iOS数据的加密解密

• Base64编码解码：

　　基于64个可打印的字符来表示二进制数据的方法。

Base64编码：

- (NSString *)encode:(NSString *)string
{
    //先将string转换成data
    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];

    NSData *base64Data = [data base64EncodedDataWithOptions:0];

    NSString *baseString = [[NSString alloc]initWithData:base64Data encoding:NSUTF8StringEncoding];

    return baseString;
}

　　Base64解码：

- (NSString *)dencode:(NSString *)base64String
{
    //NSData *base64data = [string dataUsingEncoding:NSUTF8StringEncoding];

    NSData *data = [[NSData alloc]initWithBase64EncodedString:base64String options:NSDataBase64DecodingIgnoreUnknownCharacters];

    NSString *string = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];

    return string;
}

• MD5（Message Digest Algorithm 5：消息摘要算法第5版）

　　MD5加密是从一段字符串中通过相应特征生成一段32位的数字字母混合码。对输入信息生成唯一的固定的128位散列值（32个字符），即128个0和1的二进制位，而在实际应用开发中，通常是以16进制输出的，所以正好就是32位的16进制。MD5主要特点是 不可逆，相同数据的MD5值肯定一样。

　　注意点:

　　（1）一定要和后台开发人员约定好，MD5加密的位数是16位还是32位(大多数都是32位的)，16位的可以通过32位的转换得到。

　　（2）MD5加密区分 大小写，使用时要和后台约定好。

MD5解密网站:http://www.cmd5.com/

　　加密方法：

#[email protected] MD5Encrypt : NSObject
// MD5加密
/*
*由于MD5加密是不可逆的,多用来进行验证
*/
// 32位小写
+(NSString *)MD5ForLower32Bate:(NSString *)str;
// 32位大写
+(NSString *)MD5ForUpper32Bate:(NSString *)str;
// 16为大写
+(NSString *)MD5ForUpper16Bate:(NSString *)str;
// 16位小写
+(NSString *)MD5ForLower16Bate:(NSString *)str;
@end

#import "MD5Encrypt.h"
#import <CommonCrypto/CommonDigest.h>

@implementation MD5Encrypt

#pragma mark - 32位 小写
+(NSString *)MD5ForLower32Bate:(NSString *)str{

    //要进行UTF8的转码
    const char* input = [str UTF8String];
    unsigned char result[CC_MD5_DIGEST_LENGTH];
    CC_MD5(input, (CC_LONG)strlen(input), result);

    NSMutableString *digest = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];
    for (NSInteger i = 0; i < CC_MD5_DIGEST_LENGTH; i++) {
        [digest appendFormat:@"%02x", result[i]];
    }

    return digest;
}

#pragma mark - 32位 大写
+(NSString *)MD5ForUpper32Bate:(NSString *)str{

    //要进行UTF8的转码
    const char* input = [str UTF8String];
    unsigned char result[CC_MD5_DIGEST_LENGTH];
    CC_MD5(input, (CC_LONG)strlen(input), result);

    NSMutableString *digest = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];
    for (NSInteger i = 0; i < CC_MD5_DIGEST_LENGTH; i++) {
        [digest appendFormat:@"%02X", result[i]];
    }

    return digest;
}

#pragma mark - 16位 大写
+(NSString *)MD5ForUpper16Bate:(NSString *)str{

    NSString *md5Str = [self MD5ForUpper32Bate:str];

    NSString  *string;
    for (int i=0; i<24; i++) {
        string=[md5Str substringWithRange:NSMakeRange(8, 16)];
    }
    return string;
}

#pragma mark - 16位 小写
+(NSString *)MD5ForLower16Bate:(NSString *)str{

    NSString *md5Str = [self MD5ForLower32Bate:str];

    NSString  *string;
    for (int i=0; i<24; i++) {
        string=[md5Str substringWithRange:NSMakeRange(8, 16)];
    }
    return string;
}

@end

• AES256

　　 AES:高级加密标准(Advanced Encryption Standard)

　　  加密步骤: 字符串经过AES加密得到NSData类型数据，然后在对加密后的NSData数据进行Base64转码，得出最终的字符串

　　  解密步骤: 对要解密的字符串进行Base64解码得到NSData类型数据，然后对NSData数据经过AES解密，得出原字符串

//创建一个基于NSObject的AESUtility类
#import <Foundation/Foundation.h>

@interface AESUtility : NSObject
+ (NSString *)EncryptString:(NSString *)sourceStr;
+ (NSString *)DecryptString:(NSString *)secretStr;
@end

#import "AESUtility.h"

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

//加密与解密的秘钥，保持与后台的秘钥相同
static NSString *key = @"12345678";

@implementation AESUtility

+ (NSString *)EncryptString:(NSString *)sourceStr
{
    char keyPtr[kCCKeySizeAES256 + 1];
    bzero(keyPtr, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    NSData *sourceData = [sourceStr dataUsingEncoding:NSUTF8StringEncoding];
    NSUInteger dataLength = [sourceData length];
    size_t buffersize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(buffersize);
    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding | kCCOptionECBMode, keyPtr, kCCBlockSizeAES128, NULL, [sourceData bytes], dataLength, buffer, buffersize, &numBytesEncrypted);

    if (cryptStatus == kCCSuccess) {
        NSData *encryptData = [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
        //对加密后的二进制数据进行base64转码
        return [encryptData base64EncodedStringWithOptions:NSDataBase64EncodingEndLineWithLineFeed];
    }
    else
    {
        free(buffer);
        return nil;
    }
}

+ (NSString *)DecryptString:(NSString *)secretStr
{
    //先对加密的字符串进行base64解码
    NSData *decodeData = [[NSData alloc] initWithBase64EncodedString:secretStr options:NSDataBase64DecodingIgnoreUnknownCharacters];

    char keyPtr[kCCKeySizeAES256 + 1];
    bzero(keyPtr, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    NSUInteger dataLength = [decodeData length];
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);
    size_t numBytesDecrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding | kCCOptionECBMode, keyPtr, kCCBlockSizeAES128, NULL, [decodeData bytes], dataLength, buffer, bufferSize, &numBytesDecrypted);
    if (cryptStatus == kCCSuccess) {
        NSData *data = [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
        NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
        return result;
    }
    else
    {
        free(buffer);
        return nil;
    }
}
@end

注意点：
    1. 加密与解密的秘钥key，需要与后台协商共同定义，保持与后台的秘钥相同，也可以通过接口从后台获得；
    2. 导入头文件：#import <CommonCrypto/CommonDigest.h>和#import <CommonCrypto/CommonCryptor.h>

• RSA

原文地址：https://www.cnblogs.com/Blueleaf-tech/p/9807826.html