我需要重写一个对加密文件进行解密的 Java 方法，该文件使用 AESCrypt ( http://www.aescrypt.com ) 加密。该程序使用自定义文件格式 (.aes)，需要以自定义方式处理。就像我说的那样，已经有一个 Java 方法。到目前为止，我完成了部分方法的重写，并且到目前为止它可以工作。但我被困在某个时刻。我找不到和 的等价IvParameterSpec物SecretKeySpec。
请参阅 Java 方法和我已完成的部分。如果你们能告诉我如何继续使用该方法，那就太好了。
PS。不用担心参数，因为 Java 使用 InputStream 和 OutputStream，我使用 NSFileHandle 和 NSOutputStream。
谢谢。
public void decrypt(long inSize, InputStream in, OutputStream out)
throws IOException, GeneralSecurityException {
try {
byte[] text = null, backup = null;
long total = 3 + 1 + 1 + BLOCK_SIZE + BLOCK_SIZE + KEY_SIZE + SHA_SIZE + 1 + SHA_SIZE;
int version;
text = new byte[3];
readBytes(in, text); // Heading.
if (!new String(text, "UTF-8").equals("AES")) {
throw new IOException("Invalid file header");
}
version = in.read(); // Version.
if (version < 1 || version > 2) {
throw new IOException("Unsupported version number: " + version);
}
debug("Version: " + version);
in.read(); // Reserved.
if (version == 2) { // Extensions.
text = new byte[2];
int len;
do {
readBytes(in, text);
len = ((0xff & (int) text[0]) << 8) | (0xff & (int) text[1]);
if (in.skip(len) != len) {
throw new IOException("Unexpected end of extension");
}
total += 2 + len;
debug("Skipped extension sized: " + len);
} while (len != 0);
}
text = new byte[BLOCK_SIZE];
readBytes(in, text); // Initialization Vector.
ivSpec1 = new IvParameterSpec(text);
aesKey1 = new SecretKeySpec(generateAESKey1(ivSpec1.getIV(), password), CRYPT_ALG);
debug("IV1: ", ivSpec1.getIV());
debug("AES1: ", aesKey1.getEncoded());
cipher.init(Cipher.DECRYPT_MODE, aesKey1, ivSpec1);
backup = new byte[BLOCK_SIZE + KEY_SIZE];
readBytes(in, backup); // IV and key to decrypt file contents.
debug("IV2 + AES2 ciphertext: ", backup);
text = cipher.doFinal(backup);
ivSpec2 = new IvParameterSpec(text, 0, BLOCK_SIZE);
aesKey2 = new SecretKeySpec(text, BLOCK_SIZE, KEY_SIZE, CRYPT_ALG);
debug("IV2: ", ivSpec2.getIV());
debug("AES2: ", aesKey2.getEncoded());
hmac.init(new SecretKeySpec(aesKey1.getEncoded(), HMAC_ALG));
backup = hmac.doFinal(backup);
text = new byte[SHA_SIZE];
readBytes(in, text); // HMAC and authenticity test.
if (!Arrays.equals(backup, text)) {
throw new IOException("Message has been altered or password incorrect");
}
debug("HMAC1: ", text);
total = inSize - total; // Payload size.
if (total % BLOCK_SIZE != 0) {
throw new IOException("Input file is corrupt");
}
if (total == 0) { // Hack: empty files won't enter block-processing for-loop below.
in.read(); // Skip last block size mod 16.
}
debug("Payload size: " + total);
cipher.init(Cipher.DECRYPT_MODE, aesKey2, ivSpec2);
hmac.init(new SecretKeySpec(aesKey2.getEncoded(), HMAC_ALG));
backup = new byte[BLOCK_SIZE];
text = new byte[BLOCK_SIZE];
for (int block = (int) (total / BLOCK_SIZE); block > 0; block--) {
int len = BLOCK_SIZE;
if (in.read(backup, 0, len) != len) { // Cyphertext block.
throw new IOException("Unexpected end of file contents");
}
cipher.update(backup, 0, len, text);
hmac.update(backup, 0, len);
if (block == 1) {
int last = in.read(); // Last block size mod 16.
debug("Last block size mod 16: " + last);
len = (last > 0 ? last : BLOCK_SIZE);
}
out.write(text, 0, len);
}
out.write(cipher.doFinal());
backup = hmac.doFinal();
text = new byte[SHA_SIZE];
readBytes(in, text); // HMAC and authenticity test.
if (!Arrays.equals(backup, text)) {
throw new IOException("Message has been altered or password incorrect");
}
debug("HMAC2: ", text);
} catch (InvalidKeyException e) {
throw new GeneralSecurityException(JCE_EXCEPTION_MESSAGE, e);
}
}
到目前为止的 ObjC 方法：
- (void)decrypt:(unsigned long long)filesize in:(NSFileHandle *)in out:(NSOutputStream *)out {
long total = 3 + 1 + 1 + BLOCK_SIZE + BLOCK_SIZE + KEY_SIZE + SHA_SIZE + 1 + SHA_SIZE;
int version;
int byteCounter = 0;
NSData *buffer = nil;
buffer = [in readDataOfLength:total];
NSData *headerData = [self getSubDataFrom:byteCounter To:3 withData:buffer];
byteCounter += 3;
NSString *text = [[NSString alloc] initWithData:headerData encoding:NSUTF8StringEncoding];
NSLog(@"header: %@", text);
if(![text isEqualToString:@"AES"]) {
NSLog(@"Invalid file header!");
return;
}
NSData *verData = [self getSubDataFrom:byteCounter To:1 withData:buffer];
version = [[self returnHexRepForData:verData] intValue];
byteCounter += 1;
NSLog(@"version: %d", version);
if(version < 1 || version > 2) {
NSLog(@"Unsupported version number: %d", version);
return;
}
if(version == 2) {
int len = 0;
do {
NSData *ext1 = [self getSubDataFrom:byteCounter To:1 withData:buffer];
int ext1byte = [[self returnHexRepForData:ext1] intValue];
byteCounter++;
NSData *ext2 = [self getSubDataFrom:byteCounter To:1 withData:buffer];
int ext2byte = [[self returnHexRepForData:ext2] intValue];
byteCounter++;
len = ((0xff & (int) ext1byte) << 8) | (0xff & (int) ext2byte);
total += 2 + len;
NSLog(@"Skipped extension sized: %d",len);
} while (len != 0);
}
uint8_t iv[BLOCK_SIZE];
memset((void *) iv, 0x0, (size_t) sizeof(iv));
}