Cipher
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Polyfill
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AbstractCryptoClient.php
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AbstractCryptoClientV2.php
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AesDecryptingStream.php
11 months ago
AesEncryptingStream.php
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AesGcmDecryptingStream.php
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AesGcmEncryptingStream.php
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AesStreamInterface.php
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AesStreamInterfaceV2.php
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DecryptionTrait.php
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DecryptionTraitV2.php
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EncryptionTrait.php
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EncryptionTraitV2.php
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KmsMaterialsProvider.php
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KmsMaterialsProviderV2.php
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MaterialsProvider.php
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MaterialsProviderInterface.php
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MaterialsProviderInterfaceV2.php
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MaterialsProviderV2.php
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MetadataEnvelope.php
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MetadataStrategyInterface.php
11 months ago
DecryptionTraitV2.php
250 lines
| 1 | <?php |
| 2 | namespace Aws\Crypto; |
| 3 | |
| 4 | use Aws\Exception\CryptoException; |
| 5 | use GuzzleHttp\Psr7; |
| 6 | use GuzzleHttp\Psr7\LimitStream; |
| 7 | use Psr\Http\Message\StreamInterface; |
| 8 | |
| 9 | trait DecryptionTraitV2 |
| 10 | { |
| 11 | /** |
| 12 | * Dependency to reverse lookup the openssl_* cipher name from the AESName |
| 13 | * in the MetadataEnvelope. |
| 14 | * |
| 15 | * @param $aesName |
| 16 | * |
| 17 | * @return string |
| 18 | * |
| 19 | * @internal |
| 20 | */ |
| 21 | abstract protected function getCipherFromAesName($aesName); |
| 22 | |
| 23 | /** |
| 24 | * Dependency to generate a CipherMethod from a set of inputs for loading |
| 25 | * in to an AesDecryptingStream. |
| 26 | * |
| 27 | * @param string $cipherName Name of the cipher to generate for decrypting. |
| 28 | * @param string $iv Base Initialization Vector for the cipher. |
| 29 | * @param int $keySize Size of the encryption key, in bits, that will be |
| 30 | * used. |
| 31 | * |
| 32 | * @return Cipher\CipherMethod |
| 33 | * |
| 34 | * @internal |
| 35 | */ |
| 36 | abstract protected function buildCipherMethod($cipherName, $iv, $keySize); |
| 37 | |
| 38 | /** |
| 39 | * Builds an AesStreamInterface using cipher options loaded from the |
| 40 | * MetadataEnvelope and MaterialsProvider. Can decrypt data from both the |
| 41 | * legacy and V2 encryption client workflows. |
| 42 | * |
| 43 | * @param string $cipherText Plain-text data to be encrypted using the |
| 44 | * materials, algorithm, and data provided. |
| 45 | * @param MaterialsProviderInterfaceV2 $provider A provider to supply and encrypt |
| 46 | * materials used in encryption. |
| 47 | * @param MetadataEnvelope $envelope A storage envelope for encryption |
| 48 | * metadata to be read from. |
| 49 | * @param array $options Options used for decryption. |
| 50 | * |
| 51 | * @return AesStreamInterface |
| 52 | * |
| 53 | * @throws \InvalidArgumentException Thrown when a value in $cipherOptions |
