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我需要使用openssl用8字节的麦克风解密aes 128 ccm，但我的输出总是空的，这是我的代码：

void aes(){
unsigned char * aad = extochar("0841000CF635DFAB74F06D40A6A30090");


unsigned char * cipher = extochar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
//unsigned char * mic = extochar("8f3829e8e76ee23c04f566189e63c686");
int cipher_size  = strlen("A52B1A6537FD99E79F49DABDCB2B297E096E0ACA95CF897D5099CBE43181C632DBE6BAAD8C15B0846839ADE68203C75DA7B5D415BA181105F8ADB199B707DFFE2944462948E775A7B946AFBACC7D90DA9831BEDC8961A3A49D3064EEFCABA0283ED4C55824B8BED8FCCFF2A0B4E9C86289BE3EEC3A4CE5BE1C95069CA97882E05EA211A0DD0EBF665E10CBE12B8ACBD1BAB390925FE9B5DFCB1A74EC897E220BF018DC3749A80C109976A72827DB407F491AC10D94FFF8DD0CC5738468E662CE32A5AD2A2B4FD37C50577B601E45C67199393C9B22CF4F4652E1B718FF5D2D614EA4B5CC10C954EEDFC2D3DA24E5A119E74697F708862ED5C499C7B42E55BF67C5B618E20A7EB5EB51B256825D70F38A51B0808034B4BE7A7C20CACC12CC5D8EF76E2859DF6A4089F6AC5DFB11FB49D994CDDB362340130D2BA31B0D880F4494C3E04B21C089A4B9204FB964A2080050C44E987000DE39326CDC69D95F83D47B60DA65DE0FC95271E1B082CC79B1F9E92ECE50C8FA2A9A922EC252770503310DED86ABC64C03FF0ED5EBBB2AD6CD8C997C6AA93C56D30B7C65B97F048CBC3196B338D121D10F4DE3F867EE21FCDB204EDD55867B3E3D3B703F")/2;
unsigned char * key = extochar("C7134FD10709F028D63C2E05CBB4C16C");
unsigned char * nonce = extochar("0074F06D40A6A3000000000011");
int nonce_size = strlen("0074F06D40A6A3000000000011")/2;

int aad_size = strlen("0841000CF635DFAB74F06D40A6A30090")/2;
unsigned char plain[cipher_size];
int mic_size = 8;

EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new();
EVP_CIPHER_CTX_init(ctx);

// Just set the alg
EVP_DecryptInit(ctx, EVP_aes_128_ccm(), 0, 0);

// Set nonce size
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_IVLEN, nonce_size, 0);

// Set the tag from the end of the encrypted array
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_TAG, mic_size, cipher +sizeof(unsigned char)*(cipher_size -8));

// Set key and nonce
EVP_DecryptInit(ctx, 0, key, nonce);

int outl = 0;
// We will encrypt Psize bytes
EVP_DecryptUpdate(ctx, 0, &outl, 0, cipher_size);

// Add AAD for verification
EVP_DecryptUpdate(ctx, 0, &outl, aad, aad_size);

// Time to decrypt the data into D
EVP_DecryptUpdate(ctx, plain, &outl, cipher, cipher_size);

// Not sure if this is needed
EVP_DecryptFinal(ctx, &plain[outl], &outl);


int i;
printf("plaintext");
for(i=0; i<cipher_size; i++)
    printf("%.2x",plain[i]);
printf("\n");

函数 extochar 如下：

char * extochar(char* string)
{
    unsigned char * out = malloc(sizeof(unsigned char)*strlen(string)/2);
    int i;
    for (i = 0; i < strlen(string)/2; i++)
    {
        sscanf(&string[2*i], "%02x", (unsigned int *)(&out[i]));
    }
    return out;
}

明文应该以 

AA AA 03 00 00 00 08 00 45 00 01 A9 0F DC 40 00 40 06 E6 14 27 E9 64 63 D1 55 E5 BC 8F B4 14 6C

并且此链接的最后一个测试向量 有效（我只测试了那个，将 EVP_aes_128_ccm() 更改为 EVP_aes_256_ccm() 并将麦克风大小更改为 16）

怎么了？非常感谢您的建议！

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1 回答 1

0

我已经通过以下步骤实现了 GCM 解密。请看看它是否可以帮助你。

//Step 1: Set cipher.
retval  = EVP_DecryptInit (ctx, EVP_aes_128_gcm(), (const unsigned char *)key, (const unsigned char *)iv);
if(retval <= 0) {
   //Error
}

//Step 2: Set tag. Extract the tag from the message if required.
retval  = EVP_CIPHER_CTX_ctrl (ctx, EVP_CTRL_CCM_SET_TAG, taglen, (void *)tag);
if(retval <= 0) {
    //Error
}

//Step 3: Add AAD.
retval  = EVP_DecryptUpdate (ctx, NULL, (int *)&len, (const unsigned char *)add, (int)aadlen);
if(retval <= 0) {
    //Error
}

//Step 4: Decrypt the data.
buflen = 0;
retval  = EVP_DecryptUpdate (ctx, (unsigned char *)buf, (int *)&buflen, (const unsigned char *)inbuf, inbuflen);
if(retval <= 0) {
    //Error
}


//This step is necessary
//If this step fails, means authentication fails.
retval  = EVP_DecryptFinal(ctx, (unsigned char *)buf + buflen, (int *)&buflen);
if(retval <= 0) {
  //Error and discard the decrypted data so far.
}


//Clean up.
EVP_CIPHER_CTX_cleanup (ctx);
于 2013-04-06T05:41:15.310 回答