From 866f6afd5a5709df80a084bc620d754761ef4cb7 Mon Sep 17 00:00:00 2001 From: C-3PO Date: Tue, 24 Jul 2018 18:10:07 +0200 Subject: [PATCH] =?UTF-8?q?=F0=9F=9A=A7=20Add=20decryption=20functions?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .gitignore | 1 + .vscode/settings.json | 4 ++- src/decrypt.c | 22 ++++++++++++- src/decrypt.h | 4 +++ src/main.c | 22 +++++++++++-- src/utils/decryptUtilities.c | 61 ++++++++++++++++++++++++++++++++++++ src/utils/decryptUtilities.h | 9 ++++++ 7 files changed, 119 insertions(+), 4 deletions(-) create mode 100644 src/utils/decryptUtilities.c create mode 100644 src/utils/decryptUtilities.h diff --git a/.gitignore b/.gitignore index 812878b..789ef81 100644 --- a/.gitignore +++ b/.gitignore @@ -1 +1,2 @@ +.vscode patcher-installer diff --git a/.vscode/settings.json b/.vscode/settings.json index a2e83cb..33035a9 100644 --- a/.vscode/settings.json +++ b/.vscode/settings.json @@ -1,6 +1,8 @@ { "files.associations": { "filereader.h": "c", - "decrypt.h": "c" + "decrypt.h": "c", + "stdint.h": "c", + "decryptutilities.h": "c" } } \ No newline at end of file diff --git a/src/decrypt.c b/src/decrypt.c index 628aef1..2209303 100644 --- a/src/decrypt.c +++ b/src/decrypt.c @@ -1,6 +1,26 @@ #include "decrypt.h" +#include "utils/decryptUtilities.h" + +struct DECRYPTION_DATA { + uint32_t key0; + uint32_t key1; + uint32_t key2; +}; + +struct DECRYPTION_DATA decryptor; + +void initDecryptor(uint32_t key0, uint32_t key1, uint32_t key2) { + decryptor.key0 = key0; + decryptor.key1 = key1; + decryptor.key2 = key2; +} /** Decrypts the given input in-place. The input buffer will be modified. */ void decrypt(unsigned char chunk[], unsigned long length) { - //... + for (unsigned long i = 0; i < length; i += 1) { + unsigned char testChar = chunk[i]; + testChar = testChar ^ decryptByte((uint16_t)(decryptor.key2 | 2)); + updateKeys(&(decryptor.key0), &(decryptor.key1), &(decryptor.key2), testChar); + chunk[i] = testChar; + } } diff --git a/src/decrypt.h b/src/decrypt.h index b368470..afc3529 100644 --- a/src/decrypt.h +++ b/src/decrypt.h @@ -1,4 +1,8 @@ #pragma once +#include + +void initDecryptor(uint32_t key0, uint32_t key1, uint32_t key2); + /** Decrypts the given input in-place. The input buffer will be modified. */ void decrypt(unsigned char chunk[], unsigned long length); diff --git a/src/main.c b/src/main.c index 0803815..4d49883 100644 --- a/src/main.c +++ b/src/main.c @@ -5,9 +5,11 @@ //Import our code #include "decrypt.h" #include "fileReader.h" +#include "utils/min.h" int main(int argc, unsigned char *argv[]) { printf("Hello World!\n"); + //TODO: verify argv and assign it to variables //Initialise file reader initFileReader("1234", 0UL); @@ -15,14 +17,30 @@ int main(int argc, unsigned char *argv[]) { //Skip header (30 bytes + additional length) char* fileHeader = getBytes(30UL); printf(fileHeader); + //TODO: check that header is correct //Initialise decryption (pass decryption keys) + initDecryptor(0, 0, 0);//TODO //Skip 12-byte encryption header + char* encryptionHeader = getBytes(12UL); + decrypt(encryptionHeader, 12); - //Decompress file + //Read actual file + unsigned long remainingBytes = 0xFFFF;//TODO + while (remainingBytes > 0) { + const unsigned long chunkSize = min(0xFF, remainingBytes); + char* chunk = getBytes(chunkSize); + remainingBytes -= chunkSize; - //Optionally perform xdelta3 + decrypt(chunk, chunkSize); + + //Decompress file + //TODO + + //Optionally perform xdelta3 + //TODO + } return 0; } diff --git a/src/utils/decryptUtilities.c b/src/utils/decryptUtilities.c new file mode 100644 index 0000000..19c8117 --- /dev/null +++ b/src/utils/decryptUtilities.c @@ -0,0 +1,61 @@ +#include "decryptUtilities.h" + +static uint32_t crc32_tab[] = { + 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, + 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, + 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, + 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, + 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, + 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, + 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c, + 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, + 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, + 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, + 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, + 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, + 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, + 0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, + 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, + 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, + 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, + 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, + 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, + 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, + 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, + 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, + 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, + 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, + 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, + 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, + 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, + 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, + 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, + 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, + 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28, + 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, + 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, + 0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, + 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, + 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, + 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, + 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, + 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, + 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, + 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, + 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, + 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d +}; + +uint32_t getCrc(uint32_t old_crc, unsigned char c) { +return (old_crc >> 8) ^ crc32_tab[(old_crc & 0xffU) ^ c]; +} + +void updateKeys(uint32_t *key_0, uint32_t *key_1, uint32_t *key_2, unsigned char c) { + *key_0 = getCrc(*key_0, c); + *key_1 = ((*key_1) + ((*key_0) & (uint32_t)0xffU)) * ((uint32_t)134775813U) + ((uint32_t)1U); + *key_2 = getCrc(*key_2, (*key_1) >> 24); +} + +unsigned char decryptByte(uint16_t keyPart) { + return (keyPart * (keyPart ^ 1)) >> 8; +} diff --git a/src/utils/decryptUtilities.h b/src/utils/decryptUtilities.h new file mode 100644 index 0000000..bac8be9 --- /dev/null +++ b/src/utils/decryptUtilities.h @@ -0,0 +1,9 @@ +#pragma once + +#include + +uint32_t getCrc(uint32_t old_crc, unsigned char c); + +void updateKeys(uint32_t *key_0, uint32_t *key_1, uint32_t *key_2, unsigned char c); + +unsigned char decryptByte(unsigned short keyPart);