feat: Add environment variable support for DID registration

- Bash implementation of DID creation-registration
- Move admin credentials to .env file for better security
- Add .env.example with default values
- Add dotenv support to TypeScript, Python and Bash implementations
- Update dependencies to include dotenv packages
- Fix JWT signature format in Bash implementation
- Add DER signature parsing for ES256K in Bash script

The admin DID and private key can now be configured via environment
variables, with fallback to default values if not set. This allows
for easier testing and deployment across different environments.

test-scripts/did_generator.ts

@@ -18,6 +18,7 @@
  *   ethers: For Ethereum account operations
  *   node-fetch: For API communication
  *   commander: For CLI argument parsing
+ *   dotenv: For environment variable loading
  * 
  * Usage:
  *   npm run generate-did -- [options]
@@ -37,16 +38,20 @@ import * as didJwt from 'did-jwt';
 import { ethers } from 'ethers';
 import fetch from 'node-fetch';
 import { program } from 'commander';
+import * as dotenv from 'dotenv';
+import { config } from 'dotenv';
 
-const admin_keypair  = { 
-  did: 'did:ethr:0x0000694B58C2cC69658993A90D3840C560f2F51F', 
-  privateKey: '2b6472c026ec2aa2c4235c994a63868fc9212d18b58f6cbfe861b52e71330f5b' 
-}
-// Default admin DID
+// Load environment variables
+config();
+
+const admin_keypair = {
+  did: process.env.ADMIN_DID || 'did:ethr:0x0000694B58C2cC69658993A90D3840C560f2F51F',
+  privateKey: process.env.ADMIN_PRIVATE_KEY || '2b6472c026ec2aa2c4235c994a63868fc9212d18b58f6cbfe861b52e71330f5b'
+};
+
+// Default values from environment
 const DEFAULT_ADMIN_DID = admin_keypair.did;
-
-// Add constant for default API URL
-const DEFAULT_API_URL = 'https://test-api.endorser.ch/api/v2/claim';
+const DEFAULT_API_URL = process.env.ENDORSER_API_URL || 'https://test-api.endorser.ch/api/v2/claim';
 
 /**
  * Result interface for DID creation process