now rsa

u-boot-tree/lib/rsa/Kconfig

+config RSA
+	bool "Use RSA Library"
+	select RSA_FREESCALE_EXP if FSL_CAAM && !ARCH_MX7 && !ARCH_MX6 && !ARCH_MX5
+	select RSA_SOFTWARE_EXP if !RSA_FREESCALE_EXP
+	help
+	  RSA support. This enables the RSA algorithm used for FIT image
+	  verification in U-Boot.
+	  See doc/uImage.FIT/signature.txt for more details.
+	  The Modular Exponentiation algorithm in RSA is implemented using
+	  driver model. So CONFIG_DM needs to be enabled by default for this
+	  library to function.
+	  The signing part is build into mkimage regardless of this
+	  option. The software based modular exponentiation is built into
+	  mkimage irrespective of this option.
+
+if RSA
+
+config SPL_RSA
+	bool "Use RSA Library within SPL"
+
+config RSA_SOFTWARE_EXP
+	bool "Enable driver for RSA Modular Exponentiation in software"
+	depends on DM
+	help
+	  Enables driver for modular exponentiation in software. This is a RSA
+	  algorithm used in FIT image verification. It required RSA Key as
+	  input.
+	  See doc/uImage.FIT/signature.txt for more details.
+
+config RSA_FREESCALE_EXP
+	bool "Enable RSA Modular Exponentiation with FSL crypto accelerator"
+	depends on DM && FSL_CAAM && !ARCH_MX7 && !ARCH_MX6 && !ARCH_MX5
+	help
+	Enables driver for RSA modular exponentiation using Freescale cryptographic
+	accelerator - CAAM.
+
+endif

u-boot-tree/lib/rsa/Makefile

+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (c) 2013, Google Inc.
+#
+# (C) Copyright 2000-2007
+# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+
+obj-$(CONFIG_$(SPL_)FIT_SIGNATURE) += rsa-verify.o rsa-checksum.o
+obj-$(CONFIG_RSA_SOFTWARE_EXP) += rsa-mod-exp.o

u-boot-tree/lib/rsa/rsa-checksum.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2013, Andreas Oetken.
+ */
+
+#ifndef USE_HOSTCC
+#include <common.h>
+#include <fdtdec.h>
+#include <asm/byteorder.h>
+#include <linux/errno.h>
+#include <asm/unaligned.h>
+#include <hash.h>
+#else
+#include "fdt_host.h"
+#endif
+#include <u-boot/rsa.h>
+
+int hash_calculate(const char *name,
+		    const struct image_region region[],
+		    int region_count, uint8_t *checksum)
+{
+	struct hash_algo *algo;
+	int ret = 0;
+	void *ctx;
+	uint32_t i;
+	i = 0;
+
+	ret = hash_progressive_lookup_algo(name, &algo);
+	if (ret)
+		return ret;
+
+	ret = algo->hash_init(algo, &ctx);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < region_count - 1; i++) {
+		ret = algo->hash_update(algo, ctx, region[i].data,
+					region[i].size, 0);
+		if (ret)
+			return ret;
+	}
+
+	ret = algo->hash_update(algo, ctx, region[i].data, region[i].size, 1);
+	if (ret)
+		return ret;
+	ret = algo->hash_finish(algo, ctx, checksum, algo->digest_size);
+	if (ret)
+		return ret;
+
+	return 0;
+}

u-boot-tree/lib/rsa/rsa-mod-exp.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2013, Google Inc.
+ */
+
+#ifndef USE_HOSTCC
+#include <common.h>
+#include <fdtdec.h>
+#include <asm/types.h>
+#include <asm/byteorder.h>
+#include <linux/errno.h>
+#include <asm/types.h>
+#include <asm/unaligned.h>
+#else
+#include "fdt_host.h"
+#include "mkimage.h"
+#include <fdt_support.h>
+#endif
+#include <u-boot/rsa.h>
+#include <u-boot/rsa-mod-exp.h>
+
+#define UINT64_MULT32(v, multby)  (((uint64_t)(v)) * ((uint32_t)(multby)))
+
+#define get_unaligned_be32(a) fdt32_to_cpu(*(uint32_t *)a)
+#define put_unaligned_be32(a, b) (*(uint32_t *)(b) = cpu_to_fdt32(a))
+
+/* Default public exponent for backward compatibility */
+#define RSA_DEFAULT_PUBEXP	65537
+
+/**
+ * subtract_modulus() - subtract modulus from the given value
+ *
+ * @key:	Key containing modulus to subtract
+ * @num:	Number to subtract modulus from, as little endian word array
+ */
+static void subtract_modulus(const struct rsa_public_key *key, uint32_t num[])
+{
+	int64_t acc = 0;
+	uint i;
+
+	for (i = 0; i < key->len; i++) {
+		acc += (uint64_t)num[i] - key->modulus[i];
+		num[i] = (uint32_t)acc;
+		acc >>= 32;
+	}
+}
+
+/**
+ * greater_equal_modulus() - check if a value is >= modulus
+ *
+ * @key:	Key containing modulus to check
+ * @num:	Number to check against modulus, as little endian word array
+ * @return 0 if num < modulus, 1 if num >= modulus
+ */
+static int greater_equal_modulus(const struct rsa_public_key *key,
+				 uint32_t num[])
+{
+	int i;
+
+	for (i = (int)key->len - 1; i >= 0; i--) {
+		if (num[i] < key->modulus[i])
+			return 0;
+		if (num[i] > key->modulus[i])
+			return 1;
+	}
+
+	return 1;  /* equal */
+}
+
+/**
+ * montgomery_mul_add_step() - Perform montgomery multiply-add step
+ *
+ * Operation: montgomery result[] += a * b[] / n0inv % modulus
+ *
+ * @key:	RSA key
+ * @result:	Place to put result, as little endian word array
+ * @a:		Multiplier
+ * @b:		Multiplicand, as little endian word array
+ */
+static void montgomery_mul_add_step(const struct rsa_public_key *key,
+		uint32_t result[], const uint32_t a, const uint32_t b[])
+{
+	uint64_t acc_a, acc_b;
+	uint32_t d0;
+	uint i;
+
+	acc_a = (uint64_t)a * b[0] + result[0];
+	d0 = (uint32_t)acc_a * key->n0inv;
+	acc_b = (uint64_t)d0 * key->modulus[0] + (uint32_t)acc_a;
+	for (i = 1; i < key->len; i++) {
+		acc_a = (acc_a >> 32) + (uint64_t)a * b[i] + result[i];
+		acc_b = (acc_b >> 32) + (uint64_t)d0 * key->modulus[i] +
+				(uint32_t)acc_a;
+		result[i - 1] = (uint32_t)acc_b;
+	}
+
+	acc_a = (acc_a >> 32) + (acc_b >> 32);
+
+	result[i - 1] = (uint32_t)acc_a;
+
+	if (acc_a >> 32)
+		subtract_modulus(key, result);
+}
+
+/**
+ * montgomery_mul() - Perform montgomery mutitply
+ *
+ * Operation: montgomery result[] = a[] * b[] / n0inv % modulus
+ *
