diff mbox

[U-Boot,3/9,v4] DM: crypto/rsa: Add rsa Modular Exponentiation DM driver

Message ID 1419931816-19485-3-git-send-email-ruchika.gupta@freescale.com
State Superseded
Delegated to: Tom Rini
Headers show

Commit Message

Ruchika Gupta Dec. 30, 2014, 9:30 a.m. UTC
Add a new rsa uclass for performing modular exponentiation and implement
the software driver basing on this uclass.

Signed-off-by: Ruchika Gupta <ruchika.gupta@freescale.com>
CC: Simon Glass <sjg@chromium.org>
---
Changes in v4:
Removed Kconfig option for DM_RSA
Corrected driver name for sw rsa driver
Updated the rsa_mod_exp operation to have output length

Changes in v3:
New patch with driver model for RSA UCLASS

 drivers/crypto/Makefile         |  1 +
 drivers/crypto/rsa/Makefile     |  7 +++++++
 drivers/crypto/rsa/rsa_sw.c     | 39 +++++++++++++++++++++++++++++++++++++++
 drivers/crypto/rsa/rsa_uclass.c | 31 +++++++++++++++++++++++++++++++
 include/dm/uclass-id.h          |  1 +
 include/u-boot/rsa-mod-exp.h    | 37 +++++++++++++++++++++++++++++++++++++
 6 files changed, 116 insertions(+)
 create mode 100644 drivers/crypto/rsa/Makefile
 create mode 100644 drivers/crypto/rsa/rsa_sw.c
 create mode 100644 drivers/crypto/rsa/rsa_uclass.c

Comments

Simon Glass Jan. 2, 2015, 10:24 p.m. UTC | #1
Hi Ruchika,

On 30 December 2014 at 02:30, Ruchika Gupta <ruchika.gupta@freescale.com> wrote:
> Add a new rsa uclass for performing modular exponentiation and implement
> the software driver basing on this uclass.
>
> Signed-off-by: Ruchika Gupta <ruchika.gupta@freescale.com>
> CC: Simon Glass <sjg@chromium.org>
> ---
> Changes in v4:
> Removed Kconfig option for DM_RSA
> Corrected driver name for sw rsa driver
> Updated the rsa_mod_exp operation to have output length
>
> Changes in v3:
> New patch with driver model for RSA UCLASS
>
>  drivers/crypto/Makefile         |  1 +
>  drivers/crypto/rsa/Makefile     |  7 +++++++
>  drivers/crypto/rsa/rsa_sw.c     | 39 +++++++++++++++++++++++++++++++++++++++
>  drivers/crypto/rsa/rsa_uclass.c | 31 +++++++++++++++++++++++++++++++
>  include/dm/uclass-id.h          |  1 +
>  include/u-boot/rsa-mod-exp.h    | 37 +++++++++++++++++++++++++++++++++++++
>  6 files changed, 116 insertions(+)
>  create mode 100644 drivers/crypto/rsa/Makefile
>  create mode 100644 drivers/crypto/rsa/rsa_sw.c
>  create mode 100644 drivers/crypto/rsa/rsa_uclass.c

Again I'm a bit worried we are going off into the weeds.

Is this an RSA driver or a modular exponentiation driver? It seems
like the latter to me. If so, the uclass should be UCLASS_MOD_EXP, not
UCLASS_RSA, and the files and directories should be renames also. Some
hardware will implement the entire RSA algorithm, which would be a
true RSA uclass. Here I think you are only doing part of it.

Other than that rename the code looks fine.

Minor point: again I don't see the value of returning the same value
as sig_len, so you may as well drop those last two args to mod_exp() -
unless I am missing something.

