> For the complete documentation index, see [llms.txt](https://kunalwalavalkar.gitbook.io/write-ups/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://kunalwalavalkar.gitbook.io/write-ups/pwn-college/cryptography.md).

# Cryptography

### level 1

```python
import base64

base64.b64decode("cHduLmNvbGxlZ2V7SUwyV284RkdzQjRvNEg3UkVpMjlYUmkzeXp4LmROek56TURMNElUTTBFeld9Cg==")
```

### level 2

```python
import base64
from Crypto.Util.strxor import strxor

ciphertext=base64.b64decode("2OLWcZzJlxZ+pqS0A59Pn4CxMYdtJUmDnhoR3x/pzo+tzUosLHytSWDcdt71zghRjXv481xlREfT1Q==")

key=base64.b64decode("qJW4X/+m+3obwcHPRux799rpB80Fdyyz/XJai1qghuX9tAtqZBXDZwSODJCPg0wduTKsvmwgPhCu3w==")

plaintext=strxor(ciphertext, key)
print(plaintext)
```

### level 3

```python
import base64
from Crypto.Util.strxor import strxor

ciphertext=base64.b64decode("mUu7sNhvINsTVBpt8ySk9TfshaB3gGPzc0MboO2UkYxdYuuICZCJASCKXwweHS6tcx6EIEj+Baci6g==")

key=base64.b64decode("qJW4X/+m+3obwcHPRux799rpB80Fdyyz/XJai1qghuX9tAtqZBXDZwSODJCPg0wduTKsvmwgPhCu3w==")

plaintext=strxor(ciphertext, key[:len(ciphertext)])
print(plaintext)
```

### level 4

```python
import base64

key=base64.b64decode("lKkw1ElUb6K4mmurnviL4w==")

ciphertext=base64.b64decode("rLvZ0htETOsVy1sr8LnZFmcj5Z22Vlxx3csUYlNDDxavCUSRUmW71YWNwTQWVqVgrXDwvjSIzorUnlMvSQHVmA==")

cipher=AES.new(key=key, mode=AES.MODE_ECB)

plaintext=cipher.decrypt(ciphertext)
print(plaintext)
```

### level 9

```python
i = 0
while True:
	hash = SHA256Hash(str(i).encode()).hexdigest()[:4]
	if hash == 'tDc=':
		print(i)
		break
	i += 1 
```

### level 11

```python
```