fairnesscoop / permacoop

import {Injectable} from '@nestjs/common';

import {ConfigService} from '@nestjs/config';

import {IFileEncryption} from 'src/Application/IFileEncryption';

@Injectable()

export class FileEncryptionAdapter implements IFileEncryption {

  constructor(private readonly configService: ConfigService) {}

  public async decrypt(buffer: Buffer): Promise<Buffer> {

    const key = await this.getEncryptionKey();

    const iv = buffer.slice(0, 16);

    const decipher = crypto.createDecipheriv('aes-256-ctr', key, iv);

    return Buffer.concat([decipher.update(buffer.slice(16)), decipher.final()]);

  }

  private async getEncryptionKey(): Promise<string> {

    const key = await this.configService.get<string>('FILE_ENCRYPTION_KEY');

    return crypto

      .createHash('sha256')

      .update(key)

      .digest('base64')

      .substr(0, 32);

  }

}