invented in 1976
* Allows two parties to generate a shared secret key used for symmetric encryption, without transmitting the key itself.
* Security is based on the discrete logarithm problem, involving prime numbers and modular arithmetic.
* Commonly used in secure communications to establish a shared symmetric encryption key.
53
DHE
* Diffie-Hellman Ephemeral
* Creates unique session keys for each connection
* Ensures forward secrecy: compromising one session doesn't affect others
* Commonly used in TLS/SSL protocols
Protects against retrospective decryption if long-term keys are compromised
* Slightly higher computational cost than static DH
54
ECDH
* Elliptic Curve Diffie-Hellman
* Math is based on Eliptic Curve rather than prime numbers and modulos
55
Recovery Agent (RA)
* Allow internal access to lost keys
* Possesses master key that allows access to any encrypted data in the organization
* Could be a highly privileged account or a special certificate
* e.g. EFS (Encrypting File System) for Windows has a special recovery agent account
56
PBKDF2
* Password-Based Key Derivation Function v2
* A key derivation function used to implement salted password hashing. It applies a pseudorandom function (like HMAC) to the input password along with a salt value and repeats the process many times to produce a derived key. This technique increases the computational cost of cracking passwords, enhancing security against brute-force attacks.
Key points:
* Purpose: Convert passwords into cryptographic keys
* Features: Uses salt and iteration count
* Security benefit: Slows down brute-force and rainbow table attacks
* Common use: Password storage and verification in many systems
57
How hash functions fail
* being reversible
* producing a collision (same output from different inputs)
58
58
MD5
* Message Digest 5
* 128 bit hash
* Can produce collisions and should not be used
59
SHA
* Secure Hash Algorithm
* A family of 3 algorithms
* -1 is unsecure
* -2 is most common today
* -3 uses a completely different technique, and a hash output of any length can be chosen, ready to replace SHA-2 someday
* Some don't trust SHA because of its roots in US gov't, NSA
60
SHA-1
Secure Hashing Algorithm v. 1
* 160 bit
* unsecure, prone to collision attacks
61
SHA-2
## Footnote
Recall: name, hash lengths of family members, block and word sizes per family member
Secure Hashing Algorithm v. 2
Consists of:
* SHA-224
* SHA-256 (most common)
* SHA-384
* SHA-512, -512/224, -512/256 (truncated versions with same security but smaller output)
* 224 and 256 are 512 bit block, 32 bit word, making them more efficient for 32 bit environment / applications
* 384, 512, and 512-truncated are 1024 bit block, 64 bit word, more efficient for 64 bit environment / applications
* generally considered secure, including by NIST, but follows the same principals as MD5 and SHA-1 and is therefore susceptible to the same attacks; flaws in certain configs of SHA-2 have been found
62
SHA-3
* actually secure
* allows use of any fixed-length output
* completely different mathematical basis than MD5, SHA-1 or SHA-2
63
RIPEMD
## Footnote
Recall: what it is, length outputs, which length is no longer secure
* Race Integrity Primitives Evaluation Message Digest
* 128, 160, 256, and 320 bit hash lengths
* 128 no longer secure
* created free of involvment with the US government and NSA
64
HMAC
Hash-based Message Authentication Code
Definition:
A cryptographic method that uses a **hash function** and a **secret key** to ensure **authentication** and **integrity**.
How it works:
* The secret key and the message are combined inside the HMAC function to produce a hashed **Message Authentication Code (MAC)**
* This **MAC** is what gets sent along with the message, but the secret key is kept secret by both the sender and the receiver.
* When the receiver gets the message and MAC, they use their copy of the same secret key (which they already know) to recreate the MAC and verify the message.
65
MAC
| As it relates to authentication, not networking
Message Authentication Code
The output of the MAC-generating method (hash-based or otherwise!) that combines a message with a secret key. Provides assurance of message **integrity** and sender **authenticity**.
66
ECDSA
Elliptic Curve Digital Signature Algorithm
* a cryptographic algorithm used for creating and verifying digital signatures, based on elliptic curve cryptography (ECC)
* Security: ECDSA is considered a secure and acceptable algorithm for creating and verifying digital signatures.
* Usage: It is one of the three digital signature algorithms supported for use in the U.S. government, alongside RSA and EdDSA.