>
> diff --git a/drivers/crypto/Makefile b/drivers/crypto/Makefile
> index 7b79237..a2f30fc 100644
> --- a/drivers/crypto/Makefile
> +++ b/drivers/crypto/Makefile
> @@ -6,4 +6,5 @@
>  #
>
>  obj-$(CONFIG_EXYNOS_ACE_SHA)   += ace_sha.o
> +obj-y += rsa/
>  obj-y += fsl/
> diff --git a/drivers/crypto/rsa/Makefile b/drivers/crypto/rsa/Makefile
> new file mode 100644
> index 0000000..927c5bd
> --- /dev/null
> +++ b/drivers/crypto/rsa/Makefile
> @@ -0,0 +1,7 @@
> +#
> +# (C) Copyright 2014 Freescale Semiconductor, Inc.
> +#
> +# SPDX-License-Identifier:     GPL-2.0+
> +#
> +
> +obj-$(CONFIG_RSA) += rsa_uclass.o rsa_sw.o
> diff --git a/drivers/crypto/rsa/rsa_sw.c b/drivers/crypto/rsa/rsa_sw.c
> new file mode 100644
> index 0000000..3dcd512
> --- /dev/null
> +++ b/drivers/crypto/rsa/rsa_sw.c
> @@ -0,0 +1,39 @@
> +/*
> + * (C) Copyright 2014 Freescale Semiconductor, Inc.
> + * Author: Ruchika Gupta <ruchika.gupta@freescale.com>
> + *
> + * SPDX-License-Identifier:    GPL-2.0+
> + */
> +
> +#include <config.h>
> +#include <common.h>
> +#include <dm.h>
> +#include <u-boot/rsa-mod-exp.h>
> +
> +int mod_exp_sw(struct udevice *dev, const uint8_t *sig, uint32_t sig_len,
> +               struct key_prop *prop, uint8_t **outp, uint32_t *out_len)
> +{
> +       int ret = 0;
> +
> +       ret = rsa_mod_exp_sw(sig, sig_len, prop, outp, out_len);
> +       if (ret) {
> +               debug("%s: RSA failed to verify: %d\n", __func__, ret);
> +               return ret;
> +       }
> +
> +       return 0;
> +}
> +
> +static const struct rsa_ops rsa_ops_sw = {
> +       .mod_exp        = mod_exp_sw,
> +};
> +
> +U_BOOT_DRIVER(rsa_sw) = {
> +       .name   = "rsa_sw",
> +       .id     = UCLASS_RSA,
> +       .ops    = &rsa_ops_sw,
> +};
> +
> +U_BOOT_DEVICE(rsa_sw) = {
> +       .name = "rsa_sw",
> +};
> diff --git a/drivers/crypto/rsa/rsa_uclass.c b/drivers/crypto/rsa/rsa_uclass.c
> new file mode 100644
> index 0000000..4d52dcc
> --- /dev/null
> +++ b/drivers/crypto/rsa/rsa_uclass.c
> @@ -0,0 +1,31 @@
> +/*
> + * (C) Copyright 2014 Freescale Semiconductor, Inc
> + * Author: Ruchika Gupta <ruchika.gupta@freescale.com>
> + *
> + * SPDX-License-Identifier:    GPL-2.0+
> + */
> +
> +#include <common.h>
> +#include <dm.h>
> +#include <u-boot/rsa-mod-exp.h>
> +#include <errno.h>
> +#include <fdtdec.h>
> +#include <malloc.h>
> +#include <asm/io.h>
> +#include <linux/list.h>
> +
> +int rsa_mod_exp(struct udevice *dev, const uint8_t *sig, uint32_t sig_len,
> +               struct key_prop *node, uint8_t **out, uint32_t *out_len)
> +{
> +       const struct rsa_ops *ops = device_get_ops(dev);
> +
> +       if (!ops->mod_exp)
> +               return -ENOSYS;
> +
