Can't get SP3 to accept rsa1.5

[Per-Ake Dahl Ejemark]

This seems to be a recurring problem. I need to whitelist rsa1.5 and I have followed the instructions that I've found, and nothing works.
Yes, I know that it is a weak algorithm but the IDP has decided to use this and I have no means whatsoever to make him change this so let's leave the discussions of whether to use rsa1.5 or not please.

The shibd.log says this.
2018-09-21 09:42:32 WARN XMLTooling.Decrypter [16] [default]: XMLSecurity exception while decrypting key: XSECAlgorithmMapper::mapURIToHandler - URI http://www.w3.org/2001/04/xmlenc#rsa-1_5 disallowed by whitelist/blacklist policy
2018-09-21 09:42:32 WARN XMLTooling.Decrypter [16] [default]: unable to decrypt key, generating random key for defensive purposes
2018-09-21 09:42:32 ERROR Shibboleth.SSO.SAML2 [16] [default]: failed to decrypt assertion: XMLSecurity exception while decrypting: OpenSSL:SymmetricKey::decryptFinish - Out of range padding value in final block

I have tried the following.
<AlgorithmBlacklist includeDefaultBlacklist="false"/> This doesn't work

Tried to whitelist it
<AlgorithmWhitelist>http://www.w3.org/2001/04/xmlenc#rsa-1_5</AlgorithmWhitelist> This doesn't work

I have searched the documentation for a solution but found nothing. I have searched the net a found no solution.

Am I missing something obvious here?

The project I'm currently working on really depends on this.

Best regards/ Med Vänliga Hälsningar
Per-Åke Dahl Ejemark
System Developer

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E-mail: perake.dahlejemark at holmedal.se<mailto:perake.dahlejemark at holmedal.se>
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