Keys Generated After Aps Aes 4 Way Handshake

Keys Generated After Aps Aes 4 Way Handshake Average ratng: 6,5/10 4394 reviews
  1. Keys Generated After Aps Aes 4 Way Handshake Video
  2. Keys Generated After Aps Aes 4 Way Handshake Tcp

  • 802.1X/EAP also does the job of generation and distribution of dynamic encryption keys. This is not the purpose of 802.1x though.
  • Mutual authentication is required to generate dynamic encryption keys. i.e EAP-TLS,EAP-TTLS,EAP-FAST,EAP-LEAP and all versions of EAP-PEAP generate dynamic encryption keys.
    • EAP-MD5 cannot as it only involves unidirectional authentication
  • Prior to TKIP/RC4 or CCMP/AES (i.e the RSNA encryption algorithms), WEp offered dynamic key encryption
    • they were proprietary solutions though
    • Here using the mutual authentication credentials as a seed, matching dynamic encryption keys are generated for both the supplicant and the authentication server.
    • These keys are created per session, per user .
    • This key is the unicast key
    • The broadcast key can either be manually configured on the AP or randomly generated and this is used to encrypt/decrypt all broadcast/multicast 802.11 traffic.
    • The unicast key is unique per client, but the broadcast key for all must be the same.
    • The authenticator sends this key to the client using an EAPoL message (which is encrypted by the client's unicast key)
    • Note: The dynamic encryption keys are still weak and can still be cracked. Not recommended for usage

Another important by-product of the EAP is to generate symmetric keys, such as the Master Session Key (MSK)-an all-important key. After the authentication stage has been successfully completed, next comes the four-way handshake, an Authentication and Key Management Protocol (AKMP) used in IEEE 802.11i. TLS handshake cryptography AES key query. Ask Question. Does anyone have a code for the PRF, or is there any onther way for creating AES key at client side? Elite dangerous steam key generator. Also I would like to know the real use of SHA1/256 in TLS handshake. How is session key generated for TLS?

$ begingroup$ hi @DannyNiu can you help me with AES key generation function used at client side.? I will be so thankful. $ endgroup$ – Vaibhav Nov 4 '19 at 11:47 $ begingroup$ @VaibhavTayade If you want an explanation of the different parts of a TLS handshake, you might find tls.ulfheim.net interesting. Sep 05, 2018 The 4-Way Handshake utilizes an exchange of four EAPOL-Key frames between the client and access point. In a PSK network, the exchange of frames occurs after the Open System Authentication and Association. In an 802.1X network, the 4-Way Handshake occurs after EAP authentication. Now the WPA 4-way handshake: AP sends ANonse (AP Nonce) to client, which is basically a random Integer of 256 bits. Client use the ANonce and PMK to generate PTK (Pairwise Transient Key), and send CNonce (Client Nonce) and MAC. AP sends MAC and GTK (Group Temporal Key) to client. AES (acronym of Advanced Encryption Standard) is a symmetric encryption algorithm. The algorithm was developed by two Belgian cryptographer Joan Daemen and Vincent Rijmen. AES was designed to be efficient in both hardware and software, and supports a block length of 128 bits and key lengths of 128, 192, and 256 bits. Darby the dragon download mac. Generate secp256k1 key from password.

Robust Security network (RSN)

  • RSN involves 2 802.11 stations to establish procedures to authenticate and associate with each other as well as create dynamic encryption keys through a process known as 4-way handshake.
  • The association between the 2 stations is known as a RSNA.
  • After RSNA, the station shares a key with the AP known as a Pairwise Transient key which is used to encrypt unicast traffic.
  • All the stations also share a key called the Groupwise Temporal Key(GTK)' which is used to encrypt/decrypt all broadcast and multicast traffic
  • The 802.11-2007 standard allows for the creation of pre-RSNAs.
    • i.e legacy security methods are supported in the same BSS along with RSN security mechanisms.
    • Example : Dynamic WEP,static WEP.
    • Such a network is called Transition security network
    • Here the lowest common denominator key will be used as the broadcast/multicast key. (ex: in this case, it'll be WEP)
  • Controllers do the following
    • They can create multiple SSIDs for multiple WLANs in a single coverage cell area
    • For the multiple SSID's , they create multiple virtual BSSIDs
    • Each SSID is associated with a L3 VLAN interface on the DS.

RSN Information Element

  • This is used by the clients and the APs to notify one another of their RSN capabilities
  • optional field
  • Found in 4 different frames:
    • Beacon (AP to client)
    • Probe response (AP to client)
    • Association request (client to AP)
    • Reassociation request (client to AP)
  • This contains the following info:
    • Identifies the encryption capabilities of each station
    • will indicate whether 802.1X authentication or PSK is being used. (i.e supported authentication methods)
  • The client/AP will use one cipher suite for unicast traffic and another for broadcast/multicast traffic
    • Check figure 5.10 on Page 187 of the study guide for a view of how the RSN IE will look in a frame
  • The AKM(authentication key management) field is used to indicate whether the station supports 802.1X authentication or PSK authentication.

