SHA256の実装を pythonで読むために

Transcript

1. SHA256ͷ࣮૷Λ pythonͰಡΉͨΊʹ ͸ΜͳΓpython#4(20180316) ΤΨϛ Ϣ΢εέ @egapool
2. SHA256ͷ͓͞Β͍
3. SHA256ͱ͸ ҉߸ֶతϋογϡؔ਺ͷSHA-2γϦʔζͷҰ ͭ SHA-224ɺSHA-256ɺSHA-384ɺSHA-512
4. ϋογϡؔ਺ͱ͸ ͋Δσʔλ͔Βཁ໿ʢࢦ໲ͷΑ͏ͳ΋ͷʣΛ ಘΔؔ਺
5. ҉߸ֶతϋογϡؔ਺ͱ͸ ϋογϡؔ਺ʹҎԼ͕௥Ճ͞Εͨ΋ͷ ɾҰํ޲ੑ ɹᵋϋογϡ஋Λ͔ΒݩͷϝοηʔδΛਪଌͰ͖ͳ͍ ɾিಥ଱ੑ ɹᵋ ಉ͡ϋογϡ஋Λੜ੒͢ΔϝοηʔδͷϖΞΛݟ͚ͭΔ͜ ͱ͕ࠔ೉
6. SHA256ͷ࣮૷ͷ঺հ
7. ࢓༷͸FIPS 180-2Ͱެ։ ΞϝϦΧࠃཱඪ४ٕज़ݚڀॴ (NIST) ͕ൃߦ https://csrc.nist.gov/csrc/media/ publications/fips/180/2/archive/ 2002-08-01/documents/fips180-2.pdf
8. hashlibϞδϡʔϧ hashlibͰ͸sha256ͷ࣮૷͸cpython࣮૷ͷϞδϡʔϧΛimport͍ͯ͠ Δ [hashlib] https://github.com/python/cpython/blob/3.6/Lib/hashlib.py#L89-L92 [_sha256] https://github.com/python/cpython/blob/3.6/Modules/ sha256module.c
9. nanvel/sha256.py https://gist.github.com/nanvel/ 9e606cb7271126b1cb2413b7415d560d
10. SHA256ͷΞϧΰϦζϜ
11. SHA256͸࠷ऴతʹ256bit(=32byte)ͷจࣈྻΛు ͖ग़͢ ࢓༷Ͱॳظ஋͕༩͑ΒΕ͍ͯΔ 6a09e667 bb67ae85 3c6ef372 a54ff53a 510e527f 9b05688c 1f83d9ab 5be0cd19 (4byte x 8ݸ) ͜ͷॳظ஋ΛมԽ͍ͤͯ͘͞
12. ͓͓·͔ͳྲྀΕ 1. ϝοηʔδΛ64byte͝ͱͷϒϩοΫʹ෼ׂ 2. ύσΟϯάॲཧ 3. લஈͷϋογϡͱϒϩοΫʹରͯ͠64ճͷϥ΢ϯ υॲཧΛͯ͠32byteͷϋογϡΛಘΔ 4. 3 ΛશϒϩοΫ෼ճ͢
13. ɾɾɾ ϥ΢ϯυ ϥ΢ϯυ ॳظ஋
    CZUF ϋογϡ
    CZUF ϋογϡ
    CZUF ࠷ऴతͳϋογϡ
    CZUF ͓͓·͔ͳྲྀΕ ϥ΢ϯυ
14. ύσΟϯάॲཧ w ϝοηʔδΛCZUFͰׂͬͨ࠷ޙͷϒϩοΫʹదԠ
    w CZUFʹ଍Βͳ͍෼͚ͩͰຒΊΔ
    w ͨͩ͠ɺ΋ͱϝοηʔδͷ࠷ޙʹCJUΛ௥Ճ
    w ͞ΒʹɺCZUFͷ຤ඌʹCZUFจͷ΋ͱϝοηʔδ௕ Λ͍ΕΔ
    w ݩʑ͖ͬͪΓCZUFͩͬͨ৔߹͸͞ΒʹϒϩοΫΛ ௥Ճͯ͠ɺͦΕʹରͯ͠ύσΟϯάॲཧΛࢪ͢
15. ύσΟϯάॲཧ CZUFͷϝοηʔδͷ৔߹ ˞ਐ਺Ͱ͸ਐ਺Ͱ
    ˞CZUF͸CJUɺਐ਺Ͱ͸ 
    
    BCBC
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16. ϥ΢ϯυ w CZUFͷϒϩοΫΛCZUFʹ֦ுͯ͠ݸºCZUF Λੜ੒
    w ˢͱఆ਺Λ࢖ͬͯճͷϩʔςʔγϣϯॲཧతͳ΋ͷ Λࢪ͢
17. ϥ΢ϯυ CZUFͷϒϩοΫΛCZUFʹ֦ுͯ͠ݸºCZUF Λੜ੒   ɾɾ      ɾɾ         
18. w = [0] * 64 w[0:16] = to_chunks(chunk, n=32) for i in range(16, 64): s0 = bin_xor(bin_rrot(w[i-15], 7), bin_rrot(w[i-15], 18), bin_rshift(w[i-15], 3)) s1 = bin_xor(bin_rrot(w[i-2], 17), bin_rrot(w[i-2], 19), bin_rshift(w[i-2], 10)) w[i] = bin_sum( w[i-16], s0, w[i-7], s1 ) IUUQTHJTUHJUIVCDPNOBOWFMFDCCDCCEEpMFTIBQZ-- ϥ΢ϯυ CZUFͷϒϩοΫΛCZUFʹ֦ுͯ͠ݸºCZUF Λੜ੒
19. ϥ΢ϯυ ˠͱˠͰมԽ ϥ΢ϯυॲཧ
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21. IUUQTDTSDOJTUHPWDTSDNFEJBQVCMJDBUJPOTpQTBSDIJWFEPDVNFOUTpQTQEG ϥ΢ϯυΛܦΔ౓ʹมԽ͍ͯ͘͠ ϥ΢ϯυ '*14
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23. ͓͠·͍