XCA - X Certificate and key management: RSA, DSA and EC Keys

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## 7. RSA, DSA and EC Keys

For creating certificates, keys are needed. All keys are stored encrypted in the database using the 3DES algorithm. The password can be changed for each key. The password type means:

- common: The database password provided during database load
- private: The key has its own password, which is not stored by XCA. This can be set and reset via the context menu of the key
- PIN: Security tokens are usually protected by a PIN
- No password: Public keys don't need a password

All keys carry a use counter which counts the times it is used. When creating new requests or certificates the list of available keys is reduced to the keys with a use counter of 0. This can be overridden by the checkbox next to the key list.

When importing an EC key with explicit curve parameters, the corresponding curve OID is searched and set if found.

## 7.1 Generating Keys

The dialog asks for the internal name of the key and the keysize in bits. For EC keys, a list of curves is shown. It contains all X9.62 curves and many others.

EC Brainpool curves are also supported when linking with OpenSSL 1.0.2.

Even if the drop-down list only shows the most usual key sizes, any other value may be set here by editing this box. While searching for random prime numbers a progress bar is shown in the bottom of the base application. After the key generation is done the key will be stored in the database.

When checking the `Remember as default` box, the settings (Key-type, key-size or EC curve) will be remembered and preset for the next key generation dialog. This option is not available when generating token keys.

For every connected token providing the Key-generate facility an entry in the drop-down menu of the keytypes will be shown. It contains the name of the token and the valid key-sizes.

In case of EC keys generated on a token, the list of possible curves is restricted based on informations provided by the token (Key size and FP/F2M). The token may support even less ECParameters / OIDs. When selecting an EC curve not supported by the token an error will occure. Please consult the documentation of the provider of the PKCS#11 library.

## 7.2 Key Export

Keys can be exported by either selecting the key and pressing Export or by using the context-menu. It may be chosen to export the key to the clipboard as PEM public, SSH2 public or unencrypted PEM private format. In case of a file export a dialogbox opens where next to the filename one of the following formats may be selected:

- PEM public the public part of the key in PEM format
- DER public the public part of the key in DER format
- SSH2 public the public part of the key in SSH2 format
- PEM private the private key unencrypt in PEM format
- PKCS#8 encrypted the encrypted private key in PKCS#8 format
- DER private the private key in binary DER format
- PEM encrypted the private key in PEM format with an OpenSSL specific extensions for encryption
- PKCS#8 unencrypted the private key unencrypted in PKCS#8 format

The filename is the internal name plus a `pem`, `der`, `pk8` or `pub` suffix. When changing the fileformat, the suffix of the filename changes accordingly. Only PKCS#8 or PEM files can be encrypted, because the DER format (although it could be encrypted) does not support a way to supply the encryption algorithm like e.g. `DES`. Of course, encryption does not make sense if the private part is not exported.

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