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MYCryptor.m
author snej@snej.local
Thu Apr 09 22:46:48 2009 -0700 (2009-04-09)
changeset 6 2d7692f9b6b4
parent 2 8982b8fada63
child 14 3af1d1c0ceb5
permissions -rw-r--r--
Updated the README for the 0.1 release. 
     1 //

     2 //  Cryptor.m

     3 //  MYCrypto

     4 //

     5 //  Created by Jens Alfke on 3/21/09.

     6 //  Copyright 2009 Jens Alfke. All rights reserved.

     7 //

     8 

     9 #import "MYCryptor.h"

    10 #import "MYDigest.h"

    11 #import "Test.h"

    12 

    13 #if MYCRYPTO_USE_IPHONE_API

    14 #import <Security/SecRandom.h>

    15 #else

    16 #import "MYCrypto_Private.h"

    17 #import "MYKeychain.h"

    18 #import <stdlib.h>

    19 #endif

    20 

    21 

    22 NSString* const CryptorErrorDomain = @"CCCryptor";

    23 

    24 #if !MYCRYPTO_USE_IPHONE_API

    25 static BOOL generateRandomBytes(CSSM_CSP_HANDLE module, uint32_t lengthInBytes, void *dstBytes);

    26 #endif

    27 

    28 

    29 @interface MYCryptor ()

    30 @property (readwrite, retain) NSError *error;

    31 @end

    32 

    33 

    34 

    35 @implementation MYCryptor

    36 

    37 

    38 + (NSData*) randomKeyOfLength: (size_t)lengthInBits {

    39     size_t lengthInBytes = (lengthInBits + 7)/8;

    40     NSParameterAssert(lengthInBytes<100000);

    41     uint8_t *bytes = malloc(lengthInBytes);

    42     if (!bytes) return nil;

    43 #if MYCRYPTO_USE_IPHONE_API

    44     BOOL ok = SecRandomCopyBytes(kSecRandomDefault, lengthInBytes,bytes) >= 0;

    45 #else

    46     BOOL ok = generateRandomBytes([[MYKeychain defaultKeychain] CSPHandle], lengthInBytes, bytes);

    47 #endif

    48     if (ok)

    49         return [NSData dataWithBytesNoCopy: bytes length: lengthInBytes freeWhenDone: YES];

    50     else {

    51         free(bytes);

    52         return nil;

    53     }

    54 }

    55 

    56 + (NSData*) keyOfLength: (size_t)lengthInBits

    57          fromPassphrase: (NSString*)passphrase

    58                    salt: (id)salt

    59 {

    60     // This follows algorithm PBKDF1 from PKCS#5 v2.0, with Hash=SHA-256 and c=13.

    61     Assert(passphrase);

    62     Assert(salt);

    63     passphrase = $sprintf(@"MYCrypto|%@|%@", passphrase, salt);

    64     size_t lengthInBytes = (lengthInBits + 7)/8;

    65     MYDigest *digest = [[passphrase dataUsingEncoding: NSUTF8StringEncoding] my_SHA256Digest];

    66     for (int i=0; i<12; i++)

    67         digest = digest.asData.my_SHA256Digest;

    68     if (lengthInBytes <= digest.length)

    69         return [digest.asData subdataWithRange: NSMakeRange(0,lengthInBytes)];

    70     else

    71         return nil;

    72 }

    73 

    74 

    75 - (id) initWithKey: (NSData*)key

    76          algorithm: (CCAlgorithm)algorithm

    77          operation: (CCOperation)op {

    78     self = [super init];

    79     if (self) {

    80         NSParameterAssert(key);

    81         _key = [key copy];

    82         _operation = op;

    83         _algorithm = algorithm;

    84         _options = kCCOptionPKCS7Padding;

    85     }

    86     return self;

    87 }

    88 

    89 - (id) initEncryptorWithKey: (NSData*)key algorithm: (CCAlgorithm)algorithm {

    90     return [self initWithKey: key algorithm: algorithm operation: kCCEncrypt];

    91 }

    92 

    93 - (id) initDecryptorWithKey: (NSData*)key algorithm: (CCAlgorithm)algorithm {

    94     return [self initWithKey: key algorithm: algorithm operation: kCCDecrypt];

    95 }

    96 

    97 - (void) dealloc

    98 {

    99     if (_cryptor)

   100         CCCryptorRelease(_cryptor);

   101     [_key autorelease];

   102     [_output autorelease];

   103     [_outputStream release];

   104     [super dealloc];

   105 }

   106 

   107 - (void) finalize

   108 {

   109     if (_cryptor)

