jsrsasign
opensource free pure JavaScript cryptographic library supports RSA/RSAPSS/ECDSA/DSA signing/validation, ASN.1, PKCS#1/5/8 private/public key, X.509 certificate, CRL, OCSP, CMS SignedData, TimeStamp and CAdES and JSON Web Signature(JWS)/Token(JWT)/Key(JWK)
eosjs-ecc
Elliptic curve cryptography functions
paytmchecksum
This is for paytm checksum creation and verification in node
s3-policy-v4
Amazon AWS S3 Upload Policy Generator with Signature Version 4