Yubikey - Revision history

Mg at 15:12, 27 April 2012

2012-04-27T15:12:59Z

← Older revision		Revision as of 15:12, 27 April 2012
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	== Yubikey ==		== Yubikey ==
	* USB-Token		* USB-Token
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	== Yubikey ==		== Yubikey ==
		⚫	[[Image:Yubi_auth.png]]
	=== OTP ===		=== OTP ===
	* ''secret'': 128-bit AES key		* ''secret'': 128-bit AES key
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	* Validierung der OTPs übernimmt ein Validation Server der via HTTP ansprechbar ist		* Validierung der OTPs übernimmt ein Validation Server der via HTTP ansprechbar ist
	* http://code.google.com/p/yubikey-val-server-php/wiki/ValidationProtocolV20		* http://code.google.com/p/yubikey-val-server-php/wiki/ValidationProtocolV20

⚫	[[Image:Yubi_auth.png]]

	=== Validation ===		=== Validation ===

Mg: /* Validation Protocol */

2012-04-27T15:12:18Z

Validation Protocol

← Older revision		Revision as of 15:12, 27 April 2012
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	* Validierung der OTPs übernimmt ein Validation Server der via HTTP ansprechbar ist		* Validierung der OTPs übernimmt ein Validation Server der via HTTP ansprechbar ist
	* http://code.google.com/p/yubikey-val-server-php/wiki/ValidationProtocolV20		* http://code.google.com/p/yubikey-val-server-php/wiki/ValidationProtocolV20
	[[~~File~~:Yubi_auth.png]]		[[Image:Yubi_auth.png]]

	=== Validation ===		=== Validation ===

Mg at 15:09, 27 April 2012

2012-04-27T15:09:44Z

← Older revision		Revision as of 15:09, 27 April 2012
Line 57:		Line 57:
	* Validierung der OTPs übernimmt ein Validation Server der via HTTP ansprechbar ist		* Validierung der OTPs übernimmt ein Validation Server der via HTTP ansprechbar ist
	* http://code.google.com/p/yubikey-val-server-php/wiki/ValidationProtocolV20		* http://code.google.com/p/yubikey-val-server-php/wiki/ValidationProtocolV20
			[[File:Yubi_auth.png]]

	=== Validation ===		=== Validation ===

Mg at 15:03, 27 April 2012

2012-04-27T15:03:08Z

← Older revision		Revision as of 15:03, 27 April 2012
Line 1:		Line 1:

	== Yubikey ==		== Yubikey ==
			* USB-Token
			* One-Time Password Generator

	== Zwei-Faktor-Authentifizierung ==		== Zwei-Faktor-Authentifizierung ==
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	*** smsTAN (Passwort + SIM-Karte)		*** smsTAN (Passwort + SIM-Karte)

	Yubikey: OTP als Nachweis für Besitz.		Yubikey: OTP als Nachweis für den Besitz eines bestimmten Tokens.

	== One-Time Passwords ==		== One-Time Passwords ==
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	*** OCRA OATH Challenge Response Algorithm (RFC 6287)		*** OCRA OATH Challenge Response Algorithm (RFC 6287)

	== Yubikey ~~OTP~~ ==		== Yubikey ==
			=== OTP ===
	* ''secret'': 128-bit AES key		* ''secret'': 128-bit AES key
	* ''moving factor'': (3) Counter		* ''moving factor'': (3) Counter
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	* CryptoFunction = HOTP-H-n		* CryptoFunction = HOTP-H-n
	** <math>H \in \{</math> SHA-1, SHA256, SHA512 <math>\}</math>		** <math>H \in \{</math> SHA-1, SHA256, SHA512 <math>\}</math>
	** n - Anzahl der Ziffern 4-10 oder 0		** n - Anzahl der Ziffern 4-10 oder 0 (= keiner Verkürzung)
	* DataInput = OCRASuite \| 00 \| C \| Q \| P \| S \| T		* DataInput = OCRASuite \| 00 \| C \| Q \| P \| S \| T
	** OCRASuite - mode of operation		** OCRASuite - mode of operation

Mg at 15:00, 27 April 2012

2012-04-27T15:00:32Z

New page

== Yubikey ==

== Zwei-Faktor-Authentifizierung ==
* Besitz und Wissen
* z.B.
** nPA eID(PIN + Ausweis)
** Online-Banking
*** iTAN (Passwort + TAN-Liste)
*** ChipTAN (Passwort + EC-Karte)
*** smsTAN (Passwort + SIM-Karte)

Yubikey: OTP als Nachweis für Besitz.

