c - Openssl:加密输出问题

Question

我在linux平台用c语言的openssl代码加密3gpp测试数据。我从 stack over flow 中获取示例并尝试过。但在最终的加密输出中未显示零。我需要使用 128 位 key 进行加密。提前致谢。

    #include <openssl/aes.h>
    #include <openssl/rand.h>
    #include <openssl/hmac.h>
    #include <openssl/buffer.h>
    #include <stdio.h>
    #include <string.h>
    #include <stdlib.h>
    #include <math.h>

    #define u32 unsigned int
    #define u8 unsigned char
    #define bufferSize 16

    struct ctr_state
    {
            unsigned char ivec[AES_BLOCK_SIZE];
            unsigned int  num;
            unsigned char ecount[AES_BLOCK_SIZE];
    };

    AES_KEY key;

    unsigned char indata[AES_BLOCK_SIZE];
    unsigned char outdata[AES_BLOCK_SIZE];
    unsigned char iv[AES_BLOCK_SIZE];
    struct ctr_state state;
    int init_ctr(struct ctr_state *state, const unsigned char iv[16])
    {
            /* aes_ctr128_encrypt requires 'num' and 'ecount' set to zero on the
             * first call. */
            state->num = 0;
            memset(state->ecount, 0, AES_BLOCK_SIZE);

            /* Initialise counter in 'ivec' to 0 */
            memset(state->ivec + 8, 0, 8);

            /* Copy IV into 'ivec' */
            memcpy(state->ivec, iv, 8);
    }


    int main(int argc, char *argv[])
    {

            u8 key1[16] = {
                    0xd3,0xc5,0xd5,0x92,0x32,0x7f,0xb1,0x1c,
                    0x40,0x35,0xc6,0x68,0x0a,0xf8,0xc6,0xd1
                    };
            u8  count[4] ={0x39,0x8a,0x59,0xb4};
            u32 tempCount = 0;
            u8 bearer = 0x15;
            u8 dir =0x01,i;
            u32 length = 253 ;
            u8 indata[32] = {
                    0x98, 0x1b, 0xa6, 0x82, 0x4c, 0x1b, 0xfb, 0x1a,
                    0xb4, 0x85, 0x47, 0x20, 0x29, 0xb7, 0x1d, 0x80,
                    0x8c, 0xe3, 0x3e, 0x2c, 0xc3, 0xc0, 0xb5, 0xfc,
                    0x1f, 0x3d, 0xe8, 0xa6, 0xdc, 0x66, 0xb1, 0xf0
            };

            tempCount = htonl((count[0] | (count[1] << 8) | count[2]<< 16 | count[3] << 24)); /* Jyothi Added */

            iv[0] = (tempCount >> 24) & 0xff ;
            iv[1] = (tempCount >> 16) & 0xff ;
            iv[2] = (tempCount >> 8)  & 0xff;
            iv[3] = tempCount & 0xff;
            iv[4] = htonl((( (bearer << 27) | ((dir & 0x1) << 26))));
            iv[5] = iv[6]= iv[7] = 0;

            printf("iv=\n");
            for(i=0;i<16;i++)
                    printf("%x",iv[i]);
            printf("\n");
            printf("key1=\n");
            for(i=0;i<16;i++)
                    printf("%x",key1[i]);
            printf("\n");

            //Initializing the encryption KEY
            if (AES_set_encrypt_key(key1, 128, &key) < 0)
            {
                    fprintf(stderr, "Could not set decryption key.");
                    exit(1);
            }

            init_ctr(&state, iv);//Counter call
            printf("state.ivec after call=\n");
            for(i=0;i<16;i++)
                    printf("%x",state.ivec[i]);
            printf("\n");

            printf("indata=\n");
            for(i=0;i<32;i++)
                    printf("%x",indata[i]);
            printf("\n");

            for(i=1;i<2;i++){
                    //Encrypting Blocks of 16 bytes 
                    AES_ctr128_encrypt(indata, outdata,253, &key, state.ivec, state.ecount, &state.num);

                    printf("outdata\n");
                    for(i=0;i<32;i++)
                            printf("%x",outdata[i]);
                    printf("\n");
            }
    }

我得到如下输出。

    iv=
    398a59b4ac00000000000
    key1=
    d3c5d592327fb11c4035c668af8c6d1
    state.ivec after call=
    398a59b4ac00000000000
    indata=
    981ba6824c1bfb1ab485472029b71d808ce33e2cc3c0b5fc1f3de8a6dc66b1f0
    outdata
    e9fed8a63d15534d71df2bf3e82214b2ed7dad2f233dc3c22d7bdeeed8e78





    algorithm has to generate key stream as below:
            71e57e24 710ea81e 6398b52b da5f3f94 3eede9f6 11328620 231f3f1b 328b3f88
    but instead it is generating final encryption output without zero's

    final expected output is as below:
            e9fed8a6 3d155304 d71df20b f3e82214 b20ed7da d2f233dc 3c22d7bd eeed8e78

Answer 1

更改您的 printf 格式字符串以要求每个字符输出为两个十六进制数字 - 目前您正在丢失前导零。

printf("%02x",outdata[i]);

零告诉它使用零填充最多两位数，默认为空格。