From abe93b0b75ea502419b4c8685094d34a2d24194e Mon Sep 17 00:00:00 2001
From: Ken MacKay <ken@kmackay.local>
Date: Sun, 30 Jun 2013 11:01:13 -0700
Subject: [PATCH] Added functions for conversion to and from standard octet
 representation for integers.

---
 ecc.c | 23 +++++++++++++++++++++++
 ecc.h | 24 +++++++++++++++++++++++-
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/ecc.c b/ecc.c
index d985566..7453e40 100644
--- a/ecc.c
+++ b/ecc.c
@@ -1494,3 +1494,26 @@ int ecdsa_verify(EccPoint *p_publicKey, uint32_t p_hash[NUM_ECC_DIGITS], uint32_
     /* Accept only if v == r. */
     return (vli_cmp(rx, r) == 0);
 }
+
+void ecc_bytes2int(uint32_t p_int[NUM_ECC_DIGITS], uint8_t p_bytes[NUM_ECC_DIGITS*4])
+{
+    unsigned i;
+    for(i=0; i<NUM_ECC_DIGITS; ++i)
+    {
+        uint8_t *p_digit = p_bytes + 4 * (NUM_ECC_DIGITS - 1 - i);
+        p_int[i] = (p_digit[0] << 24) | (p_digit[1] << 16) | (p_digit[2] << 8) | p_digit[3];
+    }
+}
+
+void ecc_int2bytes(uint8_t p_bytes[NUM_ECC_DIGITS*4], uint32_t p_int[NUM_ECC_DIGITS])
+{
+    unsigned i;
+    for(i=0; i<NUM_ECC_DIGITS; ++i)
+    {
+        uint8_t *p_digit = p_bytes + 4 * (NUM_ECC_DIGITS - 1 - i);
+        p_digit[0] = p_int[i] >> 24;
+        p_digit[1] = p_int[i] >> 16;
+        p_digit[2] = p_int[i] >> 8;
+        p_digit[3] = p_int[i];
+    }
+}
diff --git a/ecc.h b/ecc.h
index db71f2c..59b2146 100644
--- a/ecc.h
+++ b/ecc.h
@@ -30,7 +30,7 @@ with strange assembler messages.
 #define secp256r1 8
 #define secp384r1 12
 #ifndef ECC_CURVE
-    #define ECC_CURVE secp192r1
+    #define ECC_CURVE secp256r1
 #endif
 
 #if (ECC_CURVE != secp128r1 && ECC_CURVE != secp192r1 && ECC_CURVE != secp256r1 && ECC_CURVE != secp384r1)
@@ -130,4 +130,26 @@ Returns 1 if the signature is valid, 0 if it is invalid.
 */
 int ecdsa_verify(EccPoint *p_publicKey, uint32_t p_hash[NUM_ECC_DIGITS], uint32_t r[NUM_ECC_DIGITS], uint32_t s[NUM_ECC_DIGITS]);
 
+/* ecc_bytes2int() function.
+Convert an integer in standard octet representation to the native format.
+
+Outputs:
+    p_int - Will be filled in with the native integer value.
+
+Inputs:
+    p_bytes - The standard octet representation of the integer to convert.
+*/
+void ecc_bytes2int(uint32_t p_int[NUM_ECC_DIGITS], uint8_t p_bytes[NUM_ECC_DIGITS*4]);
+
+/* ecc_int2bytes() function.
+Convert an integer in native format to the standard octet representation.
+
+Outputs:
+    p_bytes - Will be filled in with the standard octet representation of the integer.
+
+Inputs:
+    p_int - The native integer value to convert.
+*/
+void ecc_int2bytes(uint8_t p_bytes[NUM_ECC_DIGITS*4], uint32_t p_int[NUM_ECC_DIGITS]);
+
 #endif /* _MICRO_ECC_H_ */