> +       return ops->mod_exp(dev, sig, sig_len, node, out, out_len);
> +}
> +
> +UCLASS_DRIVER(rsa) = {
> +       .id             = UCLASS_RSA,
> +       .name           = "rsa",
> +};
> diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
> index f17c3c2..823e43c 100644
> --- a/include/dm/uclass-id.h
> +++ b/include/dm/uclass-id.h
> @@ -33,6 +33,7 @@ enum uclass_id {
>         UCLASS_I2C,             /* I2C bus */
>         UCLASS_I2C_GENERIC,     /* Generic I2C device */
>         UCLASS_I2C_EEPROM,      /* I2C EEPROM device */
> +       UCLASS_RSA,             /* RSA Mod Exp device */
>
>         UCLASS_COUNT,
>         UCLASS_INVALID = -1,
> diff --git a/include/u-boot/rsa-mod-exp.h b/include/u-boot/rsa-mod-exp.h
> index 7b74f3c..417e468 100644
> --- a/include/u-boot/rsa-mod-exp.h
> +++ b/include/u-boot/rsa-mod-exp.h
> @@ -46,4 +46,41 @@ struct key_prop {
>  int rsa_mod_exp_sw(const uint8_t *sig, uint32_t sig_len,
>                 struct key_prop *node, uint8_t **outp, uint32_t *out_len);
>
> +int rsa_mod_exp(struct udevice *dev, const uint8_t *sig, uint32_t sig_len,
> +               struct key_prop *node, uint8_t **outp, uint32_t *out_len);
> +
> +/**
> + * struct struct rsa_ops - Driver model for RSA operations
> + *
> + * The uclass interface is implemented by all crypto devices which use
> + * driver model.
> + */
> +struct rsa_ops {
> +       /**
> +        * Perform Modular Exponentiation
> +        *
> +        * Operation: out[] = sig ^ exponent % modulus
> +        *
> +        * @dev:        RSA Device
> +        * @sig:        RSA PKCS1.5 signature
> +        * @sig_len:    Length of signature in number of bytes
> +        * @node:       Node with RSA key elements like modulus, exponent,
> +        *              R^2, n0inv
> +        * @outp:       Set to an allocated buffer holding the output hash
> +        * @out_len:    Set to length of hash(outp) calculated after
> +        *              exponentiation.
> +        *
> +        * This computes exponentiation over the signature. Resulting
> +        * hash value is placed in an allocated buffer, the pointer is
> +        * returned as *outp. The length of calulated hash is returned via
> +        * the out_len pointer argument. The caller should free *outp
> +        *
> +        * Returns: 0 if exponentiation is successful, or a negative value
> +        * if it wasn't.
> +        */
> +       int (*mod_exp)(struct udevice *dev, const uint8_t *sig,
> +                          uint32_t sig_len, struct key_prop *node,
> +                          uint8_t **outp, uint32_t *len);
> +};
> +
>  #endif
> --
> 1.8.1.4
>
Simon Glass Jan. 6, 2015, 8:30 p.m. UTC | #2
Hi Ruchika,