+ * @key:	RSA key
+ * @result:	Place to put result, as little endian word array
+ * @a:		Multiplier, as little endian word array
+ * @b:		Multiplicand, as little endian word array
+ */
+static void montgomery_mul(const struct rsa_public_key *key,
+		uint32_t result[], uint32_t a[], const uint32_t b[])
+{
+	uint i;
+
+	for (i = 0; i < key->len; ++i)
+		result[i] = 0;
+	for (i = 0; i < key->len; ++i)
+		montgomery_mul_add_step(key, result, a[i], b);
+}
+
+/**
+ * num_pub_exponent_bits() - Number of bits in the public exponent
+ *
+ * @key:	RSA key
+ * @num_bits:	Storage for the number of public exponent bits
+ */
+static int num_public_exponent_bits(const struct rsa_public_key *key,
+		int *num_bits)
+{
+	uint64_t exponent;
+	int exponent_bits;
+	const uint max_bits = (sizeof(exponent) * 8);
+
+	exponent = key->exponent;
+	exponent_bits = 0;
+
+	if (!exponent) {
+		*num_bits = exponent_bits;
+		return 0;
+	}
+
+	for (exponent_bits = 1; exponent_bits < max_bits + 1; ++exponent_bits)
+		if (!(exponent >>= 1)) {
+			*num_bits = exponent_bits;
+			return 0;
+		}
+
+	return -EINVAL;
+}
+
+/**
+ * is_public_exponent_bit_set() - Check if a bit in the public exponent is set
+ *
+ * @key:	RSA key
+ * @pos:	The bit position to check
+ */
+static int is_public_exponent_bit_set(const struct rsa_public_key *key,
+		int pos)
+{
+	return key->exponent & (1ULL << pos);
+}
+
+/**
+ * pow_mod() - in-place public exponentiation
+ *
+ * @key:	RSA key
+ * @inout:	Big-endian word array containing value and result
+ */
+static int pow_mod(const struct rsa_public_key *key, uint32_t *inout)
+{
+	uint32_t *result, *ptr;
+	uint i;
+	int j, k;
+
+	/* Sanity check for stack size - key->len is in 32-bit words */
+	if (key->len > RSA_MAX_KEY_BITS / 32) {
+		debug("RSA key words %u exceeds maximum %d\n", key->len,
+		      RSA_MAX_KEY_BITS / 32);
+		return -EINVAL;
+	}
+
+	uint32_t val[key->len], acc[key->len], tmp[key->len];
+	uint32_t a_scaled[key->len];
+	result = tmp;  /* Re-use location. */
+
+	/* Convert from big endian byte array to little endian word array. */
+	for (i = 0, ptr = inout + key->len - 1; i < key->len; i++, ptr--)
+		val[i] = get_unaligned_be32(ptr);
+
+	if (0 != num_public_exponent_bits(key, &k))
+		return -EINVAL;
+
+	if (k < 2) {
+		debug("Public exponent is too short (%d bits, minimum 2)\n",
+		      k);
+		return -EINVAL;
+	}
+
+	if (!is_public_exponent_bit_set(key, 0)) {
+		debug("LSB of RSA public exponent must be set.\n");
+		return -EINVAL;
+	}
+
+	/* the bit at e[k-1] is 1 by definition, so start with: C := M */
+	montgomery_mul(key, acc, val, key->rr); /* acc = a * RR / R mod n */
+	/* retain scaled version for intermediate use */
+	memcpy(a_scaled, acc, key->len * sizeof(a_scaled[0]));
+
+	for (j = k - 2; j > 0; --j) {
+		montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */
+
+		if (is_public_exponent_bit_set(key, j)) {
+			/* acc = tmp * val / R mod n */
+			montgomery_mul(key, acc, tmp, a_scaled);
+		} else {
+			/* e[j] == 0, copy tmp back to acc for next operation */
+			memcpy(acc, tmp, key->len * sizeof(acc[0]));
+		}
+	}
+
+	/* the bit at e[0] is always 1 */
+	montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */
+	montgomery_mul(key, acc, tmp, val); /* acc = tmp * a / R mod M */
+	memcpy(result, acc, key->len * sizeof(result[0]));
+
+	/* Make sure result < mod; result is at most 1x mod too large. */
+	if (greater_equal_modulus(key, result))
+		subtract_modulus(key, result);
+
+	/* Convert to bigendian byte array */
+	for (i = key->len - 1, ptr = inout; (int)i >= 0; i--, ptr++)
+		put_unaligned_be32(result[i], ptr);
+	return 0;
+}
+
+static void rsa_convert_big_endian(uint32_t *dst, const uint32_t *src, int len)
+{
+	int i;
+
+	for (i = 0; i < len; i++)
+		dst[i] = fdt32_to_cpu(src[len - 1 - i]);
+}
+
+int rsa_mod_exp_sw(const uint8_t *sig, uint32_t sig_len,
+		struct key_prop *prop, uint8_t *out)
+{
+	struct rsa_public_key key;
+	int ret;
+
+	if (!prop) {
+		debug("%s: Skipping invalid prop", __func__);
+		return -EBADF;
+	}
+	key.n0inv = prop->n0inv;
+	key.len = prop->num_bits;
+
+	if (!prop->public_exponent)
+		key.exponent = RSA_DEFAULT_PUBEXP;
+	else
+		key.exponent =
+			fdt64_to_cpu(*((uint64_t *)(prop->public_exponent)));
+
+	if (!key.len || !prop->modulus || !prop->rr) {
+		debug("%s: Missing RSA key info", __func__);
+		return -EFAULT;
+	}
+
+	/* Sanity check for stack size */
+	if (key.len > RSA_MAX_KEY_BITS || key.len < RSA_MIN_KEY_BITS) {
+		debug("RSA key bits %u outside allowed range %d..%d\n",
+		      key.len, RSA_MIN_KEY_BITS, RSA_MAX_KEY_BITS);
+		return -EFAULT;
+	}
+	key.len /= sizeof(uint32_t) * 8;
+	uint32_t key1[key.len], key2[key.len];
+
+	key.modulus = key1;
+	key.rr = key2;
+	rsa_convert_big_endian(key.modulus, (uint32_t *)prop->modulus, key.len);
+	rsa_convert_big_endian(key.rr, (uint32_t *)prop->rr, key.len);
+	if (!key.modulus || !key.rr) {
+		debug("%s: Out of memory", __func__);
+		return -ENOMEM;
+	}
+
+	uint32_t buf[sig_len / sizeof(uint32_t)];
+
+	memcpy(buf, sig, sig_len);
+
+	ret = pow_mod(&key, buf);
+	if (ret)
+		return ret;
+
+	memcpy(out, buf, sig_len);
+
+	return 0;
+}
+
+#if defined(CONFIG_CMD_ZYNQ_RSA)
+/**
+ * zynq_pow_mod - in-place public exponentiation
+ *
+ * @keyptr:	RSA key
+ * @inout:	Big-endian word array containing value and result
+ * @return 0 on successful calculation, otherwise failure error code
+ *
+ * FIXME: Use pow_mod() instead of zynq_pow_mod()
+ *        pow_mod calculation required for zynq is bit different from
+ *        pw_mod above here, hence defined zynq specific routine.
