Re: [Qemu-devel] [PATCH for-2.9 1/3] crypto: add standard des support

["Daniel P. Berrange" <berrange@redhat.com>]

On Mon, Dec 05, 2016 at 09:29:59AM +0000, Gonglei (Arei) wrote:
> >
> > >      switch (alg) {
> > > +    case QCRYPTO_CIPHER_ALG_DES:
> > >      case QCRYPTO_CIPHER_ALG_DES_RFB:
> > >      case QCRYPTO_CIPHER_ALG_AES_128:
> > >      case QCRYPTO_CIPHER_ALG_AES_192:
> > > @@ -256,11 +257,17 @@ QCryptoCipher
> > *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
> > >      ctx = g_new0(QCryptoCipherNettle, 1);
> > >
> > >      switch (alg) {
> > > +    case QCRYPTO_CIPHER_ALG_DES:
> > >      case QCRYPTO_CIPHER_ALG_DES_RFB:
> > >          ctx->ctx = g_new0(struct des_ctx, 1);
> > > -        rfbkey = qcrypto_cipher_munge_des_rfb_key(key, nkey);
> > > -        des_set_key(ctx->ctx, rfbkey);
> > > -        g_free(rfbkey);
> > > +
> > > +        if (alg == QCRYPTO_CIPHER_ALG_DES_RFB) {
> > > +            rfbkey = qcrypto_cipher_munge_des_rfb_key(key, nkey);
> > > +            des_set_key(ctx->ctx, rfbkey);
> > > +            g_free(rfbkey);
> > > +        } else {
> > > +            des_set_key(ctx->ctx, key);
> > > +        }
> > >
> > >          ctx->alg_encrypt_native = des_encrypt_native;
> > >          ctx->alg_decrypt_native = des_decrypt_native;
> > > diff --git a/crypto/cipher.c b/crypto/cipher.c
> > > index a9bca41..00d9682 100644
> > > --- a/crypto/cipher.c
> > > +++ b/crypto/cipher.c
> > > @@ -27,6 +27,7 @@ static size_t
> > alg_key_len[QCRYPTO_CIPHER_ALG__MAX] = {
> > >      [QCRYPTO_CIPHER_ALG_AES_128] = 16,
> > >      [QCRYPTO_CIPHER_ALG_AES_192] = 24,
> > >      [QCRYPTO_CIPHER_ALG_AES_256] = 32,
> > > +    [QCRYPTO_CIPHER_ALG_DES] = 8,
> > >      [QCRYPTO_CIPHER_ALG_DES_RFB] = 8,
> > >      [QCRYPTO_CIPHER_ALG_CAST5_128] = 16,
> > >      [QCRYPTO_CIPHER_ALG_SERPENT_128] = 16,
> > > @@ -41,6 +42,7 @@ static size_t
> > alg_block_len[QCRYPTO_CIPHER_ALG__MAX] = {
> > >      [QCRYPTO_CIPHER_ALG_AES_128] = 16,
> > >      [QCRYPTO_CIPHER_ALG_AES_192] = 16,
> > >      [QCRYPTO_CIPHER_ALG_AES_256] = 16,
> > > +    [QCRYPTO_CIPHER_ALG_DES] = 8,
> > >      [QCRYPTO_CIPHER_ALG_DES_RFB] = 8,
> > >      [QCRYPTO_CIPHER_ALG_CAST5_128] = 8,
> > >      [QCRYPTO_CIPHER_ALG_SERPENT_128] = 16,
> > > @@ -107,7 +109,8 @@
> > qcrypto_cipher_validate_key_length(QCryptoCipherAlgorithm alg,
> > >      }
> > >
> > >      if (mode == QCRYPTO_CIPHER_MODE_XTS) {
> > > -        if (alg == QCRYPTO_CIPHER_ALG_DES_RFB) {
> > > +        if (alg == QCRYPTO_CIPHER_ALG_DES_RFB
> > > +            || alg == QCRYPTO_CIPHER_ALG_DES) {
> > >              error_setg(errp, "XTS mode not compatible with DES-RFB");
> > >              return false;
> > >          }
> > > diff --git a/qapi/crypto.json b/qapi/crypto.json
> > > index 5c9d7d4..d403ab9 100644
> > > --- a/qapi/crypto.json
> > > +++ b/qapi/crypto.json
> > > @@ -75,7 +75,7 @@
> > >  { 'enum': 'QCryptoCipherAlgorithm',
> > >    'prefix': 'QCRYPTO_CIPHER_ALG',
> > >    'data': ['aes-128', 'aes-192', 'aes-256',
> > > -           'des-rfb',
> > > +           'des-rfb', 'des',
> > 
> > Can we call this '3des' to make it clear that this is Triple-DES and not
> > the single-DES (which des-rfb is)
> > 
> Actually the current des is not triple-DES, just the single-DES, and des-rfb in QEMU is just a variant of
> single DES, which change the standard key by calling qcrypto_cipher_munge_des_rfb_key().
> 
> I think we can add the 3des support as well in the next step.
> 
> The current single-DES in the patch set is ok to me. :)

Per my othre reply in this thread, I don't think we should be supporting
single-DES at all in QEMU / cryptodev. So IMHO, the correct fix is to
remove the single-DES support from cryptodev entirely

Regards,
Daniel
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