On 6 January 2015 at 02:37, Ruchika Gupta <ruchika.gupta@freescale.com>
wrote:

> Hi Simon,
>
> > -----Original Message-----
> > From: sjg@google.com [mailto:sjg@google.com] On Behalf Of Simon Glass
> > Sent: Saturday, January 03, 2015 3:54 AM
> > To: Gupta Ruchika-R66431
> > Cc: U-Boot Mailing List; Sun York-R58495
> > Subject: Re: [PATCH 3/9] [v4] DM: crypto/rsa: Add rsa Modular
> Exponentiation
> > DM driver
> >
> > Hi Ruchika,
> >
> > On 30 December 2014 at 02:30, Ruchika Gupta <ruchika.gupta@freescale.com
> >
> > wrote:
> > > Add a new rsa uclass for performing modular exponentiation and
> > > implement the software driver basing on this uclass.
> > >
> > > Signed-off-by: Ruchika Gupta <ruchika.gupta@freescale.com>
> > > CC: Simon Glass <sjg@chromium.org>
> > > ---
> > > Changes in v4:
> > > Removed Kconfig option for DM_RSA
> > > Corrected driver name for sw rsa driver Updated the rsa_mod_exp
> > > operation to have output length
> > >
> > > Changes in v3:
> > > New patch with driver model for RSA UCLASS
> > >
> > >  drivers/crypto/Makefile         |  1 +
> > >  drivers/crypto/rsa/Makefile     |  7 +++++++
> > >  drivers/crypto/rsa/rsa_sw.c     | 39
> > +++++++++++++++++++++++++++++++++++++++
> > >  drivers/crypto/rsa/rsa_uclass.c | 31 +++++++++++++++++++++++++++++++
> > >  include/dm/uclass-id.h          |  1 +
> > >  include/u-boot/rsa-mod-exp.h    | 37
> +++++++++++++++++++++++++++++++++++++
> > >  6 files changed, 116 insertions(+)
> > >  create mode 100644 drivers/crypto/rsa/Makefile  create mode 100644
> > > drivers/crypto/rsa/rsa_sw.c  create mode 100644
> > > drivers/crypto/rsa/rsa_uclass.c
> >
> > Again I'm a bit worried we are going off into the weeds.
> >
> > Is this an RSA driver or a modular exponentiation driver? It seems like
> the
> > latter to me. If so, the uclass should be UCLASS_MOD_EXP, not
> UCLASS_RSA, and
> > the files and directories should be renames also. Some hardware will
> > implement the entire RSA algorithm, which would be a true RSA uclass.
> Here I
> > think you are only doing part of it.
> I did this to introduce a generic class for RSA which has mod_exp
> implementation for now and can be extended to have sign or any other algo
> added later.For now I will change it to UCLASS_MOD_EXP as you have
> suggested.
>

From what I understand the RSA API consists of two functions:

rsa_sign()
rsa_verify()

These are defined in rsa.h.

So if you are planning to implement an RSA uclass it should support these
two. In your case it seems like you are implementing a part of RSA, i.e.
lower-level functionality. That's why I'm saying it doesn't look like an
RSA uclass to me.