| 54 | * is not valid. |
| 55 | * |
| 56 | * @internal |
| 57 | */ |
| 58 | public function decrypt( |
| 59 | $cipherText, |
| 60 | MaterialsProviderInterfaceV2 $provider, |
| 61 | MetadataEnvelope $envelope, |
| 62 | array $options = [] |
| 63 | ) { |
| 64 | $options['@CipherOptions'] = !empty($options['@CipherOptions']) |
| 65 | ? $options['@CipherOptions'] |
| 66 | : []; |
| 67 | $options['@CipherOptions']['Iv'] = base64_decode( |
| 68 | $envelope[MetadataEnvelope::IV_HEADER] |
| 69 | ); |
| 70 | |
| 71 | $options['@CipherOptions']['TagLength'] = |
| 72 | $envelope[MetadataEnvelope::CRYPTO_TAG_LENGTH_HEADER] / 8; |
| 73 | |
| 74 | $cek = $provider->decryptCek( |
| 75 | base64_decode( |
| 76 | $envelope[MetadataEnvelope::CONTENT_KEY_V2_HEADER] |
| 77 | ), |
| 78 | json_decode( |
| 79 | $envelope[MetadataEnvelope::MATERIALS_DESCRIPTION_HEADER], |
| 80 | true |
| 81 | ), |
| 82 | $options |
| 83 | ); |
| 84 | $options['@CipherOptions']['KeySize'] = strlen($cek) * 8; |
| 85 | $options['@CipherOptions']['Cipher'] = $this->getCipherFromAesName( |
| 86 | $envelope[MetadataEnvelope::CONTENT_CRYPTO_SCHEME_HEADER] |
| 87 | ); |
| 88 | |
| 89 | $this->validateOptionsAndEnvelope($options, $envelope); |
| 90 | |
| 91 | $decryptionStream = $this->getDecryptingStream( |
| 92 | $cipherText, |
| 93 | $cek, |
| 94 | $options['@CipherOptions'] |
| 95 | ); |
| 96 | unset($cek); |
| 97 | |
| 98 | return $decryptionStream; |
| 99 | } |
| 100 | |
| 101 | private function getTagFromCiphertextStream( |
| 102 | StreamInterface $cipherText, |
| 103 | $tagLength |
| 104 | ) { |
| 105 | $cipherTextSize = $cipherText->getSize(); |
| 106 | if ($cipherTextSize == null || $cipherTextSize <= 0) { |
| 107 | throw new \RuntimeException('Cannot decrypt a stream of unknown' |
| 108 | . ' size.'); |
| 109 | } |
| 110 | return (string) new LimitStream( |
| 111 | $cipherText, |
| 112 | $tagLength, |
| 113 | $cipherTextSize - $tagLength |
| 114 | ); |
| 115 | } |
| 116 | |
| 117 | private function getStrippedCiphertextStream( |
| 118 | StreamInterface $cipherText, |
| 119 | $tagLength |
| 120 | ) { |
| 121 | $cipherTextSize = $cipherText->getSize(); |
| 122 | if ($cipherTextSize == null || $cipherTextSize <= 0) { |
| 123 | throw new \RuntimeException('Cannot decrypt a stream of unknown' |
| 124 | . ' size.'); |
| 125 | } |
| 126 | return new LimitStream( |
| 127 | $cipherText, |
| 128 | $cipherTextSize - $tagLength, |
| 129 | 0 |
| 130 | ); |
| 131 | } |
| 132 | |
| 133 | private function validateOptionsAndEnvelope($options, $envelope) |
| 134 | { |
| 135 | $allowedCiphers = AbstractCryptoClientV2::$supportedCiphers; |
| 136 | $allowedKeywraps = AbstractCryptoClientV2::$supportedKeyWraps; |
| 137 | if ($options['@SecurityProfile'] == 'V2_AND_LEGACY') { |
| 138 | $allowedCiphers = array_unique(array_merge( |
| 139 | $allowedCiphers, |
| 140 | AbstractCryptoClient::$supportedCiphers |
| 141 | )); |
| 142 | $allowedKeywraps = array_unique(array_merge( |
| 143 | $allowedKeywraps, |
| 144 | AbstractCryptoClient::$supportedKeyWraps |
| 145 | )); |
| 146 | } |
| 147 | |
| 148 | $v1SchemaException = new CryptoException("The requested object is encrypted" |
| 149 | . " with V1 encryption schemas that have been disabled by" |
| 150 | . " client configuration @SecurityProfile=V2. Retry with" |
| 151 | . " V2_AND_LEGACY enabled or reencrypt the object."); |
| 152 | |
| 153 | if (!in_array($options['@CipherOptions']['Cipher'], $allowedCiphers)) { |
| 154 | if (in_array($options['@CipherOptions']['Cipher'], AbstractCryptoClient::$supportedCiphers)) { |
