forked from KolibriOS/kolibrios
244 lines
6.7 KiB
PHP
244 lines
6.7 KiB
PHP
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; sshlib_host.inc - SSH remote host authentication
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;
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; Copyright (C) 2021 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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; https://datatracker.ietf.org/doc/html/rfc4253#section-6.6
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; https://datatracker.ietf.org/doc/html/rfc3447
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proc sshlib_host_verify con_ptr, str_host_key, str_signature, message, message_len
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locals
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known_key_sz rb MAX_PUBLIC_KEY_SIZE
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endl
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mov eax, [con_ptr]
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cmp [eax+sshlib_connection.algo_hostkey], SSHLIB_HOSTKEY_RSA
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je .rsa
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; ..add more here
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mov eax, SSHLIB_ERR_HKEY_NO_ALGO
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ret
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.rsa:
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stdcall sshlib_host_verify_rsa, [str_host_key], [str_signature], [message], [message_len]
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test eax, eax
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jnz .err
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.lookup:
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; lea eax, [known_key_sz]
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; mov ebx, [con_ptr]
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; lea ebx, [ebx + sshlib_connection.hostname_sz]
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; invoke ini_get_str, known_hosts_file, ebx, ssh_rsa_sz, eax, MAX_PUBLIC_KEY_SIZE, null_sz
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; test eax, eax
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; jnz .unknown
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; TODO: verify cached host key
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; jne .mismatch
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jmp .unknown ; FIXME
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xor eax, eax
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ret
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.mismatch:
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lea eax, [known_key_sz]
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stdcall sshlib_callback_hostkey_problem, [con_ptr], SSHLIB_HOSTKEY_PROBLEM_MISMATCH, eax
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cmp eax, SSHLIB_HOSTKEY_ACCEPT
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je .store
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ret
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.unknown:
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lea eax, [known_key_sz]
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stdcall sshlib_callback_hostkey_problem, [con_ptr], SSHLIB_HOSTKEY_PROBLEM_UNKNOWN, eax
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cmp eax, SSHLIB_HOSTKEY_ACCEPT
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je .store
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ret
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.store:
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; TODO: write to know_hosts file and fall-through
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ret
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.err:
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ret
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endp
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; https://datatracker.ietf.org/doc/html/rfc3447#section-8.2.2
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; RSASSA-PKCS1-V1_5-VERIFY
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proc sshlib_host_verify_rsa str_host_key, str_signature, M, message_len
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locals
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h_ctx dd ?
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; Signer's RSA public key
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mpint_e dd ? ; public exponent
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mpint_n dd ? ; modulus
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mpint_m dd ?
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EM dd ?
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EM_accent dd ?
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mpint_s dd ? ; rsa_signature_blob
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; k dd ? ; length of RSA modulus n
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endl
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DEBUGF 3, "SSH: Performing RSA verification\n"
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mcall 68, 12, sizeof.crash_ctx + 5*(MAX_BITS/8+4)
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test eax, eax
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jz .err_nomem
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mov [h_ctx], eax
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add eax, sizeof.crash_ctx
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mov [mpint_e], eax
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add eax, MAX_BITS/8+4
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mov [mpint_n], eax
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add eax, MAX_BITS/8+4
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mov [mpint_m], eax
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add eax, MAX_BITS/8+4
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mov [EM], eax
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add eax, MAX_BITS/8+4
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mov [EM_accent], eax
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add eax, MAX_BITS/8+4
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mov [mpint_s], eax
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; add eax, MAX_BITS/8+4
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; Host key
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mov esi, [str_host_key]
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mov ecx, [esi]
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bswap ecx
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cmp ecx, MAX_PUBLIC_KEY_SIZE
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ja .err_key
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; Host key type (string)
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cmp dword[esi+4], 0x07000000
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jne .err_key
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cmp dword[esi+8], 'ssh-'
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jne .err_key
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cmp dword[esi+11], '-rsa'
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jne .err_key
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add esi, 4+4+7
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; mpint e
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stdcall mpint_to_little_endian, [mpint_e], esi
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add esi, eax
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add esi, 4
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; mpint n
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stdcall mpint_to_little_endian, [mpint_n], esi
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; mov [k], eax ;; HMMMM FIXME, 0-byte..
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; Signature
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mov esi, [str_signature]
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mov ecx, [esi]
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bswap ecx ; TODO: check length
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; Host key type (string)
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cmp dword[esi+4], 0x07000000
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jne .err_signature
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cmp dword[esi+8], 'ssh-'
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jne .err_signature
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cmp dword[esi+11], '-rsa'
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jne .err_signature
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add esi, 4+4+7
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; RSA signature blob
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stdcall mpint_to_little_endian, [mpint_s], esi
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; cmp eax, [k]
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;;; jne .err_signature
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; RSAVP1
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stdcall mpint_modexp, [mpint_m], [mpint_s], [mpint_e], [mpint_n]
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; I2OSP
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stdcall mpint_shrink, [mpint_m]
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stdcall mpint_grow, [mpint_m], 256
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stdcall mpint_to_big_endian, [EM], [mpint_m]
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; EMSA-PKCS1-v1_5
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invoke sha1_init, [h_ctx]
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invoke sha1_update, [h_ctx], [M], [message_len]
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invoke sha1_final, [h_ctx]
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mov edi, [EM_accent]
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mov al, 0x00
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stosb
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mov al, 0x01
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stosb
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mov ecx, 256 - (rsa_sha1_t.len + 3 + SHA1_HASH_SIZE)
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mov al, 0xff
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rep stosb
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mov al, 0x00
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stosb
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mov esi, rsa_sha1_t
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mov ecx, rsa_sha1_t.len
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rep movsb
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mov esi, [h_ctx]
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mov ecx, SHA1_HASH_SIZE
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rep movsb
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; Compare EM with EM_accent
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mov esi, [EM]
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add esi, 4
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mov edi, [EM_accent]
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mov ecx, 256/4
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xor eax, eax
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.ct_cmp_loop:
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mov ebx, [esi]
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xor ebx, [edi]
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or eax, ebx
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lea esi, [esi+4]
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lea edi, [edi+4]
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dec ecx
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jnz .ct_cmp_loop
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push eax
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mcall 68, 13, [h_ctx]
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pop eax
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test eax, eax
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jnz .fail
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DEBUGF 3, "SSH: RSA verification OK!\n"
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ret
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.fail:
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DEBUGF 3, "SSH: RSA verification failed!\n"
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mov eax, SSHLIB_ERR_HKEY_VERIFY_FAIL
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ret
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.err_nomem:
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mov eax, SSHLIB_ERR_NOMEM
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ret
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.err_signature:
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mov eax, SSHLIB_ERR_HKEY_SIGNATURE
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ret
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.err_key:
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mov eax, SSHLIB_ERR_HKEY_PUBLIC_KEY
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ret
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endp
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iglobal
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rsa_sha1_t db 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2B, 0x0E, 0x03, 0x02, 0x1A, 0x05, 0x00, 0x04, 0x14
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.len = $ - rsa_sha1_t
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endg
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