+ */
+int zynq_pow_mod(u32 *keyptr, u32 *inout)
+{
+	u32 *result, *ptr;
+	uint i;
+	struct rsa_public_key *key;
+	u32 val[RSA2048_BYTES], acc[RSA2048_BYTES], tmp[RSA2048_BYTES];
+
+	key = (struct rsa_public_key *)keyptr;
+
+	/* Sanity check for stack size - key->len is in 32-bit words */
+	if (key->len > RSA_MAX_KEY_BITS / 32) {
+		debug("RSA key words %u exceeds maximum %d\n", key->len,
+		      RSA_MAX_KEY_BITS / 32);
+		return -EINVAL;
+	}
+
+	result = tmp;  /* Re-use location. */
+
+	for (i = 0, ptr = inout; i < key->len; i++, ptr++)
+		val[i] = *(ptr);
+
+	montgomery_mul(key, acc, val, key->rr);  /* axx = a * RR / R mod M */
+	for (i = 0; i < 16; i += 2) {
+		montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod M */
+		montgomery_mul(key, acc, tmp, tmp); /* acc = tmp^2 / R mod M */
+	}
+	montgomery_mul(key, result, acc, val);  /* result = XX * a / R mod M */
+
+	/* Make sure result < mod; result is at most 1x mod too large. */
+	if (greater_equal_modulus(key, result))
+		subtract_modulus(key, result);
+
+	for (i = 0, ptr = inout; i < key->len; i++, ptr++)
+		*ptr = result[i];
+
+	return 0;
+}
+#endif

u-boot-tree/lib/rsa/rsa-sign.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2013, Google Inc.
+ */
+
+#include "mkimage.h"
+#include <stdio.h>
+#include <string.h>
+#include <image.h>
+#include <time.h>
+#include <openssl/bn.h>
+#include <openssl/rsa.h>
+#include <openssl/pem.h>
+#include <openssl/err.h>
+#include <openssl/ssl.h>
+#include <openssl/evp.h>
+#include <openssl/engine.h>
+
+#if OPENSSL_VERSION_NUMBER >= 0x10000000L
+#define HAVE_ERR_REMOVE_THREAD_STATE
+#endif
+
+#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
+	(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
+static void RSA_get0_key(const RSA *r,
+                 const BIGNUM **n, const BIGNUM **e, const BIGNUM **d)
+{
+   if (n != NULL)
+       *n = r->n;
+   if (e != NULL)
+       *e = r->e;
+   if (d != NULL)
+       *d = r->d;
+}
+#endif
+
+static int rsa_err(const char *msg)
+{
+	unsigned long sslErr = ERR_get_error();
+
+	fprintf(stderr, "%s", msg);
+	fprintf(stderr, ": %s\n",
+		ERR_error_string(sslErr, 0));
+
+	return -1;
+}
+
+/**
+ * rsa_pem_get_pub_key() - read a public key from a .crt file
+ *
+ * @keydir:	Directory containins the key
+ * @name	Name of key file (will have a .crt extension)
+ * @rsap	Returns RSA object, or NULL on failure
+ * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
+ */
+static int rsa_pem_get_pub_key(const char *keydir, const char *name, RSA **rsap)
+{
+	char path[1024];
+	EVP_PKEY *key;
+	X509 *cert;
+	RSA *rsa;
+	FILE *f;
+	int ret;
+
+	*rsap = NULL;
+	snprintf(path, sizeof(path), "%s/%s.crt", keydir, name);
+	f = fopen(path, "r");
+	if (!f) {
+		fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n",
+			path, strerror(errno));
+		return -EACCES;
+	}
+
+	/* Read the certificate */
+	cert = NULL;
+	if (!PEM_read_X509(f, &cert, NULL, NULL)) {
+		rsa_err("Couldn't read certificate");
+		ret = -EINVAL;
+		goto err_cert;
+	}
+
+	/* Get the public key from the certificate. */
+	key = X509_get_pubkey(cert);
+	if (!key) {
+		rsa_err("Couldn't read public key\n");
+		ret = -EINVAL;
+		goto err_pubkey;
+	}
+
+	/* Convert to a RSA_style key. */
+	rsa = EVP_PKEY_get1_RSA(key);
+	if (!rsa) {
+		rsa_err("Couldn't convert to a RSA style key");
+		ret = -EINVAL;
+		goto err_rsa;
+	}
+	fclose(f);
+	EVP_PKEY_free(key);
+	X509_free(cert);
+	*rsap = rsa;
+
+	return 0;
+
+err_rsa:
+	EVP_PKEY_free(key);
+err_pubkey:
+	X509_free(cert);
+err_cert:
+	fclose(f);
+	return ret;
+}
+
+/**
+ * rsa_engine_get_pub_key() - read a public key from given engine
+ *
+ * @keydir:	Key prefix
+ * @name	Name of key
+ * @engine	Engine to use
+ * @rsap	Returns RSA object, or NULL on failure
+ * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
+ */
+static int rsa_engine_get_pub_key(const char *keydir, const char *name,
+				  ENGINE *engine, RSA **rsap)
+{
+	const char *engine_id;
+	char key_id[1024];
+	EVP_PKEY *key;
+	RSA *rsa;
+	int ret;
+
+	*rsap = NULL;
+
+	engine_id = ENGINE_get_id(engine);
+
+	if (engine_id && !strcmp(engine_id, "pkcs11")) {
+		if (keydir)
+			snprintf(key_id, sizeof(key_id),
+				 "pkcs11:%s;object=%s;type=public",
+				 keydir, name);
+		else
+			snprintf(key_id, sizeof(key_id),
+				 "pkcs11:object=%s;type=public",
+				 name);
+	} else {
+		fprintf(stderr, "Engine not supported\n");
+		return -ENOTSUP;
+	}
+
+	key = ENGINE_load_public_key(engine, key_id, NULL, NULL);
+	if (!key)
+		return rsa_err("Failure loading public key from engine");
+
+	/* Convert to a RSA_style key. */
+	rsa = EVP_PKEY_get1_RSA(key);
+	if (!rsa) {
+		rsa_err("Couldn't convert to a RSA style key");
+		ret = -EINVAL;
+		goto err_rsa;
+	}
+
+	EVP_PKEY_free(key);
+	*rsap = rsa;
+
+	return 0;
+
+err_rsa:
+	EVP_PKEY_free(key);
+	return ret;
+}
+
+/**
+ * rsa_get_pub_key() - read a public key
+ *
+ * @keydir:	Directory containing the key (PEM file) or key prefix (engine)
+ * @name	Name of key file (will have a .crt extension)
+ * @engine	Engine to use
+ * @rsap	Returns RSA object, or NULL on failure
+ * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
+ */
+static int rsa_get_pub_key(const char *keydir, const char *name,
+			   ENGINE *engine, RSA **rsap)
+{
+	if (engine)
