# Decrypting received files

## Using a public key

Kryptor will convert the shared secret for the (recipient private, sender public) key pair into the unique encryption key per file/directory used for encryption.

The sender cannot decrypt the files/directories they sent; only you (the recipient) and any other recipients can.

**You must specify your private key and the sender's public key**. You'll be asked to decrypt your private key using your passphrase. For security reasons, this involves a slight delay.

Here's an example of how to use your default encryption private key:

```bash
$ kryptor -d -y Cu//2M5FqAnxmW7PiKxIqLmKEPNxT1Kdkm4U3K/Gr++6OAQ= file.txt.bin

Enter your private key passphrase:

```

Here's an example using a private key not stored in the [default folder](/tutorial/generating-a-new-key-pair.md):

```bash
$ kryptor -d -x:"C:\Users\samuel-lucas6\Documents\encryption.private" -y Cu//2M5FqAnxmW7PiKxIqLmKEPNxT1Kdkm4U3K/Gr++6OAQ= file.txt.bin

Enter your private key passphrase:

```

## Using a symmetric key

Kryptor will convert the symmetric key into the unique encryption key per file/directory used for encryption. Unlike using a passphrase, this involves no delay.

Here's an example:

```bash
$ kryptor -d -k PSK/I1SkTbgoylRxiW3w0wcYmovWTWgC54bPmpgsiQrgO3c= file.txt.bin
```


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# Agent Instructions: Querying This Documentation

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Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://www.kryptor.co.uk/tutorial/decrypting-received-files.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.