Authentication and Key Management(AKM)

  • AKM services consist of a set of one or more algorithms designed to provide authentication and key management,either individually or in combination with higer layer authentication and key-management algorithms.
    • These may include non-802 protocols
  • AKM services links together authentication and encryption
    • i.e an authentication process is necessary to generate dynamic encryption keys
  • Untill the dynamic encryption keys are crteated,the controlled port will not open
  • Refer to figure 5.14 on Page 190 of the study guide
  • Overview of AKM is as follows
    • Discovery:Active and Passive scanning
      • This includes->Discovery, authentication and association
    • Authentication: 802.1X/EAP or PSK
      • Starts when the EAP exchange starts
    • Master key creation: PMK/GMK
      • Supplicant and the authentication server generate a master encryption key called the PMK.
    • Temporal key creation : 4-way handshake creates GTK/PTK
    • Authorization : Controlled port unblocked
    • Encryption : The 802.11 data frames are encrypted

RSNA Key hierarchy

  • 5 keys make up a top-to-bottom hierarchy that is needed to establish a final RSNA
  • There are group-wise keys - used to protect a group of destinations
  • There are pair-wise keys - used to protect 2 entitites

Master session key(MSK)

  • Also called AAA key.
  • Generated from either the 802.1X/EAP process or the PSK process
  • This key is exported to both the supplicant and the authetnication server
  • Atleast 64 octects in length
  • We can think of this as a seeding material used to create other keys

Keys Generated After Aps Aes 4 Way Handshake Video

Master keys

  • After MSK is created, 2 master keys are created
  • The MSK is used to create a master key called Pairwise Master Key(PTK)
  • This resides on both the supplicant and the AS
  • A new PMK is created everytime a client authenticates or reauthenticates
  • The PMK is also sent from the AS to the authenticator
  • Another master key, Group-wise Master Key(GMK) is generated on the Authenticator
  • These master keys are not used to encrypt/decrypt data traffic
  • These are the seeding material for the 4-way handshake
  • PMK helps create the PTK
  • GMK helps create the GTK

Temporal Keys

  • PTK is comprised of 3 sections
    • Key confirmation key(KCK)
      • provides data integrity during the 4-way handshake and group key handshake
    • Key Encryption Key (KEK)
      • Is used by EAPoL frames to encrypt the 4-way handshake and the group key handshake
    • Temporal Key (TK)
      • This is used for MSDU encryption
  • The PTK/GTKs are either CCMP/AES or TKIP/RC4.

4-way handshake

  • The 4-way handshake basically does the following:
    • Confirm the existence of the PMK at the peer session
    • Ensure that the PMK is current
    • Derive a new PTK from the PMK
    • Install the PTK on the supplicant and the authenticator
    • Transfer the GTK from the authenticator to the supplicant and install the GTK on the supplicant , and if necessary on the authenticator
    • Confirm the selction of cipher suites
  • The PMK along with a nonce is used to create the PTK
  • 2 nonces are created by the 4-way handshake
    • The Authenticator nonce
    • The Supplicant nonce
  • PMK+Authenticator nonce+supplicant nonce+Authenticator MAC address + Supplicant MAC address is fed into a pseudo-random function and the PTK is generated
  • The 4-way handshake consists of the following steps
    • Message 1
      • Authenticator -> Supplicant
      • The authenticator and supplicant create their respective nonces
      • The authenticator sends it's Athenticator nonce to the supplicant
      • The supplicant now has all the info it needs to derive the PTK from the PMK.
    • Message 2
      • Supplicant -> Authenticator
      • The supplicant sends it's supplicant nonce to the authenticator
      • The supplicant also sends its RSN IE and a MIC.
      • The authenticator derives a PTK and also validates the MIC.
    • Message 3
      • Authenticator -> Supplicant
      • The authenticator derives the GTK from the GMK
      • Authenticator sends a message to the supplicant with the following information
        • ANonce
        • RSN IE
        • MIC
        • GTK
      • This message is encrypted using the PTK
    • Message 4
      • Supplicant -> Authenticator
      • Tells the authenticator that the temporal keys are now available and installed and ready for use

Keys Generated After Aps Aes 4 Way Handshake Tcp

Group Key Handshake

  • 2 frame handshake used to distribute new keys to client stations that already have a PTK and a GTK
  • Is exactly the last 2 frames of the 4-way handshake

Peer key handshake

  • 802.11-2007 gives a way for clients to talk to one another without involving the AP
  • After establsighing the individual security associations with the AP, a station-to-station link(STSL) can also be established
  • The clients use PeerKey Handshake management protocol to create peer keys.

RSNA Security Associations

  • A RSNA requires 2 802.11 stations to establish proceudres to authenticate and associate with each other as well as create dynamic encryption keys through a 4-WAY handshake

Passphrase-to-PSK matching

  • As discussed earlier, AKMP can either be derived using 802.1X/EAP or PSK
  • When using PSK, the AKM procedures are as follows
    • Discovery
    • Negotiation
      • The STA associates with the AP and negotiates a security policy.
      • The PSK becomes the PMK
    • Temporal Key Generation and Authorization
      • 4-way handshake to create temporal keys
  • Actually the RSNA PSK must be 256 bits in length when represented in hex.
  • Most end users prefer a smaller ASCII password
  • So a password-to-PSK mapping formula is defined
  • ASCII simple password is converted into a 64 character HEX RSNA PSK
  • In case of PSK AKM, the PMK of every station is the same because all of them use the same 'pre-shared key' which is nothing but the PMK
  • This is a security risk
  • This allows the hacker , who captures to frames to duplicate the PTK and thereby decrypt the encrypted frames
Handshake

Roaming and Dynamic Keys

  • Everytime a client roams to another AP, unique encryption keys must be generated using the 4-way handshake process
  • This means that everytime the client roams, the STA must perform the EAP process all over again
  • This leads to crappy VoWLAN and other time-sensitive applications when using a (WPA WPA2)Enterprise solution
  • The 802.1x process takes about 700ms or greater!
  • PSK authentication is much faster when compared to Enterprise solutions
  • Recently ratified 802.11r-2008 also known as fast BSS tranisition defines faster handoffs when roaming occurs between cells in a WLAN using 802.1X/EAP.