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AbstractCryptoClient.php
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AesDecryptingStream.php
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AesDecryptingStream.php
147 lines
| 1 | <?php |
| 2 | namespace Aws\Crypto; |
| 3 | |
| 4 | use GuzzleHttp\Psr7\StreamDecoratorTrait; |
| 5 | use \LogicException; |
| 6 | use Psr\Http\Message\StreamInterface; |
| 7 | use Aws\Crypto\Cipher\CipherMethod; |
| 8 | |
| 9 | /** |
| 10 | * @internal Represents a stream of data to be decrypted with passed cipher. |
| 11 | */ |
| 12 | class AesDecryptingStream implements AesStreamInterface |
| 13 | { |
| 14 | const BLOCK_SIZE = 16; // 128 bits |
| 15 | |
| 16 | use StreamDecoratorTrait; |
| 17 | |
| 18 | /** |
| 19 | * @var string |
| 20 | */ |
| 21 | private $buffer = ''; |
| 22 | |
| 23 | /** |
| 24 | * @var CipherMethod |
| 25 | */ |
| 26 | private $cipherMethod; |
| 27 | |
| 28 | /** |
| 29 | * @var string |
| 30 | */ |
| 31 | private $key; |
| 32 | |
| 33 | /** |
| 34 | * @var StreamInterface |
| 35 | */ |
| 36 | private $stream; |
| 37 | |
| 38 | /** |
| 39 | * @param StreamInterface $cipherText |
| 40 | * @param string $key |
| 41 | * @param CipherMethod $cipherMethod |
| 42 | */ |
| 43 | public function __construct( |
| 44 | StreamInterface $cipherText, |
| 45 | $key, |
| 46 | CipherMethod $cipherMethod |
| 47 | ) { |
| 48 | $this->stream = $cipherText; |
| 49 | $this->key = $key; |
| 50 | $this->cipherMethod = clone $cipherMethod; |
| 51 | } |
| 52 | |
| 53 | public function getOpenSslName() |
| 54 | { |
| 55 | return $this->cipherMethod->getOpenSslName(); |
| 56 | } |
| 57 | |
| 58 | public function getAesName() |
| 59 | { |
| 60 | return $this->cipherMethod->getAesName(); |
| 61 | } |
| 62 | |
| 63 | public function getCurrentIv() |
| 64 | { |
| 65 | return $this->cipherMethod->getCurrentIv(); |
| 66 | } |
| 67 | |
| 68 | public function getSize(): ?int |
| 69 | { |
| 70 | $plainTextSize = $this->stream->getSize(); |
| 71 | |
| 72 | if ($this->cipherMethod->requiresPadding()) { |
| 73 | // PKCS7 padding requires that between 1 and self::BLOCK_SIZE be |
| 74 | // added to the plaintext to make it an even number of blocks. The |
| 75 | // plaintext is between strlen($cipherText) - self::BLOCK_SIZE and |
| 76 | // strlen($cipherText) - 1 |
| 77 | return null; |
| 78 | } |
| 79 | |
| 80 | return $plainTextSize; |
| 81 | } |
| 82 | |
| 83 | public function isWritable(): bool |
| 84 | { |
| 85 | return false; |
| 86 | } |
| 87 | |
| 88 | public function read($length): string |
| 89 | { |
| 90 | if ($length > strlen($this->buffer)) { |
| 91 | $this->buffer .= $this->decryptBlock( |
| 92 | (int) ( |
| 93 | self::BLOCK_SIZE * ceil(($length - strlen($this->buffer)) / self::BLOCK_SIZE) |
| 94 | ) |
| 95 | ); |
| 96 | } |
| 97 | |
| 98 | $data = substr($this->buffer, 0, $length); |
| 99 | $this->buffer = substr($this->buffer, $length); |
| 100 | |
| 101 | return $data ? $data : ''; |
| 102 | } |
| 103 | |
| 104 | public function seek($offset, $whence = SEEK_SET): void |
| 105 | { |
| 106 | if ($offset === 0 && $whence === SEEK_SET) { |
| 107 | $this->buffer = ''; |
| 108 | $this->cipherMethod->seek(0, SEEK_SET); |
| 109 | $this->stream->seek(0, SEEK_SET); |
| 110 | } else { |
| 111 | throw new LogicException('AES encryption streams only support being' |
| 112 | . ' rewound, not arbitrary seeking.'); |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | private function decryptBlock($length) |
| 117 | { |
| 118 | if ($this->stream->eof()) { |
| 119 | return ''; |
| 120 | } |
| 121 | |
| 122 | $cipherText = ''; |
| 123 | do { |
| 124 | $cipherText .= $this->stream->read((int) ($length - strlen($cipherText))); |
| 125 | } while (strlen($cipherText) < $length && !$this->stream->eof()); |
| 126 | |
| 127 | $options = OPENSSL_RAW_DATA; |
| 128 | if (!$this->stream->eof() |
| 129 | && $this->stream->getSize() !== $this->stream->tell() |
| 130 | ) { |
| 131 | $options |= OPENSSL_ZERO_PADDING; |
| 132 | } |
| 133 | |
| 134 | $plaintext = openssl_decrypt( |
| 135 | $cipherText, |
| 136 | $this->cipherMethod->getOpenSslName(), |
| 137 | $this->key, |
| 138 | $options, |
| 139 | $this->cipherMethod->getCurrentIv() |
| 140 | ); |
| 141 | |
| 142 | $this->cipherMethod->update($cipherText); |
| 143 | |
| 144 | return $plaintext; |
| 145 | } |
| 146 | } |
| 147 |