libtomcrypt: Import SHA512/256 approved hash algorithm

SHA-512/256 is an approved hash algorithm and a vetted conditioner as
per NIST.SP.800-90B spec. We have used it to condition raw thermal
sensor noise on Developerbox to condense entropy.

It is imported from libtomcrypt:
Git url: https://github.com/libtom/libtomcrypt.git, release tag: v1.18.0.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
Acked-by: Joakim Bech <joakim.bech@linaro.org>

5 files changed, 164 insertions, 0 deletions

diff --git a/core/lib/libtomcrypt/include/tomcrypt_custom.h b/core/lib/libtomcrypt/include/tomcrypt_custom.h
index d4f8de1a..1bb2f024 100644
--- a/core/lib/libtomcrypt/include/tomcrypt_custom.h
+++ b/core/lib/libtomcrypt/include/tomcrypt_custom.h
@@ -200,6 +200,9 @@
 #ifdef CFG_CRYPTO_SHA512
 #define LTC_SHA512
 #endif
+#ifdef CFG_CRYPTO_SHA512_256
+#define LTC_SHA512_256
+#endif
 
 #define LTC_NO_MACS
 
diff --git a/core/lib/libtomcrypt/include/tomcrypt_hash.h b/core/lib/libtomcrypt/include/tomcrypt_hash.h
index 8f67ad20..6678acc3 100644
--- a/core/lib/libtomcrypt/include/tomcrypt_hash.h
+++ b/core/lib/libtomcrypt/include/tomcrypt_hash.h
@@ -255,6 +255,17 @@ int sha384_test(void);
 extern const struct ltc_hash_descriptor sha384_desc;
 #endif
 
