在PHP中加密，在IOS中解密

Question

I'm trying to figure out how to send encrypted data to my IOS app from a web page.

In php I have a page that encrypts a string and then echos it out as a base64 encoded string:

<?php
    function encode($json, $key, $iv){
        echo base64_encode($iv . "::" . openssl_encrypt ($json, 'AES-256-CTR', $key, OPENSSL_RAW_DATA, $iv));
    }

    $key = substr(sha1("super awesome key goes here", true), 0, 16);
    $iv = openssl_random_pseudo_bytes(16);
    $table = array("key1"=>"value1", "key2"=>"value2");
    $json = json_encode($table);

    encode($json, $key, $iv);
?>

I am able to take that echoed string and decode it in PHP just fine.

In IOS I have a function that opens that page and grabs the encoded string:

-(IBAction)fetchData:(id)sender{
    // Fetch data
    NSURL *url = [NSURL URLWithString: @"https://www.website.com/dataupdate.php"];

    NSURLSessionConfiguration *defaultConfigObject = [NSURLSessionConfiguration defaultSessionConfiguration];
    NSURLSession *defaultSession = [NSURLSession sessionWithConfiguration: defaultConfigObject delegate:nil  delegateQueue:[NSOperationQueue mainQueue]];
    NSMutableURLRequest *urlRequest = [NSMutableURLRequest requestWithURL:url];
    NSString *params = @"";
    [urlRequest setHTTPMethod:@"POST"];
    [urlRequest setHTTPBody:[params dataUsingEncoding:NSUTF8StringEncoding]];

    NSURLSessionDataTask *dataTask = [defaultSession dataTaskWithRequest: urlRequest completionHandler:^(NSData *data, NSURLResponse *response, NSError *error){
        NSLog(@"response: %@ %@
",response, error);
        if(error == nil){
            NSString *text = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
            NSLog(@"Data = %@", text);

            NSData *decodedData = [[NSData alloc] initWithBase64EncodedString: text options:0];
            // Fails here
            NSString *decodedString = [[NSString alloc] initWithData:decodedData encoding:NSUTF8StringEncoding];
            NSLog(@"64 Decoded: %@",decodedString);
        }
    }];
    [dataTask resume];
}

I'm assuming it's failing because of the encoding:NSUTF8StringEncoding part, but I'm not sure what to do about that. I did try encoding:NSUTF32StringEncoding but didn't fare much better.

The PHP encrypting line has OPENSSL_RAW_DATA as an option, but I have not yet found anywhere that tells what encoding RAW data is...

EDIT:

This is what I get for trying to squeeze the question out while rushing to head home...

openssl_encrypt ($json, 'AES-256-CTR', $key, OPENSSL_RAW_DATA, $iv)
returns this: ��.�m� �#6��:�ĕO;֧ ª�0`")�-�

And after I base64 encode it with the IV I get this:
INI70ZBDUjYouoGlSIFGbzo6v6Eu320Hyg2pIzaOCIw6zMSVTzvWpyDCqr0wYCIpmy2P

On the IOS side, I can use NSString *text = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; to send the base62 string into the text variable

But when I use [[NSString alloc] initWithData:decodedData encoding:NSUTF8StringEncoding]; to turn the base64 string into the openssl_encrypt string, it just returns nil

After I get get it to return a value then I can work on the actual decryption. I'm just trying to figure out one step at a time.

EDIT: Trying again...

So, playing around with it, I think I'm missing something vital...

    if(error == nil){
        NSString *key = @"05nszDCobKjjavWBfG/ZcC/A4DQ=";
        NSString *text = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
        NSArray *items = [text componentsSeparatedByString:@"::"];
        NSString *iv = [items objectAtIndex:0];
        NSString *msg = [items objectAtIndex:1];
        NSLog(@"


 IV = %@ 


 Data = %@", iv, msg);

        NSData *decodedKey = [[NSData alloc] initWithBase64EncodedString:key options:0];
        NSData *decodedIV = [[NSData alloc] initWithBase64EncodedString: iv options:0];
        NSData *decodedMsg = [[NSData alloc] initWithBase64EncodedString: msg options:0];
        NSLog(@"


 DecodedKey = %@ 


 DecodedIV = %@ 


 DecodedData = %@", decodedKey, decodedIV, decodedMsg);

