PBEWithMD5AndDES Encryption in iOS

Question

I'm having an issue with PBEWithMD5AndDES encryption in iOS. I've got my strings encrypting and decrypting using this, https://gist.github.com/788840/24bc73ecd0ac3134cbd242892c74a06ac561d37b.

The problem is I get different encrypted values depending on which class my methods are in. For example, I moved all the encryption methods into a helper class and ran it. I noticed I was getting a different encrypted value.

I now have two identical versions of the same method in different classes and I'm running them side by side. They get different encrypted values, and one cannot decrypt the others'. I'm kind of stumped on this.

Here's the helper class that does encryption/decryption.

@implementation CryptoHelper

#pragma mark -
#pragma mark Init Methods
- (id)init
{
    if(self = [super init])
    {

    }
    return self;
}

#pragma mark -
#pragma mark String Specific Methods

/** 
 *  Encrypts a string for social blast service. 
 *  
 *  @param  plainString The string to encrypt;
 *
 *  @return NSString    The encrypted string. 
 */
- (NSString *)encryptString: (NSString *) plainString{

    // Convert string to data and encrypt
    NSData *data = [self encryptPBEWithMD5AndDESData:[plainString dataUsingEncoding:NSUTF8StringEncoding] password:@"1111"];



    // Get encrypted string from data
    return [data base64EncodingWithLineLength:1024];

}


/** 
 *  Descrypts a string from social blast service. 
 *  
 *  @param  plainString The string to decrypt;
 *
 *  @return NSString    The decrypted string. 
 */
- (NSString *)decryptString: (NSString *) encryptedString{

    // decrypt the data
    NSData * data = [self decryptPBEWithMD5AndDESData:[NSData dataWithBase64EncodedString:encryptedString] password:@"1111"];

    // extract and return string
    return [NSString stringWithUTF8String:[data bytes]];

}


#pragma mark -
#pragma mark Crypto Methods

- (NSData *)encryptPBEWithMD5AndDESData:(NSData *)inData password:(NSString *)password {
    return [self encodePBEWithMD5AndDESData:inData password:password direction:1];
}

- (NSData *)decryptPBEWithMD5AndDESData:(NSData *)inData password:(NSString *)password {
    return [self encodePBEWithMD5AndDESData:inData password:password direction:0];
}

- (NSData *)encodePBEWithMD5AndDESData:(NSData *)inData password:(NSString *)password direction:(int)direction
{
    NSLog(@"helper data = %@", inData);

    static const char gSalt[] =
    {
        (unsigned char)0xAA, (unsigned char)0xAA, (unsigned char)0xAA, (unsigned char)0xAA,
        (unsigned char)0xAA, (unsigned char)0xAA, (unsigned char)0xAA, (unsigned char)0xAA
    };

    unsigned char *salt = (unsigned char *)gSalt;
    int saltLen = strlen(gSalt);
    int iterations = 15;

    EVP_CIPHER_CTX cipherCtx;


    unsigned char *mResults; // allocated storage of results
    int mResultsLen = 0;

    const char *cPassword = [password UTF8String];

    unsigned char *mData = (unsigned char *)[inData bytes];
    int mDataLen = [inData length];


    SSLeay_add_all_algorithms();
    /*X509_ALGOR *algorithm = PKCS5_pbe_set(NID_pbeWithMD5AndDES_CBC,
                                          iterations, salt, saltLen);*/
        const EVP_CIPHER *cipher = EVP_des_cbc();

    // Need to set with iv
    X509_ALGOR *algorithm = PKCS5_pbe2_set_iv(cipher, iterations, 
                                          salt, saltLen, salt, NID_hmacWithMD5);


    memset(&cipherCtx, 0, sizeof(cipherCtx));

    if (algorithm != NULL)
    {
        EVP_CIPHER_CTX_init(&(cipherCtx));



        if (EVP_PBE_CipherInit(algorithm->algorithm, cPassword, strlen(cPassword),
                               algorithm->parameter, &(cipherCtx), direction))
        {

