diff --git a/firmware/src/hal/x86/test/endian/Makefile b/firmware/src/hal/x86/test/endian/Makefile
new file mode 100644
index 00000000..6047e5ba
--- /dev/null
+++ b/firmware/src/hal/x86/test/endian/Makefile
@@ -0,0 +1,39 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2021 RSK Labs Ltd
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy of
+# this software and associated documentation files (the "Software"), to deal in
+# the Software without restriction, including without limitation the rights to
+# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+# of the Software, and to permit persons to whom the Software is furnished to do
+# so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+include ../common.mk
+
+PROG = test.out
+OBJS = test_endian.o endian.o
+
+all: $(PROG)
+
+$(PROG): $(OBJS)
+	$(CC) $(COVFLAGS) -o $@ $^
+
+.PHONY: clean test
+
+clean:
+	rm -f $(PROG) ./*.o $(COVFILES)
+
+test: all
+	./$(PROG)
diff --git a/firmware/src/hal/x86/test/endian/test_endian.c b/firmware/src/hal/x86/test/endian/test_endian.c
new file mode 100644
index 00000000..3b6495ba
--- /dev/null
+++ b/firmware/src/hal/x86/test/endian/test_endian.c
@@ -0,0 +1,61 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 RSK Labs Ltd
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <assert.h>
+#include <string.h>
+
+#include "endian.h"
+
+void assert_write_uint32_be(const uint32_t n, const uint8_t exp[]) {
+    uint8_t dest[sizeof(uint32_t)];
+
+    memset(dest, 0, sizeof(dest));
+    write_uint32_be(dest, n);
+
+    for (int i = 0; i < sizeof(dest); i++) {
+        assert(dest[i] == exp[i]);
+    }
+}
+
+void test_write_uint32_be() {
+    printf("Testing write_uint32_be... ");
+
+    assert_write_uint32_be(0xaabbccdd,
+                           (const uint8_t[]){0xaa, 0xbb, 0xcc, 0xdd});
+
+    assert_write_uint32_be(0x44, (const uint8_t[]){0x0, 0x0, 0x0, 0x44});
+
+    assert_write_uint32_be(0x4455, (const uint8_t[]){0x0, 0x0, 0x44, 0x55});
+
+    assert_write_uint32_be(0x445566, (const uint8_t[]){0x0, 0x44, 0x55, 0x66});
+
+    printf("OK\n");
+}
+
+int main() {
+    test_write_uint32_be();
+    return 0;
+}
+
diff --git a/firmware/src/hal/x86/test/keccak256/Makefile b/firmware/src/hal/x86/test/keccak256/Makefile
new file mode 100644
index 00000000..acfdf22b
--- /dev/null
+++ b/firmware/src/hal/x86/test/keccak256/Makefile
@@ -0,0 +1,38 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2021 RSK Labs Ltd
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy of
+# this software and associated documentation files (the "Software"), to deal in
+# the Software without restriction, including without limitation the rights to
+# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+# of the Software, and to permit persons to whom the Software is furnished to do
+# so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+include ../common.mk
+
+PROG = test.out
+OBJS = test_keccak256.o keccak256.o
+
+all: $(PROG)
+
+$(PROG): $(OBJS)
+	$(CC) $(COVFLAGS) -o $@ $^
+
+.PHONY: clean test
+clean:
+	rm -f $(PROG) *.o $(COVFILES)
+
+test: all
+	./$(PROG)
