WildcardTicket

The wildcard ticket is used for activating the baseband. It is stored in the file "/var/root/Library/Lockdown/activation_records/wildcard_record.plist". When activating an iPhone, the ticket is pulled from Apple's server and stored on the device. It contains all the information about sim-/netlocks. Factory- and carrier-unlocked devices receive a wildcard ticket with policies that permit all SIM cards.

Ticket Layout

0x0 Version number (=2 for iPhone 3G, 3GS)
0x4 Encrypted Ticket

The ticket is decrypted with TEA in CBC mode using a key hashed from the NORID, CHIPID, IMEI and a salt. The layout of the decrypted ticket looks like this:

0x00         Certificate Length (in bits)
0x04         Certificate Serial (usually 1)
0x08         Public Key Length (in bits)
0x0c         Public Key Exponent
0x10-0x90    Public Key (RSA Key 3)
0x90-0x110   Additional Public Key - not in use 
0x110-0x190  Certificate of the first 0x110 bytes signed with rsa_key2
0x190-0x19B  ICCID mask (relevant bits for simlock)
0x19C-0x1A3  IMEI
0x1A4-0x1B7  Hash of several hardware IDs (IMEI, norID, chipID)
0x1B8-...    Table of "policies" (netlock)

Attached to the decrypted ticket is a certificate (0x80 byte) signed with the RSA key 3 at 0x10.

Policy Table Layout

0x0          Total length of the policy table in bytes
<Policy Item>

An item is 12 byte in size and has this structure:

0x0-0x2      ID
0x2-0x4      type?
0x4-0x0C     IMSI mask

Each 4-bit nibble of a mask corresponds to a number - the wildcard is encoded as 0xE.