== One-Time Passwords ==
* generell
** ''moving factor'' MF: z.B. counter, timestamp
** ''secret'' S
** otp = ''f''(S, MF)
* konkret
** Yubikey OTP
** OATH - Initiative for open authentication
*** HOTP HMAC-Based One-time Password Algorithm (RFC 4226)
*** TOTP Time-based One-time Password Algorithm (RFC 6238)
*** OCRA OATH Challenge Response Algorithm (RFC 6287)

== Yubikey OTP ==
* ''secret'': 128-bit AES key
* ''moving factor'': (3) Counter
** session counter (16 bit)
** session use counter (8 bit)
** timestamp (24 bit)
* ''public id'' (48 bit)
* ''private id'' (48 bit)

<nowiki>
internal id s.count timestamp s.use random crc
ccff5e92d4e8 0003 275ab5 01 ead3 e90e
\ \ | / / /
ccff5e92d4e80300b55a2701d3ea0ee9
|
aes_encrypt(S)
public id |
ffda638233c7 1cd02dd852d50fbb5acb4c6808062625
\ |
ffda638233c71cd02dd852d50fbb5acb4c6808062625
|
modhex_encode()
|
vvtlhejdeeribrtcdttjgdtgcvnnglrnfrhjcjchdhdg
</nowiki>

=== Validation Protocol ===
* Validierung der OTPs übernimmt ein Validation Server der via HTTP ansprechbar ist
* http://code.google.com/p/yubikey-val-server-php/wiki/ValidationProtocolV20

=== Validation ===
* Entschlüsselung des OTP mit ''shared secret''
* CRC-Check
* Internal-ID
* Counter
** <math>s.count > s.count'</math>
** <math>s.count == s.count'</math>
*** <math>s.use > s.use'</math>
*** Zeitdifferenz der timestamps ("phishing check")

<nowiki>
vvtlhejdeeribrtcdttjgdtgcvnnglrnfrhjcjchdhdg
|
modhex_decode()
|
ffda638233c71cd02dd852d50fbb5acb4c6808062625
/ \
ffda638233c7 1cd02dd852d50fbb5acb4c6808062625
public id |
aes_decrypt(K)
|
ccff5e92d4e80300b55a2701d3ea0ee9
|
ccff5e92d4e8 0003 275ab5 01 ead3 e90e
internal id s.count timestamp s.use rand crc
</nowiki>

== HOTP RFC 4226 ==
=== Algorithmus ===
* ''moving factor'': 64-bit counter C
* ''secret'': 128-bit HMAC key K
* <math>HOTP(K, C) = Truncate(HMAC-SHA1(K, C))</math>
* >= 6 Ziffern

=== Truncate() ===
* Verkürzen der MAC auf d Ziffern
* 31-bit Zahl x exrahieren
<nowiki>
index = mac[19] & 0xf;
x = mac[index] << 24
| mac[index+1] << 16
| mac[index+2] << 8
| mac[index+3];
x &= 0x7fffffff;
</nowiki>
* otp = x mod 10^d

=== Validation ===
* <math>HOTP(K, C_{last} + 1) == otp</math> ?
* lookahead: akzeptiere <math>C_{last} + 1, \ldots, C_{last} + n</math>
* 6 Ziffern <math>\approx</math> 20 bits. mit lookahead = 8 <math>\approx</math> 17 bits
* Serverseitiges throttling um Brute-Force Angriffe zu erschweren

== TOTP RFC 6238 ==
* HOTP mit zeitbasiertem Counter
* <math>T_0</math>: Startzeit (unix time)
* <math>X</math>: time step
* <math>T = (current_time - T_0) / X</math>
* <math>TOTP = HOTP(K, T)</math>

== ORCA RFC 6287 ==
* Generalisierung/Erweiterung von HOTP/TOTP
* (mutual) challenge-response
* SHA1 nicht fest verdrahtet
* nicht wirklich verbreitet
** Problem: wie bekommt man die Challenge in das Token?