            EVP_CIPHER_CTX_set_padding(&cipherCtx, 1);

            int blockSize = EVP_CIPHER_CTX_block_size(&cipherCtx);
            int allocLen = mDataLen + blockSize + 1; // plus 1 for null terminator on decrypt
            mResults = (unsigned char *)OPENSSL_malloc(allocLen);


            unsigned char *in_bytes = mData;
            int inLen = mDataLen;
            unsigned char *out_bytes = mResults;
            int outLen = 0;



            int outLenPart1 = 0;
            if (EVP_CipherUpdate(&(cipherCtx), out_bytes, &outLenPart1, in_bytes, inLen))
            {
                out_bytes += outLenPart1;
                int outLenPart2 = 0;
                if (EVP_CipherFinal(&(cipherCtx), out_bytes, &outLenPart2))
                {
                    outLen += outLenPart1 + outLenPart2;
                    mResults[outLen] = 0;
                    mResultsLen = outLen;
                }
            } else {
                unsigned long err = ERR_get_error();

                ERR_load_crypto_strings();
                ERR_load_ERR_strings();
                char errbuff[256];
                errbuff[0] = 0;
                ERR_error_string_n(err, errbuff, sizeof(errbuff));
                NSLog(@"OpenSLL ERROR:\n\tlib:%s\n\tfunction:%s\n\treason:%s\n",
                      ERR_lib_error_string(err),
                      ERR_func_error_string(err),
                      ERR_reason_error_string(err));
                ERR_free_strings();
            }


            NSData *encryptedData = [NSData dataWithBytes:mResults length:mResultsLen]; //(NSData *)encr_buf;


            //NSLog(@"encryption result: %@\n", [encryptedData base64EncodingWithLineLength:1024]);

            EVP_cleanup();

            return encryptedData;
        }
    }
    EVP_cleanup();
    return nil;

}

@end

I'm trying to duplicate the results of this java function. I have the same salt.

public DesEncrypter(String passPhrase) {
    try {
        // Create the key
        KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt, iterationCount);
        SecretKey key = SecretKeyFactory.getInstance(
            "PBEWithMD5AndDES").generateSecret(keySpec);
        ecipher = Cipher.getInstance(key.getAlgorithm());
        dcipher = Cipher.getInstance(key.getAlgorithm());

        // Prepare the parameter to the ciphers
        AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);

        // Create the ciphers
        ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
        dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
    } catch (java.security.InvalidAlgorithmParameterException e) {
    } catch (java.security.spec.InvalidKeySpecException e) {
    } catch (javax.crypto.NoSuchPaddingException e) {
    } catch (java.security.NoSuchAlgorithmException e) {
    } catch (java.security.InvalidKeyException e) {
    }
}

Answer 1

By the way I am able to get it working with Swift. Only issue I am facing is I am getting a Data object from the objective C module, but when I try to convert to String, it gives me nil. here is the code. Please let me know what is that I am doing wrong here

static func encrypt(inString: String) -> String? {

    let passwordStr = "blablalba"
    let iterations:Int32 = 19
    let salt = [0x44,  0x44,  0x22,  0x22,  0x56,  0x35,  0xE3, 0x03] as [UInt8]
    let operation: CCOperation = UInt32(kCCEncrypt)
    let saltData = NSData(bytes: salt, length: salt.count)

    let out = CryptoHelper.cryptPBE(withMD5AndDES: operation, using: inString.data(using: .utf8), withPassword: passwordStr, andSalt: saltData as Data, andIterating: iterations) as Data

    let outString = String.init(data: out, encoding: .utf8)

    return outString
}

Answer 2

I want to thank wbyoung. His answer helped me solve the mystery for how to encrypt Data from iOS and have it decrypted from Java. Below are the additions I made to his Code.

The trick is to take the salt used to encrypt the Data, and prepend it to the result. Java will then be able to decrypt it.

@implementation NSData (PBEEncryption)

- (NSData *)encryptPBEWithMD5AndDESUsingPassword:(NSData *)password {
    unsigned char gSalt[] =
    {
        (unsigned char)0x18, (unsigned char)0x79, (unsigned char)0x6D, (unsigned char)0x6D,
        (unsigned char)0x35, (unsigned char)0x3A, (unsigned char)0x6A, (unsigned char)0x60,
        (unsigned char)0x00
    };

    NSData *salt = nil;
    salt = [NSData dataWithBytes:gSalt length:strlen(gSalt)];

    NSData* encrypted = [self encryptPBEWithMD5AndDESUsingPassword:password salt:salt iterations:1000];
    NSMutableData* result = [NSMutableData dataWithData:salt];
    [result appendData:encrypted];
    return [NSData dataWithData:result];