+		return rsa_engine_get_pub_key(keydir, name, engine, rsap);
+	return rsa_pem_get_pub_key(keydir, name, rsap);
+}
+
+/**
+ * rsa_pem_get_priv_key() - read a private key from a .key file
+ *
+ * @keydir:	Directory containing the key
+ * @name	Name of key file (will have a .key extension)
+ * @rsap	Returns RSA object, or NULL on failure
+ * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
+ */
+static int rsa_pem_get_priv_key(const char *keydir, const char *name,
+				RSA **rsap)
+{
+	char path[1024];
+	RSA *rsa;
+	FILE *f;
+
+	*rsap = NULL;
+	snprintf(path, sizeof(path), "%s/%s.key", keydir, name);
+	f = fopen(path, "r");
+	if (!f) {
+		fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n",
+			path, strerror(errno));
+		return -ENOENT;
+	}
+
+	rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path);
+	if (!rsa) {
+		rsa_err("Failure reading private key");
+		fclose(f);
+		return -EPROTO;
+	}
+	fclose(f);
+	*rsap = rsa;
+
+	return 0;
+}
+
+/**
+ * rsa_engine_get_priv_key() - read a private key from given engine
+ *
+ * @keydir:	Key prefix
+ * @name	Name of key
+ * @engine	Engine to use
+ * @rsap	Returns RSA object, or NULL on failure
+ * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
+ */
+static int rsa_engine_get_priv_key(const char *keydir, const char *name,
+				   ENGINE *engine, RSA **rsap)
+{
+	const char *engine_id;
+	char key_id[1024];
+	EVP_PKEY *key;
+	RSA *rsa;
+	int ret;
+
+	*rsap = NULL;
+
+	engine_id = ENGINE_get_id(engine);
+
+	if (engine_id && !strcmp(engine_id, "pkcs11")) {
+		if (keydir)
+			snprintf(key_id, sizeof(key_id),
+				 "pkcs11:%s;object=%s;type=private",
+				 keydir, name);
+		else
+			snprintf(key_id, sizeof(key_id),
+				 "pkcs11:object=%s;type=private",
+				 name);
+	} else {
+		fprintf(stderr, "Engine not supported\n");
+		return -ENOTSUP;
+	}
+
+	key = ENGINE_load_private_key(engine, key_id, NULL, NULL);
+	if (!key)
+		return rsa_err("Failure loading private key from engine");
+
+	/* Convert to a RSA_style key. */
+	rsa = EVP_PKEY_get1_RSA(key);
+	if (!rsa) {
+		rsa_err("Couldn't convert to a RSA style key");
+		ret = -EINVAL;
+		goto err_rsa;
+	}
+
+	EVP_PKEY_free(key);
+	*rsap = rsa;
+
+	return 0;
+
+err_rsa:
+	EVP_PKEY_free(key);
+	return ret;
+}
+
+/**
+ * rsa_get_priv_key() - read a private key
+ *
+ * @keydir:	Directory containing the key (PEM file) or key prefix (engine)
+ * @name	Name of key
+ * @engine	Engine to use for signing
+ * @rsap	Returns RSA object, or NULL on failure
+ * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
+ */
+static int rsa_get_priv_key(const char *keydir, const char *name,
+			    ENGINE *engine, RSA **rsap)
+{
+	if (engine)
+		return rsa_engine_get_priv_key(keydir, name, engine, rsap);
+	return rsa_pem_get_priv_key(keydir, name, rsap);
+}
+
+static int rsa_init(void)
+{
+	int ret;
+
+#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
+	(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
+	ret = SSL_library_init();
+#else
+	ret = OPENSSL_init_ssl(0, NULL);
+#endif
+	if (!ret) {
+		fprintf(stderr, "Failure to init SSL library\n");
+		return -1;
+	}
+#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
+	(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
+	SSL_load_error_strings();
+
+	OpenSSL_add_all_algorithms();
+	OpenSSL_add_all_digests();
+	OpenSSL_add_all_ciphers();
+#endif
+
+	return 0;
+}
+
+static int rsa_engine_init(const char *engine_id, ENGINE **pe)
+{
+	ENGINE *e;
+	int ret;
+
+	ENGINE_load_builtin_engines();
+
+	e = ENGINE_by_id(engine_id);
+	if (!e) {
+		fprintf(stderr, "Engine isn't available\n");
+		ret = -1;
+		goto err_engine_by_id;
+	}
+
+	if (!ENGINE_init(e)) {
+		fprintf(stderr, "Couldn't initialize engine\n");
+		ret = -1;
+		goto err_engine_init;
+	}
+
+	if (!ENGINE_set_default_RSA(e)) {
+		fprintf(stderr, "Couldn't set engine as default for RSA\n");
+		ret = -1;
+		goto err_set_rsa;
+	}
+
+	*pe = e;
+
+	return 0;
+
+err_set_rsa:
+	ENGINE_finish(e);
+err_engine_init:
+	ENGINE_free(e);
+err_engine_by_id:
+#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
+	(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
+	ENGINE_cleanup();
+#endif
+	return ret;
+}
+
+static void rsa_remove(void)
+{
+#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
+	(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
+	CRYPTO_cleanup_all_ex_data();
+	ERR_free_strings();
+#ifdef HAVE_ERR_REMOVE_THREAD_STATE
+	ERR_remove_thread_state(NULL);
+#else
+	ERR_remove_state(0);
+#endif
+	EVP_cleanup();
+#endif
+}
+
+static void rsa_engine_remove(ENGINE *e)
+{
+	if (e) {
+		ENGINE_finish(e);
+		ENGINE_free(e);
+	}
+}
+
+static int rsa_sign_with_key(RSA *rsa, struct padding_algo *padding_algo,
+			     struct checksum_algo *checksum_algo,
+		const struct image_region region[], int region_count,
+		uint8_t **sigp, uint *sig_size)
+{
+	EVP_PKEY *key;
+	EVP_PKEY_CTX *ckey;
+	EVP_MD_CTX *context;
+	int ret = 0;
+	size_t size;
+	uint8_t *sig;
+	int i;
+
+	key = EVP_PKEY_new();
+	if (!key)
+		return rsa_err("EVP_PKEY object creation failed");
+
+	if (!EVP_PKEY_set1_RSA(key, rsa)) {
+		ret = rsa_err("EVP key setup failed");
+		goto err_set;
+	}
+
+	size = EVP_PKEY_size(key);
+	sig = malloc(size);
+	if (!sig) {
+		fprintf(stderr, "Out of memory for signature (%zu bytes)\n",
+			size);
+		ret = -ENOMEM;
+		goto err_alloc;
+	}
+
