2.8 Summarize the basics of cryptographic concepts. Flashcards
An electronic mechanism used to prove that a message was sent from a specific user and that the message wasn’t changed while in transit. It operates using a hashing algorithm and asymmetric public-key cryptography. It is built using the sender’s private key to encrypt or sign the hash of the message.
DIGITAL SIGNATURES
Built using the recipient’s public key to encrypt a symmetric key.
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A digital envelope is the alternate public key cryptography process. When confidentiality is needed for a communication, two methods are available to exchange a symmetric key between the endpoints (see later heading “Key exchange”). One is to use a key exchange service such as Diffie-Hellman, and the other is to generate a key locally that is exchanged using a digital envelope. A digital envelope is built by the sender using the recipient’s public key to encrypt a sender generated locally randomly generated symmetric key. Upon receipt the recipient uses their private key to decrypt or open the envelope. Thus, both sender and receiver now have a shared secret key. This form of key exchange is commonly used in non-real-time communications, such as email. A sender can craft an email message, encrypt that message with a symmetric key, and then envelope that symmetric key with the recipient’s public key. The recipient is able to open the envelope with their private key to extract the symmetric key and then use the extracted symmetric key to decrypt the email message.
DIGITAL ENVELOPE
The more critical your data, the stronger the key you use to protect it should be.
KEY LENGTH
Key stretching is a collection of techniques that can potentially take a weak key or password and stretch it to become more secure, at least against brute-force attacks.
KEY STRETCHING
Secret data added to input material prior to the hashing process. This process makes the process of attacking hashes much more complicated and computationally intensive.
SALTING
Hashing is used to produce a unique data identifier. Hashing takes a variable-length input and produces a fixed-length output. It can be performed in only one direction. The hash value is used to detect violations of data integrity.
HASHING
Occurs when two different data sets produce the same hash value.
Collision (HASHING)
When this takes place in the existing and established communication channel or pathway, it is called in- band. When it takes place outside of the current communication channel or pathway, such as through a secondary channel, via a special secured exchange technique in the channel, or with a completely separate pathway technology, it is called out-of band.
KEY EXCHANGE
These are encryption keys used for a communication session. Typically, session keys are randomly selected (or generated) and then used for only one session.
SESSION KEYS
This uses a series of one-way functions and nonshared secrets to generate a shared number (which is used as a symmetric key) between two parties across an insecure conversation medium. DHE and ECDHE are improved versions of this.
DIFFIE-HELLMAN (DH)
A method of improving asymmetric cryptography algorithms to obtain stronger encryption from shorter keys.
ELLIPTICAL CURVE CRYPTOGRAPHY
A means of ensuring that the compromising of an entity’s digital certificates or public/private key pairs doesn’t compromise the security of any session’s keys. This is implemented by using ephemeral keys for each and every session.
PERFECT FORWARD SECRECY
The exploitation of quantum properties to perform encryption operations.
QUANTUM CRYPTOGRAPHY
Communications (QUANTUM)
Computing (QUANTUM)
The study and creation of cryptographic algorithms to defend against quantum supremacy in the area of encryption.
POST-QUANTUM
A key generated at the time of need for use in a short or temporary time frame. It might be used only once or could be used for a communication session before being discarded. Most session keys are (or at least should be) this type.
EPHEMERAL KEYS
Cryptography communications can be implemented in several modes, which relate to whether and how authentication is used. Crypto authentication can include single-sided and mutual authentication.
MODES OF OPERATION
Authenticated (MODES OF OPERATION)
Unauthenticated (MODES OF OPERATION)
Counter (MODES OF OPERATION)