=== ORCA CryptoFunction ===
* OCRA = CryptoFunction(K, DataInput)
* CryptoFunction = HOTP-H-n
** <math>H \in \{</math> SHA-1, SHA256, SHA512 <math>\}</math>
** n - Anzahl der Ziffern 4-10 oder 0
* DataInput = OCRASuite | 00 | C | Q | P | S | T
** OCRASuite - mode of operation
** C - Counter (optional)
** Q - Challenge
** P - hashed password/pin (optional)
** S - session information (optional)
** T - timestamp (optional)

=== ORCA Suites ===
* OCRASuite = 'Algorithm:CryptoFunction:DataInput'

* "OCRA-1:HOTP-SHA512-8:C-QN08-PSHA1"
** ''OCRA-1'': OCRA Version 1
** ''HOTP-SHA512-8'': HTOP mit SHA512 verkürzt auf 8 Ziffern
** ''C-QN08-PSHA1'':
*** ''C'': mit counter
*** ''QN08'': numerische Challenge bis zu 8 Ziffern
*** ''PSHA1'': SHA1 des Passworts

* "OCRA-1:HOTP-SHA256-6:QA10-T1M"
** ''OCRA-1'': OCRA Version 1
** ''HOTP-SHA256-6'': HTOP mit SHA256 verkürzt auf 6 Ziffern
** ''QA10-T1M'':
*** ''QA10'': alphanumerische Challenge bis zu 10 Zeichen.
*** ''T1M'': Timestamp Counter (time step = 1 minute)

=== Challenge Response Protokoll ===
<nowiki>
CLIENT SERVER
(PROVER) VERIFIER)
| |
| Verifier sends challenge to prover |
| Challenge = Q |
|<---------------------------------------|
| |
| Prover Computes Response |
| R = OCRA(K, {[C] | Q | [P | S | T]}) |
| Prover sends Response = R |
|--------------------------------------->|
| |
| Verifier Validates Response |
| If Response is valid, Server sends OK |
| If Response is not, Server sends NOK |
|<---------------------------------------|
| |
</nowiki>
http://tools.ietf.org/rfc/rfc6287.txt

=== Mututal Challenge Response Protokoll ===
<nowiki>
CLIENT SERVER
(PROVER) (VERIFIER)
| |
| 1. Client sends client-challenge |
| QC = Client-challenge |
|------------------------------------------------->|
| |
| 2. Server computes server-response |
| and sends server-challenge |
| RS = OCRA(K, [C] | QC | QS | [S | T]) |
| QS = Server-challenge |
| Response = RS, QS |
|<-------------------------------------------------|
| |
| 3. Client verifies server-response |
| and computes client-response |
| OCRA(K, [C] | QC | QS | [S | T]) != RS -> STOP |
| RC = OCRA(K, [C] | QS | QC | [P | S | T]) |
| Response = RC |
|------------------------------------------------->|
| |
| 4. Server verifies client-response |
| OCRA(K, [C] | QS | QC | [P|S|T]) != RC -> STOP |
| Response = OK |
|<-------------------------------------------------|
| |
</nowiki>
http://tools.ietf.org/rfc/rfc6287.txt

== Links ==
* http://www.yubikey.com
* http://code.google.com/p/yubikey-val-server-php/wiki/ValidationProtocolV20
* http://www.openauthentication.org/
* http://tools.ietf.org/rfc/rfc4226.txt
* http://tools.ietf.org/rfc/rfc6238.txt
* http://tools.ietf.org/rfc/rfc6287.txt