67
DSS
Digital Signature Standard
* a federal standard for digital signatures, established by the U.S. government. It specifies the use of the Digital Signature Algorithm (DSA) to ensure the authenticity and integrity of digital messages or documents
* Approved DSA's: RSA, ECDSA, EdDSA
68
EdDSA
Edwards-curve Digital Signature Algorithm
* offers faster signature generation and verification compared to traditional algorithms like ECDSA, while maintaining strong security
* uses twisted Edwards curves to provide high performance, even in constrained environments
* used for secure authentication and integrity
* one of the DSS-recommended digital signature algorithms alongside RSA and ECDSA, especially for environments requiring high efficiency.
69
RA
| In the context of PKI
Registration Authority
* An entity in Public Key Infrastructure (PKI) that verifies an applicant’s identity before passing the request to the Certificate Authority (CA) for certificate issuance. It ensures that only authenticated and authorized users receive certificates.
70
CA
| In the context of PKI
Certificate Authority
* A trusted entity in Public Key Infrastructure (PKI) that issues and digitally signs certificates, verifying the identity of certificate holders. The CA ensures the authenticity of the certificate and its associated public key.
71
SAN
| In the context of PKI
Subject Alternative Name
* An extension to an X.509 certificate that allows multiple domain names or IP addresses to be associated with a single certificate.
* Commonly used for securing multiple domains or subdomains with a single SSL/TLS certificate.
72
Certificate Stapling
An extension of OCSP in which *the certificate subjects*, rather than the end users, reach out to the OCSP server of the CA to verify the web server's certificate. This verification is "stapled" to the server's certificate and will be accepted by all of the many web browsers contacting the server throughout the day. This validation is usually valid for 24 hours and saves the CA's OCSP server from having to verify the same certificate for millions of different users millions of times a day.
73
Certificate Chaining
A process whereby you can have your internal CA trusted by a 3rd party CA and the outside world; multiple certificates are linked together to establish trust between a root certificate (trusted by all) and an end certificate. Each certificate in the chain is signed by the next higher certificate, creating a chain of trust from the root CA to the user's certificate.
Additional Explanation:
* **Root CA**: The starting point of trust, whose certificate is self-signed.
* **Intermediate CA**: Links between the root CA and end-user certificates, often signed by the root CA or another intermediate CA. This would be your "internal" CA
* **End Certificate**: The final certificate, issued to the end user or device, used for secure communication.
74
Offline CAs
Protect sensitive root keys by not being on a network. Used to sign certificates of intermediate (online) CA's belonging to the same org.
Any "top-level" / "global root" CA you see is most likely an offline CA that signed a lower CA's cert in the chain of trust.
75
DV
| Certificate Type
Domain Validation
* Verifies domain ownership
* lowest level
76
OV
| Certificate Type
Organizational Validation
* Verifies business/orginazation name against business records
* state business registrations, or reputable business databases
77
EV
| Certificate Type
Extended Validation
* extensive investigation to verify the physical existence and legitimacy of the organization
78
Distinguished Encoding Rules (DER)
| Certificate Format
## Footnote
Recall: encoding and file extensions
* Binary certificate format
* .der, .cer, .crt file extensions
* most common
79
PEM
| Certificate Format
## Footnote
Recall: encoding and file extensions
* An ASCII equivalent of the binary DER certificat format
* .pem, .cer, .crt, .key file extensions
* Can easily convert between text-based PEM and and binary DER formats using OpenSSL
* **note** that in the case of .crt or .cer files, you can't tell if it is DER or PEM without looking at it!
* Name comes from deprecated Privacy Enhanced Mail secure email standard
* The certificate format is still used even though the mail standard is not
80
PFX
| Certificate Format
## Footnote
Recall: encoding and file extensions
Personal Information Exchange
* binary format commonly used by windows systems
* .pfx or .p12 file extensions
81
P7B
| Certificate Format
## Footnote
Recall: encoding and file extensions
* ASCII text equivalent format to PFX
* also commonly used in Windows
* .p7b file extension
82
Approved DSS Algorithms
* Rivest-Shamir-Adleman (RSA)
* Elliptic Curve Digital Signature Algorithm (ECDSA)
* Edwards Curve Digital Signature Algorithm (EdDSA)
All consider secure and acceptable for use in creating and verifying digital signatures
83
SY0-701
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