+	context = EVP_MD_CTX_create();
+	if (!context) {
+		ret = rsa_err("EVP context creation failed");
+		goto err_create;
+	}
+	EVP_MD_CTX_init(context);
+
+	ckey = EVP_PKEY_CTX_new(key, NULL);
+	if (!ckey) {
+		ret = rsa_err("EVP key context creation failed");
+		goto err_create;
+	}
+
+	if (EVP_DigestSignInit(context, &ckey,
+			       checksum_algo->calculate_sign(),
+			       NULL, key) <= 0) {
+		ret = rsa_err("Signer setup failed");
+		goto err_sign;
+	}
+
+#ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
+	if (padding_algo && !strcmp(padding_algo->name, "pss")) {
+		if (EVP_PKEY_CTX_set_rsa_padding(ckey,
+						 RSA_PKCS1_PSS_PADDING) <= 0) {
+			ret = rsa_err("Signer padding setup failed");
+			goto err_sign;
+		}
+	}
+#endif /* CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT */
+
+	for (i = 0; i < region_count; i++) {
+		if (!EVP_DigestSignUpdate(context, region[i].data,
+					  region[i].size)) {
+			ret = rsa_err("Signing data failed");
+			goto err_sign;
+		}
+	}
+
+	if (!EVP_DigestSignFinal(context, sig, &size)) {
+		ret = rsa_err("Could not obtain signature");
+		goto err_sign;
+	}
+
+	#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
+		(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
+		EVP_MD_CTX_cleanup(context);
+	#else
+		EVP_MD_CTX_reset(context);
+	#endif
+	EVP_MD_CTX_destroy(context);
+	EVP_PKEY_free(key);
+
+	debug("Got signature: %d bytes, expected %zu\n", *sig_size, size);
+	*sigp = sig;
+	*sig_size = size;
+
+	return 0;
+
+err_sign:
+	EVP_MD_CTX_destroy(context);
+err_create:
+	free(sig);
+err_alloc:
+err_set:
+	EVP_PKEY_free(key);
+	return ret;
+}
+
+int rsa_sign(struct image_sign_info *info,
+	     const struct image_region region[], int region_count,
+	     uint8_t **sigp, uint *sig_len)
+{
+	RSA *rsa;
+	ENGINE *e = NULL;
+	int ret;
+
+	ret = rsa_init();
+	if (ret)
+		return ret;
+
+	if (info->engine_id) {
+		ret = rsa_engine_init(info->engine_id, &e);
+		if (ret)
+			goto err_engine;
+	}
+
+	ret = rsa_get_priv_key(info->keydir, info->keyname, e, &rsa);
+	if (ret)
+		goto err_priv;
+	ret = rsa_sign_with_key(rsa, info->padding, info->checksum, region,
+				region_count, sigp, sig_len);
+	if (ret)
+		goto err_sign;
+
+	RSA_free(rsa);
+	if (info->engine_id)
+		rsa_engine_remove(e);
+	rsa_remove();
+
+	return ret;
+
+err_sign:
+	RSA_free(rsa);
+err_priv:
+	if (info->engine_id)
+		rsa_engine_remove(e);
+err_engine:
+	rsa_remove();
+	return ret;
+}
+
+/*
+ * rsa_get_exponent(): - Get the public exponent from an RSA key
+ */
+static int rsa_get_exponent(RSA *key, uint64_t *e)
+{
+	int ret;
+	BIGNUM *bn_te;
+	const BIGNUM *key_e;
+	uint64_t te;
+
+	ret = -EINVAL;
+	bn_te = NULL;
+
+	if (!e)
+		goto cleanup;
+
+	RSA_get0_key(key, NULL, &key_e, NULL);
+	if (BN_num_bits(key_e) > 64)
+		goto cleanup;
+
+	*e = BN_get_word(key_e);
+
+	if (BN_num_bits(key_e) < 33) {
+		ret = 0;
+		goto cleanup;
+	}
+
+	bn_te = BN_dup(key_e);
+	if (!bn_te)
+		goto cleanup;
+
+	if (!BN_rshift(bn_te, bn_te, 32))
+		goto cleanup;
+
+	if (!BN_mask_bits(bn_te, 32))
+		goto cleanup;
+
+	te = BN_get_word(bn_te);
+	te <<= 32;
+	*e |= te;
+	ret = 0;
+
+cleanup:
+	if (bn_te)
+		BN_free(bn_te);
+
+	return ret;
+}
+
+/*
+ * rsa_get_params(): - Get the important parameters of an RSA public key
+ */
+int rsa_get_params(RSA *key, uint64_t *exponent, uint32_t *n0_invp,
+		   BIGNUM **modulusp, BIGNUM **r_squaredp)
+{
+	BIGNUM *big1, *big2, *big32, *big2_32;
+	BIGNUM *n, *r, *r_squared, *tmp;
+	const BIGNUM *key_n;
+	BN_CTX *bn_ctx = BN_CTX_new();
+	int ret = 0;
+
+	/* Initialize BIGNUMs */
+	big1 = BN_new();
+	big2 = BN_new();
+	big32 = BN_new();
+	r = BN_new();
+	r_squared = BN_new();
+	tmp = BN_new();
+	big2_32 = BN_new();
+	n = BN_new();
+	if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 ||
+	    !n) {
+		fprintf(stderr, "Out of memory (bignum)\n");
+		return -ENOMEM;
+	}
+
+	if (0 != rsa_get_exponent(key, exponent))
+		ret = -1;
+
+	RSA_get0_key(key, &key_n, NULL, NULL);
+	if (!BN_copy(n, key_n) || !BN_set_word(big1, 1L) ||
+	    !BN_set_word(big2, 2L) || !BN_set_word(big32, 32L))
+		ret = -1;
+
+	/* big2_32 = 2^32 */
+	if (!BN_exp(big2_32, big2, big32, bn_ctx))
+		ret = -1;
+
+	/* Calculate n0_inv = -1 / n[0] mod 2^32 */
+	if (!BN_mod_inverse(tmp, n, big2_32, bn_ctx) ||
+	    !BN_sub(tmp, big2_32, tmp))
+		ret = -1;
+	*n0_invp = BN_get_word(tmp);
+
+	/* Calculate R = 2^(# of key bits) */
+	if (!BN_set_word(tmp, BN_num_bits(n)) ||
+	    !BN_exp(r, big2, tmp, bn_ctx))
+		ret = -1;
+
+	/* Calculate r_squared = R^2 mod n */
+	if (!BN_copy(r_squared, r) ||
+	    !BN_mul(tmp, r_squared, r, bn_ctx) ||
+	    !BN_mod(r_squared, tmp, n, bn_ctx))
+		ret = -1;
+
+	*modulusp = n;
+	*r_squaredp = r_squared;
+
+	BN_free(big1);
+	BN_free(big2);
+	BN_free(big32);
+	BN_free(r);
+	BN_free(tmp);
+	BN_free(big2_32);
+	if (ret) {
+		fprintf(stderr, "Bignum operations failed\n");
+		return -ENOMEM;
+	}
+
+	return ret;
+}
+
+static int fdt_add_bignum(void *blob, int noffset, const char *prop_name,
+			  BIGNUM *num, int num_bits)
+{
+	int nwords = num_bits / 32;
+	int size;
+	uint32_t *buf, *ptr;
+	BIGNUM *tmp, *big2, *big32, *big2_32;
+	BN_CTX *ctx;
+	int ret;
+
+	tmp = BN_new();
+	big2 = BN_new();
+	big32 = BN_new();
+	big2_32 = BN_new();
+
+	/*
+	 * Note: This code assumes that all of the above succeed, or all fail.
