Hi there,
I've released R6RS Springkussen v1.0.0 today.
https://github.com/ktakashi/r6rs-springkussen/
R6RS Springkussen is a cryptographic library for R6RS Scheme.
The library provides comprehensive cryptographic operations, such as
block ciphers, asymmetric ciphers, certificate, signature, keystore etc.
Cheers,
Takashi