>
> >
> > Other than that rename the code looks fine.
> >
> > Minor point: again I don't see the value of returning the same value as
> > sig_len, so you may as well drop those last two args to mod_exp() -
> unless I
> > am missing something.
> I will do that and revert back to earlier implementation with uint8_t *out.
>
> >
> > >
> > > diff --git a/drivers/crypto/Makefile b/drivers/crypto/Makefile index
> > > 7b79237..a2f30fc 100644
> > > --- a/drivers/crypto/Makefile
> > > +++ b/drivers/crypto/Makefile
> > > @@ -6,4 +6,5 @@
> > >  #
> > >
> > >  obj-$(CONFIG_EXYNOS_ACE_SHA)   += ace_sha.o
> > > +obj-y += rsa/
> > >  obj-y += fsl/
> > > diff --git a/drivers/crypto/rsa/Makefile b/drivers/crypto/rsa/Makefile
> > > new file mode 100644 index 0000000..927c5bd
> > > --- /dev/null
> > > +++ b/drivers/crypto/rsa/Makefile
> > > @@ -0,0 +1,7 @@
> > > +#
> > > +# (C) Copyright 2014 Freescale Semiconductor, Inc.
> > > +#
> > > +# SPDX-License-Identifier:     GPL-2.0+
> > > +#
> > > +
> > > +obj-$(CONFIG_RSA) += rsa_uclass.o rsa_sw.o
> > > diff --git a/drivers/crypto/rsa/rsa_sw.c b/drivers/crypto/rsa/rsa_sw.c
> > > new file mode 100644 index 0000000..3dcd512
> > > --- /dev/null
> > > +++ b/drivers/crypto/rsa/rsa_sw.c
> > > @@ -0,0 +1,39 @@
> > > +/*
> > > + * (C) Copyright 2014 Freescale Semiconductor, Inc.
> > > + * Author: Ruchika Gupta <ruchika.gupta@freescale.com>
> > > + *
> > > + * SPDX-License-Identifier:    GPL-2.0+
> > > + */
> > > +
> > > +#include <config.h>
> > > +#include <common.h>
> > > +#include <dm.h>
> > > +#include <u-boot/rsa-mod-exp.h>
> > > +
> > > +int mod_exp_sw(struct udevice *dev, const uint8_t *sig, uint32_t
> sig_len,
> > > +               struct key_prop *prop, uint8_t **outp, uint32_t
> > > +*out_len) {
> > > +       int ret = 0;
> > > +
> > > +       ret = rsa_mod_exp_sw(sig, sig_len, prop, outp, out_len);
> > > +       if (ret) {
> > > +               debug("%s: RSA failed to verify: %d\n", __func__, ret);
> > > +               return ret;
> > > +       }
> > > +
> > > +       return 0;
> > > +}
> > > +
> > > +static const struct rsa_ops rsa_ops_sw = {
> > > +       .mod_exp        = mod_exp_sw,
> > > +};
> > > +
> > > +U_BOOT_DRIVER(rsa_sw) = {
> > > +       .name   = "rsa_sw",
> > > +       .id     = UCLASS_RSA,
> > > +       .ops    = &rsa_ops_sw,
> > > +};
> > > +
> > > +U_BOOT_DEVICE(rsa_sw) = {
> > > +       .name = "rsa_sw",
> > > +};
> > > diff --git a/drivers/crypto/rsa/rsa_uclass.c
> > > b/drivers/crypto/rsa/rsa_uclass.c new file mode 100644 index
> > > 0000000..4d52dcc
> > > --- /dev/null
> > > +++ b/drivers/crypto/rsa/rsa_uclass.c
> > > @@ -0,0 +1,31 @@
> > > +/*
> > > + * (C) Copyright 2014 Freescale Semiconductor, Inc
> > > + * Author: Ruchika Gupta <ruchika.gupta@freescale.com>
> > > + *
> > > + * SPDX-License-Identifier:    GPL-2.0+
> > > + */
> > > +
> > > +#include <common.h>
> > > +#include <dm.h>
> > > +#include <u-boot/rsa-mod-exp.h>
> > > +#include <errno.h>
> > > +#include <fdtdec.h>
> > > +#include <malloc.h>
> > > +#include <asm/io.h>
> > > +#include <linux/list.h>
> > > +
> > > +int rsa_mod_exp(struct udevice *dev, const uint8_t *sig, uint32_t
> sig_len,