+#ifdef LTC_SHA512_256
+#ifndef LTC_SHA512
+   #error LTC_SHA512 is required for LTC_SHA512_256
+#endif
+int sha512_256_init(hash_state * md);
+#define sha512_256_process sha512_process
+int sha512_256_done(hash_state * md, unsigned char *hash);
+int sha512_256_test(void);
+extern const struct ltc_hash_descriptor sha512_256_desc;
+#endif
+
 #if defined(LTC_SHA256) || defined(LTC_SHA256_ARM32_CE)
 int sha256_init(hash_state * md);
 int sha256_process(hash_state * md, const unsigned char *in, unsigned long inlen);
diff --git a/core/lib/libtomcrypt/src/hashes/sha2/sha512_256.c b/core/lib/libtomcrypt/src/hashes/sha2/sha512_256.c
new file mode 100644
index 00000000..a10c083f
--- /dev/null
+++ b/core/lib/libtomcrypt/src/hashes/sha2/sha512_256.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+/**
+   @param sha512_256.c
+   SHA512/256 hash included in sha512.c
+*/
+
+#include "tomcrypt.h"
+
+#if defined(LTC_SHA512_256) && defined(LTC_SHA512)
+
+const struct ltc_hash_descriptor sha512_256_desc =
+{
+    "sha512-256",
+    16,
+    32,
+    128,
+
+    /* OID */
+   { 2, 16, 840, 1, 101, 3, 4, 2, 6,  },
+   9,
+
+    &sha512_256_init,
+    &sha512_process,
+    &sha512_256_done,
+    &sha512_256_test,
+    NULL
+};
+
+/**
+   Initialize the hash state
+   @param md   The hash state you wish to initialize
+   @return CRYPT_OK if successful
+*/
+int sha512_256_init(hash_state * md)
+{
+    LTC_ARGCHK(md != NULL);
+
+    md->sha512.curlen = 0;
+    md->sha512.length = 0;
+    md->sha512.state[0] = CONST64(0x22312194FC2BF72C);
+    md->sha512.state[1] = CONST64(0x9F555FA3C84C64C2);
+    md->sha512.state[2] = CONST64(0x2393B86B6F53B151);
+    md->sha512.state[3] = CONST64(0x963877195940EABD);
+    md->sha512.state[4] = CONST64(0x96283EE2A88EFFE3);
+    md->sha512.state[5] = CONST64(0xBE5E1E2553863992);
+    md->sha512.state[6] = CONST64(0x2B0199FC2C85B8AA);
+    md->sha512.state[7] = CONST64(0x0EB72DDC81C52CA2);
+    return CRYPT_OK;
+}
+
+/**
+   Terminate the hash to get the digest
+   @param md  The hash state
+   @param out [out] The destination of the hash (48 bytes)
+   @return CRYPT_OK if successful
+*/
+int sha512_256_done(hash_state * md, unsigned char *out)
+{
+   unsigned char buf[64];
+
+   LTC_ARGCHK(md  != NULL);
+   LTC_ARGCHK(out != NULL);
+
+    if (md->sha512.curlen >= sizeof(md->sha512.buf)) {
+       return CRYPT_INVALID_ARG;
+    }
+
+   sha512_done(md, buf);
+   XMEMCPY(out, buf, 32);
+#ifdef LTC_CLEAN_STACK
+   zeromem(buf, sizeof(buf));
+#endif
+   return CRYPT_OK;
+}
+
+/**
+  Self-test the hash
+  @return CRYPT_OK if successful, CRYPT_NOP if self-tests have been disabled
+*/
+int  sha512_256_test(void)
+{
+ #ifndef LTC_TEST
+    return CRYPT_NOP;
+ #else
+  static const struct {
+      const char *msg;
+      unsigned char hash[32];
+  } tests[] = {
+    { "abc",
+      { 0x53, 0x04, 0x8E, 0x26, 0x81, 0x94, 0x1E, 0xF9,
+        0x9B, 0x2E, 0x29, 0xB7, 0x6B, 0x4C, 0x7D, 0xAB,
+        0xE4, 0xC2, 0xD0, 0xC6, 0x34, 0xFC, 0x6D, 0x46,
+        0xE0, 0xE2, 0xF1, 0x31, 0x07, 0xE7, 0xAF, 0x23 }
+    },
+    { "abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu",
+      { 0x39, 0x28, 0xE1, 0x84, 0xFB, 0x86, 0x90, 0xF8,
+        0x40, 0xDA, 0x39, 0x88, 0x12, 0x1D, 0x31, 0xBE,
+        0x65, 0xCB, 0x9D, 0x3E, 0xF8, 0x3E, 0xE6, 0x14,
+        0x6F, 0xEA, 0xC8, 0x61, 0xE1, 0x9B, 0x56, 0x3A }
+    },
+  };
+
+  int i;
+  unsigned char tmp[32];
+  hash_state md;
+
+  for (i = 0; i < (int)(sizeof(tests) / sizeof(tests[0])); i++) {
+      sha512_256_init(&md);
+      sha512_256_process(&md, (unsigned char*)tests[i].msg, (unsigned long)strlen(tests[i].msg));
+      sha512_256_done(&md, tmp);
+      if (compare_testvector(tmp, sizeof(tmp), tests[i].hash, sizeof(tests[i].hash), "SHA512-265", i)) {
+         return CRYPT_FAIL_TESTVECTOR;
+      }
+  }
+  return CRYPT_OK;
+ #endif
+}
+
+#endif /* defined(LTC_SHA384) && defined(LTC_SHA512) */
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */
diff --git a/core/lib/libtomcrypt/src/hashes/sha2/sub.mk b/core/lib/libtomcrypt/src/hashes/sha2/sub.mk
index e6ff9bf5..aa88b46c 100644
--- a/core/lib/libtomcrypt/src/hashes/sha2/sub.mk
+++ b/core/lib/libtomcrypt/src/hashes/sha2/sub.mk
@@ -15,3 +15,4 @@ endif
 
 srcs-$(CFG_CRYPTO_SHA384) += sha384.c
 srcs-$(CFG_CRYPTO_SHA512) += sha512.c
+srcs-$(CFG_CRYPTO_SHA512_256) += sha512_256.c
diff --git a/core/lib/libtomcrypt/src/tee_ltc_provider.c b/core/lib/libtomcrypt/src/tee_ltc_provider.c
index 686f7112..d9ebf0de 100644
--- a/core/lib/libtomcrypt/src/tee_ltc_provider.c
+++ b/core/lib/libtomcrypt/src/tee_ltc_provider.c
@@ -2726,6 +2726,23 @@ TEE_Result hash_sha256_check(const uint8_t *hash, const uint8_t *data,
 }
 #endif
 
+#if defined(CFG_CRYPTO_SHA512_256)
+TEE_Result hash_sha512_256_compute(uint8_t *digest, const uint8_t *data,
+		size_t data_size)
+{
+	hash_state hs;
+
+	if (sha512_256_init(&hs) != CRYPT_OK)
+		return TEE_ERROR_GENERIC;
+	if (sha512_256_process(&hs, data, data_size) != CRYPT_OK)
+		return TEE_ERROR_GENERIC;
+	if (sha512_256_done(&hs, digest) != CRYPT_OK)
+		return TEE_ERROR_GENERIC;
+
+	return TEE_SUCCESS;
+}
+#endif
+
 TEE_Result crypto_aes_expand_enc_key(const void *key, size_t key_len,
 				     void *enc_key, unsigned int *rounds)
 {