Difference between revisions of "Nonce"

From The iPhone Wiki
Jump to: navigation, search
m (BBTicket)
m (BBTicket: It is not a "2G".)
Line 7: Line 7:
 
===BBTicket===
 
===BBTicket===
 
*No iPod touch (or iPad Wi-Fi) has been signed with the BBTicket, since by definition it has no baseband.
 
*No iPod touch (or iPad Wi-Fi) has been signed with the BBTicket, since by definition it has no baseband.
*[[M68ap|iPhone 2G]] (bootloaders can be neutered to cancel this signchecks). [[N82ap|iPhone 3G]], [[N88ap|iPhone 3GS]] and [[K48ap|iPad Wi-Fi+3G]] - if the baseband is higher or equal (or just higher on bootloader 3.9 on iPhone 2G). Some bootloaders allow downgrade of the baseband if it is still signed.
+
*[[M68ap|iPhone]] (bootloaders can be neutered to cancel this signchecks). [[N82ap|iPhone 3G]], [[N88ap|iPhone 3GS]] and [[K48ap|iPad Wi-Fi+3G]] - if the baseband is higher or equal (or just higher on bootloader 3.9 on iPhone 2G). Some bootloaders allow downgrade of the baseband if it is still signed.
 
*[[N90ap|iPhone 4 (iPhone3,1)]], [[N92ap|iPhone 4 (iPhone3,3)]], [[N94ap|iPhone 4S]], and [[K94ap|iPad 2 (iPad2,2)]] and [[K95ap|iPad 2 (iPad2,3)]] - [[AT+XNONCE]] - restores the baseband only if Apple is still signing it. On bootloaders 2.8, 2.13, Trek and Phoenix, both the [[AT+XNONCE]] and the "higher or equal" checks happen.
 
*[[N90ap|iPhone 4 (iPhone3,1)]], [[N92ap|iPhone 4 (iPhone3,3)]], [[N94ap|iPhone 4S]], and [[K94ap|iPad 2 (iPad2,2)]] and [[K95ap|iPad 2 (iPad2,3)]] - [[AT+XNONCE]] - restores the baseband only if Apple is still signing it. On bootloaders 2.8, 2.13, Trek and Phoenix, both the [[AT+XNONCE]] and the "higher or equal" checks happen.
   

Revision as of 13:47, 5 October 2014

Nonce is a signing method that randomizes Apple's cryptographic signature hash blobs (SHSH blobs) and is used with the BBTicket (baseband signing ticket) and the APTicket (firmware signing ticket).

Method

The device bootloaders (baseband or firmware) generate a random number at the restore, then send them to iTunes which sends them to Apple. Then Apple sends the APTicket / BBTicket SHSH certificate with the number generated. This level is the most critical: the number within the certificate is matched to the number generated on device, and if they match iTunes will prepare the matched certificate and finally will stitch the randomized blobs to the firmware. If the blobs don't match the restore will fail and the bootloaders will reject the certificate.

Usage

BBTicket

APTicket

Jailbreak difficulties

With nonce signatures, signatures can't be cached, because signatures will not match if they have been reused. In other words, the widely used replay attack is no longer possible.

See also