Difference between revisions of "Nonce"

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*Devices with the [[S5L8900]] get [[SHSH]] blobs without APTicket on 4.0 - 4.2.1, even though they are not required and can be avoided with [[Pwnage]]+[[Pwnage 2.0]].
 
*Devices with the [[S5L8900]] get [[SHSH]] blobs without APTicket on 4.0 - 4.2.1, even though they are not required and can be avoided with [[Pwnage]]+[[Pwnage 2.0]].
 
*Devices with the [[S5L8720]] get [[SHSH]] blobs without APTicket from 3.1.1 and on, even though [[Bootrom 240.4]] doesn't require them and they can be avoided with the [[0x24000 Segment Overflow]]
 
*Devices with the [[S5L8720]] get [[SHSH]] blobs without APTicket from 3.1.1 and on, even though [[Bootrom 240.4]] doesn't require them and they can be avoided with the [[0x24000 Segment Overflow]]
*Devices with the [[S5L8920]], [[S5L8922]], [[S5L8930]] and [[S5L8940]] got [[SHSH]] blobs without APTicket between 3.0 - 4.3.5, and they can not be avoided (except for the [[iBoot-359.3]] with the 0x24000 Segment Overflow)
+
*Devices with the [[S5L8920]], [[S5L8922]], [[S5L8930]] and [[S5L8940]] got [[SHSH]] blobs without APTicket between 3.0 - 4.3.5, and they can not be avoided (except for the [[Bootrom 359.3]] with the 0x24000 Segment Overflow)
 
*Devices with the [[S5L8920]], [[S5L8922]], [[S5L8930]] and [[S5L8940]] get APTicket SHSH blobs on 5.0+, and they can not be avoided (except for the [[Bootrom 359.3]] with 0x24000 Segment Overflow)
 
*Devices with the [[S5L8920]], [[S5L8922]], [[S5L8930]] and [[S5L8940]] get APTicket SHSH blobs on 5.0+, and they can not be avoided (except for the [[Bootrom 359.3]] with 0x24000 Segment Overflow)
   

Revision as of 16:06, 11 March 2012

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