}

- (NSData *)encryptPBEWithMD5AndDESUsingPassword:(NSData *)password salt:(NSData *)salt iterations:(NSUInteger)iterations {
    unsigned char md5[CC_MD5_DIGEST_LENGTH] = {};

    CC_MD5_CTX ctx;
    CC_MD5_Init(&ctx);
    CC_MD5_Update(&ctx, [password bytes], [password length]);
    CC_MD5_Update(&ctx, [salt bytes], [salt length]);
    CC_MD5_Final(md5, &ctx);

    for (NSUInteger i = 1; i < iterations; i++) {
        CC_MD5(md5, CC_MD5_DIGEST_LENGTH, md5);
    }

    // initialization vector is the second half of the MD5 from building the key
    unsigned char iv[kCCBlockSizeDES];
    assert(kCCBlockSizeDES == CC_MD5_DIGEST_LENGTH / 2);
    memcpy(iv, md5 + kCCBlockSizeDES, sizeof(iv));

    NSMutableData *output = [NSMutableData dataWithLength:([self length] + kCCBlockSize3DES)];
    size_t outputLength = 0;
    CCCryptorStatus status =
    CCCrypt(kCCEncrypt, kCCAlgorithmDES, kCCOptionPKCS7Padding, md5, kCCBlockSizeDES, iv,
            [self bytes], [self length], [output mutableBytes], [output length], &outputLength);

    if (status == kCCSuccess) { [output setLength:outputLength]; }
    else { output = nil; }

    return output;
}


@end

The Corresponding Swift Code to Encrypt a String:

static func encryptForOverTheWire(string: String) -> String {
    let stringData = string.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)
    let passwordData = PASSWORD.dataUsingEncoding(NSUTF8StringEncoding)
    let encryptedData = stringData?.encryptPBEWithMD5AndDESUsingPassword(passwordData)
    let base64 = encryptedData?.base64EncodedDataWithOptions(NSDataBase64EncodingOptions())

    guard base64 != nil else { return "" }

    let result = String(data: base64!, encoding: NSUTF8StringEncoding)
    return result ?? ""
}

Answer 3

Using johwayner's response, I fixed this up a little for my purposes of decrypting Java's PBEWithMD5AndDES from jasypt. Here's what I ended up with:

@interface NSData (PBEEncryption)

/**
 * Decrypt the receiver using PKCS#5 PBE with MD5 and DES assuming that the salt is prefixed into the first 8 bytes of
 * the data and the number of key obtention iterations is 1000. This is compatible with Java's PBEWithMD5AndDES
 * encryption when the encryption generates a random salt for the data (the default when providing no salt).
 */
- (NSData *)decrytpPBEWithMD5AndDESUsingPassword:(NSData *)password;

/**
 * Decrypt the receiver using PKCS#5 PBE with MD5 and DES. Explicitly provide the salt and number of key obtention
 * iterations.
 */
- (NSData *)decrytpPBEWithMD5AndDESUsingPassword:(NSData *)password salt:(NSData *)salt iterations:(NSUInteger)iterations;

@end


@implementation NSData (PBEEncryption)

- (NSData *)decrytpPBEWithMD5AndDESUsingPassword:(NSData *)password {
    NSData *salt = nil;
    NSData *input = self;
    if ([input length] > 8) {
        salt = [input subdataWithRange:NSMakeRange(0, 8)];
        input = [input subdataWithRange:NSMakeRange(8, [input length] - 8)];
    }
    return [input decrytpPBEWithMD5AndDESUsingPassword:password salt:salt iterations:1000];
}

- (NSData *)decrytpPBEWithMD5AndDESUsingPassword:(NSData *)password salt:(NSData *)salt iterations:(NSUInteger)iterations {
    unsigned char md5[CC_MD5_DIGEST_LENGTH] = {};

    CC_MD5_CTX ctx;
    CC_MD5_Init(&ctx);
    CC_MD5_Update(&ctx, [password bytes], [password length]);
    CC_MD5_Update(&ctx, [salt bytes], [salt length]);
    CC_MD5_Final(md5, &ctx);

    for (NSUInteger i = 1; i < iterations; i++) {
        CC_MD5(md5, CC_MD5_DIGEST_LENGTH, md5);
    }

    // initialization vector is the second half of the MD5 from building the key
    unsigned char iv[kCCBlockSizeDES];
    assert(kCCBlockSizeDES == CC_MD5_DIGEST_LENGTH / 2);
    memcpy(iv, md5 + kCCBlockSizeDES, sizeof(iv));

