How to Implement MD5 Encoding in Tizen Native Application

Original Created Jun 16, 2016 | Regeneration Apr 22, 2026

Question

I'm trying to implement MD5 encoding functionality in a Tizen Native application. I've written the following code using OpenSSL's MD5 functions:

#include <openssl/md5.h>

char lsBuff[] = "abc";
unsigned char lucpMD5[100];
unsigned long lulLen = strlen(lsBuff);
MD5_CTX lmdContext;

MD5_Init(&lmdContext);
MD5_Update(&lmdContext, lsBuff, lulLen);
MD5_Final(lucpMD5, &lmdContext);
dlog_print(DLOG_INFO, "tag", "MD5 result: %s", lucpMD5);

However, when encoding "abc", I get this output:

MD5 result: РPШ<╥O░╓Ц?}(сr░Юл╕╕Ц│╕иuр┐√Dм╢алл╕

The correct MD5 hash for "abc" should be:

900150983cd24fb0d6963f7d28e17f72

How can I fix this issue to get the proper MD5 hash output?

Answer

Problem Understanding

The issue occurs because the MD5 hash is being printed directly as a string, while it's actually a binary digest. To display it correctly, you need to convert the binary hash to a hexadecimal string representation.

Solution Methods

Convert binary MD5 hash to hexadecimal string:
- The MD5 hash is 16 bytes long (128 bits)
- Each byte should be converted to two hexadecimal characters
- The final string should be 32 characters long
Use proper string formatting:
- Use sprintf with %02x format specifier
- Ensure proper buffer size for the hexadecimal string

Code Examples

Here's a complete working example:

char* get_md5_hash(const char* input) {
    unsigned char digest[MD5_DIGEST_LENGTH];
    MD5_CTX context;
    
    MD5_Init(&context);
    MD5_Update(&context, input, strlen(input));
    MD5_Final(digest, &context);
    
    char* hash = malloc(33); // 32 characters + null terminator
    for(int i = 0; i < 16; i++) {
        sprintf(&hash[i*2], "%02x", (unsigned int)digest[i]);
    }
    hash[32] = '\0';
    
    return hash;
}

// Usage example:
char* md5_hash = get_md5_hash("abc");
dlog_print(DLOG_INFO, "MD5", "Hash: %s", md5_hash);
free(md5_hash);

Additional Tips

Remember to free the allocated memory after use
For security purposes, consider using more secure hashing algorithms than MD5 when possible
The hexadecimal output should always be 32 characters long for MD5
Test with known values to verify your implementation (e.g., "abc" should produce "900150983cd24fb0d6963f7d28e17f72")