DIDWW Encrypted File Upload — Go Example

A Go example demonstrating how to encrypt and upload a file to the DIDWW API v3 using hybrid encryption (RSA-OAEP + AES-256-CBC).

How It Works

1. Fetch public keys — retrieves two RSA public keys from GET /public_keys (no auth required).
2. Calculate fingerprint — computes SHA1(DER_keyA):::SHA1(DER_keyB) to identify the key pair.
3. Encrypt the file — hybrid encryption:
   • Generates a random AES-256 key and IV.
   • Encrypts file data with AES-256-CBC (PKCS#7 padding).
   • Encrypts the AES key+IV with RSA-OAEP (SHA-256, MGF1-SHA-256) using both public keys.
   • Produces: [RSA_A(key||iv) | RSA_B(key||iv) | AES(data)].
4. Upload — sends the encrypted file via multipart POST /encrypted_files.

Prerequisites

• Go 1.21+
• A DIDWW API key (sign up)

Usage

# Clone the repository
git clone git@github.com:didww/go-encrypt-sample.git
cd go-encrypt-sample

# Run with the included example.pdf
DIDWW_API_KEY=your_api_key go run main.go

# Or build and run
go build -o didww-upload
DIDWW_API_KEY=your_api_key ./didww-upload

Environment Variables

Variable	Required	Default	Description
DIDWW_API_KEY	Yes	—	Your DIDWW API key
DIDWW_API_BASE_URL	No	https://sandbox-api.didww.com/v3	API base URL. Set to https://api.didww.com/v3 for production

Custom File

To upload a different file, update the filePath constant in main.go:

const filePath = "path/to/your/file.pdf"

Example Output

Read example.pdf (589 bytes)
Fingerprint: 66b91934f62a92153c2e86d87e6599703aa82051:::9c82ff6d35e15691c8d8f5a9d297ef5f5b4c1ba5
Encrypted size: 1616 bytes
Uploaded encrypted file IDs: [ac769056-ef70-4162-bc4b-2afb2fe5a05e]

Project Structure

.
├── main.go        # Full encrypt-and-upload implementation
├── example.pdf    # Sample PDF file ("Hello From Go!")
├── go.mod         # Go module definition
└── README.md

Encryption Details

Component	Algorithm	Details
Symmetric encryption	AES-256-CBC	32-byte random key, 16-byte random IV, PKCS#7 padding
Key encryption	RSA-OAEP	SHA-256 hash, MGF1-SHA-256, applied with both public keys
Fingerprint	SHA-1	Hex-encoded SHA-1 of each key's DER bytes, joined by :::

API Endpoints Used

Method	Endpoint	Auth	Description
GET	/public_keys	None	Fetch RSA public keys
POST	/encrypted_files	Api-Key header	Upload encrypted file (multipart)

License

MIT