Remedy Archive System
From Just Solve the File Format Problem
(Difference between revisions)
RavuAlHemio (Talk | contribs) m (→Format details: LE) |
RavuAlHemio (Talk | contribs) m (translate description to C due to range of int32_t) |
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<pre> | <pre> | ||
| − | + | void decrypt(uint8_t *buf, size_t count, int32_t key) { | |
| − | if key == 0 | + | size_t i; |
| − | key | + | uint8_t a; |
| − | + | uint8_t b; | |
| − | for i | + | |
| − | a | + | if (key == 0) { |
| − | b | + | key = 1; |
| − | + | } | |
| − | + | for (i = 0; i < count; i++) { | |
| − | + | uint8_t a = buf[i]; | |
| − | + | uint8_t b = ((uint8_t)(i % 5)) & 7; | |
| − | + | buf[i] = rotateLeftByte(a, b); | |
| − | + | key = key * 171 + (key / 177) * -30269; | |
| − | + | buf[i] = (((((uint8_t)i) + 3) * 6) ^ buf[i]) + ((uint8_t)key); | |
| − | + | } | |
| − | + | } | |
| − | + | ||
| − | + | ||
| − | + | ||
</pre> | </pre> | ||
| − | If your programming language doesn't support the <code> | + | If your programming language doesn't support the <code>rotateLeftByte</code> operation, it can be emulated using: |
<pre> | <pre> | ||
| − | + | uint8_t rotateLeftByte(uint8_t a, uint8_t b) { | |
| − | return ( | + | return (a << b) | (a >> (8 - b)); |
| + | } | ||
</pre> | </pre> | ||
[[Category:Remedy Entertainment]] | [[Category:Remedy Entertainment]] | ||
Revision as of 16:12, 21 November 2025
Remedy Archive System is used to store game data for Remedy Entertainment games such as Max Payne and Max Payne 2. The metadata (central directory) following the header is encrypted.
Contents |
Identification
Files begin with signature bytes 52 41 53 00.
Format details
Numbers are in little-endian byte order.
The file's header has the following structure:
struct RASHeader {
uint8_t magic[4]; // "RAS\0"
uint32_t encryptionKey;
};
The next section of the header must be decrypted first:
// decrypted structure
struct RASMetadata {
};
Encryption
Depending on the generation of the RAS file format, different encryption schemes are used.
RAS1 (Max Payne)
void decrypt(uint8_t *buf, size_t count, int32_t key) {
size_t i;
uint8_t a;
uint8_t b;
if (key == 0) {
key = 1;
}
for (i = 0; i < count; i++) {
uint8_t a = buf[i];
uint8_t b = ((uint8_t)(i % 5)) & 7;
buf[i] = rotateLeftByte(a, b);
key = key * 171 + (key / 177) * -30269;
buf[i] = (((((uint8_t)i) + 3) * 6) ^ buf[i]) + ((uint8_t)key);
}
}
If your programming language doesn't support the rotateLeftByte operation, it can be emulated using:
uint8_t rotateLeftByte(uint8_t a, uint8_t b) {
return (a << b) | (a >> (8 - b));
}
