C base64解码长度大于8192的文件？

每当我尝试对大于8192的base64文件进行解码（使用OpenSSL的

BIO_f_base64（）

）时，我似乎总是得到一些错误的值

这个神奇的数字8192是怎么回事？非常感谢您对我的任何帮助

更新：

以下是我的部分代码：

int dgst(char *alg)
 {
 EVP_MD_CTX ctx;
 const EVP_MD *md;
 unsigned char md_value[EVP_MAX_MD_SIZE];
 unsigned int md_len, i;
 char *toB64val = NULL;
 char *data = NULL;

 OpenSSL_add_all_digests();

 md = EVP_get_digestbyname(alg);

 if(!md) {
        printf("Unknown message digest %s\n", alg);
        exit(1);
 }

 data = readFileBuffer("file_out");
 printf("strlen(data) %d\n", strlen(data));
 EVP_MD_CTX_init(&ctx);
 EVP_DigestInit_ex(&ctx, md, NULL);
 EVP_DigestUpdate(&ctx, data, strlen(data));

 EVP_DigestFinal_ex(&ctx, md_value, &md_len); //retrieve digest from ctx unto md_value and #bytes written is copied into   md_len
 EVP_MD_CTX_cleanup(&ctx);
 unsigned char *copy = malloc(md_len);
 memcpy(copy, md_value, md_len);
 char *buff = encbase64(copy, md_len);

 printf("Digest is:%s\n ", buff);

 free(buff);
 free(toB64val);
 free(data);
 return 0;
 }


char *readFileBuffer(char *name)
{
    FILE *file;
    char *buffer = NULL;
    unsigned long fileLen;
    //Open file
    file = fopen(name, "rb");
    if (!file)
    {
        fprintf(stderr, "Unable to open file %s", name);
        return;
    }
    //Get file length
    fseek(file, 0, SEEK_END);
    fileLen=ftell(file);
    printf("file length  = %ld\n", fileLen);
    fseek(file, 0, SEEK_SET);

    //printf("Allocate memory\n");
    buffer=(char *)malloc(fileLen+1);
    printf("length of write buffer = %d\n", strlen(buffer));
    if (!buffer)
    {
        fprintf(stderr, "Memory error!");

    }

    long int n = fread(buffer,1, fileLen,file);
    buffer[n] = '\0';
    printf("Read no. of bytes = %ld into buffer \n", n);
    printf("len of buffer  %d  \n", strlen(buffer));
    if (!buffer)
    {
        fprintf(stderr, "Memory error!");
        fclose(file);
    }
    fclose(file);
    return buffer;

}

char *encbase64( char *input, int length)
{
BIO *bmem, *b64;
BUF_MEM *bptr;

b64 = BIO_new(BIO_f_base64());
//BIO_set_flags(b64,BIO_FLAGS_BASE64_NO_NL);
bmem = BIO_new(BIO_s_mem());
b64 = BIO_push(b64, bmem);

BIO_write(b64, input, length);
BIO_flush(b64);
BIO_get_mem_ptr(b64, &bptr);


char *buff = (char *)malloc(bptr->length);
memcpy(buff, bptr->data, bptr->length-1);
buff[bptr->length-1] = 0;


BIO_free_all(b64);

return buff;
}

---

8k边界似乎没有任何问题。你能告诉我们你怎么称呼它吗

更新：

int dgst(char *alg)
 {
 EVP_MD_CTX ctx;
 const EVP_MD *md;
 unsigned char md_value[EVP_MAX_MD_SIZE];
 unsigned int md_len, i;
 char *toB64val = NULL;
 char *data = NULL;

 OpenSSL_add_all_digests();

 md = EVP_get_digestbyname(alg);

 if(!md) {
        printf("Unknown message digest %s\n", alg);
        exit(1);
 }

 data = readFileBuffer("file_out");
 //printf("strlen(data) %d\n", strlen(data)); <- don't use strlen on binary data
 EVP_MD_CTX_init(&ctx);
 EVP_DigestInit_ex(&ctx, md, NULL);
 EVP_DigestUpdate(&ctx, data, strlen(data));

