Andrew Boyson / crypto

A simple library to support serving https.

Dependents:   oldheating gps motorhome heating

hmac/hmac-sha1.c@7:94ef5824c3c0, 2019-09-05 (annotated)

Committer:
andrewboyson
Date:
Thu Sep 05 12:58:41 2019 +0000
Revision:
7:94ef5824c3c0
Child:
9:f354b4859b0b
Client handshake is now verified

Who changed what in which revision?

UserRevisionLine numberNew contents of line
andrewboyson 7:94ef5824c3c0 1 #include <stdint.h>
andrewboyson 7:94ef5824c3c0 2
andrewboyson 7:94ef5824c3c0 3 #include "hmac-sha1.h"
andrewboyson 7:94ef5824c3c0 4 #include "sha1.h"
andrewboyson 7:94ef5824c3c0 5
andrewboyson 7:94ef5824c3c0 6 #define BLOCK_SIZE 64
andrewboyson 7:94ef5824c3c0 7 #define HASH_SIZE 20
andrewboyson 7:94ef5824c3c0 8
andrewboyson 7:94ef5824c3c0 9 void HmacSha1(const uint8_t* key, int keyLength, const uint8_t* message, int messageLength, uint8_t* mac)
andrewboyson 7:94ef5824c3c0 10 {
andrewboyson 7:94ef5824c3c0 11 uint8_t hmacKey[BLOCK_SIZE];
andrewboyson 7:94ef5824c3c0 12
andrewboyson 7:94ef5824c3c0 13 //Make the key BLOCK_SIZE bytes long by hashing longer ones or padding shorter one with 0s
andrewboyson 7:94ef5824c3c0 14 if (keyLength > BLOCK_SIZE)
andrewboyson 7:94ef5824c3c0 15 {
andrewboyson 7:94ef5824c3c0 16 Sha1(key, keyLength, hmacKey);
andrewboyson 7:94ef5824c3c0 17 for (int i = HASH_SIZE; i < BLOCK_SIZE; i++) hmacKey[i] = 0;
andrewboyson 7:94ef5824c3c0 18 }
andrewboyson 7:94ef5824c3c0 19 else
andrewboyson 7:94ef5824c3c0 20 {
andrewboyson 7:94ef5824c3c0 21 for (int i = 0; i < keyLength; i++) hmacKey[i] = key[i];
andrewboyson 7:94ef5824c3c0 22 for (int i = keyLength; i < BLOCK_SIZE; i++) hmacKey[i] = 0;
andrewboyson 7:94ef5824c3c0 23 }
andrewboyson 7:94ef5824c3c0 24
andrewboyson 7:94ef5824c3c0 25 //Make the inner and outer padded keys
andrewboyson 7:94ef5824c3c0 26 uint8_t oKeyPad[BLOCK_SIZE];
andrewboyson 7:94ef5824c3c0 27 uint8_t iKeyPad[BLOCK_SIZE];
andrewboyson 7:94ef5824c3c0 28 for (int i = 0; i < BLOCK_SIZE; i++)
andrewboyson 7:94ef5824c3c0 29 {
andrewboyson 7:94ef5824c3c0 30 oKeyPad[i] = hmacKey[i] ^ 0x5c; //Outer padded key
andrewboyson 7:94ef5824c3c0 31 iKeyPad[i] = hmacKey[i] ^ 0x36; //Inner padded key
andrewboyson 7:94ef5824c3c0 32 }
andrewboyson 7:94ef5824c3c0 33
andrewboyson 7:94ef5824c3c0 34 //hash(o_key_pad + hash(i_key_pad + message) where + is concatenation
andrewboyson 7:94ef5824c3c0 35 uint8_t* tempi = alloca(BLOCK_SIZE + messageLength);
andrewboyson 7:94ef5824c3c0 36 for (int i = 0; i < BLOCK_SIZE; i++) tempi[i ] = iKeyPad[i];
andrewboyson 7:94ef5824c3c0 37 for (int i = 0; i < messageLength; i++) tempi[i + BLOCK_SIZE] = message[i];
andrewboyson 7:94ef5824c3c0 38 uint8_t tmpHash[HASH_SIZE];
andrewboyson 7:94ef5824c3c0 39 Sha1(tempi, BLOCK_SIZE + messageLength, tmpHash);
andrewboyson 7:94ef5824c3c0 40
andrewboyson 7:94ef5824c3c0 41 uint8_t tmpMsg[BLOCK_SIZE + HASH_SIZE];
andrewboyson 7:94ef5824c3c0 42 for (int i = 0; i < BLOCK_SIZE; i++) tmpMsg[i ] = oKeyPad[i];