+	 * In practice memory allocations generally do not fail (unless the
+	 * process is killed), so it does not seem worth handling each of these
+	 * as a separate case. Technicaly this could leak memory on failure,
+	 * but a) it won't happen in practice, and b) it doesn't matter as we
+	 * will immediately exit with a failure code.
+	 */
+	if (!tmp || !big2 || !big32 || !big2_32) {
+		fprintf(stderr, "Out of memory (bignum)\n");
+		return -ENOMEM;
+	}
+	ctx = BN_CTX_new();
+	if (!tmp) {
+		fprintf(stderr, "Out of memory (bignum context)\n");
+		return -ENOMEM;
+	}
+	BN_set_word(big2, 2L);
+	BN_set_word(big32, 32L);
+	BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */
+
+	size = nwords * sizeof(uint32_t);
+	buf = malloc(size);
+	if (!buf) {
+		fprintf(stderr, "Out of memory (%d bytes)\n", size);
+		return -ENOMEM;
+	}
+
+	/* Write out modulus as big endian array of integers */
+	for (ptr = buf + nwords - 1; ptr >= buf; ptr--) {
+		BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */
+		*ptr = cpu_to_fdt32(BN_get_word(tmp));
+		BN_rshift(num, num, 32); /*  N = N/B */
+	}
+
+	/*
+	 * We try signing with successively increasing size values, so this
+	 * might fail several times
+	 */
+	ret = fdt_setprop(blob, noffset, prop_name, buf, size);
+	free(buf);
+	BN_free(tmp);
+	BN_free(big2);
+	BN_free(big32);
+	BN_free(big2_32);
+
+	return ret ? -FDT_ERR_NOSPACE : 0;
+}
+
+int rsa_add_verify_data(struct image_sign_info *info, void *keydest)
+{
+	BIGNUM *modulus, *r_squared;
+	uint64_t exponent;
+	uint32_t n0_inv;
+	int parent, node;
+	char name[100];
+	int ret;
+	int bits;
+	RSA *rsa;
+	ENGINE *e = NULL;
+
+	debug("%s: Getting verification data\n", __func__);
+	if (info->engine_id) {
+		ret = rsa_engine_init(info->engine_id, &e);
+		if (ret)
+			return ret;
+	}
+	ret = rsa_get_pub_key(info->keydir, info->keyname, e, &rsa);
+	if (ret)
+		goto err_get_pub_key;
+	ret = rsa_get_params(rsa, &exponent, &n0_inv, &modulus, &r_squared);
+	if (ret)
+		goto err_get_params;
+	bits = BN_num_bits(modulus);
+	parent = fdt_subnode_offset(keydest, 0, FIT_SIG_NODENAME);
+	if (parent == -FDT_ERR_NOTFOUND) {
+		parent = fdt_add_subnode(keydest, 0, FIT_SIG_NODENAME);
+		if (parent < 0) {
+			ret = parent;
+			if (ret != -FDT_ERR_NOSPACE) {
+				fprintf(stderr, "Couldn't create signature node: %s\n",
+					fdt_strerror(parent));
+			}
+		}
+	}
+	if (ret)
+		goto done;
+
+	/* Either create or overwrite the named key node */
+	snprintf(name, sizeof(name), "key-%s", info->keyname);
+	node = fdt_subnode_offset(keydest, parent, name);
+	if (node == -FDT_ERR_NOTFOUND) {
+		node = fdt_add_subnode(keydest, parent, name);
+		if (node < 0) {
+			ret = node;
+			if (ret != -FDT_ERR_NOSPACE) {
+				fprintf(stderr, "Could not create key subnode: %s\n",
+					fdt_strerror(node));
+			}
+		}
+	} else if (node < 0) {
+		fprintf(stderr, "Cannot select keys parent: %s\n",
+			fdt_strerror(node));
+		ret = node;
+	}
+
+	if (!ret) {
+		ret = fdt_setprop_string(keydest, node, "key-name-hint",
+				 info->keyname);
+	}
+	if (!ret)
+		ret = fdt_setprop_u32(keydest, node, "rsa,num-bits", bits);
+	if (!ret)
+		ret = fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv);
+	if (!ret) {
+		ret = fdt_setprop_u64(keydest, node, "rsa,exponent", exponent);
+	}
+	if (!ret) {
+		ret = fdt_add_bignum(keydest, node, "rsa,modulus", modulus,
+				     bits);
+	}
+	if (!ret) {
+		ret = fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared,
+				     bits);
+	}
+	if (!ret) {
+		ret = fdt_setprop_string(keydest, node, FIT_ALGO_PROP,
+					 info->name);
+	}
+	if (!ret && info->require_keys) {
+		ret = fdt_setprop_string(keydest, node, "required",
+					 info->require_keys);
+	}
+done:
+	BN_free(modulus);
+	BN_free(r_squared);
+	if (ret)
+		ret = ret == -FDT_ERR_NOSPACE ? -ENOSPC : -EIO;
+err_get_params:
+	RSA_free(rsa);
+err_get_pub_key:
+	if (info->engine_id)
+		rsa_engine_remove(e);
+
+	return ret;
+}

u-boot-tree/lib/rsa/rsa-verify.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2013, Google Inc.
+ */
+
+#ifndef USE_HOSTCC
+#include <common.h>
+#include <fdtdec.h>
+#include <asm/types.h>
+#include <asm/byteorder.h>
+#include <linux/errno.h>
+#include <asm/types.h>
+#include <asm/unaligned.h>
+#include <dm.h>
+#else
+#include "fdt_host.h"
+#include "mkimage.h"
+#include <fdt_support.h>
+#endif
+#include <u-boot/rsa-mod-exp.h>
+#include <u-boot/rsa.h>
+
+/* Default public exponent for backward compatibility */
+#define RSA_DEFAULT_PUBEXP	65537
+
+/**
+ * rsa_verify_padding() - Verify RSA message padding is valid
+ *
+ * Verify a RSA message's padding is consistent with PKCS1.5
+ * padding as described in the RSA PKCS#1 v2.1 standard.
+ *
+ * @msg:	Padded message
+ * @pad_len:	Number of expected padding bytes
+ * @algo:	Checksum algo structure having information on DER encoding etc.
