Secret keys and plaintexts are considered highly sensitive information and to securely erase from memory or storage Cosmian KMS implements data zeroization. The term zeroization originates from the process of setting all relevant bits to zero, effectively rendering the data unreadable and unrecoverable. This practice is essential to prevent unwanted memory residue of critical data, especially in scenarios where the confidentiality and integrity of data are paramount.

This is particularly crucial in environments where multiple users or processes access the same resources but this does not prevent in any way an attacker reading from live memory as the latter may not be encrypted.

It is good to notice that in the source code, only keys and plaintexts represented as byte arrays are being zeroized using the zeroize crate. Regarding OpenSSL PKey types, they are being zeroized by OpenSSL itself which is triggered on drop by rust.

EVP_PKEYs are dropped with EVP_PKEY_free which should use the appropriate cipher-internal freeing function which in turn should cleanse all private data unless there is a a bug in the underlying OpenSSL library […]. source

Regulatory Compliance

Cosmian KMS thus adheres to relevant industry standards and regulatory requirements concerning data security and privacy such as the rust guidelines from ANSSI. The use of zeroization aligns with this standard, demonstrating our commitment to safeguarding sensitive information and meeting the necessary compliance obligations.