public static Cipher createAndInitCipher()

in src/main/java/software/amazon/encryption/s3/internal/CipherProvider.java [32:60]
25 lines of code
7 McCabe index (conditional complexity)

    public static Cipher createAndInitCipher(final CryptographicMaterials materials, byte[] iv) {
        // Validate that the IV has been populated. There is a small chance
        // that an IV containing only 0s is (validly) randomly generated,
        // but the tradeoff is worth the protection, and an IV of 0s is
        // not entirely unlike randomly generating "password" as your password.
        if (Arrays.equals(iv, new byte[iv.length])) {
            throw new S3EncryptionClientSecurityException("IV has not been initialized!");
        }
        try {
            Cipher cipher = CryptoFactory.createCipher(materials.algorithmSuite().cipherName(), materials.cryptoProvider());
            switch (materials.algorithmSuite()) {
                case ALG_AES_256_GCM_IV12_TAG16_NO_KDF:
                    cipher.init(materials.cipherMode().opMode(), materials.dataKey(), new GCMParameterSpec(materials.algorithmSuite().cipherTagLengthBits(), iv));
                    break;
                case ALG_AES_256_CTR_IV16_TAG16_NO_KDF:
                case ALG_AES_256_CBC_IV16_NO_KDF:
                    if (materials.cipherMode().opMode() == Cipher.ENCRYPT_MODE) {
                        throw new S3EncryptionClientException("Encryption is not supported for algorithm: " + materials.algorithmSuite().cipherName());
                    }
                    cipher.init(materials.cipherMode().opMode(), materials.dataKey(), new IvParameterSpec(iv));
                    break;
                default:
                    throw new S3EncryptionClientException("Unknown algorithm: " + materials.algorithmSuite().cipherName());
            }
            return cipher;
        } catch (Exception exception) {
            throw new S3EncryptionClientException(exception.getMessage(), exception);
        }
    }