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96 lines
3.3 KiB
Markdown
96 lines
3.3 KiB
Markdown
# External flash
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External 256kbytes flash is a unique feature of the RDV4 edition.
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## Addresses
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Flash memory is
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* 256kb (0x40000= 262144)
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* divided into 4 pages of 64kb (0x10000 = 65536)
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* 4 pages divided into 16 sectors of 4kb (0x1000 = 4096), so last sector is at 0x3F000
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Therefore a flash address can be interpreted as such:
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```
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0xPSxxx e.g. 0x3FF7F
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^ page ^ page 3
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^ sector ^ sector 0xF
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^^^ offset ^^^ offset 0xF7F
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```
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## Layout
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Page 0:
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* available for user data
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* to dump it: `mem dump f page0_dump o 0 l 65536`
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* to erase it: `mem wipe p 0`
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Page 1:
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* available for user data
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* to dump it: `mem dump f page1_dump o 65536 l 65536`
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* to erase it: `mem wipe p 1`
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Page 2:
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* available for user data
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* to dump it: `mem dump f page2_dump o 131072 l 65536`
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* to erase it: `mem wipe p 2`
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Page 3:
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* used by Proxmark3 RDV4 specific functions: flash signature and keys dictionaries, see below for details
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* to dump it: `mem dump f page3_dump o 196608 l 65536`
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* to erase it:
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* **Beware** it will erase your flash signature (see below) so better to back it up first as you won't be able to regenerate it by yourself!
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* It's possible to erase completely page 3 by erase the entire flash memory with the voluntarily undocumented command `mem wipe i`.
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* Updating keys dictionaries doesn't require to erase page 3.
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## Page3 Layout
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Page3 is used as follows by the Proxmark3 RDV4 firmware:
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* **MF_KEYS**
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* offset: page 3 sector 9 (0x9) @ 3*0x10000+9*0x1000=0x39000
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* length: 2 sectors
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* **ICLASS_KEYS**
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* offset: page 3 sector 11 (0xB) @ 3*0x10000+11*0x1000=0x3B000
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* length: 1 sector
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* **T55XX_KEYS**
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* offset: page 3 sector 12 (0xC) @ 3*0x10000+12*0x1000=0x3C000
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* length: 1 sector
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* **T55XX_CONFIG**
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* offset: page 3 sector 13 (0xD) @ 3*0x10000+13*0x1000=0x3D000
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* length: 1 sector (actually only a few bytes are used to store `t55xx_config` structure)
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* **RSA SIGNATURE**, see below for details
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* offset: page 3 sector 15 (0xF) offset 0xF7F @ 3*0x10000+15*0x1000+0xF7F=0x3FF7F
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* length: 128 bytes
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* offset should have been 0x3FF80 but historically it's one byte off and therefore the last byte of the flash is unused
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## RSA signature
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To ensure your Proxmark3 RDV4 is not a counterfeit product, its external flash contains a RSA signature of the flash unique ID.
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You can verify it with: `mem info`
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```
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[usb] pm3 --> mem info
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[=] --- Flash memory Information ---------
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[=] -------------------------------------------------------------
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[=] ID | xx xx xx xx xx xx xx xx
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[=] SHA1 | xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx
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[=] RSA SIGNATURE |
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[00] | xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx
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[01] | xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx
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[02] | xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx
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[03] | xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx xx
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[=] KEY length | 128
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[+] RSA key validation ok
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[+] RSA Verification ok
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```
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For a backup of the signature: `mem dump p f flash_signature_dump o 262015 l 128`
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