CipherBuilderTrait.php
72 lines
| 1 | <?php |
| 2 | namespace Aws\Crypto\Cipher; |
| 3 | |
| 4 | use Aws\Exception\CryptoException; |
| 5 | |
| 6 | trait CipherBuilderTrait |
| 7 | { |
| 8 | /** |
| 9 | * Returns an identifier recognizable by `openssl_*` functions, such as |
| 10 | * `aes-256-cbc` or `aes-128-ctr`. |
| 11 | * |
| 12 | * @param string $cipherName Name of the cipher being used for encrypting |
| 13 | * or decrypting. |
| 14 | * @param int $keySize Size of the encryption key, in bits, that will be |
| 15 | * used. |
| 16 | * |
| 17 | * @return string |
| 18 | */ |
| 19 | protected function getCipherOpenSslName($cipherName, $keySize) |
| 20 | { |
| 21 | return "aes-{$keySize}-{$cipherName}"; |
| 22 | } |
| 23 | |
| 24 | /** |
| 25 | * Constructs a CipherMethod for the given name, initialized with the other |
| 26 | * data passed for use in encrypting or decrypting. |
| 27 | * |
| 28 | * @param string $cipherName Name of the cipher to generate for encrypting. |
| 29 | * @param string $iv Base Initialization Vector for the cipher. |
| 30 | * @param int $keySize Size of the encryption key, in bits, that will be |
| 31 | * used. |
| 32 | * |
| 33 | * @return CipherMethod |
| 34 | * |
| 35 | * @internal |
| 36 | */ |
| 37 | protected function buildCipherMethod($cipherName, $iv, $keySize) |
| 38 | { |
| 39 | switch ($cipherName) { |
| 40 | case 'cbc': |
| 41 | return new Cbc( |
| 42 | $iv, |
| 43 | $keySize |
| 44 | ); |
| 45 | default: |
| 46 | return null; |
| 47 | } |
| 48 | } |
| 49 | |
| 50 | /** |
| 51 | * Performs a reverse lookup to get the openssl_* cipher name from the |
| 52 | * AESName passed in from the MetadataEnvelope. |
| 53 | * |
| 54 | * @param $aesName |
| 55 | * |
| 56 | * @return string |
| 57 | * |
| 58 | * @internal |
| 59 | */ |
| 60 | protected function getCipherFromAesName($aesName) |
| 61 | { |
| 62 | switch ($aesName) { |
| 63 | case 'AES/GCM/NoPadding': |
| 64 | return 'gcm'; |
| 65 | case 'AES/CBC/PKCS5Padding': |
| 66 | return 'cbc'; |
| 67 | default: |
| 68 | throw new CryptoException('Unrecognized or unsupported' |
| 69 | . ' AESName for reverse lookup.'); |
| 70 | } |
| 71 | } |
| 72 | } |