iOS开发之Objective-c的MD5/SHA1加密算法的实现

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 Objective-c实现MD5和SHA1算法相对还是比较简单的，可以直接调用系统的C/C++共享库来实现调用
 MD5即Message Digest Algorithm 5（信息-摘要算法 5），用于确保信息传输完整一致。是计算机广泛使用的杂凑算法之一
 SHA即Secure Hash Algorithm（安全散列算法) 是美国国家安全局 (NSA) 设计，美国国家标准与技术研究院 (NIST) 发布的一系列密码散列函数。


 使用方式如下:
 MD5加密方式

 SString *) md5
 {
     const charchar *cStr = [self UTF8String];
     unsigned char digest[CC_MD5_DIGEST_LENGTH];
     CC_MD5( cStr, strlen(cStr), digest );

     NSMutableString *output = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];

     for(int i = 0; i < CC_MD5_DIGEST_LENGTH; i++)
         [output appendFormat:@"%02x", digest[i]];

     return output;
 }
 SHA1加密方式

 - (NSString*) sha1
 {
     const charchar *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding];
     NSData *data = [NSData dataWithBytes:cstr length:self.length];

     uint8_t digest[CC_SHA1_DIGEST_LENGTH];

     CC_SHA1(data.bytes, data.length, digest);

     NSMutableString* output = [NSMutableString stringWithCapacity:CC_SHA1_DIGEST_LENGTH * 2];

     for(int i = 0; i < CC_SHA1_DIGEST_LENGTH; i++)
         [output appendFormat:@"%02x", digest[i]];

     return output;
 }
 当然也可以结合BASE64来使用,这里的BASE64编码使用 GTMBase64实现，需要导入

 - (NSString *) sha1_base64
 {
     const charchar *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding];
     NSData *data = [NSData dataWithBytes:cstr length:self.length];

     uint8_t digest[CC_SHA1_DIGEST_LENGTH];

     CC_SHA1(data.bytes, data.length, digest);

     NSData * base64 = [[NSData alloc]initWithBytes:digest length:CC_SHA1_DIGEST_LENGTH];
     base64 = [GTMBase64 encodeData:base64];

     NSString * output = [[NSString alloc] initWithData:base64 encoding:NSUTF8StringEncoding];
     return output;
 }

 - (NSString *) md5_base64
 {
     const charchar *cStr = [self UTF8String];
     unsigned char digest[CC_MD5_DIGEST_LENGTH];
     CC_MD5( cStr, strlen(cStr), digest );

     NSData * base64 = [[NSData alloc]initWithBytes:digest length:CC_MD5_DIGEST_LENGTH];
     base64 = [GTMBase64 encodeData:base64];

     NSString * output = [[NSString alloc] initWithData:base64 encoding:NSUTF8StringEncoding];
     return output;
 }
 通过拓展NSString，实现完整功能，全部代码

 @interface NSString (encrypto)
 - (NSString *) md5;
 - (NSString *) sha1;
 - (NSString *) sha1_base64;
 - (NSString *) md5_base64;
 - (NSString *) base64;

 @end
 @implementation NSString (encrypto)
 - (NSString*) sha1
 {
     const charchar *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding];
     NSData *data = [NSData dataWithBytes:cstr length:self.length];

     uint8_t digest[CC_SHA1_DIGEST_LENGTH];

     CC_SHA1(data.bytes, data.length, digest);

     NSMutableString* output = [NSMutableString stringWithCapacity:CC_SHA1_DIGEST_LENGTH * 2];

     for(int i = 0; i < CC_SHA1_DIGEST_LENGTH; i++)
         [output appendFormat:@"%02x", digest[i]];

     return output;
 }

 -(NSString *) md5
 {
     const charchar *cStr = [self UTF8String];
     unsigned char digest[CC_MD5_DIGEST_LENGTH];
     CC_MD5( cStr, strlen(cStr), digest );

     NSMutableString *output = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];

     for(int i = 0; i < CC_MD5_DIGEST_LENGTH; i++)
         [output appendFormat:@"%02x", digest[i]];

     return output;
 }

 - (NSString *) sha1_base64
 {
     const charchar *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding];
     NSData *data = [NSData dataWithBytes:cstr length:self.length];

     uint8_t digest[CC_SHA1_DIGEST_LENGTH];

     CC_SHA1(data.bytes, data.length, digest);

     NSData * base64 = [[NSData alloc]initWithBytes:digest length:CC_SHA1_DIGEST_LENGTH];
     base64 = [GTMBase64 encodeData:base64];

     NSString * output = [[NSString alloc] initWithData:base64 encoding:NSUTF8StringEncoding];
     return output;
 }

 - (NSString *) md5_base64
 {
     const charchar *cStr = [self UTF8String];
     unsigned char digest[CC_MD5_DIGEST_LENGTH];
     CC_MD5( cStr, strlen(cStr), digest );

     NSData * base64 = [[NSData alloc]initWithBytes:digest length:CC_MD5_DIGEST_LENGTH];
     base64 = [GTMBase64 encodeData:base64];

     NSString * output = [[NSString alloc] initWithData:base64 encoding:NSUTF8StringEncoding];
     return output;
 }

 - (NSString *) base64
 {
     NSData * data = [self dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
     data = [GTMBase64 encodeData:data];
     NSString * output = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
     return output;
 }
 @end
 实现时候不要忘记导入CC相关的库的头文件
 CommonCrypto/CommonDigest.h