172 lines
5.0 KiB
PHP
172 lines
5.0 KiB
PHP
; hmac.inc - HMAC: Keyed-Hashing for Message Authentication
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;
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; Copyright (C) 2016 Denis Karpenko
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; Copyright (C) 2016 Jeffrey Amelynck
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;
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with this program. If not, see <http://www.gnu.org/licenses/>.
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; Main concept:
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; To compute HMAC over the data `text' we perform
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; H(K XOR opad, H(K XOR ipad, text))
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struct hmac_sha256_context
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hash rb SHA256_HASH_SIZE
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ipad_ctx ctx_sha224256
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opad_ctx ctx_sha224256
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ends
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; We will precompute partial hashes of K XOR ipad and K XOR opad,
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; and store them in the context structure.
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proc hmac_sha256_setkey ctx, key, key_length
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locals
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k_temp rb SHA224256_BLOCK_SIZE
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endl
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pusha
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; input esi = key, ecx=key_length
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mov ecx, [key_length]
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cmp ecx, SHA224256_BLOCK_SIZE
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ja .hash_it
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; Key is smaller then or equal to blocksize,
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; copy key to ipad
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mov esi, [key]
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lea edi, [k_temp]
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rep movsb
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mov ecx, SHA224256_BLOCK_SIZE
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sub ecx, [key_length]
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jz .finish
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; append zeros to the key
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xor al, al
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rep stosb
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jmp .finish
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; Given key is larger then key size, hash it
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.hash_it:
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invoke sha256_init, [ctx]
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invoke sha256_update, [ctx], [key], [key_length]
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invoke sha256_final, [ctx]
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mov esi, [ctx]
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lea edi, [k_temp]
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mov ecx, SHA256_HASH_SIZE/4
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rep movsd
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xor eax, eax
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mov ecx, (SHA224256_BLOCK_SIZE-SHA256_HASH_SIZE)/4
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rep stosd
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.finish:
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; xor ipad buffer with 0x36363...
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lea esi, [k_temp]
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mov ecx, SHA224256_BLOCK_SIZE/4
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@@:
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xor dword[esi], 0x36363636 ; ipad constant
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add esi, 4
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dec ecx
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jnz @r
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; Init our hash with k_xor_ipad
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mov ebx, [ctx]
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lea edi, [ebx+hmac_sha256_context.ipad_ctx]
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invoke sha256_init, edi
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lea esi, [k_temp]
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DEBUGF 1, "HASH: "
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stdcall dump_hex, esi, SHA224256_BLOCK_SIZE/4
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mov ebx, [ctx]
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lea edi, [ebx+hmac_sha256_context.ipad_ctx]
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invoke sha256_update, edi, esi, SHA224256_BLOCK_SIZE
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; xor opad buffer with 0x5c5c5...
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lea esi, [k_temp]
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mov ecx, SHA224256_BLOCK_SIZE/4
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@@:
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xor dword[esi], 0x36363636 xor 0x5c5c5c5c ; opad constant
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add esi, 4
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dec ecx
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jnz @r
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; Init our hash with k_xor_opad
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mov ebx, [ctx]
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lea edi, [ebx+hmac_sha256_context.opad_ctx]
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invoke sha256_init, edi
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lea esi, [k_temp]
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DEBUGF 1, "HASH: "
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stdcall dump_hex, esi, SHA224256_BLOCK_SIZE/4
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mov ebx, [ctx]
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lea edi, [ebx+hmac_sha256_context.opad_ctx]
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invoke sha256_update, edi, esi, SHA224256_BLOCK_SIZE
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popa
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ret
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endp
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; Copy our pre-computed partial hashes to the stack, complete and finalize them.
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; TODO: prevent unnescessary copying of output hash
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; TODO: remove unnescessary pushing/popping
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proc hmac_sha256 ctx, _data, _length
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locals
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inner_ctx ctx_sha224256
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outer_ctx ctx_sha224256
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endl
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pusha
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DEBUGF 1, "HMAC: "
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mov ebx, [_length]
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shr ebx, 2
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stdcall dump_hex, [_data], ebx
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; Copy partial hashes of ipad and opad to our temporary buffers
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mov esi, [ctx]
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lea esi, [esi+hmac_sha256_context.ipad_ctx]
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lea edi, [inner_ctx]
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repeat (sizeof.ctx_sha224256)/4*2
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movsd
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end repeat
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; Append provided data to inner hash and finalize
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lea ebx, [inner_ctx]
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invoke sha256_update, ebx, [_data], [_length]
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lea ebx, [inner_ctx]
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invoke sha256_final, ebx
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DEBUGF 1, "Inner Hash: "
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lea esi, [inner_ctx.hash]
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stdcall dump_hex, esi, SHA256_HASH_SIZE/4
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; Calculate outer hash
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lea ebx, [outer_ctx]
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lea esi, [inner_ctx.hash]
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invoke sha256_update, ebx, esi, SHA256_HASH_SIZE
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lea ebx, [outer_ctx]
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invoke sha256_final, ebx
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; Copy output hash to ctx structure ; FIXME
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lea esi, [outer_ctx.hash]
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mov edi, [ctx]
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repeat SHA256_HASH_SIZE/4
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movsd
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end repeat
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popa
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ret
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endp
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