    NSMutableData *output = [NSMutableData dataWithLength:([self length] + kCCBlockSize3DES)];
    size_t outputLength = 0;
    CCCryptorStatus status =
        CCCrypt(kCCDecrypt, kCCAlgorithmDES, kCCOptionPKCS7Padding, md5, kCCBlockSizeDES, iv,
                [self bytes], [self length], [output mutableBytes], [output length], &outputLength);

    if (status == kCCSuccess) { [output setLength:outputLength]; }
    else { output = nil; }

    return output;
}

@end

Use like so:

NSString *password = @"myTopSecretPassword";
NSData *inputData = [NSData dataFromBase64String:@"base64string"];
NSData *outputData = [inputData decrytpPBEWithMD5AndDESUsingPassword:
                      [password dataUsingEncoding:NSUTF8StringEncoding]];

Answer 4

The accepted answer appears to use OpenSSL which is not included in the iOS SDK. Here is an encrypting and decrypting solution that uses the included CommonCrypto library (in libSystem). I'm a bit of an ObjC n00b, so take this code with a grain of salt. By the way, this code will successfully decrypt data encrypted using java's PBEWithMD5AndDES cipher. Hopefully this will save a day or two for someone else.

#include <CommonCrypto/CommonDigest.h>
#include <CommonCrypto/CommonCryptor.h>


+(NSData*) cryptPBEWithMD5AndDES:(CCOperation)op usingData:(NSData*)data withPassword:(NSString*)password andSalt:(NSData*)salt andIterating:(int)numIterations {
    unsigned char md5[CC_MD5_DIGEST_LENGTH];
    memset(md5, 0, CC_MD5_DIGEST_LENGTH);
    NSData* passwordData = [password dataUsingEncoding:NSUTF8StringEncoding];

    CC_MD5_CTX ctx;
    CC_MD5_Init(&ctx);
    CC_MD5_Update(&ctx, [passwordData bytes], [passwordData length]);
    CC_MD5_Update(&ctx, [salt bytes], [salt length]);
    CC_MD5_Final(md5, &ctx);

    for (int i=1; i<numIterations; i++) {
        CC_MD5(md5, CC_MD5_DIGEST_LENGTH, md5);
    }

    size_t cryptoResultDataBufferSize = [data length] + kCCBlockSizeDES;
    unsigned char cryptoResultDataBuffer[cryptoResultDataBufferSize];
    size_t dataMoved = 0;

    unsigned char iv[kCCBlockSizeDES];
    memcpy(iv, md5 + (CC_MD5_DIGEST_LENGTH/2), sizeof(iv)); //iv is the second half of the MD5 from building the key

    CCCryptorStatus status =
        CCCrypt(op, kCCAlgorithmDES, kCCOptionPKCS7Padding, md5, (CC_MD5_DIGEST_LENGTH/2), iv, [data bytes], [data length],
            cryptoResultDataBuffer, cryptoResultDataBufferSize, &dataMoved);

    if(0 == status) {
        return [NSData dataWithBytes:cryptoResultDataBuffer length:dataMoved];
    } else {
        return NULL;
    }
}

Answer 5

Not sure what the protocol is here for accepting answers/upvoting them. I apologize if I'm doing this wrong. The answer turned out to be the lack of a final byte in the salt. I actually didn't need the IV with the 3DES encryption. I upvoted the other answer because it was helpful in understanding more about encryption.

Here's the final objective c class.

@implementation CryptoHelper

#pragma mark -
#pragma mark Init Methods
- (id)init
{
    if(self = [super init])
    {

    }
    return self;
}

#pragma mark -
#pragma mark String Specific Methods

/** 
 *  Encrypts a string for social blast service. 
 *  
 *  @param  plainString The string to encrypt;
 *
 *  @return NSString    The encrypted string. 
 */
- (NSString *)encryptString: (NSString *) plainString{

    // Convert string to data and encrypt
    NSData *data = [self encryptPBEWithMD5AndDESData:[plainString dataUsingEncoding:NSUTF8StringEncoding] password:@"1111"];



    // Get encrypted string from data
    return [data base64EncodingWithLineLength:1024];

}


/** 
 *  Descrypts a string from social blast service. 
 *  
 *  @param  plainString The string to decrypt;
 *
 *  @return NSString    The decrypted string. 
 */
- (NSString *)decryptString: (NSString *) encryptedString{

