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Date: Sat, 24 Jan 2004 22:25:15 +0100
To: Timm Friebe <thekid@thekid.de>
Cc: internals@lists.php.net
Message-ID: <20040124222515.71c59b5e.paj@pearfr.org>
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Subject: Re: [PHP-DEV] openssl_public_encrypt() length limitation
From: paj@pearfr.org (Pierre-Alain Joye)

On Sat, 24 Jan 2004 18:26:15 +0000
Timm Friebe <thekid@thekid.de> wrote:

> Hello,
> 
> first of all, I'm not into this at all, a colleague at work told me
> about this. The following is the problem: When enrypting data with
> openssl_public_encrypt(), this goes well up to a certain length
> (tested limit: 245 bytes of data to be encrypted), but as of a certain
> length(246 bytes), the function returns FALSE with no note whatsoever
> why it went wrong.
> 
> Is this expected behaviour? Is the length of the input data limited or
> constrained by the length of the public key? In this case, shouldn't
> there be a warning?

The maximum length of the input depends of the padding mode:

PKCS1_PADDING         max=rsalength-1
PKCS1_OAEP_PADDING    max=rsalength-4

AFAIR :) Everyone with more clue: correct me if I'm wrong :)

pierre