Code for Assign 5 for PRES, ECEN 5813-001B, Fall 2022

main()
 |
 *-----> time_pbkdf2_hmac_isha()
                   |
                   *-----> pbkdf2_hmac_isha()
                                 |
                                 *-----> F()
                                         | 
                                         *-----> hmac_isha()
                                                     |
                                                     *-----> ISHAReset()
                                                     |
                                                     *-----> ISHAInput()
                                                     |           |
                                                     |           *-----> ISHAProcessMessageBlock()
                                                     |
                                                     *-----> ISHAResult()
                                                                 |
                                                                 *-----> ISHAPadMessage()
                                                                               |
                                                                               *-----> ISHAProcessMessageBlock()

• Build Configuration : Release
• Optimization : -O0
• Target : Program flash action using PEMicro probes
• Total Size Before Optimization : 19708
• Total Size After Optimization : 15200
• Timing Test Before Optimization: 8752 ms
• Timing Test After Optimization : 3040 ms

• Size Before Optimization: 0x00000108
• Size After Optimization: 0x00000108
• Changes:
  • None
• During time_pbkdf2_hmac_isha(), the function pbkdf2_hmac_isha() is invoked from 1 separate line:

• Size Before Optimization: 0x000001b8
• Size After Optimization: 0x00000134
• Changes:
  • Defined iterator i as register storage
  • Used same iterator i in all loops (other than loop using iterator j) rather than having each loop declare its own iterator i
• During time_pbkdf2_hmac_isha(), the function F() is invoked from 1 separate line:

• Size Before Optimization: 0x00000184
• Size After Optimization: 0x000000c2
• Changes:
  • Removed if(key_len > ISHA_BLOCKLEN) conditional since code does not ever go into this branch. This introduces limitation of catching case where key_len > ISHA_BLOCKLEN
  • Combined for(i=0; i<key_len; i++) and for(i=key_len; i<ISHA_BLOCKLEN; i++) loops and added a conditional within loop itself
  • Combined both for(i=0; i<ISHA_BLOCKLEN; i++) loops
  • Removed keypad array and assigned directly to ipad + opad
  • Defined iterator i as register storage
• During time_pbkdf2_hmac_isha(), the function hmac_isha() is invoked from 2 separate lines:

• Size Before Optimization: 0x00000060
• Size After Optimization: 0x00000054
• Changes:
  • Removed ctx->corrupted flag
  • Removed logic for Length_High/Length_Low bits and replaced with Length_Bytes
• During time_pbkdf2_hmac_isha(), the function ISHAReset() is invoked from 3 separate lines:

• Size Before Optimization: 0x000000ae
• Size After Optimization: 0x000000c8
• Changes:
  • Stored length into register iterator i and replaced all instances of length with iterator i
  • Removed ctx->corrupted flag
  • Incremented message_length in-line
  • Removed logic for Length_High/Length_Low bits and replaced with Length_Bytes
  • Improved loop to go 1 byte at a time to 64 bytes at a time. Also utilized memcpy to achieve this
• During time_pbkdf2_hmac_isha(), the function ISHAInput() is invoked from 5 separate lines:

• Size Before Optimization: 0x000000c0
• Size After Optimization: 0x00000096
• Changes:
  • Replaced all instances of (i/4) with (t >> 2)
  • Removed ctx->corrupted flag
• During time_pbkdf2_hmac_isha(), the function ISHAResult() is invoked from 3 separate lines:

• Size Before Optimization: 0x0000010e
• Size After Optimization: 0x000000e6
• Changes:
  • Removed while(ctx->MB_Idx < 56) loops out of if/else and put it after since it is unconditional
  • Removed logic for Length_High/Length_Low bits and replaced with Length_Bytes. This introduces limitation of not supporting message length over 0xFFFFFFFF bytes
• During time_pbkdf2_hmac_isha(), the function ISHAPadMessage() is invoked from 1 separate line:

• Size Before Optimization: 0x00000152
• Size After Optimization: 0x000000e6
• Changes:
  • Replaced all instances of (t * 4) with (t << 2)
  • Combined both for(t = 0; t < 16; t++) loops
  • Defined iterator t as register storage
  • Removed W array and assigned directly into temp. This may decrease readability but increases performance
• During time_pbkdf2_hmac_isha(), the function ISHAProcessMessageBlock() is invoked from 3 separate lines: