Cryptography

Understand 5.1 Confidentiality some cryptographic solutions can be used to make data illegible to unauthorized people (can be read, not understood) Integrity and authenticity some cryptographic solutions can be used to verify data has not been modified, or that the data comes from the declared source Data sensitivity many kinds of data need to be protected in terms of both confidentiality and integrity (PII, EPHI) Regulatory and industry best practice crypto is required by some laws and many standards PCI DSS, HIPPA

Understand 5.2 Crypto terms Plaintext - data in a readable form Ciphertext - plain text after a crypto system, encrypted Encryption - process of converting plain text to ciphertext Decryption - reverse process of ^{^} Cryptographic key - unique key that only the authorized individual has to decrypt and cipher Work factor - the amount of time to try all the potential keys for a potential crypto system to decrypt it Key space - number of potential keys for a given crypto system Initialization vector - way to add randomization to the ciphertext so that the output is always different Strength of encryption keys typically, longer the key, higher the work factor asymmetric cryptosystems tend to need longer keys to provide the same protection as symmetric cryptosystems current modern algorithm widely perceived as secure: AES 256 Hashing hashing is not cryptography, but often used in conjunction with it a one-way mathematical conversion of the plaintext to a representation of the plaintext, called the "message digest," or the "hash" hashing algorithms convert messages of any size to a digest of a fixed size every message, when hashed, creates a unique digest used to demonstrate integrity Outmoded hashing algorithms: MD5, SHA Current acceptable hashing algorithms: SHA256, SHA3 Traits of a good hash function deterministic: a given plaintext will always result in a specific digest collision-resistant: for any given digest, it is unlikely to find 2 sensible input plaintexts avalanche effect: changing any one character of the input plaintext changes the entire digest strictly one-way: should be mathematically unfeasible to learn the plaintext from the digest Salting encryption and hashing are both deterministic: if you put the same plaintext in, all the time, you will get the same output, everytime can be bad for operational security; any change in a regular message can be detected by surveillance, even if the message can't be read to address this, we can add a string of random characters to the message, every time the message is encrypted/hashed, such that the output is different every time in hashing, this practice is called "salting"; in crypto its called the "initialization vector" Symmetric/Asymmetric/Elliptic Curve Cryptography Symmetric same key is used to encrypt and decrypt the message usually called "shared key" or "shared secret" crypto relatively fast only provides confidentiality does not scale well requires out-of-band key distribution Asymmetric one key to encrypt, another, related key to decrypt can provide confidentiality and/or nonrepudiation depending on how it is used nonrepudiation can be implemented in ways to offer authentication Elliptic Curve Cryptography (ECC) Uses algebraic structure of elliptic curves (different from discrete logs) Can provide equivalent security with smaller key sizes Nonrepudiation a participant in a transaction cannot deny afterward that they took part digital signatures/certificates hash-based message authentication code (HMAC) can provide integrity and authenticity of a message using symmetric crypto and hashing audit trails - who sent what and where Digital signature provides integrity and nonrepudiation does NOT provide confidentiality typically uses a hash function and the private key form asymmetric crypto Digital Certificate a 3rd party confirmation of someone's public key uses public keys from asymmetric crypto and digital signatures only asserts ownership of a given public key uses the X509 format established by PKI (public key infrastructure) PKI (public key infrastructure) the way we create and distribute digital certificates a way of providing trust between 2 entities electronically requires the use of a trusted 3rd party to the transaction an organization can setup its own PKI for its own participants Cryptographic attacks, cryptanalysis, and countermeasures not much; unlikely to be on exam brute force trying to overcome the work factor by trying all possible keys quantum trying to deduce original input of a hashed message by creating a list of all possible inputs and all possible hashes (rainbow table) math breaking the algorithm to "solve" the crypto without the key doing statistical analysis on an encrypted message most common and effective: exploiting crypto implementation

Understand 5.3 Services and protocols IPsec Adds elements to a standard IP packet to provide more security functions AH - authentication header; ensures integrity and origin of the header ESP - encapsulating security payload; encrypts the payload SA - security association; the sender and recipient negotiate which type of crypto they'll use trailer - integrity check Transport Mode: end-end encryption (original IP header stays intact) Tunnel Mode: point-point encryption (original IP header encrypted and replaced with IPsec header) SSL/TLS S/MIME public standard for securing email available in most modern email applications uses asymmetric encryption and digital signature to offer confidentiality, nonrepudiation, and authentication of emails DKIM additional email option for appending a digital signature based on the authenticated domain of the sender many protocols used in modern communication are not inherently secure other protocols were created as secure alternatives when designing systems/processes, the enterprise architect might consider the used of secure protocols (understanding that these add more overhead and have negative impact on productivity) Not Secure - http smtp ftp Secure - https s/mime sftp tls

Understand 5.4 Fundamental key management concepts storage - don't store the keys with the thing its used with. rotation - don't use old keys composition - the longer the key, the greater the work factor (more computational overhead) generation - don't let users use the same passphrases or passwords for the cipher system destruction exchange revocation - certificate revocation list escrow - if a key becomes lost, that encrypted data is not recoverable. Backup and copy keys (still risky) Web of Trust (WOT) used to authenticate public key/owner bindings alternative to PKI decentralized; based on individual trust Pretty Good Privacy (PGP) origin of WOT concept asymmetric crypto for secure email GNU Privacy Guard (GPG) open source version of PGP (interoperable) blockchain: recent attempts to implement a decentralized reputational system with WOT