How can I implement OAEP padding in RSA

anouri · 2024-08-23 23:22:22

Hi,
Can't find in documentation. I need:
OaepPadding
OaepHash = sha256

ab · 2024-08-24 06:39:36

Only RSASSA-PKCS1-v1_5 and RSASSA-PSS are supported yet.
RSASSA-PKCS1-v1_5 is what OpenSSL uses for its open/seal functions.

anouri · 2024-08-24 07:00:09

So, I can't use X509 for this?

ab · 2024-08-24 07:10:26

mormot.crypt.rsa.pas does not support OAEP yet.

What is your use case?

anouri · 2024-08-24 07:22:29

It is requierment of taxpayer system.
Taxpayer document says:
After encryption of the bill, through the AES/GCM algorithm, the encrypted symmetric key and IV must be placed next to the encrypted bill. To encrypt the symmetric key, the asymmetric RSA-OAEP-SHA256 method must be used, which is obtained from the public key(s) of the taxpayer system with a length of 4096 bits. A valid intermediate center is used (the public key of the taxpayer system is obtained using the GET_SERVER_INFORMATION method).
C# example of this document is :
https://jsfiddle.net/8w2u3sex/

Last edited by anouri (2024-08-24 08:23:00)

ab · 2024-08-25 07:08:36

Taxes are good if well spend.
When I see the specs, I can tell you it is not the case here. Using 4096-bit and OAEP is just a joke.

I will see how to add OAEP padding.

anouri · 2024-09-24 08:38:46

Is there a future plan to implement OAEP ?

ab · 2024-09-24 10:02:24

Not yet.

Any pull request is welcome.

jaclas · 2025-09-25 10:49:30

Is OAEP already available? Also for government issues I need it.

ab · 2025-09-25 18:29:38

No, OAEP is not available yet.

Any pull request is welcome.

ttomas · 2026-05-09 10:55:36

I needed too. Just implement needed encryption/decryption, for similar Api, using openssl 3.
Small test in gist https://gist.github.com/TTomas/c65727c6 … 1ea9586df4
I have a problem in decrypt, function EVP_PKEY_CTX_set_rsa_oaep_md return error:03000094:digital envelope routines::invalid operation. Same function in encrypt is OK!
Workaround, I add EVP_PKEY_CTX_set_rsa_oaep_md_name in mormot.lib.openssl11.pas, diff in gist. In some forums, I find suggestion for openssl 3 to use this function.

mORMot Open Source

#1 2024-08-23 23:22:22

How can I implement OAEP padding in RSA

#2 2024-08-24 06:39:36

Re: How can I implement OAEP padding in RSA

#3 2024-08-24 07:00:09

Re: How can I implement OAEP padding in RSA

#4 2024-08-24 07:10:26

Re: How can I implement OAEP padding in RSA

#5 2024-08-24 07:22:29

Re: How can I implement OAEP padding in RSA

#6 2024-08-25 07:08:36

Re: How can I implement OAEP padding in RSA

#7 2024-09-24 08:38:46

Re: How can I implement OAEP padding in RSA

#8 2024-09-24 10:02:24

Re: How can I implement OAEP padding in RSA

#9 2025-09-25 10:49:30

Re: How can I implement OAEP padding in RSA

#10 2025-09-25 18:29:38

Re: How can I implement OAEP padding in RSA

#11 2026-05-09 10:55:36

Re: How can I implement OAEP padding in RSA

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