   110         CCCryptorRelease(_cryptor);

   111     [super finalize];

   112 }

   113 

   114 

   115 @synthesize key=_key, algorithm=_algorithm, options=_options,

   116     outputStream=_outputStream, error=_error;

   117 

   118 

   119 - (BOOL) _check: (CCCryptorStatus)status {

   120     if (status == kCCSuccess)

   121         return YES;

   122     else {

   123         Warn(@"MYCryptor: CCCryptor error %i", status);

   124         self.error = [NSError errorWithDomain: CryptorErrorDomain code: status userInfo: nil];

   125         return NO;

   126     }

   127 }

   128 

   129 

   130 - (BOOL) _outputBytes: (const void*)bytes length: (size_t)length {

   131     if (_outputStream) {

   132         size_t written = [_outputStream write: bytes maxLength: length];

   133         if (written < 0) {

   134             self.error = _outputStream.streamError;

   135             if (_error)

   136                 Warn(@"MYCryptor: NSOutputStream error %@", _error);

   137             else

   138                 [self _check: kMYCryptorErrorOutputStreamChoked];

   139             return NO;

   140         } else if (written < length) {

   141             [self _check: kMYCryptorErrorOutputStreamChoked];

   142             return NO;

   143         }

   144     } else if (length > 0) {

   145         [_output appendBytes: bytes length: length];

   146     }

   147     return YES;

   148 }

   149 

   150 

   151 - (BOOL) _start {

   152     if (!_cryptor && !_error) {

   153         if ([self _check: CCCryptorCreate(_operation, _algorithm, _options,

   154                                           _key.bytes, _key.length, NULL, &_cryptor)]) {

   155             _output = [[NSMutableData alloc] initWithCapacity: 1024];

   156         }

   157     }

   158     return !_error;

   159 }

   160 

   161 

   162 - (BOOL) addBytes: (const void*)bytes length: (size_t)length {

   163     if (length > 0) {

   164         NSParameterAssert(bytes!=NULL);

   165         if(!_error && (_cryptor || [self _start])) {

   166             size_t outputLength = CCCryptorGetOutputLength(_cryptor,length,false);

   167             void *output = malloc(outputLength);

   168             if ([self _check: CCCryptorUpdate(_cryptor, bytes, length,

   169                                               output, outputLength, &outputLength)]) {

   170                 [self _outputBytes: output length: outputLength];

   171             }

   172             free(output);

   173         }

   174     }

   175     return !_error;

   176 }

   177 

   178 - (BOOL) addData: (NSData*)data

   179 {

   180     return [self addBytes: data.bytes length: data.length];

   181 }

   182 

   183 - (BOOL) addString: (NSString*)str {

   184     return [self addData: [str dataUsingEncoding: NSUTF8StringEncoding]];

   185 }

   186 

   187 

   188 - (BOOL) addFromStream: (NSInputStream*)input

   189 {

   190     uint8_t inputBuffer[1024];

   191     size_t avail;

   192     while (!_error && input.hasBytesAvailable) {

   193         avail = sizeof(inputBuffer);

   194         NSInteger nRead = [input read: inputBuffer maxLength: sizeof(inputBuffer)];

   195         if (nRead < 0) {

   196             self.error = input.streamError;

   197             return NO;

   198         } else if (nRead == 0) {

   199             break;

   200         } else if (![self addBytes: inputBuffer length: nRead])

   201             return NO;

   202     }

   203     return YES;

   204 }

   205 

   206 

   207 - (BOOL) finish

   208 {

   209     if(!_error && (_cryptor || [self _start])) {

   210         size_t outputLength = 100; //CCCryptorGetOutputLength(_cryptor,1,true);

   211         void *output = malloc(outputLength);

   212         if ([self _check: CCCryptorFinal(_cryptor, output, outputLength, &outputLength)]) {

   213             [self _outputBytes: output length: outputLength];

   214         }

   215         free(output);

   216     }

   217     CCCryptorRelease(_cryptor);

   218     _cryptor = NULL;

   219     return !_error;

   220 }

   221 

   222 

   223 - (NSData*) outputData {

   224     if (_cryptor) [self finish];

   225     if(_error) {

   226         [_output release];

   227         _output = nil;

   228     }

   229     return _output;

   230 }

   231 

   232 - (NSString*) outputString {

   233     NSData *output = self.outputData;

   234     if (output) {

   235         NSString *str = [[NSString alloc] initWithData: output encoding: NSUTF8StringEncoding];

   236         return [str autorelease];

   237     } else

   238         return nil;

   239 }

   240 

   241 

   242 // NSStream delegate method

   243 - (void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)eventCode {

   244     switch (eventCode) {

   245         case NSStreamEventHasBytesAvailable:

   246             [self addFromStream: (NSInputStream*)stream];

   247             break;

   248         case NSStreamEventEndEncountered:

   249             [self finish];

   250             break;

   251         case NSStreamEventErrorOccurred:

   252             if (!_error)

   253                 self.error = stream.streamError;

   254             break;

   255         default:

   256             break;

   257     }

   258 }

   259 

   260 

   261 

   262 @end

   263 

   264 

   265 

   266 

   267 #if !MYCRYPTO_USE_IPHONE_API

   268 static BOOL generateRandomBytes(CSSM_CSP_HANDLE module, uint32_t lengthInBytes, void *dstBytes) {

   269     // Adapted from code in Keychain.framework's KeychainUtils.m by Wade Tregaskis.

   270     CSSM_CC_HANDLE ccHandle;

   271     if (!checkcssm(CSSM_CSP_CreateRandomGenContext(module, CSSM_ALGID_APPLE_YARROW, NULL,

   272                                                   lengthInBytes, &ccHandle),

   273                    @"CSSM_CSP_CreateRandomGenContext"))

   274         return NO;

   275     CSSM_DATA data = {.Data=dstBytes, .Length=lengthInBytes};

   276     BOOL ok = checkcssm(CSSM_GenerateRandom(ccHandle, &data), @"CSSM_GenerateRandom");

   277     CSSM_DeleteContext(ccHandle);

   278     return ok;

   279 }

   280 #endif

   281 

   282 

   283 

   284 

   285 TestCase(MYCryptor) {

   286     // Encryption:

   287     NSData *key = [MYCryptor randomKeyOfLength: 256];

   288     Log(@"Key = %@",key);

   289     MYCryptor *enc = [[MYCryptor alloc] initEncryptorWithKey: key algorithm: kCCAlgorithmAES128];

   290     CAssert(enc);

   291     CAssert([enc addString: @"This is a test. "]);

   292     CAssert([enc addString: @"This is only a test."]);

   293     CAssertEqual(enc.error, nil);

   294     NSData *encrypted = enc.outputData;

   295     CAssertEqual(enc.error, nil);

   296     CAssert(encrypted.length > 0);

   297     [enc release];

   298     Log(@"Encrypted = %@", encrypted);

   299     

   300     // Decryption:

   301     MYCryptor *dec = [[MYCryptor alloc] initDecryptorWithKey: key algorithm: kCCAlgorithmAES128];

   302     CAssert(dec);

   303     CAssert([dec addData: encrypted]);

   304     NSString *decrypted = dec.outputString;

   305     CAssertEqual(dec.error, nil);

   306     [dec release];

   307     Log(@"Decrypted = '%@'", decrypted);

   308     CAssertEqual(decrypted, @"This is a test. This is only a test.");

   309     

   310     // Encryption to stream:

   311     key = [MYCryptor randomKeyOfLength: 256];

   312     Log(@"Key = %@",key);

   313     enc = [[MYCryptor alloc] initEncryptorWithKey: key algorithm: kCCAlgorithmAES128];

   314     CAssert(enc);

   315     enc.outputStream = [NSOutputStream outputStreamToMemory];

   316     [enc.outputStream open];

   317     CAssert([enc addString: @"This is a test. "]);

   318     CAssert([enc addString: @"This is only a test."]);

   319     CAssert([enc finish]);

   320     CAssertEqual(enc.error, nil);

   321     encrypted = [[enc.outputStream propertyForKey: NSStreamDataWrittenToMemoryStreamKey] retain];

   322     CAssert(encrypted.length > 0);

   323     [enc release];

   324     Log(@"Encrypted = %@", encrypted);

   325     

   326     dec = [[MYCryptor alloc] initDecryptorWithKey: key algorithm: kCCAlgorithmAES128];

   327     CAssert(dec);

   328     dec.outputStream = [NSOutputStream outputStreamToMemory];

   329     [dec.outputStream open];

   330     CAssert([dec addData: encrypted]);

   331     CAssert([dec finish]);

   332     CAssertEqual(dec.error, nil);

   333     NSData *decryptedData = [dec.outputStream propertyForKey: NSStreamDataWrittenToMemoryStreamKey];

   334     [dec release];

   335     decrypted = [[NSString alloc] initWithData: decryptedData

   336                                                       encoding: NSUTF8StringEncoding];

   337     Log(@"Decrypted = '%@'", decrypted);

   338     CAssertEqual(decrypted, @"This is a test. This is only a test.");

   339     [encrypted release];

   340     [decrypted release];

   341 }
MYCrypto