diff --git a/firmware/src/hal/x86/test/keccak256/test_keccak256.c b/firmware/src/hal/x86/test/keccak256/test_keccak256.c
new file mode 100644
index 00000000..d410bf02
--- /dev/null
+++ b/firmware/src/hal/x86/test/keccak256/test_keccak256.c
@@ -0,0 +1,159 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 RSK Labs Ltd
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "keccak256.h"
+
+#define KECCAK256_HASH_SIZE 32
+
+void assert_keccak256(const uint8_t* data,
+                      const uint16_t data_size,
+                      const uint8_t* expected) {
+    SHA3_CTX ctx;
+    uint8_t hash[KECCAK256_HASH_SIZE];
+
+    keccak_init(&ctx);
+    keccak_update(&ctx, data, data_size);
+    keccak_final(&ctx, hash);
+
+    printf("Expected hash: ");
+    for (int i = 0; i < KECCAK256_HASH_SIZE; i++) {
+        printf("%02x", expected[i]);
+    }
+    printf("\n");
+
+    printf("Computed hash: ");
+    for (int i = 0; i < KECCAK256_HASH_SIZE; i++) {
+        printf("%02x", hash[i]);
+    }
+    printf("\n");
+
+    assert(memcmp(hash, expected, KECCAK256_HASH_SIZE) == 0);
+}
+
+int main() {
+    {
+        uint8_t data[] = {
+            0xbd, 0x47, 0x7c, 0xdb, 0xd1, 0x03, 0xf2, 0xf3, 0xe1, 0xce, 0x10,
+            0x0d, 0xe2, 0xc8, 0xd7, 0x59, 0xea, 0x55, 0xa9, 0xed, 0x16, 0xf7,
+            0xe1, 0x07, 0xba, 0x75, 0x46, 0x52, 0x53, 0x4b, 0x42, 0x4c, 0x4f,
+            0x43, 0x4b, 0x3a, 0x77, 0x87, 0xe3, 0xb6, 0xa2, 0x26, 0x24, 0x61,
+            0x48, 0x66, 0xc2, 0x1d, 0xee, 0x14, 0x62, 0xcc, 0xa6, 0x7a, 0x82,
+            0x0d, 0xae, 0xfc, 0x51, 0x34, 0x98, 0xdd, 0xe3, 0xf6, 0xc4, 0x70,
+            0xc8, 0xa4, 0xff, 0xff, 0xff, 0xff, 0x01, 0x00, 0xf2, 0x05, 0x2a,
+            0x01, 0x00, 0x00, 0x00, 0x23, 0x21, 0x02, 0x98, 0x58, 0xd5, 0x67,
+            0x01, 0xbf, 0x60, 0x7d, 0x66, 0xb5, 0x2a, 0xf1, 0xbe, 0x2b, 0xdb,
+            0xeb, 0xc9, 0x06, 0xe4, 0x28, 0x89, 0xa7, 0x4a, 0x12, 0x44, 0x6e,
+            0x94, 0x0a, 0x68, 0x40, 0xc8, 0x6a, 0xac, 0x00, 0x00, 0x00, 0x00,
+        };
+
+        uint8_t expected[] = {
+            0x00, 0x70, 0x1a, 0x12, 0x0f, 0x86, 0x03, 0x52, 0x87, 0x3c, 0xa8,
+            0x94, 0xb0, 0x25, 0xa0, 0x88, 0xed, 0x1d, 0x41, 0xb3, 0x84, 0xbe,
+            0xaf, 0x3d, 0x1c, 0x18, 0xaf, 0xb9, 0x91, 0x83, 0x28, 0xfb,
+        };
+        printf("Case 1:\n");
+        assert_keccak256(data, sizeof(data), expected);
+    }
+
+    {
+        uint8_t data[] = "thisisamessage";
+
+        uint8_t expected[] = {0x34, 0x8f, 0x3f, 0xcb, 0x24, 0x99, 0x30, 0x86,
+                              0x7d, 0x7c, 0x88, 0xdb, 0x8a, 0x47, 0xfa, 0x49,
+                              0xe5, 0x09, 0x0f, 0xbd, 0xbc, 0x1e, 0x8c, 0xcc,
+                              0x95, 0x06, 0x2a, 0x18, 0x4d, 0x41, 0xce, 0xa2};
+        printf("Case 2:\n");
+        assert_keccak256(data, sizeof(data) - 1, expected);
+    }
+
+    {
+        uint8_t data[] = {
+            0xf9, 0x02, 0x34, 0xa0, 0x8d, 0xa9, 0x6f, 0x21, 0x20, 0xc2, 0xc4,
+            0x65, 0x39, 0x69, 0x77, 0x6a, 0xa2, 0x38, 0x82, 0x42, 0xc4, 0xd2,
+            0x47, 0x62, 0x0d, 0x68, 0x66, 0xfe, 0xcf, 0x2a, 0x2b, 0x27, 0x7e,
