iPhone开发中 验证”字符串“/“文件”的MD5的加密

+(NSString*) md5:(NSString*) str
{  
    const char *cStr = [str UTF8String];  
    unsigned char result[CC_MD5_DIGEST_LENGTH];  
    CC_MD5( cStr, strlen(cStr), result );  
    
    NSMutableString *hash = [NSMutableString string];
    for(int i=0;i<CC_MD5_DIGEST_LENGTH;i++)
    {
        [hash appendFormat:@"%02X",result[i]];
    }
    return [hash lowercaseString];
}
#define CHUNK_SIZE 1024  
+(NSString *)file_md5:(NSString*) path
{  
    NSFileHandle* handle = [NSFileHandle fileHandleForReadingAtPath:path];  
    if(handle == nil)  
        return nil;  
    
    CC_MD5_CTX md5_ctx;  
    CC_MD5_Init(&md5_ctx);  
    
    NSData* filedata;  
    do {  
        filedata = [handle readDataOfLength:CHUNK_SIZE];  
        CC_MD5_Update(&md5_ctx, [filedata bytes], [filedata length]);  
    }  
    while([filedata length]);  
    
    unsigned char result[CC_MD5_DIGEST_LENGTH];  
    CC_MD5_Final(result, &md5_ctx);  
    
    [handle closeFile];  
    
    NSMutableString *hash = [NSMutableString string];
    for(int i=0;i<CC_MD5_DIGEST_LENGTH;i++)
    {
        [hash appendFormat:@"%02x",result[i]];
    }
    return [hash lowercaseString];
}
 
 
+(NSString *)NSStringToMD5String:(NSString *)str{
    NSString *result = nil;
    if(str) {
        unsigned char digest[16];
        const char *cStr=[str UTF8String];
        CC_MD5(cStr, strlen(cStr), digest);
        
        result = [NSString stringWithFormat: @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
                  digest[0], digest[1], 
                  digest[2], digest[3],
                  digest[4], digest[5],
                  digest[6], digest[7],
                  digest[8], digest[9],
                  digest[10], digest[11],
                  digest[12], digest[13],
                  digest[14], digest[15]];
        result = [result uppercaseString];
    }
    return result;
}