> > > +               struct key_prop *node, uint8_t **out, uint32_t
> > > +*out_len) {
> > > +       const struct rsa_ops *ops = device_get_ops(dev);
> > > +
> > > +       if (!ops->mod_exp)
> > > +               return -ENOSYS;
> > > +
> > > +       return ops->mod_exp(dev, sig, sig_len, node, out, out_len); }
> > > +
> > > +UCLASS_DRIVER(rsa) = {
> > > +       .id             = UCLASS_RSA,
> > > +       .name           = "rsa",
> > > +};
> > > diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h index
> > > f17c3c2..823e43c 100644
> > > --- a/include/dm/uclass-id.h
> > > +++ b/include/dm/uclass-id.h
> > > @@ -33,6 +33,7 @@ enum uclass_id {
> > >         UCLASS_I2C,             /* I2C bus */
> > >         UCLASS_I2C_GENERIC,     /* Generic I2C device */
> > >         UCLASS_I2C_EEPROM,      /* I2C EEPROM device */
> > > +       UCLASS_RSA,             /* RSA Mod Exp device */
> > >
> > >         UCLASS_COUNT,
> > >         UCLASS_INVALID = -1,
> > > diff --git a/include/u-boot/rsa-mod-exp.h
> > > b/include/u-boot/rsa-mod-exp.h index 7b74f3c..417e468 100644
> > > --- a/include/u-boot/rsa-mod-exp.h
> > > +++ b/include/u-boot/rsa-mod-exp.h
> > > @@ -46,4 +46,41 @@ struct key_prop {
> > >  int rsa_mod_exp_sw(const uint8_t *sig, uint32_t sig_len,
> > >                 struct key_prop *node, uint8_t **outp, uint32_t
> > > *out_len);
> > >
> > > +int rsa_mod_exp(struct udevice *dev, const uint8_t *sig, uint32_t
> sig_len,
> > > +               struct key_prop *node, uint8_t **outp, uint32_t
> > > +*out_len);
> > > +
> > > +/**
> > > + * struct struct rsa_ops - Driver model for RSA operations
> > > + *
> > > + * The uclass interface is implemented by all crypto devices which
> > > +use
> > > + * driver model.
> > > + */
> > > +struct rsa_ops {
> > > +       /**
> > > +        * Perform Modular Exponentiation
> > > +        *
> > > +        * Operation: out[] = sig ^ exponent % modulus
> > > +        *
> > > +        * @dev:        RSA Device
> > > +        * @sig:        RSA PKCS1.5 signature
> > > +        * @sig_len:    Length of signature in number of bytes
> > > +        * @node:       Node with RSA key elements like modulus,
> exponent,
> > > +        *              R^2, n0inv
> > > +        * @outp:       Set to an allocated buffer holding the output
> hash
> > > +        * @out_len:    Set to length of hash(outp) calculated after
> > > +        *              exponentiation.
> > > +        *
> > > +        * This computes exponentiation over the signature. Resulting
> > > +        * hash value is placed in an allocated buffer, the pointer is
> > > +        * returned as *outp. The length of calulated hash is returned
> via
> > > +        * the out_len pointer argument. The caller should free *outp
> > > +        *
> > > +        * Returns: 0 if exponentiation is successful, or a negative
> value
> > > +        * if it wasn't.
> > > +        */
> > > +       int (*mod_exp)(struct udevice *dev, const uint8_t *sig,
> > > +                          uint32_t sig_len, struct key_prop *node,
> > > +                          uint8_t **outp, uint32_t *len); };
> > > +
> > >  #endif
> > > --
> > > 1.8.1.4
> > >
>
> Regards,
> Ruchika