+            0x6b, 0xfd, 0x6c, 0xa0, 0x1d, 0xcc, 0x4d, 0xe8, 0xde, 0xc7, 0x5d,
+            0x7a, 0xab, 0x85, 0xb5, 0x67, 0xb6, 0xcc, 0xd4, 0x1a, 0xd3, 0x12,
+            0x45, 0x1b, 0x94, 0x8a, 0x74, 0x13, 0xf0, 0xa1, 0x42, 0xfd, 0x40,
+            0xd4, 0x93, 0x47, 0x94, 0x5b, 0x24, 0x27, 0x72, 0x9a, 0x74, 0x66,
+            0x7f, 0x6c, 0xc9, 0xec, 0xe0, 0xb8, 0x50, 0x00, 0x4c, 0x1b, 0x75,
+            0xc6, 0x36, 0xa0, 0x25, 0xa7, 0x98, 0x60, 0x13, 0x29, 0xc5, 0x54,
+            0x7a, 0x96, 0x25, 0xb4, 0x21, 0x19, 0x6d, 0x6b, 0xcf, 0x2f, 0x4a,
+            0x2b, 0x02, 0xe1, 0xf5, 0x04, 0xfe, 0xb0, 0xda, 0xeb, 0x4d, 0xaa,
+            0xaf, 0x48, 0xa0, 0x98, 0x12, 0x48, 0x35, 0xd3, 0xfd, 0xb6, 0x38,
+            0x8f, 0x0e, 0xc7, 0x85, 0x0f, 0xfb, 0xe2, 0xc2, 0x51, 0x8d, 0x6e,
+            0x1a, 0x3c, 0x1b, 0x59, 0xce, 0x1c, 0x4a, 0xa8, 0x27, 0x43, 0x09,
+            0xf9, 0xfb, 0xa0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0xb9, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00,
+            0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00,
+            0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00,
+            0x10, 0x00, 0x00, 0x08, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x02, 0x00,
+            0x00, 0x00, 0x80, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x02, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00,
+            0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x80,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x20, 0x00, 0x40, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x82, 0x04,
+            0xe2, 0x83, 0x67, 0xc2, 0x80, 0x80, 0x84, 0x5f, 0x35, 0xc0, 0x1f,
+            0x92, 0xd1, 0x01, 0x8f, 0x50, 0x41, 0x50, 0x59, 0x52, 0x55, 0x53,
+            0x2d, 0x65, 0x66, 0x61, 0x31, 0x61, 0x30, 0x64, 0x80, 0x00, 0x80,
+            0x80, 0xb8, 0x50, 0x71, 0x11, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0xa5, 0xa4, 0xc1, 0x10,
+            0x74, 0x6d, 0x62, 0x15, 0x31, 0x6f, 0xaf, 0x7c, 0x0c, 0xdd, 0x06,
+            0x28, 0x16, 0x2b, 0xea, 0x46, 0xc7, 0x5d, 0xdb, 0x8b, 0x08, 0xb1,
+            0x6a, 0xc0, 0xe4, 0x5a, 0x2d, 0x22, 0xc0, 0x35, 0x5f, 0xff, 0xff,
+            0x7f, 0x21, 0x00, 0x00, 0x00, 0x06};
+
+        uint8_t expected[] = {0x98, 0x72, 0x8e, 0x67, 0x93, 0xf9, 0xe9, 0x55,
+                              0x7a, 0x42, 0xf1, 0x14, 0xb2, 0x55, 0x67, 0xb5,
+                              0x88, 0x46, 0xae, 0x68, 0xfa, 0xbf, 0xd7, 0x6a,
+                              0xd6, 0x24, 0xa6, 0x2b, 0x4f, 0x38, 0x57, 0xb8};
+        printf("Case 3:\n");
+        assert_keccak256(data, sizeof(data), expected);
+    }
+
+    return 0;
+}
+
diff --git a/firmware/src/hal/x86/test/run-all.sh b/firmware/src/hal/x86/test/run-all.sh
index e7cc9829..1a466aa5 100755
--- a/firmware/src/hal/x86/test/run-all.sh
+++ b/firmware/src/hal/x86/test/run-all.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 ROOTDIR=$(dirname $0)/../../../../..
 TESTDIR=$(realpath $(dirname $0) --relative-to $ROOTDIR)
-TESTDIRS="bip32 hmac_sha256"
+TESTDIRS="bip32 endian hmac_sha256 keccak256"
 TESTDIRS=${1:-"$TESTDIRS"}
 
 for d in $TESTDIRS; do