Apple SCEP Clients Can’t Process FIPS‑Compliant RSA‑OAEP EnvelopedData

Question

Created May ’25

Replies 2

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We are currently working on a SCEP server implementation that operates in FIPS-approved mode. In this mode, RSA PKCS#1 v1.5 encryption is disallowed due to compliance requirements, and only FIPS-approved padding schemes such as RSA-OAEP are permitted.

However, we have observed that the SCEP client functionality on Apple devices currently does not support RSA-OAEP for CMS EnvelopedData decryption. This creates a challenge for us in ensuring FIPS compliance while maintaining compatibility with Apple devices during certificate enrollment through SCEP.

We would appreciate your guidance on the following:

Are there any alternative FIPS-approved encryption algorithms or configurations supported by Apple devices for SCEP CMS EnvelopedData decryption?
Is there any plan or timeline for future support of RSA-OAEP on Apple platforms for this use case?

Feedback raised along with sysdiagnose logs as well : FB17655410

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Answer 1

MDM iOS Dev OP

Sep ’25

I wanted to follow up on my earlier question regarding RSA-OAEP support for SCEP CMS EnvelopedData decryption on Apple devices.

Whether there are any FIPS-approved alternatives supported today, and If there are any plans or timelines for adding RSA-OAEP support in the SCEP client?

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Answer 2

priyankachouhan28 OP

1d

We are facing the same issue while performing SCEP / CMS-based enrollment using OpenSSL.

When OpenSSL is operated in FIPS mode (OpenSSL 3.x FIPS provider), CMS EnvelopedData using RSA recipients no longer supports RSAES-PKCS1-v1_5 key transport and instead generates RSAES-OAEP (corresponding to RSA_PKCS1_OAEP_PADDING in OpenSSL) for encrypting the content-encryption key.

However, Apple’s MDM / Keychain CMS implementation on both iOS and macOS does not appear to support RSAES-OAEP and fails to import the encrypted PKCS#12 payload.

Could you clarify whether there are plans to add support for RSAES-OAEP in CMS EnvelopedData for MDM / Keychain.

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