<초기 헤더 정보>
- [0-3] : 메타정보(version, type, flags, info)
- [4-19] : AES 복호화를 위한 IV값 (128bit)
- [20-35] : MD5 Hash 값
- [36-39] : Blob의 길이(Integer 타입)
- [40~ ] : Key blob (SoftwareKeyblob, Qcom blob 등등)
------------------------------------------------------------------------------
<SoftwareKeyblob 구조>
[00-03] MAGIC NUM : PK#8
[04-07] KEY TYPE : EVP_PKEY_EC, EVP_PKEY_DSA, EVP_PKEY_RSA
[08-11] Public key length(RSA) // 항상 0, 이건 대체 왜 넣는지 모르겠음
[12-15] Private key length(RSA)
[16~ ] Private key data
소스에서 확인 (헤더(4byte) + 키타입(4byte) + 공개키길이(4byte) + 개인키길이(4byte) + 개인키)
* https://android.googlesource.com/platform/system/security/+/master/softkeymaster/keymaster_openssl.cpp
<16 byte 이후로는 ASN.1 구조로 구성되어 있음>
308204A4
020100
02820101
00B1CF6BDC79B~~~
[00-00] 0x30 : 00110000 => Class : 00, P/C : 1, 10000 : 16(SEQUENCE)
| Octet 1 | Octet 2 onwards | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 |
| Tag class | P/C | Tag number (0–30) | N/A | ||||||||||||
| 31 | More | Tag number | |||||||||||||
[01-03] 0x820276
0x82 : 10000010 => Form : 1, Number : 0000010
0x0276 : Length : 1166
| Form | Bits | |||||||
|---|---|---|---|---|---|---|---|---|
| 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | |
| Definite, short | 0 | Length (0–127) | ||||||
| Indefinite | 1 | 0 | ||||||
| Definite, long | 1 | Number of following octets (1–126) | ||||||
| Reserved | 1 | 127 | ||||||
[04-06] 0x020100
0x02 : INTEGER
0x01 : Length - 1 byte
0x00 : Value - 0
| Name | Value encodings | Tag number | |
|---|---|---|---|
| Decimal | Hexadecimal | ||
| End-of-Content (EOC) | Primitive | 0 | 0 |
| BOOLEAN | Primitive | 1 | 1 |
| INTEGER | Primitive | 2 | 2 |
| BIT STRING | Both | 3 | 3 |
| OCTET STRING | Both | 4 | 4 |
| NULL | Primitive | 5 | 5 |
| OBJECT IDENTIFIER | Primitive | 6 | 6 |
| Object Descriptor | Both | 7 | 7 |
| EXTERNAL | Constructed | 8 | 8 |
| REAL (float) | Primitive | 9 | 9 |
| ENUMERATED | Primitive | 10 | A |
| EMBEDDED PDV | Constructed | 11 | B |
| UTF8String | Both | 12 | C |
| RELATIVE-OID | Primitive | 13 | D |
| Reserved | 14 | E | |
| Reserved | 15 | F | |
| SEQUENCE and SEQUENCE OF | Constructed | 16 | 10 |
| SET and SET OF | Constructed | 17 | 11 |
| NumericString | Both | 18 | 12 |
| PrintableString | Both | 19 | 13 |
| T61String | Both | 20 | 14 |
| VideotexString | Both | 21 | 15 |
| IA5String | Both | 22 | 16 |
| UTCTime | Both | 23 | 17 |
| GeneralizedTime | Both | 24 | 18 |
| GraphicString | Both | 25 | 19 |
| VisibleString | Both | 26 | 1A |
| GeneralString | Both | 27 | 1B |
| UniversalString | Both | 28 | 1C |
| CHARACTER STRING | Both | 29 | 1D |
| BMPString | Both | 30 | 1E |
[07-10] 0x02820101
0x02 : INTEGER
0x82 : Length - 2 byte
0x0101 : Value - 257
[11-267] : Private Key
00B1CF6BDC79B~~~
-----------------------------------------------------------------------------
openssl 을 이용하여서 RSA private key 의 ASN.1 포맷을 출력하여 분석한 예제는 다음과 같습니다.