        NSString *hexKey = NSDataToHex(decodedKey);
        NSString *hexIV = NSDataToHex(decodedIV);
        NSString *hexMsg = NSDataToHex(decodedMsg);
        NSLog(@"


 HexKey = %@ 


 HexIV = %@ 


 HexData = %@", hexKey, hexIV, hexMsg);

        CkoCrypt2 *decrypt = [[CkoCrypt2 alloc] init];

        decrypt.CryptAlgorithm = @"aes";
        decrypt.CipherMode = @"ctr";
        decrypt.KeyLength = [NSNumber numberWithInt: 256];
        decrypt.EncodingMode = @"hex";
        [decrypt SetEncodedIV:hexIV encoding:@"hex"];
        [decrypt SetEncodedKey:hexKey encoding:@"hex"];

        NSString *decryptedStringHex = [decrypt DecryptEncoded:hexMsg];

        NSData *decryptedData = [decrypt DecryptBytes:decodedMsg];
        NSString *decryptedStringData = [[NSString alloc] initWithData:decryptedData encoding:NSUTF8StringEncoding];
        NSLog(@"decoded and decrypted Hex: %@ /n/nData: %@",decryptedStringHex, decryptedStringData);

    }

And then for my Data to hex:

static inline char itoh(int i){
    if (i > 9) return 'A' + (i - 10);
    return '0' + i;
}

NSString * NSDataToHex(NSData *data) {
    NSUInteger i, len;
    unsigned char *buf, *bytes;

    len = data.length;
    bytes = (unsigned char*)data.bytes;
    buf = malloc(len*2);

    for (i=0; i<len; i++){
        buf[i*2] = itoh((bytes[i] >> 4) & 0xF);
        buf[i*2+1] = itoh(bytes[i] & 0xF);
    }

    return [[NSString alloc] initWithBytesNoCopy:buf length:len*2 encoding:NSASCIIStringEncoding freeWhenDone:YES];
}

NSString *decryptedString = [decrypt DecryptEncoded:hexMsg]; returns nil.

`NSData *decryptedData = [decrypt DecryptBytes:decodedMsg]; NSString *decryptedString = [[NSString alloc] initWithData:decryptedData encoding:NSUTF8StringEncoding];' Also returns nil.

Here is my log:

2017-03-24 13:20:26.222 GWM[47000:3317901]

IV = xiiRvStJen2M2VrUuavHZg==

Data = c4Okkz+MCpdSX935O6nNudoJ0ud+oS4sz9GbPFMDsCL5+yJaQ0mzJckP7S6Q/oE=

2017-03-24 13:49:40.548 GWM[47283:3332493]

DecodedKey =

DecodedIV =

DecodedData = <7383a493 3f8c0a97 525fddf9 3ba9cdb9 da09d2e7 7ea12e2c cfd19b3c 5303b022 f9fb225a 4349b325 c90fed2e 90fe81

2017-03-24 13:49:40.548 GWM[47283:3332493]

HexKey = D399ECCC30A86CA8E36AF5817C6FD9702FC0E034

HexIV = C62891BD2B497A7D8CD95AD4B9ABC766

HexData = 7383A4933F8C0A97525FDDF93BA9CDB9DA09D2E77EA12E2CCFD19B3C5303B022F9FB225A4349B325C90FED2E90FE81

2017-03-24 13:49:49.779 GWM[47283:3332493] decoded and decrypted

Hex: (null)

Data:

Answer 1

I ended up getting this to work using RNCryptor because it has versions for both IOS and PHP, and even Android for down the road. This way I don't have to try to work around different methods on each platform.

PHP:

$table = array("first"=>"First Value", "second"=>"Second value");

$json = json_encode($table);

$password = "my super awesome password";
$cryptor = new \RNCryptor\RNCryptor\Encryptor;
$base64Encrypted = $cryptor->encrypt($json, $password);
echo $base64Encrypted;

XCode:

NSURL *url = [NSURL URLWithString:@"https://www.website.com/dataupdate.php"];
NSData *encryptedData = [[NSData alloc] initWithBase64EncodedString: [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:nil] options:0];

NSString *password = @"my super awesome password";
NSError *error = nil;
NSData *decryptedData = [RNDecryptor decryptData: encryptedData withPassword:password error:&error];

self.jsonList = [NSJSONSerialization JSONObjectWithData:decryptedData options:NSJSONReadingMutableContainers error:&error];