我想使用CFB加密模式在Objective-C中创建不带填充的AES 128加密。

Question

我希望创建一个使用CFB加密的AES 128位加密，没有填充即无补位 i.e.

示例 1：秘密数据为“HELLO WORLD” 密钥：10 A5 88 69 D7 4B E5 A3 74 CF 86 7C FB 47 38 59 初始化向量：00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 明文（未加密）：48 45 4C 4C 4F 20 57 4F 52 4C 44 加密后的文本：25 60 52 25 0B 90 06 AF 1C E6 2B

但我得到的加密十六进制字符串为空，即没有字符串。 我的加密成功了，但没有加密数据。 有什么建议吗？

以下是代码：

NSData *commandData = [@"HELLO WORLD" dataUsingEncoding:NSASCIIStringEncoding];
calling Method [commandData AES128OperationWithCreate:kCCEncrypt key:@"10a58869d74be5a374cf867cfb473859" iv:@"00000000000000000000000000000000"]

@implementation NSData (AES)
- (NSData *)AES128OperationWithCreate:(CCOperation)operation key:(NSString *)key iv:(NSString *)iv{
 char ivPtr[kCCBlockSizeAES128 + 1];
            bzero(ivPtr, sizeof(ivPtr));
            if (iv) {
                [iv getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];
            }

            char keyPtr[kCCKeySizeAES128 + 1];
            bzero(keyPtr, sizeof(keyPtr));
            [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];


            CCCryptorRef cryptor = NULL;
            CCCryptorStatus result = CCCryptorCreateWithMode(operation,
                                                             kCCModeCFB,
                                                             kCCAlgorithmAES128,
                                                             ccNoPadding,
                                                             ivPtr,
                                                             keyPtr,
                                                             kCCKeySizeAES128,
                                                             NULL,
                                                             0,
                                                             0,
                                                             0,
                                                             &cryptor);

            if (result != kCCSuccess) {

                NSLog(@"encryptAESCTRData: createWithMode error: %@", @(result));
                result = CCCryptorRelease(cryptor);
                return nil;
            }
            size_t bufferLength = CCCryptorGetOutputLength(cryptor, [self length], true);
            NSMutableData *buffer = [NSMutableData dataWithLength:bufferLength];
            NSMutableData *cipherData = [NSMutableData data];

            size_t outLength;
            result = CCCryptorUpdate(cryptor,
                                     [self bytes],
                                     [self length],
                                     [buffer mutableBytes],
                                     [buffer length],
                                     &outLength);

            // FIXME: Release cryptor and return error
            if (result != kCCSuccess) {

                NSLog(@"encryptAESCTRData: CCCryptorUpdate error: %@", @(result));
                result = CCCryptorRelease(cryptor);
                return nil;
            }

            result = CCCryptorFinal(cryptor,
                                    [buffer mutableBytes],
                                    [buffer length],
                                    &outLength);

            // FIXME: Release cryptor and return error
            if (result != kCCSuccess) {

                NSLog(@"encryptAESCTRData: CCCryptorFinal error: %@", @(result));
                result = CCCryptorRelease(cryptor);
                return nil;
            }
           [cipherData appendBytes:buffer.bytes length:outLength];
           return cipherData;
           //return [NSData dataWithBytesNoCopy:(__bridge void * _Nonnull)(buffer) length:outLength freeWhenDone:YES];
        }

- Girijesh Kumar

---

当我在CCCryptorCreateWithMode方法中传递ccPKCS7Padding时，它会给出字符串Encrypted Hex String == e8d1e4f9dd75ae80fb27d6a50e919a78，但使用ccNoPadding填充时没有数据加密。有什么建议吗？ - Girijesh Kumar

Answer 1

我用这种方法解决了这个问题。

- (NSData *)AES128OperationWithEncriptionMode:(CCOperation)operation key:(NSData *)key iv:(NSData *)iv {


    CCCryptorRef cryptor = NULL;
    // 1. Create a cryptographic context.
    CCCryptorStatus status = CCCryptorCreateWithMode(operation, kCCModeCFB, kCCAlgorithmAES, ccNoPadding, [iv bytes], [key bytes], [key length], NULL, 0, 0, kCCModeOptionCTR_BE, &cryptor);

    NSAssert(status == kCCSuccess, @"Failed to create a cryptographic context.");

    NSMutableData *retData = [NSMutableData new];

    // 2. Encrypt or decrypt data.
    NSMutableData *buffer = [NSMutableData data];
    [buffer setLength:CCCryptorGetOutputLength(cryptor, [self length], true)]; // We'll reuse the buffer in -finish

    size_t dataOutMoved;
    status = CCCryptorUpdate(cryptor, self.bytes, self.length, buffer.mutableBytes, buffer.length, &dataOutMoved);
    NSAssert(status == kCCSuccess, @"Failed to encrypt or decrypt data");
    [retData appendData:[buffer subdataWithRange:NSMakeRange(0, dataOutMoved)]];

    // 3. Finish the encrypt or decrypt operation.
    status = CCCryptorFinal(cryptor, buffer.mutableBytes, buffer.length, &dataOutMoved);
    NSAssert(status == kCCSuccess, @"Failed to finish the encrypt or decrypt operation");
    [retData appendData:[buffer subdataWithRange:NSMakeRange(0, dataOutMoved)]];
    CCCryptorRelease(cryptor);

    return [retData copy];
}

- Girijesh Kumar