| 155 | throw $v1SchemaException; |
| 156 | } |
| 157 | throw new CryptoException("The requested object is encrypted with" |
| 158 | . " the cipher '{$options['@CipherOptions']['Cipher']}', which is not" |
| 159 | . " supported for decryption with the selected security profile." |
| 160 | . " This profile allows decryption with: " |
| 161 | . implode(", ", $allowedCiphers)); |
| 162 | } |
| 163 | if (!in_array( |
| 164 | $envelope[MetadataEnvelope::KEY_WRAP_ALGORITHM_HEADER], |
| 165 | $allowedKeywraps |
| 166 | )) { |
| 167 | if (in_array( |
| 168 | $envelope[MetadataEnvelope::KEY_WRAP_ALGORITHM_HEADER], |
| 169 | AbstractCryptoClient::$supportedKeyWraps) |
| 170 | ) { |
| 171 | throw $v1SchemaException; |
| 172 | } |
| 173 | throw new CryptoException("The requested object is encrypted with" |
| 174 | . " the keywrap schema '{$envelope[MetadataEnvelope::KEY_WRAP_ALGORITHM_HEADER]}'," |
| 175 | . " which is not supported for decryption with the current security" |
| 176 | . " profile."); |
| 177 | } |
| 178 | |
| 179 | $matdesc = json_decode( |
| 180 | $envelope[MetadataEnvelope::MATERIALS_DESCRIPTION_HEADER], |
| 181 | true |
| 182 | ); |
| 183 | if (isset($matdesc['aws:x-amz-cek-alg']) |
| 184 | && $envelope[MetadataEnvelope::CONTENT_CRYPTO_SCHEME_HEADER] !== |
| 185 | $matdesc['aws:x-amz-cek-alg'] |
| 186 | ) { |
| 187 | throw new CryptoException("There is a mismatch in specified content" |
| 188 | . " encryption algrithm between the materials description value" |
| 189 | . " and the metadata envelope value: {$matdesc['aws:x-amz-cek-alg']}" |
| 190 | . " vs. {$envelope[MetadataEnvelope::CONTENT_CRYPTO_SCHEME_HEADER]}."); |
| 191 | } |
| 192 | } |
| 193 | |
| 194 | /** |
| 195 | * Generates a stream that wraps the cipher text with the proper cipher and |
| 196 | * uses the content encryption key (CEK) to decrypt the data when read. |
| 197 | * |
| 198 | * @param string $cipherText Plain-text data to be encrypted using the |
| 199 | * materials, algorithm, and data provided. |
| 200 | * @param string $cek A content encryption key for use by the stream for |
| 201 | * encrypting the plaintext data. |
| 202 | * @param array $cipherOptions Options for use in determining the cipher to |
| 203 | * be used for encrypting data. |
| 204 | * |
| 205 | * @return AesStreamInterface |
| 206 | * |
| 207 | * @internal |
| 208 | */ |
| 209 | protected function getDecryptingStream( |
| 210 | $cipherText, |
| 211 | $cek, |
| 212 | $cipherOptions |
| 213 | ) { |
| 214 | $cipherTextStream = Psr7\Utils::streamFor($cipherText); |
| 215 | switch ($cipherOptions['Cipher']) { |
| 216 | case 'gcm': |
| 217 | $cipherOptions['Tag'] = $this->getTagFromCiphertextStream( |
| 218 | $cipherTextStream, |
| 219 | $cipherOptions['TagLength'] |
| 220 | ); |
| 221 | |
| 222 | return new AesGcmDecryptingStream( |
| 223 | $this->getStrippedCiphertextStream( |
| 224 | $cipherTextStream, |
| 225 | $cipherOptions['TagLength'] |
| 226 | ), |
| 227 | $cek, |
| 228 | $cipherOptions['Iv'], |
| 229 | $cipherOptions['Tag'], |
| 230 | $cipherOptions['Aad'] = isset($cipherOptions['Aad']) |
| 231 | ? $cipherOptions['Aad'] |
| 232 | : '', |
| 233 | $cipherOptions['TagLength'] ?: null, |
| 234 | $cipherOptions['KeySize'] |
| 235 | ); |
| 236 | default: |
| 237 | $cipherMethod = $this->buildCipherMethod( |
| 238 | $cipherOptions['Cipher'], |
| 239 | $cipherOptions['Iv'], |
| 240 | $cipherOptions['KeySize'] |
| 241 | ); |
| 242 | return new AesDecryptingStream( |
| 243 | $cipherTextStream, |
| 244 | $cek, |
| 245 | $cipherMethod |
| 246 | ); |
| 247 | } |
| 248 | } |
| 249 | } |
| 250 |