Initial commit: Elydora Open Source — self-hosted audit platform for AI agents

Full self-hosted port of the Elydora tamper-evident audit protocol:
- Hono API server with PostgreSQL, Redis, MinIO adapters
- Ed25519 signed operations, chain hashing, Merkle epoch rollups
- PBKDF2 password hashing, HMAC-SHA256 JWT, 5-role RBAC
- Next.js management console
- Node.js, Python, and Go SDKs
- Docker Compose for local deployment
- Helm chart for Kubernetes
- Comprehensive security hardening and audit fixes applied

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

sdks/python/elydora/utils.py

@@ -0,0 +1,59 @@
+"""Utility helpers: UUIDv7, nonce generation, base64url encoding."""
+
+from __future__ import annotations
+
+import base64
+import os
+import struct
+import time
+
+
+def base64url_encode(data: bytes) -> str:
+    """Encode bytes to base64url string with no padding."""
+    return base64.urlsafe_b64encode(data).rstrip(b"=").decode("ascii")
+
+
+def base64url_decode(s: str) -> bytes:
+    """Decode a base64url string (with or without padding) to bytes."""
+    s = s.replace("-", "+").replace("_", "/")
+    padding = 4 - len(s) % 4
+    if padding != 4:
+        s += "=" * padding
+    return base64.b64decode(s)
+
+
+def generate_nonce() -> str:
+    """Generate a 16-byte random nonce, base64url encoded."""
+    return base64url_encode(os.urandom(16))
+
+
+def generate_uuidv7() -> str:
+    """Generate a UUIDv7 (time-ordered, random) as a string.
+
+    Layout (RFC 9562):
+      - 48-bit Unix timestamp in milliseconds
+      - 4-bit version (0b0111)
+      - 12-bit random
+      - 2-bit variant (0b10)
+      - 62-bit random
+    """
+    timestamp_ms = int(time.time() * 1000)
+
+    # 48-bit timestamp
+    ts_bytes = struct.pack(">Q", timestamp_ms)[2:]  # last 6 bytes of 8-byte big-endian
+
+    # 2 bytes: version (4 bits = 0x7) + 12 random bits
+    rand_a = struct.unpack(">H", os.urandom(2))[0]
+    rand_a = (rand_a & 0x0FFF) | 0x7000  # set version nibble
+
+    # 8 bytes: variant (2 bits = 0b10) + 62 random bits
+    rand_b = bytearray(os.urandom(8))
+    rand_b[0] = (rand_b[0] & 0x3F) | 0x80  # set variant bits
+
+    uuid_bytes = ts_bytes + struct.pack(">H", rand_a) + bytes(rand_b)
+
+    hex_str = uuid_bytes.hex()
+    return (
+        f"{hex_str[0:8]}-{hex_str[8:12]}-{hex_str[12:16]}-"
+        f"{hex_str[16:20]}-{hex_str[20:32]}"
+    )