计算 MD5值

//
//  MD5Value.h
//  iOSEdu
//
//  Created by littest on 16/2/26.
//  Copyright © 2016年 littest. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonDigest.h>
#define FileHashDefaultChunkSizeForReadingData 1024*8 // 8K
@interface MD5Value : NSObject
// 计算 NSData 的 MD5 值

+(NSString*)getMD5WithData:(NSData*)data;

// 计算字符串的 MD5 值，

+(NSString*)getmd5WithString:(NSString*)string;

// 计算大文件的 MD5 值

+(NSString*)getFileMD5WithPath:(NSString*)path;
@end

//
//  MD5Value.m
//  iOSEdu
//
//  Created by littest on 16/2/26.
//  Copyright © 2016年 littest. All rights reserved.
//

#import "MD5Value.h"

@implementation MD5Value
+ (NSString*)getmd5WithString:(NSString *)string

{
    
    const char* original_str=[string UTF8String];
    
    unsigned char digist[CC_MD5_DIGEST_LENGTH]; //CC_MD5_DIGEST_LENGTH = 16
    
    CC_MD5(original_str, strlen(original_str), digist);
    
    NSMutableString* outPutStr = [NSMutableString stringWithCapacity:10];
    
    for(int  i =0; i<CC_MD5_DIGEST_LENGTH;i++){
        
        [outPutStr appendFormat:@"%02x", digist[i]];// 小写 x 表示输出的是小写 MD5 ，大写 X 表示输出的是大写 MD5
        
    }
    
    return [outPutStr lowercaseString];
    
}

+ (NSString*)getMD5WithData:(NSData *)data{
    
    const char* original_str = (const char *)[data bytes];
    
    unsigned char digist[CC_MD5_DIGEST_LENGTH]; //CC_MD5_DIGEST_LENGTH = 16
    
    CC_MD5(original_str, strlen(original_str), digist);
    
    NSMutableString* outPutStr = [NSMutableString stringWithCapacity:10];
    
    for(int  i =0; i<CC_MD5_DIGEST_LENGTH;i++){
        
        [outPutStr appendFormat:@"%02x",digist[i]];// 小写 x 表示输出的是小写 MD5 ，大写 X 表示输出的是大写 MD5
        
    }
    
    
    
    // 也可以定义一个字节数组来接收计算得到的 MD5 值
    
    //    Byte byte[16];
    
    //    CC_MD5(original_str, strlen(original_str), byte);
    
    //    NSMutableString* outPutStr = [NSMutableString stringWithCapacity:10];
    
    //    for(int  i = 0; i<CC_MD5_DIGEST_LENGTH;i++){
    
    //        [outPutStr appendFormat:@"%02x",byte[i]];
    
    //    }
    
    //    [temp release];
    
    
    
    return [outPutStr lowercaseString];
    
    
    
}

+(NSString*)getFileMD5WithPath:(NSString*)path

{
    
    return (__bridge  NSString *)FileMD5HashCreateWithPath((__bridge CFStringRef)path,FileHashDefaultChunkSizeForReadingData);
    
}

CFStringRef FileMD5HashCreateWithPath(CFStringRef filePath,
                                      
                                      size_t chunkSizeForReadingData) {
    
    
    
    // Declare needed variables
    
    CFStringRef result = NULL;
    
    CFReadStreamRef readStream = NULL;
    
    
    
    // Get the file URL
    
    CFURLRef fileURL =
    
    CFURLCreateWithFileSystemPath(kCFAllocatorDefault,
                                  
                                  (CFStringRef)filePath,
                                  
                                  kCFURLPOSIXPathStyle,
                                  
                                  (Boolean)false);
    
    
    
    CC_MD5_CTX hashObject;
    
    bool hasMoreData = true;
    
    bool didSucceed;
    
    
    
    if (!fileURL) goto done;
    
    
    
    // Create and open the read stream
    
    readStream = CFReadStreamCreateWithFile(kCFAllocatorDefault,
                                            
                                            (CFURLRef)fileURL);
    
    if (!readStream) goto done;
    
    didSucceed = (bool)CFReadStreamOpen(readStream);
    
    if (!didSucceed) goto done;
    
    
    
    // Initialize the hash object
    
    CC_MD5_Init(&hashObject);
    
    
    
    // Make sure chunkSizeForReadingData is valid
    
    if (!chunkSizeForReadingData) {
        
        chunkSizeForReadingData = FileHashDefaultChunkSizeForReadingData;
        
    }
    
    
    
    // Feed the data to the hash object
    
    while (hasMoreData) {
        
        uint8_t buffer[chunkSizeForReadingData];
        
        CFIndex readBytesCount = CFReadStreamRead(readStream,
                                                  
                                                  (UInt8 *)buffer,
                                                  
                                                  (CFIndex)sizeof(buffer));
        
        if (readBytesCount == -1)break;
        
        if (readBytesCount == 0) {
            
            hasMoreData =false;
            
            continue;
            
        }
        
        CC_MD5_Update(&hashObject,(const void *)buffer,(CC_LONG)readBytesCount);
        
    }
    
    
    
    // Check if the read operation succeeded
    
    didSucceed = !hasMoreData;
    
    
    
    // Compute the hash digest
    
    unsigned char digest[CC_MD5_DIGEST_LENGTH];
    
    CC_MD5_Final(digest, &hashObject);
    
    
    
    // Abort if the read operation failed
    
    if (!didSucceed) goto done;
    
    
    
    // Compute the string result
    
    char hash[2 *sizeof(digest) + 1];
    
    for (size_t i =0; i < sizeof(digest); ++i) {
        
        snprintf(hash + (2 * i),3, "%02x", (int)(digest[i]));
        
    }
    
    result = CFStringCreateWithCString(kCFAllocatorDefault,
                                       
                                       (const char *)hash,
                                       
                                       kCFStringEncodingUTF8);
    
    
    
done:
    
    
    
    if (readStream) {
        
        CFReadStreamClose(readStream);
        
        CFRelease(readStream);
        
    }
    
    if (fileURL) {
        
        CFRelease(fileURL);
        
    }
    
    return result;
    
}
@end