+ * @return 0 on success, != 0 on failure
+ */
+static int rsa_verify_padding(const uint8_t *msg, const int pad_len,
+			      struct checksum_algo *algo)
+{
+	int ff_len;
+	int ret;
+
+	/* first byte must be 0x00 */
+	ret = *msg++;
+	/* second byte must be 0x01 */
+	ret |= *msg++ ^ 0x01;
+	/* next ff_len bytes must be 0xff */
+	ff_len = pad_len - algo->der_len - 3;
+	ret |= *msg ^ 0xff;
+	ret |= memcmp(msg, msg+1, ff_len-1);
+	msg += ff_len;
+	/* next byte must be 0x00 */
+	ret |= *msg++;
+	/* next der_len bytes must match der_prefix */
+	ret |= memcmp(msg, algo->der_prefix, algo->der_len);
+
+	return ret;
+}
+
+int padding_pkcs_15_verify(struct image_sign_info *info,
+			   uint8_t *msg, int msg_len,
+			   const uint8_t *hash, int hash_len)
+{
+	struct checksum_algo *checksum = info->checksum;
+	int ret, pad_len = msg_len - checksum->checksum_len;
+
+	/* Check pkcs1.5 padding bytes. */
+	ret = rsa_verify_padding(msg, pad_len, checksum);
+	if (ret) {
+		debug("In RSAVerify(): Padding check failed!\n");
+		return -EINVAL;
+	}
+
+	/* Check hash. */
+	if (memcmp((uint8_t *)msg + pad_len, hash, msg_len - pad_len)) {
+		debug("In RSAVerify(): Hash check failed!\n");
+		return -EACCES;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
+static void u32_i2osp(uint32_t val, uint8_t *buf)
+{
+	buf[0] = (uint8_t)((val >> 24) & 0xff);
+	buf[1] = (uint8_t)((val >> 16) & 0xff);
+	buf[2] = (uint8_t)((val >>  8) & 0xff);
+	buf[3] = (uint8_t)((val >>  0) & 0xff);
+}
+
+/**
+ * mask_generation_function1() - generate an octet string
+ *
+ * Generate an octet string used to check rsa signature.
+ * It use an input octet string and a hash function.
+ *
+ * @checksum:	A Hash function
+ * @seed:	Specifies an input variable octet string
+ * @seed_len:	Size of the input octet string
+ * @output:	Specifies the output octet string
+ * @output_len:	Size of the output octet string
+ * @return 0 if the octet string was correctly generated, others on error
+ */
+static int mask_generation_function1(struct checksum_algo *checksum,
+				     uint8_t *seed, int seed_len,
+				     uint8_t *output, int output_len)
+{
+	struct image_region region[2];
+	int ret = 0, i, i_output = 0, region_count = 2;
+	uint32_t counter = 0;
+	uint8_t buf_counter[4], *tmp;
+	int hash_len = checksum->checksum_len;
+
+	memset(output, 0, output_len);
+
+	region[0].data = seed;
+	region[0].size = seed_len;
+	region[1].data = &buf_counter[0];
+	region[1].size = 4;
+
+	tmp = malloc(hash_len);
+	if (!tmp) {
+		debug("%s: can't allocate array tmp\n", __func__);
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	while (i_output < output_len) {
+		u32_i2osp(counter, &buf_counter[0]);
+
+		ret = checksum->calculate(checksum->name,
+					  region, region_count,
+					  tmp);
+		if (ret < 0) {
+			debug("%s: Error in checksum calculation\n", __func__);
+			goto out;
+		}
+
+		i = 0;
+		while ((i_output < output_len) && (i < hash_len)) {
+			output[i_output] = tmp[i];
+			i_output++;
+			i++;
+		}
+
+		counter++;
+	}
+
+out:
+	free(tmp);
+
+	return ret;
+}
+
+static int compute_hash_prime(struct checksum_algo *checksum,
+			      uint8_t *pad, int pad_len,
+			      uint8_t *hash, int hash_len,
+			      uint8_t *salt, int salt_len,
+			      uint8_t *hprime)
+{
+	struct image_region region[3];
+	int ret, region_count = 3;
+
+	region[0].data = pad;
+	region[0].size = pad_len;
+	region[1].data = hash;
+	region[1].size = hash_len;
+	region[2].data = salt;
+	region[2].size = salt_len;
+
+	ret = checksum->calculate(checksum->name, region, region_count, hprime);
+	if (ret < 0) {
+		debug("%s: Error in checksum calculation\n", __func__);
+		goto out;
+	}
+
+out:
+	return ret;
+}
+
+int padding_pss_verify(struct image_sign_info *info,
+		       uint8_t *msg, int msg_len,
+		       const uint8_t *hash, int hash_len)
+{
+	uint8_t *masked_db = NULL;
+	int masked_db_len = msg_len - hash_len - 1;
+	uint8_t *h = NULL, *hprime = NULL;
+	int h_len = hash_len;
+	uint8_t *db_mask = NULL;
+	int db_mask_len = masked_db_len;
+	uint8_t *db = NULL, *salt = NULL;
+	int db_len = masked_db_len, salt_len = msg_len - hash_len - 2;
+	uint8_t pad_zero[8] = { 0 };
+	int ret, i, leftmost_bits = 1;
+	uint8_t leftmost_mask;
+	struct checksum_algo *checksum = info->checksum;
+
+	/* first, allocate everything */
+	masked_db = malloc(masked_db_len);
+	h = malloc(h_len);
+	db_mask = malloc(db_mask_len);
+	db = malloc(db_len);
+	salt = malloc(salt_len);
+	hprime = malloc(hash_len);
+	if (!masked_db || !h || !db_mask || !db || !salt || !hprime) {
+		printf("%s: can't allocate some buffer\n", __func__);
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	/* step 4: check if the last byte is 0xbc */
+	if (msg[msg_len - 1] != 0xbc) {
+		printf("%s: invalid pss padding (0xbc is missing)\n", __func__);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* step 5 */
+	memcpy(masked_db, msg, masked_db_len);
+	memcpy(h, msg + masked_db_len, h_len);
+
+	/* step 6 */
+	leftmost_mask = (0xff >> (8 - leftmost_bits)) << (8 - leftmost_bits);
+	if (masked_db[0] & leftmost_mask) {
+		printf("%s: invalid pss padding ", __func__);
+		printf("(leftmost bit of maskedDB not zero)\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* step 7 */
+	mask_generation_function1(checksum, h, h_len, db_mask, db_mask_len);
+
+	/* step 8 */
+	for (i = 0; i < db_len; i++)
+		db[i] = masked_db[i] ^ db_mask[i];
+
+	/* step 9 */
+	db[0] &= 0xff >> leftmost_bits;
+
+	/* step 10 */
+	if (db[0] != 0x01) {
+		printf("%s: invalid pss padding ", __func__);
+		printf("(leftmost byte of db isn't 0x01)\n");
+		ret = EINVAL;
+		goto out;
+	}
+
+	/* step 11 */
+	memcpy(salt, &db[1], salt_len);
+
+	/* step 12 & 13 */
+	compute_hash_prime(checksum, pad_zero, 8,
+			   (uint8_t *)hash, hash_len,
+			   salt, salt_len, hprime);
+
+	/* step 14 */
+	ret = memcmp(h, hprime, hash_len);
+
+out:
+	free(hprime);
+	free(salt);
+	free(db);
+	free(db_mask);
+	free(h);
+	free(masked_db);
+
+	return ret;
+}
+#endif
+
+/**
+ * rsa_verify_key() - Verify a signature against some data using RSA Key
+ *
+ * Verify a RSA PKCS1.5 signature against an expected hash using
+ * the RSA Key properties in prop structure.