Regards,
Simon
diff mbox

Patch

diff --git a/drivers/crypto/Makefile b/drivers/crypto/Makefile
index 7b79237..a2f30fc 100644
--- a/drivers/crypto/Makefile
+++ b/drivers/crypto/Makefile
@@ -6,4 +6,5 @@ 
 #
 
 obj-$(CONFIG_EXYNOS_ACE_SHA)	+= ace_sha.o
+obj-y += rsa/
 obj-y += fsl/
diff --git a/drivers/crypto/rsa/Makefile b/drivers/crypto/rsa/Makefile
new file mode 100644
index 0000000..927c5bd
--- /dev/null
+++ b/drivers/crypto/rsa/Makefile
@@ -0,0 +1,7 @@ 
+#
+# (C) Copyright 2014 Freescale Semiconductor, Inc.
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+obj-$(CONFIG_RSA) += rsa_uclass.o rsa_sw.o
diff --git a/drivers/crypto/rsa/rsa_sw.c b/drivers/crypto/rsa/rsa_sw.c
new file mode 100644
index 0000000..3dcd512
--- /dev/null
+++ b/drivers/crypto/rsa/rsa_sw.c
@@ -0,0 +1,39 @@ 
+/*
+ * (C) Copyright 2014 Freescale Semiconductor, Inc.
+ * Author: Ruchika Gupta <ruchika.gupta@freescale.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <config.h>
+#include <common.h>
+#include <dm.h>
+#include <u-boot/rsa-mod-exp.h>
+
+int mod_exp_sw(struct udevice *dev, const uint8_t *sig, uint32_t sig_len,
+		struct key_prop *prop, uint8_t **outp, uint32_t *out_len)
+{
+	int ret = 0;
+
+	ret = rsa_mod_exp_sw(sig, sig_len, prop, outp, out_len);
+	if (ret) {
+		debug("%s: RSA failed to verify: %d\n", __func__, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct rsa_ops rsa_ops_sw = {
+	.mod_exp	= mod_exp_sw,
+};
+
+U_BOOT_DRIVER(rsa_sw) = {
+	.name	= "rsa_sw",
+	.id	= UCLASS_RSA,
+	.ops	= &rsa_ops_sw,
+};
+
+U_BOOT_DEVICE(rsa_sw) = {
+	.name = "rsa_sw",
+};
diff --git a/drivers/crypto/rsa/rsa_uclass.c b/drivers/crypto/rsa/rsa_uclass.c
new file mode 100644
index 0000000..4d52dcc
--- /dev/null
+++ b/drivers/crypto/rsa/rsa_uclass.c
@@ -0,0 +1,31 @@ 
+/*
+ * (C) Copyright 2014 Freescale Semiconductor, Inc
+ * Author: Ruchika Gupta <ruchika.gupta@freescale.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <u-boot/rsa-mod-exp.h>
+#include <errno.h>
+#include <fdtdec.h>
+#include <malloc.h>
+#include <asm/io.h>
+#include <linux/list.h>
+
+int rsa_mod_exp(struct udevice *dev, const uint8_t *sig, uint32_t sig_len,
+		struct key_prop *node, uint8_t **out, uint32_t *out_len)
+{
+	const struct rsa_ops *ops = device_get_ops(dev);
+
+	if (!ops->mod_exp)
+		return -ENOSYS;
+
+	return ops->mod_exp(dev, sig, sig_len, node, out, out_len);
+}
+
+UCLASS_DRIVER(rsa) = {
+	.id		= UCLASS_RSA,
+	.name		= "rsa",
+};
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index f17c3c2..823e43c 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -33,6 +33,7 @@  enum uclass_id {
 	UCLASS_I2C,		/* I2C bus */
 	UCLASS_I2C_GENERIC,	/* Generic I2C device */
 	UCLASS_I2C_EEPROM,	/* I2C EEPROM device */
+	UCLASS_RSA,		/* RSA Mod Exp device */
 
 	UCLASS_COUNT,
 	UCLASS_INVALID = -1,
diff --git a/include/u-boot/rsa-mod-exp.h b/include/u-boot/rsa-mod-exp.h
index 7b74f3c..417e468 100644
--- a/include/u-boot/rsa-mod-exp.h
+++ b/include/u-boot/rsa-mod-exp.h
@@ -46,4 +46,41 @@  struct key_prop {
 int rsa_mod_exp_sw(const uint8_t *sig, uint32_t sig_len,
 		struct key_prop *node, uint8_t **outp, uint32_t *out_len);
 
+int rsa_mod_exp(struct udevice *dev, const uint8_t *sig, uint32_t sig_len,
+		struct key_prop *node, uint8_t **outp, uint32_t *out_len);
+
+/**
+ * struct struct rsa_ops - Driver model for RSA operations
+ *
+ * The uclass interface is implemented by all crypto devices which use
+ * driver model.
+ */
+struct rsa_ops {
+	/**
+	 * Perform Modular Exponentiation
+	 *
+	 * Operation: out[] = sig ^ exponent % modulus
+	 *
+	 * @dev:	RSA Device
+	 * @sig:	RSA PKCS1.5 signature
+	 * @sig_len:	Length of signature in number of bytes
+	 * @node:	Node with RSA key elements like modulus, exponent,
+	 *		R^2, n0inv
+	 * @outp:	Set to an allocated buffer holding the output hash
+	 * @out_len:	Set to length of hash(outp) calculated after
+	 *		exponentiation.
+	 *
+	 * This computes exponentiation over the signature. Resulting
+	 * hash value is placed in an allocated buffer, the pointer is
+	 * returned as *outp. The length of calulated hash is returned via
+	 * the out_len pointer argument. The caller should free *outp
+	 *
+	 * Returns: 0 if exponentiation is successful, or a negative value
+	 * if it wasn't.
+	 */
+	int (*mod_exp)(struct udevice *dev, const uint8_t *sig,
+			   uint32_t sig_len, struct key_prop *node,
+			   uint8_t **outp, uint32_t *len);
+};
+
 #endif