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RSA Private Key Format

Length Encoding

  • 0 ~ 0x7f : 00 ~ 7f
  • 0x80 ~ 0xff : 81 80 ~ 81 ff
  • 0x0100 ~ 0xffff : 82 01 00 ~ 82 ff ff
  • 0x010000 ~ 0xffffff : 83 01 00 00 ~ 83 ff ff ff
  • ...

Traslation

-----BEGIN RSA PRIVATE KEY-----
MIIBOQIBAAJBAIOLepgdqXrM07O4dV/nJ5gSA12jcjBeBXK5mZO7Gc778HuvhJi+
RvqhSi82EuN9sHPx1iQqaCuXuS1vpuqvYiUCAwEAAQJATRDbCuFd2EbFxGXNxhjL
loj/Fc3a6UE8GeFoeydDUIJjWifbCAQsptSPIT5vhcudZgWEMDSXrIn79nXvyPy5
BQIhAPU+XwrLGy0Hd4Roug+9IRMrlu0gtSvTJRWQ/b7m0fbfAiEAiVB7bUMynZf4
SwVJ8NAF4AikBmYxOJPUxnPjEp8D23sCIA3ZcNqWL7myQ0CZ/W/oGVcQzhwkDbck
3GJEZuAB/vd3AiASmnvOZs9BuKgkCdhlrtlM6/7E+y1p++VU6bh2+mI8ZwIgf4Qh
u+zYCJfIjtJJpH1lHZW+A60iThKtezaCk7FiAC4= 
-----END RSA PRIVATE KEY-----

Base64 decode : (display in hex format) 
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  • 30 : ASN.1 tag for sequence
  • 82 01 39 : length of following sequence (in byte), 82 01 39 represent 0x139
  • 02 : ASN.1 tag for int
    • 01 : length of this int (in byte)
    • 00 : Version
  • 02 : ANS.1 tag for int
    • 41 : length of this int (in byte)
    • ... : \(n\)
  • 02 : ANS.1 tag for int
    • 03 : length of this int (in byte)
    • ... : \(e\)
  • 02 : ANS.1 tag for int
    • 40 : length of this int (in byte)
    • ... : \(d\)
  • 02 : ANS.1 tag for int
    • 21 : length of this int (in byte)
    • ... : \(p\)
  • 02 : ANS.1 tag for int
    • 21 : length of this int (in byte)
    • ... : \(q\)
  • 02 : ANS.1 tag for int
    • 20 : length of this int (in byte)
    • ... : \(d \pmod {p - 1}\)
  • 02 : ANS.1 tag for int
    • 20 : length of this int (in byte)
    • ... : \(d \pmod {q - 1}\)
  • 02 : ANS.1 tag for int
    • 20 : length of this int (in byte)
    • ... : \(q ^ {-1} \pmod {p - 1}\)