# openssl.exe asn1parse -in key.pem -inform PEM
0:d=0 hl=4 l= 603 cons: SEQUENCE
4:d=1 hl=2 l= 1 prim: INTEGER :00 <- Version
7:d=1 hl=3 l= 129 prim: INTEGER :C6ACA7101D8D0E8D08C5AAA3947E2DE0 <- Modulus
C708DA88017AD7276372B7745C0CB9ACD2A22E45438C472DBC81F62AAEE0521EE6DC283768D9C20C
C523B52478AF2B2ED9BCC7717BB25560E63FBA603A1C0E0351367CECFE45DB67EB50014031B4D652
4C95EA9B71819C175F17FCCAAB8DCE1B1F7D7BD24C211E210E1D5C2D91066163
139:d=1 hl=2 l= 3 prim: INTEGER :010001 <- Public Exponent
144:d=1 hl=3 l= 128 prim: INTEGER :2BACB2C1292DE41FFEE8AD3D6E9C5A6B <- Private Exponent
8A7598CCC33E84E3C4C9E8286D3FE2E56A1C7AFD80FEEA7AD470E173BAA3D789B1887E52C7FAEEDC
ADCDCEB968CA613C74EE6135AFA7EEAD72362A6DE12B2E2AD70208CFBDC2C8E87B472E93A725ECF0
027341BB873F0A14AA0DA5625373E529927E54E510D1E7A436CB68D1EA6AC781
275:d=1 hl=2 l= 65 prim: INTEGER :F3CEAEA8E9B862D9C19845E700EDC445 <- Prime 1
0F9FF33A6274FFE527F5F6A4120E736BFC98CA4CD39AB3A9D418EFBBC8B9C995886E739CE66B09E8
6987474E6F262A41
342:d=1 hl=2 l= 65 prim: INTEGER :D09C292A5B2EE02EF4F7F92C33877724 <- Prime 2
9A742865DA8388344F1CAB5EC58CD53121A462451C564BFE60781F45A2BB21439576118336A42D61
5821E0D1ECF6FAA3
409:d=1 hl=2 l= 64 prim: INTEGER :72949FE12276557EA14D3F0CE192DCBA <- Exponent 1
D82D03D25C933FF02267A61255AA14F49B31F36147D15CBE63BF946B5C5A7432A27BC639E6D04747
C2D0A0E26BBA3401
475:d=1 hl=2 l= 64 prim: INTEGER :794F8684D217B558B92E06E194699F78 <- Exponent 2
52B55FD4B338B019333449D7C7EBB902643CF2C49BD0F74A4B112FA65016A0266C2107D8150B6E34
608AFAF138EAFB1F
541:d=1 hl=2 l= 64 prim: INTEGER :3D8D967868A0FA34D0622D33981C97C9 <- Coefficient
493CD82CF234F587D398CF005BA7E9970D39AC3CFA6B161192A996377CD6AD7F2D28AFD5085114C1
15D34705A84447EE
<PKCS#1 개인키 구조>
-----BEGIN RSA PRIVATE KEY-----
RSAPrivateKey ::= SEQUENCE {
version Version,
modulus INTEGER, -- n
publicExponent INTEGER, -- e
privateExponent INTEGER, -- d
prime1 INTEGER, -- p
prime2 INTEGER, -- q
exponent1 INTEGER, -- d mod (p-1)
exponent2 INTEGER, -- d mod (q-1)
coefficient INTEGER, -- (inverse of q) mod p
otherPrimeInfos OtherPrimeInfos OPTIONAL
}
-----END RSA PRIVATE KEY-----
<참고자료>
https://etherhack.co.uk/asymmetric/docs/rsa_key_breakdown.html