andrewboyson 7:94ef5824c3c0 43 for (int i = 0; i < HASH_SIZE; i++) tmpMsg[i + BLOCK_SIZE] = tmpHash[i];
andrewboyson 7:94ef5824c3c0 44 Sha1(tmpMsg, BLOCK_SIZE + HASH_SIZE, mac);
andrewboyson 7:94ef5824c3c0 45 }
andrewboyson 7:94ef5824c3c0 46 void HmacSha1Start(struct HmacSha1Struct* md, const uint8_t* key, int keyLength)
andrewboyson 7:94ef5824c3c0 47 {
andrewboyson 7:94ef5824c3c0 48 //Make the key BLOCK_SIZE bytes long by hashing longer ones or padding shorter one with 0s
andrewboyson 7:94ef5824c3c0 49 if (keyLength > BLOCK_SIZE)
andrewboyson 7:94ef5824c3c0 50 {
andrewboyson 7:94ef5824c3c0 51 Sha1(key, keyLength, md->hmacKey);
andrewboyson 7:94ef5824c3c0 52 for (int i = HASH_SIZE; i < BLOCK_SIZE; i++) md->hmacKey[i] = 0;
andrewboyson 7:94ef5824c3c0 53 }
andrewboyson 7:94ef5824c3c0 54 else
andrewboyson 7:94ef5824c3c0 55 {
andrewboyson 7:94ef5824c3c0 56 for (int i = 0; i < keyLength; i++) md->hmacKey[i] = key[i];
andrewboyson 7:94ef5824c3c0 57 for (int i = keyLength; i < BLOCK_SIZE; i++) md->hmacKey[i] = 0;
andrewboyson 7:94ef5824c3c0 58 }
andrewboyson 7:94ef5824c3c0 59 Sha1Start(&md->shaStruct);
andrewboyson 7:94ef5824c3c0 60
andrewboyson 7:94ef5824c3c0 61 //Make the inner and outer padded keys
andrewboyson 7:94ef5824c3c0 62 uint8_t iKeyPad[BLOCK_SIZE];
andrewboyson 7:94ef5824c3c0 63 for (int i = 0; i < BLOCK_SIZE; i++)
andrewboyson 7:94ef5824c3c0 64 {
andrewboyson 7:94ef5824c3c0 65 iKeyPad[i] = md->hmacKey[i] ^ 0x36; //Inner padded key
andrewboyson 7:94ef5824c3c0 66 }
andrewboyson 7:94ef5824c3c0 67 Sha1Add(&md->shaStruct, iKeyPad, BLOCK_SIZE);
andrewboyson 7:94ef5824c3c0 68 }
andrewboyson 7:94ef5824c3c0 69 void HmacSha1Add(struct HmacSha1Struct* md, const uint8_t* message, int messageLength)
andrewboyson 7:94ef5824c3c0 70 {
andrewboyson 7:94ef5824c3c0 71 Sha1Add(&md->shaStruct, message, messageLength);
andrewboyson 7:94ef5824c3c0 72 }
andrewboyson 7:94ef5824c3c0 73 void HmacSha1Finish(struct HmacSha1Struct* md, uint8_t* mac)
andrewboyson 7:94ef5824c3c0 74 {
andrewboyson 7:94ef5824c3c0 75 //Make the inner and outer padded keys
andrewboyson 7:94ef5824c3c0 76 uint8_t oKeyPad[BLOCK_SIZE];
andrewboyson 7:94ef5824c3c0 77 for (int i = 0; i < BLOCK_SIZE; i++)
andrewboyson 7:94ef5824c3c0 78 {
andrewboyson 7:94ef5824c3c0 79 oKeyPad[i] = md->hmacKey[i] ^ 0x5c; //Outer padded key
andrewboyson 7:94ef5824c3c0 80 }
andrewboyson 7:94ef5824c3c0 81
andrewboyson 7:94ef5824c3c0 82 uint8_t innerHash[HASH_SIZE];
andrewboyson 7:94ef5824c3c0 83 Sha1Finish(&md->shaStruct, innerHash);
andrewboyson 7:94ef5824c3c0 84
andrewboyson 7:94ef5824c3c0 85 Sha1Start(&md->shaStruct);
andrewboyson 7:94ef5824c3c0 86 Sha1Add(&md->shaStruct, oKeyPad, BLOCK_SIZE);
andrewboyson 7:94ef5824c3c0 87 Sha1Add(&md->shaStruct, innerHash, HASH_SIZE);
andrewboyson 7:94ef5824c3c0 88
andrewboyson 7:94ef5824c3c0 89 Sha1Finish(&md->shaStruct, mac);
andrewboyson 7:94ef5824c3c0 90 }