On Tue, Nov 12, 2002, Developer via RT wrote:
>
> Hi,
>
> Situation:
> ==========
>
> 1.) Call: pCipher=EVP_get_cipherbyname("RC2-CBC")
> 2.) Call: EVP_CIPHER_CTX_init(&ec_ctx)
> 3.) Call: EVP_CipherInit(&ec_ctx,pCipher,byKey,byIV,1)
>
> byKey contains 16 octets (128bit RC2 key)
>
> 4.) Call: VP_CIPHER_CTX_ctrl(&ec_ctx,EVP_CTRL_SET_RC2_KEY_BITS,40,0L);
>
> to set effective key length to 40bit
>
> Bug:
> ====
>
> Effective key length is updated in struct. but RC2 key data
> is NOT updated (bugfix seems to be impossible because
> VP_CIPHER_CTX_ctrl does not have access to raw key material !?).
>
That's not how you call EVP when you want to change parameters. The correct
sequence is:
EVP_CipherInit(ctx, cipher, NULL, NULL, 1);
/* Ctrls such as RC4 key length */
EVP_CipherInit(ctx, NULL, key, iv, 1);
See the manual pages for more info.
Steve.
--
Dr. Stephen Henson [EMAIL PROTECTED]
OpenSSL Project http://www.openssl.org/~steve/
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