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```bash
┌──(kali㉿kali)-[~/Desktop/babyrev]
└─$ file baby-rev
baby-rev: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=995dafe783aef67cc95910e4f3c2a0152eeb34c0, for GNU/Linux 3.2.0, not stripped
```

If we use Ghidra to analyze the file we can see this code in the main function

```C
printf("Enter a string: ");
fgets(userInput,32,stdin);
sVar1 = strlen(userInput);
if (sVar1 == 24) {
myfunc(userInput);
}
else {
puts(":P\n");
```

If we enter a string that is 23 characters + the newline character we should execute `myfunc()` which looks like the following:

```C
void myfunc(char *inputStr)

{
if (*inputStr == 'B') {
if (((((((inputStr[4] == 'C') && (inputStr[13] == 'm')) && (inputStr[19] == 'r')) &&
(((inputStr[3] == 'S' && (inputStr[10] == 'l')) &&
((inputStr[2] == 'T' && ((inputStr[14] == 'e' && (inputStr[17] == '0')))))))) &&
((inputStr[22] == '}' &&
(((inputStr[7] == '{' && (inputStr[5] == 'T')) && (inputStr[15] == '_')))))) &&
(((inputStr[1] == 'I' && (inputStr[21] == 'v')) &&
(((inputStr[8] == 'w' && ((inputStr[11] == 'c' && (inputStr[6] == 'F')))) &&
(inputStr[20] == '3')))))) &&
((((inputStr[9] == '3' && (inputStr[12] == '0')) && (inputStr[16] == 't')) &&
(inputStr[18] == '_')))) {
puts("Yippee :3\n");
}
}
else {
puts(":PP\n");
}
return;
}
```

At this point it's a matter of reversing what the inputStr character indexes are. Which is:

Flag: `BITSCTF{w3lc0me_t0_r3v}`