I need to sign a JWT using an RSA private key (.pem) inside a SnapLogic pipeline to authenticate a REST call via HTTP Client Snap. Planning to use a Script Snap (Python). What's the recommended way to store the PEM securely? Pipeline parameter, SLFS, or another approach? Also, which Python libraries are available in the Script Snap runtime for JWT signing (RS256)?
Hi Alan - Here is what SnapGPT recommended, to get you some things to consider quickly: This covers three important areas: secure PEM storage, Python JWT libraries in Script Snap, and wiring it all together. Let me break this down thoroughly. 🔐 1. Secure PEM Storage — Recommendations Here's a ranked comparison of your options: ✅ Option A: SnapLogic Secrets Management (Most Secure — Recommended) If you're on a Groundplex, this is the gold standard:
Integrates withAWS Secrets Manager,Azure Key Vault,HashiCorp Vault, orCyberArk Conjur
The PEM keynever touches SnapLogic storage— it's fetched at runtime directly from your secrets manager
Supports aSecrets Cachefor performance optimization on frequent calls
⚠️Only available on Groundplexes, not Cloudplexes
✅ Option B: SnapLogic File System (SLFS) (Good for Groundplex/Cloudplex)
Upload the.pemfile to theSnapLogic Manager > Filessection (SLDB)
Reference it in your Script Snap via apipeline parameterpointing to the SLFS path (e.g.,sldb:///your-project/keys/private.pem)
Access is controlled by SnapLogic project-level permissions
The file is encrypted at rest in SnapLogic's secure S3 bucket
⚠️ Option C: Pipeline Parameter (Convenient but Less Ideal)
You can store the PEM string as asensitive pipeline parameter
SnapLogic encrypts sensitive parameters using org-level asymmetric key encryption
However, the key material is visible to anyone with pipeline edit access
Known limitation: Multi-line PEM keys passed via Pipeline Execute Snap require explicit\nnewline characters to be interpreted correctly
Best used only fornon-production/devscenarios
❌ Avoid: Hardcoding in Script Never embed the PEM directly in the Script Snap code — no encryption, fully visible in pipeline config. 🐍 2. Python Libraries Available in Script Snap for JWT/RS256
⚠️ Critical caveat: The Script Snap runs on Jython 2.7.x (JVM-based Python), not CPython. This has major implications for library availability.
What's available natively (Jython + JVM): LibraryAvailable?Notesjava.security / javax.crypto✅ YesFull JVM crypto — can do RSA signingorg.bouncycastle✅ Likely (if on Groundplex)Powerful crypto librarybase64, hashlib, hmac✅ Yes (Jython stdlib)Basic crypto primitivesjson✅ YesStandard JythonPyJWT❌ NoCPython-only, not installable in Jythoncryptography (Python pkg)❌ NoRequires CPython C extensionspython-jose❌ NoCPython-only ✅ Recommended Approach: Use Java Crypto via Jython Since Jython has full access to the JVM, you can use Java's built-in RSA signing directly:
from com.snaplogic.scripting.language import ScriptHook
import java.security.KeyFactory as KeyFactory
import java.security.Signature as Signature
import java.security.spec.PKCS8EncodedKeySpec as PKCS8EncodedKeySpec
import java.util.Base64 as Base64
import json
class JWTScript(ScriptHook):
def __init__(self, input, output, error, log):
self.input = input
self.output = output
self.error = error
self.log = log
def base64url_encode(self, data):
encoder = Base64.getUrlEncoder().withoutPadding()
if isinstance(data, str):
data = data.encode('utf-8')
return encoder.encodeToString(data).rstrip('=')
def sign_jwt(self, header, payload, pem_key_str):
# Strip PEM headers and decode
pem_clean = pem_key_str \
.replace("-----BEGIN PRIVATE KEY-----", "") \
.replace("-----END PRIVATE KEY-----", "") \
.replace("-----BEGIN RSA PRIVATE KEY-----", "") \
.replace("-----END RSA PRIVATE KEY-----", "") \
.replace("\n", "").strip()
key_bytes = Base64.getDecoder().decode(pem_clean)
key_spec = PKCS8EncodedKeySpec(key_bytes)
kf = KeyFactory.getInstance("RSA")
private_key = kf.generatePrivate(key_spec)
header_enc = self.base64url_encode(json.dumps(header))
payload_enc = self.base64url_encode(json.dumps(payload))
signing_input = "%s.%s" % (header_enc, payload_enc)
signer = Signature.getInstance("SHA256withRSA")
signer.initSign(private_key)
signer.update(signing_input.encode('utf-8'))
sig_bytes = signer.sign()
signature = self.base64url_encode(sig_bytes)
return "%s.%s" % (signing_input, signature)
def execute(self):
while self.input.hasNext():
data = self.input.next()
pem_key = data.get("pem_key") # passed in from pipeline param or SLFS
header = {"alg": "RS256", "typ": "JWT"}
payload = {"sub": "service-account", "iss": "your-client-id", "iat": 1234567890}
token = self.sign_jwt(header, payload, pem_key)
self.output.write({"jwt_token": token})
hook = JWTScript(input, output, error, log)💡 Note: If your PEM is in PKCS#1 format (BEGIN RSA PRIVATE KEY), you may need BouncyCastle to parse it. PKCS#8 format (BEGIN PRIVATE KEY) works directly with Java's KeyFactory.
🔗 3. Recommended End-to-End Architecture
[Pipeline Param / SLFS]
↓ (PEM key injected)
[Script Snap — Jython RS256 JWT signing]
↓ (outputs JWT token)
[Mapper Snap — builds Authorization header]
↓
[HTTP Client Snap — REST call with Bearer token]📋 Summary Recommendations ConcernRecommendationPEM StorageSecrets Management (Groundplex) > SLFS > Pipeline ParamJWT Signing LibraryUse Java Signature (SHA256withRSA) via Jython JVM interopPEM FormatConvert to PKCS#8 for easiest Java compatibilitySecure Python ModeBe aware of scripting.python.security.enabled — if enabled on your Snaplex, some modules may be blockedNewlines in PEMWhen passing via Pipeline Execute, use explicit \n characters