原理什么的不在本篇的范畴,网上很多大牛总结的很好了 请参考AES加密过程详解
1. 苹果默认是CBC模式的,有文档为证:
/*!
@enum CCOptions
@abstract Options flags, passed to CCCryptorCreate().
@constant kCCOptionPKCS7Padding Perform PKCS7 padding.
@constant kCCOptionECBMode Electronic Code Book Mode.
Default is CBC.
*/
enum {
/* options for block ciphers */
kCCOptionPKCS7Padding = 0x0001,
kCCOptionECBMode = 0x0002
/* stream ciphers currently have no options */
};
2. 一般来说,我们客户端单纯只是做做业务的话,接触的加密算法或者需要我们去深入底层的东西少之又少,通常是后端提供加密的key(秘钥)和iv(偏移量)给前端小伙伴们使用.
3. CBC和EBC,在调用方看来,仅仅只是一个枚举值的区别
//CBC模式
kCCOptionPKCS7Padding
//ECB模式
kCCOptionPKCS7Padding | kCCOptionECBMode
4. 下面👇贴一段ECB加密解密的代码
@implementation NSData (AESEncryption)
//AES128加密
- (NSData *)AES128ParmEncryptWithKey:(NSString *)key iv:(NSString *)iv
{
char keyPtr[kCCKeySizeAES128+1];
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
char ivPtr[kCCBlockSizeAES128 + 1];
bzero(ivPtr, sizeof(ivPtr));
[iv getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128,
kCCOptionPKCS7Padding | kCCOptionECBMode,
keyPtr, kCCBlockSizeAES128,
ivPtr,
[self bytes], dataLength,
buffer, bufferSize,
&numBytesEncrypted);
if (cryptStatus == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
}
free(buffer);
return nil;
}
//解密
- (NSData *)AES128ParmDecryptWithKey:(NSString *)key iv:(NSString *)iv
{
char keyPtr[kCCKeySizeAES128 + 1];
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
char ivPtr[kCCBlockSizeAES128 + 1];
bzero(ivPtr, sizeof(ivPtr));
[iv getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128,
kCCOptionPKCS7Padding|kCCOptionECBMode,
keyPtr, kCCBlockSizeAES128,
ivPtr,
[self bytes], dataLength,
buffer, bufferSize,
&numBytesDecrypted);
if (cryptStatus == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free(buffer);
return nil;
}
@end
5. 最后在Demo地址
