First off, I don't have any experience with this one. But it looks like it encodes/decodes with an XTEA algorithm. Key is a 16 byte code. Here is some info on it from their readme file. And best of all, it is free.
I would think that hex is hex, and whether it is PBP, CCS, etc, the hex would not look any different to a bootloader.
http://www.diolan.com/pic/bootloader_dwn.html
Code:XTEA Encoder/Decoder ==================== XTEA Algorithm backgrounds --------------------------- The XTEA encoder/decoder input byte stream is separated into 8 byte chunks [ b0 b1 b2 b3 b4 b5 b6 b7 ], [ b8 b9 ........... ], ... Chunk is treated as two 32 bit little endian integers x1 and x2. For chunk0: x1 = (b3<<24) + (b2<<16) + (b1<<8) + b0 x2 = (b4<<24) + (b5<<16) + (b6<<8) + b7 Encoding/Decoding is performed for every single chunk. KEY is a 16 bytes string treated as key[4], where key[i] is 32 bit little endian integer KEY k0 k1 k2 k3 k4 ..... k15 key[0] = (k3<<24) + (k2<<16) + (k1<<8) + k0 DELTA is 32 bit integer constant DELTA = 0x9E3779B9 Chunk Encoding: sum=0; for( i=0; i<XTEA_ITER; i++ ) { x1 += (((x2<<4) ^ (x2>>5)) + x2) ^ (sum + key[sum&0x03]); sum+= DELTA; x2 += (((x1<<4) ^ (x1>>5)) + x1) ^ (sum + $KEY[(sum>>11)&0x03]); } Chunk Decoding: sum = DELTA* XTEA_ITER; for( i=0; i<XTEA_ITER; i++ ) { x2 -= (((x1<<4) ^ (x1>>5)) + x1) ^ (sum + key[(sum>>11)&0x03]); sum-= DELTA; x1 -= (((x2<<4) ^ (x2>>5)) + x2) ^ (sum + key[sum&0x03]); } XTEA Encoder/Decoder configuration ---------------------------------- You can change following parameters to configure XTEA encoder/decoder - XTEA encoder/decoder KEY File : xtea.asm Identifier : XTEA_KEY - XTEA encoder/decoder number of iterations File : xtea.asm Identifier : XTEA_ITERATIONS and DELTA_ITER The number of iterations defines level of security. The 16 iterations are quite enough for bootloader. Default value is 64 iterations. If you change number of iterations do not forget to change DELTA_ITER, that is precalculated value of DELTA*XTEA_ITERATIONS used by decoder Example: XTEA_ITERATIONS equ 0x40 ; Number of iterations on x1,x2 DELTA_ITER db 0x40,0x6e,0xde,0x8d ; Delta*XTEA_ITERATIONS Code Protection =============== Following Configuration Registers settings are recomended to secure FW from anauthorised access and protect bootloader section from undesired changes by external or internall agent. This setting will allow proper operation of bootloader but will not let any external access to FW. Config Register Value Description 0x300006.bit7 1 Background Debug Disabled 0x300008 0x08 Code Protect 0x0800-0x1FFF Enabled Code Protect 0x2000-0x3FFF Enabled Code Protect 0x4000-0x5FFF Enabled 0x300009 0x80 Data EE Read Protect Disabled Code Protect Boot Enabled 0x30000A 0x0F Table Write Protect 0x0800-0x1FFF Disabled Table Write Protect 0x2000-0x3FFF Disabled Table Write Protect 0x4000-0x5FFF Disabled 0x30000B 0x80 Data EE Write Protect Disabled Table Write Protect Boot Enabled Config Write Protect Enabled 0x30000C 0x0F Table Read Protect 0x0800-0x1FFF Disabled Table Read Protect 0x2000-0x3FFF Disabled Table Read Protect 0x4000-0x5FFF Disabled 0x30000D 0x00 Table Read Protect Boot Enabled
Originally Posted by aberco
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