feat: Implement DigiID URI generation and define core types

- Create initial source directory structure (src/).
- Define core interfaces (DigiIDUriOptions, DigiIDCallbackData, etc.) and DigiIDError class in src/types.ts.
- Set up main export file src/index.ts.
- Implement the generateDigiIDUri function in src/digiid.ts for creating DigiID authentication URIs according to the specification.
- Include helper function for generating secure nonces using Node crypto.
- Add TSDoc comments for clarity and maintainability.

1 files changed, 55 insertions, 0 deletions

diff --git a/src/types.ts b/src/types.ts
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index 0000000..937cfd2
--- /dev/null
+++ b/src/types.ts
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+/**
+ * Options for generating a DigiID URI.
+ */
+export interface DigiIDUriOptions {
+  /** The full URL that the user's DigiID wallet will send the verification data back to. */
+  callbackUrl: string;
+  /** A unique, unpredictable nonce (number used once) for this authentication request. If not provided, a secure random one might be generated (implementation specific). */
+  nonce?: string;
+  /** Set to true for testing over HTTP (insecure), defaults to false (HTTPS required). */
+  unsecure?: boolean;
+}
+
+/**
+ * Data structure typically received from the DigiID wallet callback.
+ */
+export interface DigiIDCallbackData {
+  /** The DigiByte address used for signing. */
+  address: string;
+  /** The DigiID URI that was originally presented to the user. */
+  uri: string;
+  /** The signature proving ownership of the address, signing the URI. */
+  signature: string;
+}
+
+/**
+ * Options for verifying a DigiID callback.
+ */
+export interface DigiIDVerifyOptions {
+  /** The expected callback URL (or parts of it, like domain/path) that should match the one in the received URI. */
+  expectedCallbackUrl: string | URL;
+  /** The specific nonce that was originally generated for this authentication attempt, to prevent replay attacks. */
+  expectedNonce?: string;
+}
+
+/**
+ * Result of a successful DigiID verification.
+ */
+export interface DigiIDVerificationResult {
+  /** Indicates the verification was successful. */
+  isValid: true;
+  /** The DigiByte address that was successfully verified. */
+  address: string;
+  /** The nonce extracted from the verified URI. */
+  nonce: string;
+}
+
+/**
+ * Represents an error during DigiID processing.
+ */
+export class DigiIDError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = 'DigiIDError';
+  }
+}