    // decrypt the data
    NSData * data = [self decryptPBEWithMD5AndDESData:[NSData dataWithBase64EncodedString:encryptedString] password:@"1111"];

    // extract and return string
    return [NSString stringWithUTF8String:[data bytes]];

}


#pragma mark -
#pragma mark Crypto Methods

- (NSData *)encryptPBEWithMD5AndDESData:(NSData *)inData password:(NSString *)password {
    return [self encodePBEWithMD5AndDESData:inData password:password direction:1];
}

- (NSData *)decryptPBEWithMD5AndDESData:(NSData *)inData password:(NSString *)password {
    return [self encodePBEWithMD5AndDESData:inData password:password direction:0];
}

- (NSData *)encodePBEWithMD5AndDESData:(NSData *)inData password:(NSString *)password direction:(int)direction
{
    NSLog(@"helper data = %@", inData);

    static const char gSalt[] =
    {
        (unsigned char)0xAA, (unsigned char)0xAA, (unsigned char)0xAA, (unsigned char)0xAA,
        (unsigned char)0xAA, (unsigned char)0xAA, (unsigned char)0xAA, (unsigned char)0xAA,
        (unsigned char)0x00
    };

    unsigned char *salt = (unsigned char *)gSalt;
    int saltLen = strlen(gSalt);
    int iterations = 15;

    EVP_CIPHER_CTX cipherCtx;


    unsigned char *mResults; // allocated storage of results
    int mResultsLen = 0;

    const char *cPassword = [password UTF8String];

    unsigned char *mData = (unsigned char *)[inData bytes];
    int mDataLen = [inData length];


    SSLeay_add_all_algorithms();
    X509_ALGOR *algorithm = PKCS5_pbe_set(NID_pbeWithMD5AndDES_CBC,
                                          iterations, salt, saltLen);



    memset(&cipherCtx, 0, sizeof(cipherCtx));

    if (algorithm != NULL)
    {
        EVP_CIPHER_CTX_init(&(cipherCtx));



        if (EVP_PBE_CipherInit(algorithm->algorithm, cPassword, strlen(cPassword),
                               algorithm->parameter, &(cipherCtx), direction))
        {

            EVP_CIPHER_CTX_set_padding(&cipherCtx, 1);

            int blockSize = EVP_CIPHER_CTX_block_size(&cipherCtx);
            int allocLen = mDataLen + blockSize + 1; // plus 1 for null terminator on decrypt
            mResults = (unsigned char *)OPENSSL_malloc(allocLen);


            unsigned char *in_bytes = mData;
            int inLen = mDataLen;
            unsigned char *out_bytes = mResults;
            int outLen = 0;



            int outLenPart1 = 0;
            if (EVP_CipherUpdate(&(cipherCtx), out_bytes, &outLenPart1, in_bytes, inLen))
            {
                out_bytes += outLenPart1;
                int outLenPart2 = 0;
                if (EVP_CipherFinal(&(cipherCtx), out_bytes, &outLenPart2))
                {
                    outLen += outLenPart1 + outLenPart2;
                    mResults[outLen] = 0;
                    mResultsLen = outLen;
                }
            } else {
                unsigned long err = ERR_get_error();

                ERR_load_crypto_strings();
                ERR_load_ERR_strings();
                char errbuff[256];
                errbuff[0] = 0;
                ERR_error_string_n(err, errbuff, sizeof(errbuff));
                NSLog(@"OpenSLL ERROR:\n\tlib:%s\n\tfunction:%s\n\treason:%s\n",
                      ERR_lib_error_string(err),
                      ERR_func_error_string(err),
                      ERR_reason_error_string(err));
                ERR_free_strings();
            }


            NSData *encryptedData = [NSData dataWithBytes:mResults length:mResultsLen]; //(NSData *)encr_buf;


            //NSLog(@"encryption result: %@\n", [encryptedData base64EncodingWithLineLength:1024]);

            EVP_cleanup();

            return encryptedData;
        }
    }
    EVP_cleanup();
    return nil;

}

@end

Answer 6

The problem is that you are not specifying an IV for your encryption, this way a random number will automatically be generated for you, that's also the reason why you get a different result each time.

Try using PKCS5_pbe2_set_iv instead of PKCS5_pbe2_set providing an explicit IV value, that you may randomly choose, much like your salt value.