AcornSSL is the RISC OS TLS module used by browser and network clients. This port is version 1.09 and is built against Mbed TLS 4.1.0.
The module identifies itself as:
AcornSSL 1.09 (23 May 2026) (Mbed TLS 4.1.0)
- Updated the compatibility layer for the Mbed TLS 4.1.0 API and PSA crypto interface.
- Updated socket, timeout, certificate-confirmation and upcall handling for the current TCPIPLibs interfaces.
- Added a RISC OS boolean compatibility header and explicit resource generation input for reproducible DDE builds.
- Added DDE/AMU defaults for the Mbed TLS, AsmUtils, Toolbox, Wimp and TCP/IP libraries.
- Uses CMunge to generate the 32-bit module header and exports the linked Mbed TLS version in the module help text.
Build from a RISC OS DDE or AMU environment with the Mbed TLS 4.1.0 export and TCPIPLibs available:
riscos-amu
The default build produces the 32-bit RAM module at:
rm32/AcornSSL,ffa
The Mbed TLS include and library locations can be overridden when invoking AMU:
riscos-amu MBEDTLSINC=-IC:mbedTLS MBEDTLSLIB=C:mbedTLS.o.mbedTLSzm-32
The module build uses the project licence in LICENCE.
AcornSSL uses the CryptRandom_Block SWI when the CryptRandom module is
available. It has a fallback entropy source, but systems using CryptRandom
should load CryptRandom before AcornSSL during boot. CryptRandom 0.13 is
installed as System:Modules.CryptRand and AcornSSL 1.09 as
System:Modules.Network.URL.AcornSSL:
RMEnsure CryptRandom 0.13 RMLoad System:Modules.CryptRand
RMEnsure CryptRandom 0.13 Error CryptRandom 0.13 or later is required
RMEnsure AcornSSL 1.09 RMLoad System:Modules.Network.URL.AcornSSL
RMEnsure AcornSSL 1.09 Error AcornSSL 1.09 or later is required
Keep these lines in this order in the boot sequence. Loading AcornSSL before CryptRandom means its initialisation may use the fallback instead.