SSYDigester.h

#import <Cocoa/Cocoa.h>
#import <CommonCrypto/CommonDigest.h>

enum SSYDigesterAlgorithm_enum {
	SSYDigesterAlgorithmMd5,
	SSYDigesterAlgorithmSha1,
    SSYDigesterAlgorithmSha256,
    SSYDigesterAlgorithmSha512,
} ;
typedef enum SSYDigesterAlgorithm_enum SSYDigesterAlgorithm ;

/*!
 @brief    A class for computing message digests incrementally.
*/
@interface SSYDigester : NSObject {
    SSYDigesterAlgorithm m_algorithm ;
    CC_MD5_CTX m_context_md5 ;
	CC_SHA1_CTX m_context_sha1 ;
    CC_SHA256_CTX m_context_sha256 ;
    CC_SHA512_CTX m_context_sha512 ;
}

/*!
 @brief    Initializes a new message digest with a given
 algorithm type.
*/
- (id)initWithAlgorithm:(SSYDigesterAlgorithm)algorithm ;

/*!
 @brief    Incrementally updates the message digest to
 account for additional given data.
*/
- (void)updateWithData:(NSData*)data ;

/*!
 @brief    Incrementally updates the message digest to
 account for an additional given string which is first
 converted to a C string with a given encoding.
 
 @details  The NULL terminator on the C string *is*
 included in the additional data.
 
 @param    encoding  The string encoding to be used to
 convert the given string to data.  Must be one of the
 following:
 *  NSUTF8StringEncoding
 *  NSASCIIStringEncoding 
 *  NSUnicodeStringEncoding
 *  NSUTF16StringEncoding
 *  NSUTF16BigEndianStringEncoding
 *  NSUTF16LittleEndianStringEncoding
 */
- (void)updateWithString:(NSString*)string
				encoding:(NSStringEncoding)encoding ;

/*!
 @brief    Returns the final message digest.

 @details  After sending this message to the receiver,
 you should release/deallocate it.  Sending a
 further message to the receiver afer sending -finalize
 for the first time will result in an assertion being
 raised.
*/
- (NSData*)finalizeDigest ;

@end

#if 0
/* The following method was used to test this class on 20150304, when it was
 converted to use CommonCrypto instead of openssl.  The "expected" results
 were obtained using the old openssl code. */
+ (void)testSSYDigester {
    SSYDigester* digester ;
    NSData* data ;
    NSData* expected ;
    
    digester = [[SSYDigester alloc] initWithAlgorithm:SSYDigesterAlgorithmMd5] ;
    data = [@"Foo One" dataUsingEncoding:NSUTF8StringEncoding] ;
    [digester updateWithData:data] ;
    [digester updateWithString:@"Foo Two"
                      encoding:NSUTF8StringEncoding] ;
    data = [@"Foo Three" dataUsingEncoding:NSUTF8StringEncoding] ;
    [digester updateWithData:data] ;
    [digester updateWithString:@"Foo Four!!"
                      encoding:NSUTF8StringEncoding] ;
    data = [digester finalizeDigest] ;
    NSLog(@" md5 result = %@", data) ;
    [digester release] ;
    
    char bytes[20] ;
    bytes[0] = 0x0c ;
    bytes[1] = 0xab ;
    bytes[2] = 0x25 ;
    bytes[3] = 0x8a ;
    bytes[4] = 0xbb ;
    bytes[5] = 0xc7 ;
    bytes[6] = 0x16 ;
    bytes[7] = 0xdf ;
    bytes[8] = 0x72 ;
    bytes[9] = 0x5e ;
    bytes[10] = 0x83 ;
    bytes[11] = 0xd9 ;
    bytes[12] = 0x53 ;
    bytes[13] = 0xa8 ;
    bytes[14] = 0xaf ;
    bytes[15] = 0x21 ;
    expected = [[NSData alloc] initWithBytes:bytes
                                      length:16] ;
    NSLog(@" md5 expect = %@", expected) ;
    NSLog(@"md5 test %@", [data isEqual:expected] ? @"passed" : @"failed") ;
    
    digester = [[SSYDigester alloc] initWithAlgorithm:SSYDigesterAlgorithmSha1] ;
    data = [@"Foo One" dataUsingEncoding:NSUTF8StringEncoding] ;
    [digester updateWithData:data] ;
    [digester updateWithString:@"Foo Two"
                      encoding:NSUTF8StringEncoding] ;
    data = [@"Foo Three" dataUsingEncoding:NSUTF8StringEncoding] ;
    [digester updateWithData:data] ;
    [digester updateWithString:@"Foo Four!!"
                      encoding:NSUTF8StringEncoding] ;
    data = [digester finalizeDigest] ;
    NSLog(@"sha1 result = %@", data) ;
    [digester release] ;
    
    bytes[0] = 0x97 ;
    bytes[1] = 0x59 ;
    bytes[2] = 0xf0 ;
    bytes[3] = 0xd1 ;
    bytes[4] = 0xc0 ;
    bytes[5] = 0x71 ;
    bytes[6] = 0xb2 ;
    bytes[7] = 0x30 ;
    bytes[8] = 0xdd ;
    bytes[9] = 0x98 ;
    bytes[10] = 0x2c ;
    bytes[11] = 0x0a ;
    bytes[12] = 0x27 ;
    bytes[13] = 0xb3 ;
    bytes[14] = 0xff ;
    bytes[15] = 0x16 ;
    bytes[16] = 0x10 ;
    bytes[17] = 0x4a ;
    bytes[18] = 0xe9 ;
    bytes[19] = 0x33 ;
    expected = [[NSData alloc] initWithBytes:bytes
                                      length:20] ;
    NSLog(@"sha1 expect = %@", expected) ;
    NSLog(@"sha1 test %@", [data isEqual:expected] ? @"passed" : @"failed") ;
}

#endif