 EVP_DigestFinal_ex(&ctx, md_value, &md_len); //retrieve digest from ctx unto md_value and #bytes written is copied into   md_len
 EVP_MD_CTX_cleanup(&ctx);
 unsigned char *copy = malloc(md_len);
 memcpy(copy, md_value, md_len);
 char *buff = encbase64(copy, md_len);

 printf("Digest is:%s\n ", buff);

 free(buff);
 free(toB64val);
 free(data);
 return 0;
 }


char *readFileBuffer(char *name)
{
    FILE *file;
    char *buffer = NULL;
    unsigned long fileLen;
    //Open file
    file = fopen(name, "rb");
    if (!file)
    {
        fprintf(stderr, "Unable to open file %s", name);
        return;
    }
    //Get file length
    fseek(file, 0, SEEK_END);
    fileLen=ftell(file);
    printf("file length  = %ld\n", fileLen);
    fseek(file, 0, SEEK_SET);

    //printf("Allocate memory\n");
    buffer=(char *)malloc(fileLen/*+1*/); // <- not a string - no need to +1
    //printf("length of write buffer = %d\n", strlen(buffer)); <- again strlen on binary data (you just allocated it, so it contains random bytes)
    if (!buffer)
    {
        fprintf(stderr, "Memory error!");

    }

    long int n = fread(buffer,1, fileLen,file);
    //buffer[n] = '\0';                  // not a string - no need to end it
    printf("Read no. of bytes = %ld into buffer \n", n);
    //printf("len of buffer  %d  \n", strlen(buffer));  <- buffer length is in 'n'
    if (!buffer)
    {
        fprintf(stderr, "Memory error!");
        fclose(file);
    }
    fclose(file);
    return buffer;

}

char *encbase64( char *input, int length)
{
BIO *bmem, *b64;
BUF_MEM *bptr;

b64 = BIO_new(BIO_f_base64());
//BIO_set_flags(b64,BIO_FLAGS_BASE64_NO_NL);
bmem = BIO_new(BIO_s_mem());
b64 = BIO_push(b64, bmem);

BIO_write(b64, input, length);
BIO_flush(b64);
BIO_get_mem_ptr(b64, &bptr);


char *buff = (char *)malloc(bptr->length);
memcpy(buff, bptr->data, bptr->length/*-1*/); // removed '+1'
//buff[bptr->length-1] = 0;       // not a string


BIO_free_all(b64);

return buff;
}

intdgst（char*alg）
{
执行副总裁MD CTX CTX；
工程执行副总裁(总经理)总经理(总经理);；
无符号字符md_值[EVP_MAX_md_SIZE]；
无符号整数md_len，i；
char*toB64val=NULL；
char*data=NULL；
OpenSSL_添加_所有_摘要（）；
md=EVP_get_digestbyname（alg）；
如果（！md）{
printf（“未知消息摘要%s\n”，alg）；
出口（1）；
}
数据=readFileBuffer（“文件输出”）；
//printf（“strlen（data）%d\n”，strlen（data））；你好，fazo，我已经用代码更新了我的帖子。请看一下，然后你需要调整你的代码，因为你在二进制数据上使用strlen（例如，当你调用EVP_DigestUpdate时）我猜在上面的代码中，我遗漏了base64解码部分。因此，正在读取的二进制文件是要用SHA1消化的文件。重要的部分是printf（“缓冲区%d的len\n”，strlen（缓冲区））；在readFileBuffer中返回一位数的值，而上一行中的“n”返回确切的文件长度，这意味着fread可以工作：（谢谢你的观点。我正在重新使用readFileBuffer函数来读取base64编码的文件以及二进制文件，这就是为什么你会看到使用strlen的原因。但是我没有意识到这对于二进制文件来说是失败的。有没有办法使用通用的文件读取函数（我的代码太大了）…谢谢
EVP\u MAX\u MD\u SIZE
的值是什么？Openssl\u add\u all\u digests（）的头文件是什么。？