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// genpass
// get asr key for 3.x firmware
//
// by posixninja, geohot, chronic, and #iphone-rce

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <openssl/sha.h>
#include <openssl/evp.h>

#define BUF_SIZE 0x100000
#define SHA256_DIGEST_LENGTH 32

typedef unsigned char uint8;
typedef unsigned int uint32;
typedef unsigned long long uint64;

uint64 u32_to_u64(uint32 msq, uint32 lsq) {
	uint64 ms = (uint64)msq;
	uint64 ls = (uint64)lsq;
	return ls | (ms << 32);
}

uint64 hash_platform(const char* platform) {
	uint8* md = malloc(SHA_DIGEST_LENGTH);
	SHA1(platform, strlen(platform), md);
	
	uint64 hash = u32_to_u64(
							 ((md[0] << 24) | (md[1] << 16) | (md[2] << 8) | md[3]),
							 ((md[4] << 24) | (md[5] << 16) | (md[6] << 8) | md[7])
							 );
	free(md);
	return hash;
}

uint64 ramdisk_size(const char* ramdisk) {
	struct stat filestat;
	if(stat(ramdisk, &filestat) < 0) {
		return 0;
	}
	
	return (uint64)filestat.st_size;
}

void keydump(uint8* passphrase,int l) {
	int i=0;
	for(i=0; i<l; i++) {
		printf("%02x", passphrase[i]);
	} printf("\n");
}


int compare(const uint32* a, const uint32* b) {
	if(*a < *b) return -1;
	if(*a > *b) return 1;
	return 0;
}

const char platform[]="s5l8900x";
const char ramdisk[]="ramdisk.dmg";


int main(int argc, char* argv[]) {
	
	if(argc<3) {printf("%s: <platform> <ramdisk> <main>\n", argv[0]); return -1;}
	
	uint32 saltedHash[4];
	uint64 salt[4];
	
	salt[0] = 0xad79d29de5e2ac9e;
	salt[1] = 0xe6af2eb19e23925b;
	salt[2] = 0x3f1375b4bd88815c;
	salt[3] = 0x3bdff4e5564a9f87;
	
	FILE* fd = fopen(argv[2], "rb");
	int i = 0;
	int x = 0;
	SHA256_CTX ctx;
	uint8* buffer = NULL;
	uint8* passphrase = NULL;
	uint64 totalSize = ramdisk_size(argv[2]);
	uint64 platformHash = hash_platform(argv[1]);
	
	/*printf("size: %I64x  plat: %s  plathash %I64x\n", totalSize,
	 platform,platformHash);*/
	
	for(i=0;i<4;i++)
	{
		salt[i]+=platformHash;
		//printf("%d: %I64x\n", i, salt[i]);
	}
	
	for(i = 0; i < 4; i++) {
		saltedHash[i] = ((uint32)(salt[i] % totalSize)) & 0xFFFFFE00;
	}
	
	qsort(&saltedHash, 4, 4, &compare);
	
	SHA256_Init(&ctx);
	SHA256_Update(&ctx, salt, 32);
	
	
	int r=0;
	i=0;    //hash count
	
	buffer = malloc(BUF_SIZE);
	passphrase = malloc(SHA256_DIGEST_LENGTH);
	
	while(r<totalSize) {
		x = fread(buffer, 1, BUF_SIZE, fd);
		SHA256_Update(&ctx, buffer, x);
		
		if(i<4)         //some salts remain
		{
			if(r >= (saltedHash[i]+0x4000)) i++;
			else if(  r < saltedHash[i] && saltedHash[i] < (r+x) )
			{
				if( (saltedHash[i]+0x4000) < r ) 
					SHA256_Update(&ctx, buffer, saltedHash[i]-r);
				else SHA256_Update(&ctx, buffer+(saltedHash[i]-r), 
								   ( (x-(saltedHash[i]-r))<0x4000) ? (x-(saltedHash[i]-r)) : 0x4000 );
			}
		}
		r+=x;
	}
	
	fclose(fd);
	
	SHA256_Final(passphrase, &ctx);
	printf("passphrase: ");
	keydump(passphrase, SHA256_DIGEST_LENGTH);
	
	if(buffer) free(buffer);
	
	if(argc==4)             //do main as well
	{
		fd=fopen(argv[3],"rb");
		EVP_CIPHER_CTX ctx;
		
		int offset=0x1D4;
		uint8 data[0x30];
		uint8 out[0x30]; int outlen,tmplen;
		int a;
		for(a=0;a<7;a++)
		{
			fseek(fd, offset, SEEK_SET); offset+=0x268;
			fread(data, 1, 0x30, fd);
			EVP_CIPHER_CTX_init(&ctx);
			EVP_DecryptInit_ex(&ctx, EVP_des_ede3_cbc(),
							   NULL, passphrase, &passphrase[24]);
			EVP_DecryptUpdate(&ctx, out, &outlen, data, 0x30);
			if(!EVP_DecryptFinal_ex(&ctx, out + outlen, &tmplen))
				printf("not block %d\n", a);
			else
				break;
		}
		printf("vfdecryptk: ");
		keydump(out, 0x24);
	}
	
	if(passphrase) free(passphrase);
	
	return 0;
}