+ *
+ * @info:	Specifies key and FIT information
+ * @prop:	Specifies key
+ * @sig:	Signature
+ * @sig_len:	Number of bytes in signature
+ * @hash:	Pointer to the expected hash
+ * @key_len:	Number of bytes in rsa key
+ * @return 0 if verified, -ve on error
+ */
+static int rsa_verify_key(struct image_sign_info *info,
+			  struct key_prop *prop, const uint8_t *sig,
+			  const uint32_t sig_len, const uint8_t *hash,
+			  const uint32_t key_len)
+{
+	int ret;
+#if !defined(USE_HOSTCC)
+	struct udevice *mod_exp_dev;
+#endif
+	struct checksum_algo *checksum = info->checksum;
+	struct padding_algo *padding = info->padding;
+	int hash_len = checksum->checksum_len;
+
+	if (!prop || !sig || !hash || !checksum)
+		return -EIO;
+
+	if (sig_len != (prop->num_bits / 8)) {
+		debug("Signature is of incorrect length %d\n", sig_len);
+		return -EINVAL;
+	}
+
+	debug("Checksum algorithm: %s", checksum->name);
+
+	/* Sanity check for stack size */
+	if (sig_len > RSA_MAX_SIG_BITS / 8) {
+		debug("Signature length %u exceeds maximum %d\n", sig_len,
+		      RSA_MAX_SIG_BITS / 8);
+		return -EINVAL;
+	}
+
+	uint8_t buf[sig_len];
+
+#if !defined(USE_HOSTCC)
+	ret = uclass_get_device(UCLASS_MOD_EXP, 0, &mod_exp_dev);
+	if (ret) {
+		printf("RSA: Can't find Modular Exp implementation\n");
+		return -EINVAL;
+	}
+
+	ret = rsa_mod_exp(mod_exp_dev, sig, sig_len, prop, buf);
+#else
+	ret = rsa_mod_exp_sw(sig, sig_len, prop, buf);
+#endif
+	if (ret) {
+		debug("Error in Modular exponentation\n");
+		return ret;
+	}
+
+	ret = padding->verify(info, buf, key_len, hash, hash_len);
+	if (ret) {
+		debug("In RSAVerify(): padding check failed!\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * rsa_verify_with_keynode() - Verify a signature against some data using
+ * information in node with prperties of RSA Key like modulus, exponent etc.
+ *
+ * Parse sign-node and fill a key_prop structure with properties of the
+ * key.  Verify a RSA PKCS1.5 signature against an expected hash using
+ * the properties parsed
+ *
+ * @info:	Specifies key and FIT information
+ * @hash:	Pointer to the expected hash
+ * @sig:	Signature
+ * @sig_len:	Number of bytes in signature
+ * @node:	Node having the RSA Key properties
+ * @return 0 if verified, -ve on error
+ */
+static int rsa_verify_with_keynode(struct image_sign_info *info,
+				   const void *hash, uint8_t *sig,
+				   uint sig_len, int node)
+{
+	const void *blob = info->fdt_blob;
+	struct key_prop prop;
+	int length;
+	int ret = 0;
+
+	if (node < 0) {
+		debug("%s: Skipping invalid node", __func__);
+		return -EBADF;
+	}
+
+	prop.num_bits = fdtdec_get_int(blob, node, "rsa,num-bits", 0);
+
+	prop.n0inv = fdtdec_get_int(blob, node, "rsa,n0-inverse", 0);
+
+	prop.public_exponent = fdt_getprop(blob, node, "rsa,exponent", &length);
+	if (!prop.public_exponent || length < sizeof(uint64_t))
+		prop.public_exponent = NULL;
+
+	prop.exp_len = sizeof(uint64_t);
+
+	prop.modulus = fdt_getprop(blob, node, "rsa,modulus", NULL);
+
+	prop.rr = fdt_getprop(blob, node, "rsa,r-squared", NULL);
+
+	if (!prop.num_bits || !prop.modulus) {
+		debug("%s: Missing RSA key info", __func__);
+		return -EFAULT;
+	}
+
+	ret = rsa_verify_key(info, &prop, sig, sig_len, hash,
+			     info->crypto->key_len);
+
+	return ret;
+}
+
+int rsa_verify(struct image_sign_info *info,
+	       const struct image_region region[], int region_count,
+	       uint8_t *sig, uint sig_len)
+{
+	const void *blob = info->fdt_blob;
+	/* Reserve memory for maximum checksum-length */
+	uint8_t hash[info->crypto->key_len];
+	int ndepth, noffset;
+	int sig_node, node;
+	char name[100];
+	int ret;
+
+	/*
+	 * Verify that the checksum-length does not exceed the
+	 * rsa-signature-length
+	 */
+	if (info->checksum->checksum_len >
+	    info->crypto->key_len) {
+		debug("%s: invlaid checksum-algorithm %s for %s\n",
+		      __func__, info->checksum->name, info->crypto->name);
+		return -EINVAL;
+	}
+
+	sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME);
+	if (sig_node < 0) {
+		debug("%s: No signature node found\n", __func__);
+		return -ENOENT;
+	}
+
+	/* Calculate checksum with checksum-algorithm */
+	ret = info->checksum->calculate(info->checksum->name,
+					region, region_count, hash);
+	if (ret < 0) {
+		debug("%s: Error in checksum calculation\n", __func__);
+		return -EINVAL;
+	}
+
+	/* See if we must use a particular key */
+	if (info->required_keynode != -1) {
+		ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
+			info->required_keynode);
+		if (!ret)
+			return ret;
+	}
+
+	/* Look for a key that matches our hint */
+	snprintf(name, sizeof(name), "key-%s", info->keyname);
+	node = fdt_subnode_offset(blob, sig_node, name);
+	ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node);
+	if (!ret)
+		return ret;
+
+	/* No luck, so try each of the keys in turn */
+	for (ndepth = 0, noffset = fdt_next_node(info->fit, sig_node, &ndepth);
+			(noffset >= 0) && (ndepth > 0);
+			noffset = fdt_next_node(info->fit, noffset, &ndepth)) {
+		if (ndepth == 1 && noffset != node) {
+			ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
+						      noffset);
+			if (!ret)
+				break;
+		}
+	}
+
+	return ret;
+}