Abstract: Systems and methods for securely passing user authentication data between a Pre-Boot Authentication (PBA) environment and an Operating System (OS) are described. In some embodiments, an Information Handling System (IHS) may include a processor; and a Basic I/O System (BIOS) coupled to the processor, the BIOS having program instructions stored thereon that, upon execution by the processor, cause the computer system to: identify an encrypted Single-Sign-On (SSO) token and a Trusted Platform Module (TPM) key pair provisioned by an Operating System (OS) and stored in an OS registry; extract a TPM public key from the TPM key pair; encrypt a PBA private key generated by a PBA application with the TPM public key; and store the encrypted PBA private key, the TPM key pair, and the encrypted SSO token in a shadow partition of a self-encrypting hard drive coupled to the IHS.